Provide a new completion function for the argument of "info
registers", "info all-registers", and the "lr" command in dbx mode.
Without this patch the default symbol completer is used, which is more
confusing than helpful.
Also add a test for this new feature to "completion.exp": Determine
the target's available set of registers/reggroups and compare this to
the completion of "info registers ". For determining the available
registers involve the new "maint print user-registers" command.
gdb/ChangeLog:
* completer.c: Include "target.h", "reggroups.h", and
"user-regs.h".
(reg_or_group_completer): New.
* completer.h (reg_or_group_completer): Declare.
* infcmd.c (_initialize_infcmd): Set reg_or_group_completer for
the "info registers" and "info all-registers" commands and the
dbx-mode "lr" command.
gdb/testsuite/ChangeLog:
* gdb.base/completion.exp: Add test for completion of "info
registers ".
This adds a command for listing the "user" registers. So far GDB
offered no means of determining the set of user registers and omitted
them from all other register listings.
gdb/ChangeLog:
* user-regs.c: Include "arch-utils.h", "command.h", and
"cli/cli-cmds.h".
(maintenance_print_user_registers): New.
(_initialize_user_regs): Register new "maint print user-registers"
subcommand.
* NEWS: Mention new GDB command "maint print user-registers".
gdb/doc/ChangeLog:
* gdb.texinfo: Document "maint print user-registers".
1. Background information
The MIPS architecture, as originally designed and implemented in
mid-1980s has a uniform instruction word size that is 4 bytes, naturally
aligned. As such all MIPS instructions are located at addresses that
have their bits #1 and #0 set to zeroes, and any attempt to execute an
instruction from an address that has any of the two bits set to one
causes an address error exception. This may for example happen when a
jump-register instruction is executed whose register value used as the
jump target has any of these bits set.
Then in mid 1990s LSI sought a way to improve code density for their
TinyRISC family of MIPS cores and invented an alternatively encoded
instruction set in a joint effort with MIPS Technologies (then a
subsidiary of SGI). The new instruction set has been named the MIPS16
ASE (Application-Specific Extension) and uses a variable instruction
word size, which is 2 bytes (as the name of the ASE suggests) for most,
but there are a couple of exceptions that take 4 bytes, and then most of
the 2-byte instructions can be treated with a 2-byte extension prefix to
expand the range of the immediate operands used.
As a result instructions are no longer 4-byte aligned, instead they are
aligned to a multiple of 2. That left the bit #0 still unused for code
references, be it for the standard MIPS (i.e. as originally invented) or
for the MIPS16 instruction set, and based on that observation a clever
trick was invented that on one hand allowed the processor to be
seamlessly switched between the two instruction sets at any time at the
run time while on the other avoided the introduction of any special
control register to do that.
So it is the bit #0 of the instruction address that was chosen as the
selector and named the ISA bit. Any instruction executed at an even
address is interpreted as a standard MIPS instruction (the address still
has to have its bit #1 clear), any instruction executed at an odd
address is interpreted as a MIPS16 instruction.
To switch between modes ordinary jump instructions are used, such as
used for function calls and returns, specifically the bit #0 of the
source register used in jump-register instructions selects the execution
(ISA) mode for the following piece of code to be interpreted in.
Additionally new jump-immediate instructions were added that flipped the
ISA bit to select the opposite mode upon execution. They were
considered necessary to avoid the need to make register jumps in all
cases as the original jump-immediate instructions provided no way to
change the bit #0 at all.
This was all important for cases where standard MIPS and MIPS16 code had
to be mixed, either for compatibility with the existing binary code base
or to access resources not reachable from MIPS16 code (the MIPS16
instruction set only provides access to general-purpose registers, and
not for example floating-point unit registers or privileged coprocessor
0 registers) -- pieces of code in the opposite mode can be executed as
ordinary subroutine calls.
A similar approach has been more recently adopted for the MIPS16
replacement instruction set defined as the so called microMIPS ASE.
This is another instruction set encoding introduced to the MIPS
architecture. Just like the MIPS16 ASE, the microMIPS instruction set
uses a variable-length encoding, where each instruction takes a multiple
of 2 bytes. The ISA bit has been reused and for microMIPS-capable
processors selects between the standard MIPS and the microMIPS mode
instead.
2. Statement of the problem
To put it shortly, MIPS16 and microMIPS code pointers used by GDB are
different to these observed at the run time. This results in the same
expressions being evaluated producing different results in GDB and in
the program being debugged. Obviously it's the results obtained at the
run time that are correct (they define how the program behaves) and
therefore by definition the results obtained in GDB are incorrect.
A bit longer description will record that obviously at the run time the
ISA bit has to be set correctly (refer to background information above
if unsure why so) or the program will not run as expected. This is
recorded in all the executable file structures used at the run time: the
dynamic symbol table (but not always the static one!), the GOT, and
obviously in all the addresses embedded in code or data of the program
itself, calculated by applying the appropriate relocations at the static
link time.
While a program is being processed by GDB, the ISA bit is stripped off
from any code addresses, presumably to make them the same as the
respective raw memory byte address used by the processor to access the
instruction in the instruction fetch access cycle. This stripping is
actually performed outside GDB proper, in BFD, specifically
_bfd_mips_elf_symbol_processing (elfxx-mips.c, see the piece of code at
the very bottom of that function, starting with an: "If this is an
odd-valued function symbol, assume it's a MIPS16 or microMIPS one."
comment).
This function is also responsible for symbol table dumps made by
`objdump' too, so you'll never see the ISA bit reported there by that
tool, you need to use `readelf'.
This is however unlike what is ever done at the run time, the ISA bit
once present is never stripped off, for example a cast like this:
(short *) main
will not strip the ISA bit off and if the resulting pointer is intended
to be used to access instructions as data, for example for software
instruction decoding (like for fault recovery or emulation in a signal
handler) or for self-modifying code then the bit still has to be
stripped off by an explicit AND operation.
This is probably best illustrated with a simple real program example.
Let's consider the following simple program:
$ cat foobar.c
int __attribute__ ((mips16)) foo (void)
{
return 1;
}
int __attribute__ ((mips16)) bar (void)
{
return 2;
}
int __attribute__ ((nomips16)) foo32 (void)
{
return 3;
}
int (*foo32p) (void) = foo32;
int (*foop) (void) = foo;
int fooi = (int) foo;
int
main (void)
{
return foop ();
}
$
This is plain C with no odd tricks, except from the instruction mode
attributes. They are not necessary to trigger this problem, I just put
them here so that the program can be contained in a single source file
and to make it obvious which function is MIPS16 code and which is not.
Let's try it with Linux, so that everyone can repeat this experiment:
$ mips-linux-gnu-gcc -mips16 -g -O2 -o foobar foobar.c
$
Let's have a look at some interesting symbols:
$ mips-linux-gnu-readelf -s foobar | egrep 'table|foo|bar'
Symbol table '.dynsym' contains 7 entries:
Symbol table '.symtab' contains 95 entries:
55: 00000000 0 FILE LOCAL DEFAULT ABS foobar.c
66: 0040068c 4 FUNC GLOBAL DEFAULT [MIPS16] 12 bar
68: 00410848 4 OBJECT GLOBAL DEFAULT 21 foo32p
70: 00410844 4 OBJECT GLOBAL DEFAULT 21 foop
78: 00400684 8 FUNC GLOBAL DEFAULT 12 foo32
80: 00400680 4 FUNC GLOBAL DEFAULT [MIPS16] 12 foo
88: 00410840 4 OBJECT GLOBAL DEFAULT 21 fooi
$
Hmm, no sight of the ISA bit, but notice how foo and bar (but not
foo32!) have been marked as MIPS16 functions (ELF symbol structure's
`st_other' field is used for that).
So let's try to run and poke at this program with GDB. I'll be using a
native system for simplicity (I'll be using ellipses here and there to
remove unrelated clutter):
$ ./foobar
$ echo $?
1
$
So far, so good.
$ gdb ./foobar
[...]
(gdb) break main
Breakpoint 1 at 0x400490: file foobar.c, line 23.
(gdb) run
Starting program: .../foobar
Breakpoint 1, main () at foobar.c:23
23 return foop ();
(gdb)
Yay, it worked! OK, so let's poke at it:
(gdb) print main
$1 = {int (void)} 0x400490 <main>
(gdb) print foo32
$2 = {int (void)} 0x400684 <foo32>
(gdb) print foo32p
$3 = (int (*)(void)) 0x400684 <foo32>
(gdb) print bar
$4 = {int (void)} 0x40068c <bar>
(gdb) print foo
$5 = {int (void)} 0x400680 <foo>
(gdb) print foop
$6 = (int (*)(void)) 0x400681 <foo>
(gdb)
A-ha! Here's the difference and finally the ISA bit!
(gdb) print /x fooi
$7 = 0x400681
(gdb) p/x $pc
p/x $pc
$8 = 0x400491
(gdb)
And here as well...
(gdb) advance foo
foo () at foobar.c:4
4 }
(gdb) disassemble
Dump of assembler code for function foo:
0x00400680 <+0>: jr ra
0x00400682 <+2>: li v0,1
End of assembler dump.
(gdb) finish
Run till exit from #0 foo () at foobar.c:4
main () at foobar.c:24
24 }
Value returned is $9 = 1
(gdb) continue
Continuing.
[Inferior 1 (process 14103) exited with code 01]
(gdb)
So let's be a bit inquisitive...
(gdb) run
Starting program: .../foobar
Breakpoint 1, main () at foobar.c:23
23 return foop ();
(gdb)
Actually we do not like to run foo here at all. Let's run bar instead!
(gdb) set foop = bar
(gdb) print foop
$10 = (int (*)(void)) 0x40068c <bar>
(gdb)
Hmm, no ISA bit. Is it going to work?
(gdb) advance bar
bar () at foobar.c:9
9 }
(gdb) p/x $pc
$11 = 0x40068c
(gdb) disassemble
Dump of assembler code for function bar:
=> 0x0040068c <+0>: jr ra
0x0040068e <+2>: li v0,2
End of assembler dump.
(gdb) finish
Run till exit from #0 bar () at foobar.c:9
Program received signal SIGILL, Illegal instruction.
bar () at foobar.c:9
9 }
(gdb)
Oops!
(gdb) p/x $pc
$12 = 0x40068c
(gdb)
We're still there!
(gdb) continue
Continuing.
Program terminated with signal SIGILL, Illegal instruction.
The program no longer exists.
(gdb)
So let's try something else:
(gdb) run
Starting program: .../foobar
Breakpoint 1, main () at foobar.c:23
23 return foop ();
(gdb) set foop = foo
(gdb) advance foo
foo () at foobar.c:4
4 }
(gdb) disassemble
Dump of assembler code for function foo:
=> 0x00400680 <+0>: jr ra
0x00400682 <+2>: li v0,1
End of assembler dump.
(gdb) finish
Run till exit from #0 foo () at foobar.c:4
Program received signal SIGILL, Illegal instruction.
foo () at foobar.c:4
4 }
(gdb) continue
Continuing.
Program terminated with signal SIGILL, Illegal instruction.
The program no longer exists.
(gdb)
The same problem!
(gdb) run
Starting program:
/net/build2-lucid-cs/scratch/macro/mips-linux-fsf-gcc/isa-bit/foobar
Breakpoint 1, main () at foobar.c:23
23 return foop ();
(gdb) set foop = foo32
(gdb) advance foo32
foo32 () at foobar.c:14
14 }
(gdb) disassemble
Dump of assembler code for function foo32:
=> 0x00400684 <+0>: jr ra
0x00400688 <+4>: li v0,3
End of assembler dump.
(gdb) finish
Run till exit from #0 foo32 () at foobar.c:14
main () at foobar.c:24
24 }
Value returned is $14 = 3
(gdb) continue
Continuing.
[Inferior 1 (process 14113) exited with code 03]
(gdb)
That did work though, so it's the ISA bit only!
(gdb) quit
Enough!
That's the tip of the iceberg only though. So let's rebuild the
executable with some dynamic symbols:
$ mips-linux-gnu-gcc -mips16 -Wl,--export-dynamic -g -O2 -o foobar-dyn foobar.c
$ mips-linux-gnu-readelf -s foobar-dyn | egrep 'table|foo|bar'
Symbol table '.dynsym' contains 32 entries:
6: 004009cd 4 FUNC GLOBAL DEFAULT 12 bar
8: 00410b88 4 OBJECT GLOBAL DEFAULT 21 foo32p
9: 00410b84 4 OBJECT GLOBAL DEFAULT 21 foop
15: 004009c4 8 FUNC GLOBAL DEFAULT 12 foo32
17: 004009c1 4 FUNC GLOBAL DEFAULT 12 foo
25: 00410b80 4 OBJECT GLOBAL DEFAULT 21 fooi
Symbol table '.symtab' contains 95 entries:
55: 00000000 0 FILE LOCAL DEFAULT ABS foobar.c
69: 004009cd 4 FUNC GLOBAL DEFAULT 12 bar
71: 00410b88 4 OBJECT GLOBAL DEFAULT 21 foo32p
72: 00410b84 4 OBJECT GLOBAL DEFAULT 21 foop
79: 004009c4 8 FUNC GLOBAL DEFAULT 12 foo32
81: 004009c1 4 FUNC GLOBAL DEFAULT 12 foo
89: 00410b80 4 OBJECT GLOBAL DEFAULT 21 fooi
$
OK, now the ISA bit is there for a change, but the MIPS16 `st_other'
attribute gone, hmm... What does `objdump' do then:
$ mips-linux-gnu-objdump -Tt foobar-dyn | egrep 'SYMBOL|foo|bar'
foobar-dyn: file format elf32-tradbigmips
SYMBOL TABLE:
00000000 l df *ABS* 00000000 foobar.c
004009cc g F .text 00000004 0xf0 bar
00410b88 g O .data 00000004 foo32p
00410b84 g O .data 00000004 foop
004009c4 g F .text 00000008 foo32
004009c0 g F .text 00000004 0xf0 foo
00410b80 g O .data 00000004 fooi
DYNAMIC SYMBOL TABLE:
004009cc g DF .text 00000004 Base 0xf0 bar
00410b88 g DO .data 00000004 Base foo32p
00410b84 g DO .data 00000004 Base foop
004009c4 g DF .text 00000008 Base foo32
004009c0 g DF .text 00000004 Base 0xf0 foo
00410b80 g DO .data 00000004 Base fooi
$
Hmm, the attribute (0xf0, printed raw) is back, and the ISA bit gone
again.
Let's have a look at some DWARF-2 records GDB uses (I'll be stripping
off a lot here for brevity) -- debug info:
$ mips-linux-gnu-readelf -wi foobar
Contents of the .debug_info section:
[...]
Compilation Unit @ offset 0x88:
Length: 0xbb (32-bit)
Version: 4
Abbrev Offset: 62
Pointer Size: 4
<0><93>: Abbrev Number: 1 (DW_TAG_compile_unit)
<94> DW_AT_producer : (indirect string, offset: 0x19e): GNU C 4.8.0 20120513 (experimental) -meb -mips16 -march=mips32r2 -mhard-float -mllsc -mplt -mno-synci -mno-shared -mabi=32 -g -O2
<98> DW_AT_language : 1 (ANSI C)
<99> DW_AT_name : (indirect string, offset: 0x190): foobar.c
<9d> DW_AT_comp_dir : (indirect string, offset: 0x225): [...]
<a1> DW_AT_ranges : 0x0
<a5> DW_AT_low_pc : 0x0
<a9> DW_AT_stmt_list : 0x27
<1><ad>: Abbrev Number: 2 (DW_TAG_subprogram)
<ae> DW_AT_external : 1
<ae> DW_AT_name : foo
<b2> DW_AT_decl_file : 1
<b3> DW_AT_decl_line : 1
<b4> DW_AT_prototyped : 1
<b4> DW_AT_type : <0xc2>
<b8> DW_AT_low_pc : 0x400680
<bc> DW_AT_high_pc : 0x400684
<c0> DW_AT_frame_base : 1 byte block: 9c (DW_OP_call_frame_cfa)
<c2> DW_AT_GNU_all_call_sites: 1
<1><c2>: Abbrev Number: 3 (DW_TAG_base_type)
<c3> DW_AT_byte_size : 4
<c4> DW_AT_encoding : 5 (signed)
<c5> DW_AT_name : int
<1><c9>: Abbrev Number: 4 (DW_TAG_subprogram)
<ca> DW_AT_external : 1
<ca> DW_AT_name : (indirect string, offset: 0x18a): foo32
<ce> DW_AT_decl_file : 1
<cf> DW_AT_decl_line : 11
<d0> DW_AT_prototyped : 1
<d0> DW_AT_type : <0xc2>
<d4> DW_AT_low_pc : 0x400684
<d8> DW_AT_high_pc : 0x40068c
<dc> DW_AT_frame_base : 1 byte block: 9c (DW_OP_call_frame_cfa)
<de> DW_AT_GNU_all_call_sites: 1
<1><de>: Abbrev Number: 2 (DW_TAG_subprogram)
<df> DW_AT_external : 1
<df> DW_AT_name : bar
<e3> DW_AT_decl_file : 1
<e4> DW_AT_decl_line : 6
<e5> DW_AT_prototyped : 1
<e5> DW_AT_type : <0xc2>
<e9> DW_AT_low_pc : 0x40068c
<ed> DW_AT_high_pc : 0x400690
<f1> DW_AT_frame_base : 1 byte block: 9c (DW_OP_call_frame_cfa)
<f3> DW_AT_GNU_all_call_sites: 1
<1><f3>: Abbrev Number: 5 (DW_TAG_subprogram)
<f4> DW_AT_external : 1
<f4> DW_AT_name : (indirect string, offset: 0x199): main
<f8> DW_AT_decl_file : 1
<f9> DW_AT_decl_line : 21
<fa> DW_AT_prototyped : 1
<fa> DW_AT_type : <0xc2>
<fe> DW_AT_low_pc : 0x400490
<102> DW_AT_high_pc : 0x4004a4
<106> DW_AT_frame_base : 1 byte block: 9c (DW_OP_call_frame_cfa)
<108> DW_AT_GNU_all_tail_call_sites: 1
[...]
$
-- no sign of the ISA bit anywhere -- frame info:
$ mips-linux-gnu-readelf -wf foobar
[...]
Contents of the .debug_frame section:
00000000 0000000c ffffffff CIE
Version: 1
Augmentation: ""
Code alignment factor: 1
Data alignment factor: -4
Return address column: 31
DW_CFA_def_cfa_register: r29
DW_CFA_nop
00000010 0000000c 00000000 FDE cie=00000000 pc=00400680..00400684
00000020 0000000c 00000000 FDE cie=00000000 pc=00400684..0040068c
00000030 0000000c 00000000 FDE cie=00000000 pc=0040068c..00400690
00000040 00000018 00000000 FDE cie=00000000 pc=00400490..004004a4
DW_CFA_advance_loc: 6 to 00400496
DW_CFA_def_cfa_offset: 32
DW_CFA_offset: r31 at cfa-4
DW_CFA_advance_loc: 6 to 0040049c
DW_CFA_restore: r31
DW_CFA_def_cfa_offset: 0
DW_CFA_nop
DW_CFA_nop
DW_CFA_nop
[...]
$
-- no sign of the ISA bit anywhere -- range info (GDB doesn't use arange):
$ mips-linux-gnu-readelf -wR foobar
Contents of the .debug_ranges section:
Offset Begin End
00000000 00400680 00400690
00000000 00400490 004004a4
00000000 <End of list>
$
-- no sign of the ISA bit anywhere -- line info:
$ mips-linux-gnu-readelf -wl foobar
Raw dump of debug contents of section .debug_line:
[...]
Offset: 0x27
Length: 78
DWARF Version: 2
Prologue Length: 31
Minimum Instruction Length: 1
Initial value of 'is_stmt': 1
Line Base: -5
Line Range: 14
Opcode Base: 13
Opcodes:
Opcode 1 has 0 args
Opcode 2 has 1 args
Opcode 3 has 1 args
Opcode 4 has 1 args
Opcode 5 has 1 args
Opcode 6 has 0 args
Opcode 7 has 0 args
Opcode 8 has 0 args
Opcode 9 has 1 args
Opcode 10 has 0 args
Opcode 11 has 0 args
Opcode 12 has 1 args
The Directory Table is empty.
The File Name Table:
Entry Dir Time Size Name
1 0 0 0 foobar.c
Line Number Statements:
Extended opcode 2: set Address to 0x400681
Special opcode 6: advance Address by 0 to 0x400681 and Line by 1 to 2
Special opcode 7: advance Address by 0 to 0x400681 and Line by 2 to 4
Special opcode 55: advance Address by 3 to 0x400684 and Line by 8 to 12
Special opcode 7: advance Address by 0 to 0x400684 and Line by 2 to 14
Advance Line by -7 to 7
Special opcode 131: advance Address by 9 to 0x40068d and Line by 0 to 7
Special opcode 7: advance Address by 0 to 0x40068d and Line by 2 to 9
Advance PC by 3 to 0x400690
Extended opcode 1: End of Sequence
Extended opcode 2: set Address to 0x400491
Advance Line by 21 to 22
Copy
Special opcode 6: advance Address by 0 to 0x400491 and Line by 1 to 23
Special opcode 60: advance Address by 4 to 0x400495 and Line by -1 to 22
Special opcode 34: advance Address by 2 to 0x400497 and Line by 1 to 23
Special opcode 62: advance Address by 4 to 0x40049b and Line by 1 to 24
Special opcode 32: advance Address by 2 to 0x40049d and Line by -1 to 23
Special opcode 6: advance Address by 0 to 0x40049d and Line by 1 to 24
Advance PC by 7 to 0x4004a4
Extended opcode 1: End of Sequence
[...]
-- a-ha, the ISA bit is there! However it's not always right for some
reason, I don't have a small test case to show it, but here's an excerpt
from MIPS16 libc, a prologue of a function:
00019630 <__libc_init_first>:
19630: e8a0 jrc ra
19632: 6500 nop
00019634 <_init>:
19634: f000 6a11 li v0,17
19638: f7d8 0b08 la v1,15e00 <_DYNAMIC+0x15c54>
1963c: f400 3240 sll v0,16
19640: e269 addu v0,v1
19642: 659a move gp,v0
19644: 64f6 save 48,ra,s0-s1
19646: 671c move s0,gp
19648: d204 sw v0,16(sp)
1964a: f352 984c lw v0,-27828(s0)
1964e: 6724 move s1,a0
and the corresponding DWARF-2 line info:
Line Number Statements:
Extended opcode 2: set Address to 0x19631
Advance Line by 44 to 45
Copy
Special opcode 8: advance Address by 0 to 0x19631 and Line by 3 to 48
Special opcode 66: advance Address by 4 to 0x19635 and Line by 5 to 53
Advance PC by constant 17 to 0x19646
Special opcode 25: advance Address by 1 to 0x19647 and Line by 6 to 59
Advance Line by -6 to 53
Special opcode 33: advance Address by 2 to 0x19649 and Line by 0 to 53
Special opcode 39: advance Address by 2 to 0x1964b and Line by 6 to 59
Advance Line by -6 to 53
Special opcode 61: advance Address by 4 to 0x1964f and Line by 0 to 53
-- see that "Advance PC by constant 17" there? It clears the ISA bit,
however code at 0x19646 is not standard MIPS code at all. For some
reason the constant is always 17, I've never seen DW_LNS_const_add_pc
used with any other value -- is that a binutils bug or what?
3. Solution:
I think we should retain the value of the ISA bit in code references,
that is effectively treat them as cookies as they indeed are (although
trivially calculated) rather than raw memory byte addresses.
In a perfect world both the static symbol table and the respective
DWARF-2 records should be fixed to include the ISA bit in all the cases.
I think however that this is infeasible.
All the uses of `_bfd_mips_elf_symbol_processing' can not necessarily be
tracked down. This function is used by `elf_slurp_symbol_table' that in
turn is used by `bfd_canonicalize_symtab' and
`bfd_canonicalize_dynamic_symtab', which are public interfaces.
Similarly DWARF-2 records are used outside GDB, one notable if a bit
questionable is the exception unwinder (libgcc/unwind-dw2.c) -- I have
identified at least bits in `execute_cfa_program' and
`uw_frame_state_for', both around the calls to `_Unwind_IsSignalFrame',
that would need an update as they effectively flip the ISA bit freely;
see also the comment about MASK_RETURN_ADDR in gcc/config/mips/mips.h.
But there may be more places. Any change in how DWARF-2 records are
produced would require an update there and would cause compatibility
problems with libgcc.a binaries already distributed; given that this is
a static library a complex change involving function renames would
likely be required.
I propose therefore to accept the existing inconsistencies and deal with
them entirely within GDB. I have figured out that the ISA bit lost in
various places can still be recovered as long as we have symbol
information -- that'll have the `st_other' attribute correctly set to
one of standard MIPS/MIPS16/microMIPS encoding.
Here's the resulting change. It adds a couple of new `gdbarch' hooks,
one to update symbol information with the ISA bit lost in
`_bfd_mips_elf_symbol_processing', and two other ones to adjust DWARF-2
records as they're processed. The ISA bit is set in each address
handled according to information retrieved from the symbol table for the
symbol spanning the address if any; limits are adjusted based on the
address they point to related to the respective base address.
Additionally minimal symbol information has to be adjusted accordingly
in its gdbarch hook.
With these changes in place some complications with ISA bit juggling in
the PC that never fully worked can be removed from the MIPS backend.
Conversely, the generic dynamic linker event special breakpoint symbol
handler has to be updated to call the minimal symbol gdbarch hook to
record that the symbol is a MIPS16 or microMIPS address if applicable or
the breakpoint will be set at the wrong address and either fail to work
or cause SIGTRAPs (this is because the symbol is handled early on and
bypasses regular symbol processing).
4. Results obtained
The change fixes the example above -- to repeat only the crucial steps:
(gdb) break main
Breakpoint 1 at 0x400491: file foobar.c, line 23.
(gdb) run
Starting program: .../foobar
Breakpoint 1, main () at foobar.c:23
23 return foop ();
(gdb) print foo
$1 = {int (void)} 0x400681 <foo>
(gdb) set foop = bar
(gdb) advance bar
bar () at foobar.c:9
9 }
(gdb) disassemble
Dump of assembler code for function bar:
=> 0x0040068d <+0>: jr ra
0x0040068f <+2>: li v0,2
End of assembler dump.
(gdb) finish
Run till exit from #0 bar () at foobar.c:9
main () at foobar.c:24
24 }
Value returned is $2 = 2
(gdb) continue
Continuing.
[Inferior 1 (process 14128) exited with code 02]
(gdb)
-- excellent!
The change removes about 90 failures per MIPS16 multilib in mips-sde-elf
testing too, results for MIPS16 are now similar to that for standard
MIPS; microMIPS results are a bit worse because of host-I/O problems in
QEMU used instead of MIPSsim for microMIPS testing only:
=== gdb Summary ===
# of expected passes 14299
# of unexpected failures 187
# of expected failures 56
# of known failures 58
# of unresolved testcases 11
# of untested testcases 52
# of unsupported tests 174
MIPS16:
=== gdb Summary ===
# of expected passes 14298
# of unexpected failures 187
# of unexpected successes 2
# of expected failures 54
# of known failures 58
# of unresolved testcases 12
# of untested testcases 52
# of unsupported tests 174
microMIPS:
=== gdb Summary ===
# of expected passes 14149
# of unexpected failures 201
# of unexpected successes 2
# of expected failures 54
# of known failures 58
# of unresolved testcases 7
# of untested testcases 53
# of unsupported tests 175
2014-12-12 Maciej W. Rozycki <macro@codesourcery.com>
Maciej W. Rozycki <macro@mips.com>
Pedro Alves <pedro@codesourcery.com>
gdb/
* gdbarch.sh (elf_make_msymbol_special): Change type to `F',
remove `predefault' and `invalid_p' initializers.
(make_symbol_special): New architecture method.
(adjust_dwarf2_addr, adjust_dwarf2_line): Likewise.
(objfile, symbol): New declarations.
* arch-utils.h (default_elf_make_msymbol_special): Remove
prototype.
(default_make_symbol_special): New prototype.
(default_adjust_dwarf2_addr): Likewise.
(default_adjust_dwarf2_line): Likewise.
* mips-tdep.h (mips_unmake_compact_addr): New prototype.
* arch-utils.c (default_elf_make_msymbol_special): Remove
function.
(default_make_symbol_special): New function.
(default_adjust_dwarf2_addr): Likewise.
(default_adjust_dwarf2_line): Likewise.
* dwarf2-frame.c (decode_frame_entry_1): Call
`gdbarch_adjust_dwarf2_addr'.
* dwarf2loc.c (dwarf2_find_location_expression): Likewise.
* dwarf2read.c (create_addrmap_from_index): Likewise.
(process_psymtab_comp_unit_reader): Likewise.
(add_partial_symbol): Likewise.
(add_partial_subprogram): Likewise.
(process_full_comp_unit): Likewise.
(read_file_scope): Likewise.
(read_func_scope): Likewise. Call `gdbarch_make_symbol_special'.
(read_lexical_block_scope): Call `gdbarch_adjust_dwarf2_addr'.
(read_call_site_scope): Likewise.
(dwarf2_ranges_read): Likewise.
(dwarf2_record_block_ranges): Likewise.
(read_attribute_value): Likewise.
(dwarf_decode_lines_1): Call `gdbarch_adjust_dwarf2_line'.
(new_symbol_full): Call `gdbarch_adjust_dwarf2_addr'.
* elfread.c (elf_symtab_read): Don't call
`gdbarch_elf_make_msymbol_special' if unset.
* mips-linux-tdep.c (micromips_linux_sigframe_validate): Strip
the ISA bit from the PC.
* mips-tdep.c (mips_unmake_compact_addr): New function.
(mips_elf_make_msymbol_special): Set the ISA bit in the symbol's
address appropriately.
(mips_make_symbol_special): New function.
(mips_pc_is_mips): Set the ISA bit before symbol lookup.
(mips_pc_is_mips16): Likewise.
(mips_pc_is_micromips): Likewise.
(mips_pc_isa): Likewise.
(mips_adjust_dwarf2_addr): New function.
(mips_adjust_dwarf2_line): Likewise.
(mips_read_pc, mips_unwind_pc): Keep the ISA bit.
(mips_addr_bits_remove): Likewise.
(mips_skip_trampoline_code): Likewise.
(mips_write_pc): Don't set the ISA bit.
(mips_eabi_push_dummy_call): Likewise.
(mips_o64_push_dummy_call): Likewise.
(mips_gdbarch_init): Install `mips_make_symbol_special',
`mips_adjust_dwarf2_addr' and `mips_adjust_dwarf2_line' gdbarch
handlers.
* solib.c (gdb_bfd_lookup_symbol_from_symtab): Get
target-specific symbol address adjustments.
* gdbarch.h: Regenerate.
* gdbarch.c: Regenerate.
2014-12-12 Maciej W. Rozycki <macro@codesourcery.com>
gdb/testsuite/
* gdb.base/func-ptrs.c: New file.
* gdb.base/func-ptrs.exp: New file.
Hi,
I see many fails in dw2-dir-file-name.exp on arm target when test
case is compiled with -marm, however, these fails are disappeared when
test case is compiled with -mthumb.
The difference of pass and fail shown below is that "0x000085d4 in" isn't
printed out, but test case expects to see it.
-Breakpoint 2, compdir_missing__ldir_missing__file_basename () at tmp-dw2-dir-file-name.c:999^M
-(gdb) FAIL: gdb.dwarf2/dw2-dir-file-name.exp: compdir_missing__ldir_missing__file_basename: continue to breakpoint: compdir_missing__ldir_missing__file_basename
+Breakpoint 2, 0x000085d4 in compdir_missing__ldir_missing__file_basename () at tmp-dw2-dir-file-name.c:999^M
+(gdb) PASS: gdb.dwarf2/dw2-dir-file-name.exp: compdir_missing__ldir_missing__file_basename: continue to breakpoint: compdir_missing__ldir_missing__file_basename
This difference is caused by setting breakpoint at the first instruction
in the function (actually, the first instruction in prologue, at [1]),
so that frame_show_address returns false, and print_frame doesn't print the
address.
0x00008620 <+0>: push {r11} ; (str r11, [sp, #-4]!) <--[1]
0x00008624 <+4>: add r11, sp, #0
0x00008628 <+8>: ldr r3, [pc, #24] ; 0x8648 <compdir_missing__ldir_missing__file_basename+40>
0x0000862c <+12>: ldr r3, [r3]
0x00008630 <+16>: add r3, r3, #1
0x00008634 <+20>: ldr r2, [pc, #12] ; 0x8648 <compdir_missing__ldir_missing__file_basename+40>
Then, it must be the arm_skip_prologue's fault that unable to skip
instructions in prologue. At the end of arm_skip_prologue, it matches
several instructions, such as "str r(0123),[r11,#-nn]" and
"str r(0123),[sp,#nn]", but "push {r11}" isn't handled.
These instruction matching code in arm_skip_prologue, which can be regarded
as leftover of development for many years, should be merged to
arm_analyze_prologue and use arm_analyze_prologue in arm_skip_prologue.
Here is the something like the history of arm_{skip,scan,analyze}_prologue.
Around 2002, there are arm_skip_prologue and arm_scan_prologue, but code are
duplicated to some extent. When match an instruction, both functions should
be modified, for example in Michael Snyder's patch
https://sourceware.org/ml/gdb-patches/2002-05/msg00205.html and Michael
expressed the willingness to merge both into one. Daniel added code call
thumb_analyze_prologue in arm_skip_prologue in 2006, but didn't handle its
counterpart arm_analyze_prologue, which is added in 2010
<https://sourceware.org/ml/gdb-patches/2010-03/msg00820.html>
however, the instructions matching at the bottom of arm_skip_prologue wasn't
cleaned up. This patch is to merge them into arm_analyze_prologue.
gdb:
2014-12-12 Yao Qi <yao@codesourcery.com>
PR tdep/14261
* arm-tdep.c (arm_skip_prologue): Remove unused local variable
'skip_pc'. Remove code skipping prologue instructions, use
arm_analyze_prologue instead.
(arm_analyze_prologue): Stop the scanning for unrecognized
instruction when skipping prologue.
This patch is to stop prologue analysis past epilogue in for arm mode,
while we've already had done the same to thumb mode (see
thumb_instruction_restores_sp). This is useful to parse functions
with empty body (epilogue follows prologue).
gdb:
2014-12-12 Yao Qi <yao@codesourcery.com>
* arm-tdep.c (arm_instruction_restores_sp): New function.
(arm_analyze_prologue): Call arm_instruction_restores_sp.
(arm_in_function_epilogue_p): Move code to
arm_instruction_restores_sp.
On Linux native, if dprintfs are inserted when detaching, they are left
in the inferior which causes it to crash from a SIGTRAP. It also happens
with dprintfs on remote targets, when set disconnected-dprintf is off.
The rationale of the line modified by the patch was to leave dprintfs
inserted in order to support disconnected dprintfs. However, not all
dprintfs are persistent. Also, there's no reason other kinds of
breakpoints can't be persistent either. So this replaces the bp_dprintf
check with a check on whether the location is persistent.
bl->target_info.persist will be 1 only if disconnected-dprintf is on and
we are debugging a remote target. On native, it will always be 0,
regardless of the value of disconnected-dprintf. This makes sense, since
disconnected dprintfs are not supported by the native target.
One issue about the test is that it does not pass when using
--target_board=native-extended-gdbserver, partly due to bug 17302 [1].
One quick hack I tried for this was to add a useless "next" between the
call to getpid() and detach, which avoids the bug. There is still one
case where the test fails, and that is with:
- breakpoint always-inserted on
- dprintf-style agent
- disconnected-dprintf on
What happens is that my detach does not actually detach the process,
because some persistent commands (the disconnected dprintf) is present.
However since gdbserver is ran with --once, when gdb disconnects,
gdbserver goes down and takes with it all the processes it spawned and
that are still under its control (which includes my test process).
When the test checks if the test process is still alive, it obvisouly
fails. Investigating about that led me to ask a question on the ML [2]
about the behavior of detach.
Until the remote case is sorted out, the problematic test is marked as
KFAIL.
[1] https://sourceware.org/bugzilla/show_bug.cgi?id=17302
[2] https://sourceware.org/ml/gdb/2014-08/msg00115.html
gdb/Changelog:
PR breakpoints/17012
* breakpoint.c (remove_breakpoints_pid): Skip removing
breakpoint if it is marked as persistent.
gdb/testsuite/ChangeLog:
PR breakpoints/17012
* gdb.base/dprintf-detach.c: New file.
* gdb.base/dprintf-detach.exp: New file.
When a thread exits, the terminal is left in mode "terminal_is_ours"
while the target executes. This patch fixes that.
We need to manually restore the terminal setting in this particular
observer. In the case of the other MI observers that call
target_terminal_ours, gdb will end up resuming the inferior later in the
execution and call target_terminal_inferior. In the case of the thread
exit event, we still need to call target_terminal_ours to be able to
print something, but there is nothing that gdb will need to resume after
that. We therefore need to call target_terminal_inferior ourselves.
gdb/ChangeLog:
PR gdb/17627
* target.c (cleanup_restore_target_terminal): New function.
(make_cleanup_restore_target_terminal): New function.
* target.h (make_cleanup_restore_target_terminal): New
declaration.
* mi/mi-interp.c (mi_thread_exit): Use the new cleanup.
Signed-off-by: Simon Marchi <simon.marchi@ericsson.com>
That's right, block_lookup_symbol_primary()'s additional requirement over
block_lookup_symbol() is:
Function is useful if one iterates all global/static blocks of an
objfile.
Which is satisfied both in lookup_symbol_in_objfile_symtabs() and in
lookup_global_symbol_from_objfile() thanks to their's ALL_OBJFILE_COMPUNITS.
In fact after reverting that ba715d7fe4 above
the lines of code were exactly the same.
So instead of accelerating both lookup_symbol_in_objfile_symtabs() and
lookup_global_symbol_from_objfile() I just accelerated
lookup_symbol_in_objfile_symtabs() and I am proposing to reuse
lookup_symbol_in_objfile_symtabs() in lookup_global_symbol_from_objfile()
instead. In fact such unification would already save some lines of code even
before the checked-in acceleration patch above.
gdb/ChangeLog
2014-12-05 Jan Kratochvil <jan.kratochvil@redhat.com>
* symtab.c (lookup_symbol_in_objfile_symtabs): New declaration.
(lookup_global_symbol_from_objfile): Call it.
I am just not sure if we should go the route of
struct objfile * -> const struct objfile *
or the other way of:
const struct objfile * -> struct objfile *
Normally const adding is better but here I do not see much useful to have any
struct objfile * const and then it just causes pointer compatibility problems.
On Wed, 03 Dec 2014 18:18:44 +0100, Doug Evans wrote:
struct objfile is one case where I've decided to just leave the const
out and not worry about it.
gdb/ChangeLog
2014-12-05 Jan Kratochvil <jan.kratochvil@redhat.com>
Remove const from struct objfile *.
* solib-darwin.c, solib-spu.c, solib-svr4.c, solib.c, solist.h,
symtab.c, symtab.h: In these files.
This patch causes regressions in ada's operator_bp.exp test.
That's because it uses wild_match which expects arguments in
the original order.
There is still a bug here. It's hard to see because either minsyms
save the day, or the needed symtab gets expanded before linespecs
need it because of the call to cp_canonicalize_string_no_typedefs
in linespec.c:find_linespec_symbols.
But if you disable both of those things, then the bug is visible.
bash$ ./gdb -D ./data-directory testsuite/gdb.cp/anon-ns
(gdb) b doit(void)
Function "doit(void)" not defined.
gdb/ChangeLog:
Revert:
PR symtab/17602
* linespec.c (iterate_name_matcher): Fix arguments to symbol_name_cmp.
During debugging I get 10-30 seconds for a response to simple commands like:
(gdb) print vectorvar.size()
With this patch the performance gets to 1-2 seconds which is somehow
acceptable. The problem is that dwarf2_gdb_index_functions.lookup_symbol
(quick_symbol_functions::lookup_symbol) may return (and returns) NULL even for
symbols which are present in .gdb_index but which can be found in already
expanded symtab. But searching in the already expanded symtabs is just too
slow when there are 400000+ expanded symtabs. There would be needed some
single global hash table for each objfile so that one does not have to iterate
all symtabs. Which .gdb_index could perfectly serve for, just its
lookup_symbol() would need to return authoritative yes/no answers.
Even after such fix these two simple patches are useful for example for
non-.gdb_index files.
One can reproduce the slugging interactive GDB performance with:
#include <string>
using namespace std;
string var;
class C {
public:
void m() {}
};
int main() {
C c;
c.m();
return 0;
}
g++ -o slow slow.C -Wall -g $(pkg-config --libs gtkmm-3.0)
gdb ./slow -ex 'b C::m' -ex 'maintenance set per-command space' -ex 'maintenance set per-command symtab' -ex 'maintenance set per-command
time' -ex r
[...]
(gdb) p <tab><tab>
Display all 183904 possibilities? (y or n) n
(gdb) p/r var
$1 = {static npos = <optimized out>, _M_dataplus = {<std::allocator<char>> = {<__gnu_cxx::new_allocator<char>> = {<No data fields>}, <No
data fields>}, _M_p = 0x3a4db073d8 <std::string::_Rep::_S_empty_rep_storage+24> ""}}
Command execution time: 20.023000 (cpu), 20.118665 (wall)
^^^^^^^^^
Space used: 927997952 (+0 for this command)
Without DWZ there are X global blocks for X primary symtabs for X CUs of
objfile. With DWZ there are X+Y global blocks for X+Y primary symtabs for
X+Y CUs where Y are 'DW_TAG_partial_unit's.
For 'DW_TAG_partial_unit's (Ys) their blockvector is usually empty. But not
always, I have found there typedef symbols, there can IMO be optimized-out
static variables etc.
Neither of the patches should cause any visible behavior change.
gdb/ChangeLog
2014-12-04 Jan Kratochvil <jan.kratochvil@redhat.com>
* block.c (block_lookup_symbol_primary): New function.
* block.h (block_lookup_symbol_primary): New declaration.
* symtab.c (lookup_symbol_in_objfile_symtabs): Assert BLOCK_INDEX.
Call block_lookup_symbol_primary.
The necessity for this change has been revealed in the course of
investigation related to proposed changes in the treatment of the ISA
bit encoded in function symbols on the MIPS target. This change adds
support for Linux signal trampolines encoded with the microMIPS
instruction set. Such trampolines are used by the Linux kernel if
compiled as a microMIPS binary (even if the binary run/debugged itself
contains no microMIPS code at all).
To see if we need to check whether the execution mode selected matches
the given trampoline I have checked what the bit patterns of all the
trampoline sequences decode to in the opposite instruction set. This
produced useless or at least unusual code in most cases, for example:
microMIPS/EB, o32 sigreturn, decoded as MIPS code:
30401017 andi zero,v0,0x1017
00008b7c dsll32 s1,zero,0xd
MIPS/EL, o32 sigreturn, decoded as microMIPS code:
1017 2402 addi zero,s7,9218
000c 0000 sll zero,t0,0x0
However in some corner cases reasonable code can mimic a trampoline, for
example:
MIPS/EB, n32 rt_sigreturn, decoded as microMIPS code:
2402 sll s0,s0,1
1843 0000 sb v0,0(v1)
000c 0f3c jr t0
-- here the first instruction is a 16-bit one, making things nastier
even as there are some other microMIPS instructions whose first 16-bit
halfword is 0x000c and therefore matches this whole trampoline pattern.
To overcome this problem I have decided the signal trampoline unwinder
has to ask the platform backend whether it can apply a given trampoline
pattern to the code location being concerned or not. Anticipating the
acceptance of the ISA bit proposal I decided the handler not to merely
be a predicate, but also to be able to provide an adjusted PC if
required. I decided that returning zero will mean that the trampoline
pattern is not applicable and any other value is the adjusted PC to use;
a handler may return the value requested if the trampoline pattern and
the PC requested as-is are both accepted.
This changes the semantics of the trampoline unwinder a bit in that the
zero PC now has a special value. I think this should be safe as a NULL
pointer is generally supposed to be invalid.
* tramp-frame.h (tramp_frame): Add `validate' member.
* tramp-frame.c (tramp_frame_start): Validate trampoline before
scanning.
* mips-linux-tdep.c (MICROMIPS_INST_LI_V0): New macro.
(MICROMIPS_INST_POOL32A, MICROMIPS_INST_SYSCALL): Likewise.
(mips_linux_o32_sigframe): Initialize `validate' member.
(mips_linux_o32_rt_sigframe): Likewise.
(mips_linux_n32_rt_sigframe): Likewise.
(mips_linux_n64_rt_sigframe): Likewise.
(micromips_linux_o32_sigframe): New variable.
(micromips_linux_o32_rt_sigframe): Likewise.
(micromips_linux_n32_rt_sigframe): Likewise.
(micromips_linux_n64_rt_sigframe): Likewise.
(mips_linux_o32_sigframe_init): Handle microMIPS trampolines.
(mips_linux_n32n64_sigframe_init): Likewise.
(mips_linux_sigframe_validate): New function.
(micromips_linux_sigframe_validate): Likewise.
(mips_linux_init_abi): Install microMIPS trampoline unwinders.
Remove native-only core file handling on Sparc Solaris. Instead,
enable the sparc target generic core regset logic on Solaris by
providing appropriate register offset maps.
Thanks to Joel Brobecker for testing!
gdb/
* config/sparc/sol2.mh (NATDEPFILES): Remove core-regset.o.
* sparc-sol2-tdep.c: Include "regset.h".
(sparc32_sol2_supply_core_gregset): New function.
(sparc32_sol2_collect_core_gregset): Likewise.
(sparc32_sol2_supply_core_fpregset): Likewise.
(sparc32_sol2_collect_core_fpregset): Likewise.
(sparc32_sol2_gregset, sparc32_sol2_fpregset): New variables.
(sparc32_sol2_init_abi): Set tdep->gregset/sizeof_gregset and
tdep->fpregset/sizeof_fpregset.
* sparc64-sol2-tdep.c: Include "regset.h".
(sparc64_sol2_supply_core_gregset): New function.
(sparc64_sol2_collect_core_gregset): Likewise.
(sparc64_sol2_supply_core_fpregset): Likewise.
(sparc64_sol2_collect_core_fpregset): Likewise.
(sparc64_sol2_gregset, sparc64_sol2_fpregset): New variables.
(sparc64_sol2_init_abi): Set tdep->gregset/sizeof_gregset and
tdep->fpregset/sizeof_fpregset.
The definition does not use the typedef for the dtor function pointer
type that the declaration uses. It's a cosmetic-only change.
ChangeLog:
* common/cleanups.c (make_cleanup_dtor): Use typedef for dtor
type.
This patch reverts the addition of cplus_specific added here:
2010-07-16 Sami Wagiaalla <swagiaal@redhat.com>
* symtab.h (symbol_set_demangled_name): Now takes an optional objfile*
argument.
(cplus_specific): New struct.
* symtab.c (symbol_set_demangled_name): Updated.
Use cplus_specific for cplus symbols.
(symbol_get_demangled_name): Retrive the name from the cplus_specific
struct for cplus symbols.
(symbol_init_language_specific): Set cplus_specific for cplus symbols.
(symbol_set_names): Pass objfile to symbol_set_demangled_name.
* symtab.c (symbol_init_cplus_specific): New function.
It was added in anticipation of improved template support:
https://sourceware.org/ml/gdb-patches/2010-05/msg00594.htmlhttps://sourceware.org/ml/gdb-patches/2010-07/msg00284.html
However, minsyms pay the price for this space too.
For my standard benchmark this patch gets back 44MB of memory
when gdb starts. [There's still ~440MB of memory used
by the demangled ELF symbols of this benchmark, but that's another topic.]
When the improved templated support is added,
I wonder if this can be moved to struct symbol.
Hmmm, we already have a special version of
struct symbol for templates (struct template_symbol).
gdb/ChangeLog:
* symtab.c (symbol_init_cplus_specific): Delete.
(symbol_set_demangled_name): Remove special c++ support.
(symbol_get_demangled_name, symbol_set_language): Ditto.
* symtab.h (struct cplus_specific): Delete.
(struct general_symbol_info) <language_specific>: Remove
cplus_specific.
Fix a typo in the expedited registers for s390-te-linux64.
gdb/ChangeLog:
* features/Makefile (s390-te-linux64-expedite): Replace
non-existant r14 and r15 by r14l and r15l, respectively.
* regformats/s390-te-linux64.dat: Regenerate.
Remove native-only core file handling on GNU Hurd. Instead, enable the
x86 target generic core regset logic on the Hurd by providing an
appropriate register offset map.
Thanks to Samuel Thibault for testing!
gdb/
* config/i386/i386gnu.mh (NATDEPFILES): Remove core-regset.o.
* i386gnu-nat.c: Do not include <sys/procfs.h> or "gregset.h".
(CREG_OFFSET, creg_offset, CREG_ADDR): Remove.
(supply_gregset, supply_fpregset): Remove.
* i386gnu-tdep.c (i386gnu_gregset_reg_offset): New variable.
(i386gnu_init_abi): Set tdep->gregset_reg_offset, gregset_num_regs,
and sizeof_gregset.
There is already "add-auto-load-safe-path" which works
like "set auto-load safe-path" but in append mode.
There was missing an append equivalent for "set auto-load scripts-directory".
ABRT has directory /var/cache/abrt-di/ as an alternative one
to /usr/lib/debug/ . Therefore ABRT needs to use -iex parameters to add this
/var/cache/abrt-di/ directory as a first-class debuginfo directory.
Using absolute "set auto-load scripts-directory" would hard-code the path
possibly overriding local system directory additions; besides it would not be
nice anyway.
gdb/ChangeLog
2014-11-30 Jan Kratochvil <jan.kratochvil@redhat.com>
Add add-auto-load-scripts-directory.
* NEWS (Changes since GDB 7.8): Add add-auto-load-scripts-directory.
* auto-load.c (add_auto_load_dir): New function.
(_initialize_auto_load): Install it.
gdb/doc/ChangeLog
2014-11-30 Jan Kratochvil <jan.kratochvil@redhat.com>
Add add-auto-load-scripts-directory.
* gdb.texinfo (Auto-loading): Add add-auto-load-scripts-directory link.
(objfile-gdbdotext file): Add add-auto-load-scripts-directory.
I noticed in frame_id_eq() we were checking for the "l" frame_id being
invalid twice instead of checking both "l" and "r", so this patch
corrects it.
gdb/ChangeLog:
* frame.c (frame_id_eq): Fix the check for FID_STACK_INVALID.
This fixes a regression introduced by 6c659fc2c7.
gdb/ChangeLog:
* eval.c (evaluate_subexp): Check that thread stack temporaries
are not already enabled before enabling them.
I find local variables framereg and framesize is only used when cache
isn't NULL. This patch to move the code into "if (cache)" block.
gdb:
2014-11-29 Yao Qi <yao@codesourcery.com>
* arm-tdep.c (arm_analyze_prologue): Move local variables
'framereg' and 'framesize' to inner block. Move code to
inner block too.
gdb/ChangeLog:
* eval.c: Include gdbthread.h.
(evaluate_subexp): Enable thread stack temporaries before
evaluating a complete expression and clean them up after the
evaluation is complete.
* gdbthread.h: Include common/vec.h.
(value_ptr): New typedef.
(VEC (value_ptr)): New vector type.
(value_vec): New typedef.
(struct thread_info): Add new fields stack_temporaries_enabled
and stack_temporaries.
(enable_thread_stack_temporaries)
(thread_stack_temporaries_enabled_p, push_thread_stack_temporary)
(get_last_thread_stack_temporary)
(value_in_thread_stack_temporaries): Declare.
* gdbtypes.c (class_or_union_p): New function.
* gdbtypes.h (class_or_union_p): Declare.
* infcall.c (call_function_by_hand): Store return values of class
type as temporaries on stack.
* thread.c (enable_thread_stack_temporaries): New function.
(thread_stack_temporaries_enabled_p, push_thread_stack_temporary)
(get_last_thread_stack_temporary): Likewise.
(value_in_thread_stack_temporaries): Likewise.
* value.c (value_force_lval): New function.
* value.h (value_force_lval): Declare.
gdb/testsuite/ChangeLog:
* gdb.cp/chained-calls.cc: New file.
* gdb.cp/chained-calls.exp: New file.
* gdb.cp/smartp.exp: Remove KFAIL for "p c2->inta".
Dwarf register numbers are defined in "System V Application Binary
Interface AMD64 Architecture Processor Supplement Draft Version 0.99.6"
The amd64_dwarf_regmap array is missing the 8 MMX registers in Figure
3.36: DWARF Register Number Mapping page 57. This leads to a wrong
value for the registers past this point.
gdb/ChangeLog:
Pushed by Joel Brobecker <brobecker@adacore.com>.
* amd64-tdep.c (amd64_dwarf_regmap array): Add missing MMX
registers.
Tested on x86_64-linux.
Since Andreas Arnez' recent patch series, all Linux targets install
gdbarch_iterate_over_regset_sections routines. This means that on
Linux native targets, old-style core sniffers are never used.
Most Linux targets haven't been using such sniffers for a long time
anyway, but a couple remain: ia64 and sparc use core-regset.o, and
m68k installs its own core_fns. All this is now dead code, which
this commit removes.
gdb/
2014-11-28 Ulrich Weigand <uweigand@de.ibm.com>
* config/ia64/linux.mh (NATDEPFILES): Remove core-regset.o.
* config/sparc/linux.mh (NATDEPFILES): Likewise.
* config/sparc/linux64.mh (NATDEPFILES): Likewise.
* m68klinux-nat.c (fetch_core_registers): Remove.
(linux_elf_core_fns): Remove.
(_initialize_m68k_linux_nat): Do not call deprecated_add_core_fns.
Rework the comment to explain why we're still relying on GetFullPathName
even though gnulib ensures that canonicalize_file_name is now available
on all platforms, including Windows.
gdb/ChangeLog:
* utils.c (gdb_realpath): Rework comment about handling on
Windows.
Since lstat gnulib module is imported, we can use it unconditionally.
lstat usage was introduced by this patch
https://sourceware.org/ml/gdb-patches/2012-01/msg00390.html
during the review, it was suggested to import gnulib lstat module, but
we didn't do that.
gdb:
2014-11-28 Yao Qi <yao@codesourcery.com>
* configure.ac (AC_CHECK_FUNCS): Remove lstat.
* config.in, configure: Regenerate.
* symfile.c (find_separate_debug_file_by_debuglink): Remove
code checking HAVE_LSTAT is defined.
Since readlink module is imported, we can use it unconditionally.
This patch is to remove configure checks and HAVE_READLINK checks in
code. It was mentioned in the patch below
[RFA/commit] gdbserver: return ENOSYS if readlink not supported.
https://sourceware.org/ml/gdb-patches/2012-02/msg00148.html
to use readlink in gdbserver, but we chose something simple at that
moment.
gdb:
2014-11-28 Yao Qi <yao@codesourcery.com>
* configure.ac (AC_CHECK_FUNCS): Remove readlink.
* config.in, configure: Re-generate.
* inf-child.c (inf_child_fileio_readlink): Don't check
HAVE_READLINK is defined.
gdb/gdbserver:
2014-11-28 Yao Qi <yao@codesourcery.com>
* configure.ac(AC_CHECK_FUNCS): Remove readlink.
* config.in, configure: Re-generate.
* hostio.c (handle_unlink): Remove code checking HAVE_READLINK
is defined.
This patch is to import readlink gnulib module. stat module is imported
too, but it isn't used by gdb.
gdb:
2014-11-28 Yao Qi <yao@codesourcery.com>
* gnulib/update-gnulib.sh (IMPORTED_GNULIB_MODULES): Add readlink.
* gnulib/aclocal.m4: Re-generated.
* gnulib/config.in: Likewise.
* gnulib/configure: Likewise.
* gnulib/import/Makefile.am: Likewise.
* gnulib/import/Makefile.in: Likewise.
* gnulib/import/m4/gnulib-cache.m4: Likewise.
* gnulib/import/m4/gnulib-comp.m4: Likewise.
* gnulib/import/dosname.h: New file
* gnulib/import/m4/largefile.m4: New file.
* gnulib/import/m4/readlink.m4: New file.
* gnulib/import/m4/stat.m4: New file.
* gnulib/import/readlink.c: New file.
* gnulib/import/stat.c: New file.
2014-11-25 Sandra Loosemore <sandra@codesourcery.com>
gdb/
* nios2-tdep.c (nios2_analyze_prologue): Replace restriction
that there can be only one stack adjustment in the prologue
with tests to detect specific disallowed stack adjustments.
instruction matching.
2014-11-25 Sandra Loosemore <sandra@codesourcery.com>
gdb/
* nios2-tdep.c (nios2_fetch_insn): Move up in file. Disassemble
the instruction as well as reading it from memory.
(nios2_match_add): New.
(nios2_match_sub): New.
(nios2_match_addi): New.
(nios2_match_orhi): New.
(nios2_match_stw): New.
(nios2_match_ldw): New.
(nios2_match_rdctl): New.
(enum branch_condition): New.
(nios2_match_branch): New.
(nios2_match_jmpi): New.
(nios2_match_calli): New.
(nios2_match_jmpr): New.
(nios2_match_callr): New.
(nios2_match_break): New.
(nios2_match_trap): New.
(nios2_in_epilogue_p): Rewrite to use new functions.
(nios2_analyze_prologue): Likewise.
(nios2_skip_prologue): Delete unused local limit_pc.
(nios2_breakpoint_from_pc): Make R1-specific encodings explicit.
(nios2_get_next_pc): Rewrite to use new functions.
2014-11-24 Samuel Thibault <samuel.thibault@ens-lyon.org>
* gdb/gnu-nat.c (inf_validate_procinfo): Multiply the number of
elements pi_len by the size of the elements before calling
vm_deallocate.
(inf_validate_task_sc): Likewise, and properly deallocate the
noise array.
gdb/ChangeLog:
* gdbtypes.c (print_args): Renamed from print_arg_types. Print arg
number and name if present. All callers updated.
(dump_fn_fieldlists): Fix indentation of args.
A recent change...
commit 1a853c5224
Date: Wed Nov 12 10:10:49 2014 +0000
Subject: make "permanent breakpoints" per location and disableable
... broke function calls on sparc-elf when running over QEMU. Any
function call should demonstrate the problem.
For instance, seen from the debugger:
(gdb) call pn(1234)
[Inferior 1 (Remote target) exited normally]
The program being debugged exited while in a function called from GDB.
Evaluation of the expression containing the function
And seen from QEMU:
qemu: fatal: Trap 0x02 while interrupts disabled, Error state
[register dump removed]
What happens in this case is that GDB sets the inferior function call
by not only creating the dummy frame, but also writing a breakpoint
instruction at the return address for our function call. See infcall.c:
/* Write a legitimate instruction at the point where the infcall
breakpoint is going to be inserted. While this instruction
is never going to be executed, a user investigating the
memory from GDB would see this instruction instead of random
uninitialized bytes. We chose the breakpoint instruction
as it may look as the most logical one to the user and also
valgrind 3.7.0 needs it for proper vgdb inferior calls.
If software breakpoints are unsupported for this target we
leave the user visible memory content uninitialized. */
bp_addr_as_address = bp_addr;
bp_bytes = gdbarch_breakpoint_from_pc (gdbarch, &bp_addr_as_address,
&bp_size);
if (bp_bytes != NULL)
write_memory (bp_addr_as_address, bp_bytes, bp_size);
This instruction triggers a change introduced by the commit above,
where we consider bp locations as being permanent breakpoints
if there is already a breakpoint instruction at that address:
+ if (bp_loc_is_permanent (loc))
+ {
+ loc->inserted = 1;
+ loc->permanent = 1;
+ }
As a result, when resuming the program's execution for the inferior
function call, GDB decides that it does not need to insert a breakpoint
at this address, expecting the target to just report a SIGTRAP when
trying to execute that instruction.
But unfortunately for us, at least some versions of QEMU for SPARC
just terminate the execution entirely instead of reporting a breakpoint,
thus producing the behavior reported here.
Although it appears like QEMU might be misbehaving and should therefore
be fixed (to be verified) from the user's point of view, the recent
change does introduce a regression. So this patch tries to mitigate
a bit the damage by handling such infcall breakpoints as special and
making sure that they are never considered permanent, thus restoring
the previous behavior specifically for those breakpoints.
The option of not writing the breakpoint instructions in the first
place was considered, and would probably work also. But the comment
associated to it seems to indicate that there is still reason to
keep it.
gdb/ChangeLog:
* breakpoint.c (bp_loc_is_permanent): Return 0 if LOC corresponds
to a bp_call_dummy breakpoint type.
Tested on x86_64-linux. Also testing on sparc-elf/QEMU using
AdaCore's testsuite.
SA_RESTART allows system calls to be restarted across a signal handler.
By specifying this flag we fix the issue where if the user is being
prompted to answer yes or no, and the terminal gets resized in the
meantime, the prompt will think that the user sent an EOF and so it will
take the default action for that prompt (in the case of the quit prompt,
it will quit GDB).
gdb/ChangeLog:
* tui/tui-win.c (tui_initialize_win): Specify SA_RESTART when
registering the signal handler.
This patch fixes the annoying bug where key sequences such as Alt_F or
Alt_B (go forward or backwards by a word) do not behave promptly in TUI.
You have to press a third key in order for the key sequence to register.
This is mostly ncurses' fault. Calling wgetch() normally causes ncurses
to read only a single key from stdin. However if the key read is the
start-sequence key (^[ a.k.a. ESC) then wgetch() reads TWO keys from
stdin, storing the 2nd key into an internal FIFO buffer and returning
the start-sequence key. The extraneous read of the 2nd key makes us
miss its corresponding stdin event, so the event loop blocks until a
third key is pressed. This explains why such key sequences do not
behave promptly in TUI.
To fix this issue, we must somehow compensate for the missed stdin event
corresponding to the 2nd byte of a key sequence. This patch achieves
this by hacking up the stdin event handler to conditionally execute the
readline callback multiple times in a row. This is done via a new
global variable, call_stdin_event_handler_again_p, which is set from
tui_getc() when we receive a start-sequence key and notice extra pending
input in the ncurses buffer.
Tested on x86_64-unknown-linux-gnu.
gdb/ChangeLog:
* event-top.h (call_stdin_event_handler_again_p): Declare.
* event-top.c (call_stdin_event_handler_again_p): Define.
(stdin_event_handler): Use it.
* tui/tui-io.c (tui_getc): Prepare to call the stdin event
handler again if there is pending input following a
start sequence.
This way the user can know the index of the latest checkpoint without
having to run "info checkpoints" afterwards.
gdb/ChangeLog:
* linux-fork.c (checkpoint_command): Print index of new
checkpoint in response message.
In read_string, we have this line
chunksize = (len == -1 ? min (8, fetchlimit) : fetchlimit);
but chunksize is only used in the block that lne == -1, so IWBN to
move chunksize to the block in which it is used, and simplify the
condition setting chunksize. This patch also moves 'found_nul' to
inner block. This patch also splits a paragraph of comment into two,
and move them to different condition blocks (len > 0 and len == -1)
respectively.
gdb:
2014-11-23 Yao Qi <yao@codesourcery.com>
* valprint.c (read_string): Move local variables 'found_nul',
'chunksize' and 'limit' to inner scope. Update comments.
errno.h is included in common/common-defs.h, and gnulib errno module
was imported to gdb. This patch is to import it explicitly.
gdb:
* gnulib/update-gnulib.sh (IMPORTED_GNULIB_MODULES): Add
errno.
* gnulib/import/Makefile.am: Re-generated.
* gnulib/import/Makefile.in: Likewise.
* gnulib/import/m4/gnulib-cache.m4: Likewise.
As gnulib modules wchar and wctype is imported, we can include wchar.h
and wctype.h unconditionally. This patch is also to remove HAVE_WCHAR_H
check.
gdb:
2014-11-21 Yao Qi <yao@codesourcery.com>
* gdb_wchar.h: Include wchar.h and wctype.h.
[HAVE_ICONV && HAVE_BTOWC]: Don't check HAVE_WCHAR_T and don't
include wchar.h and wctype.h.
Don't check HAVE_WCHAR_H.
gnulib module wchar and wctype-h was imported as a dependency, but
they are used by gdb_wchar.h too. This patch is to import them
explicitly.
gdb:
* gnulib/update-gnulib.sh (IMPORTED_GNULIB_MODULES): Add wchar
and wctype-h.
* gnulib/import/Makefile.am: Re-generated.
* gnulib/import/Makefile.in: Likewise.
* gnulib/import/m4/gnulib-cache.m4: Likewise.
memchr has been used in gdb source and gnulib memchr module was
imported as a dependency. This patch is to import it explicitly.
gdb:
* gnulib/update-gnulib.sh (IMPORTED_GNULIB_MODULES): Add
memchr.
* gnulib/import/Makefile.am: Re-generated.
* gnulib/import/Makefile.in: Likewise.
* gnulib/import/m4/gnulib-cache.m4: Likewise.
Since gnulib alloca module was imported, we can include alloca.h in
both gdb and gdbserver unconditionally, so this patch adds inclusion
of alloca.h in common-defs.h. This patch also removes AC_FUNC_ALLOCA
in configure.ac because we don't need to check alloca any more.
This patch below is removed in fact.
[RFA/commit] include alloca.h if available.
https://www.sourceware.org/ml/gdb-patches/2010-08/msg00566.html
Since alloca.h is from gnulib now, we don't have to check malloc.h in
configure and include malloc.h in code. This patch also remove them
too.
gdb:
2014-11-21 Yao Qi <yao@codesourcery.com>
* common/common-defs.h: Include alloca.h
* configure.ac: Don't invoke AC_FUNC_ALLOCA.
* configure: Re-generated.
* defs.h: Remove code handling alloca.
* utils.c (gdb_realpath): Don't check HAVE_ALLOCA is defined
or not.
gdb/gdbserver:
2014-11-21 Yao Qi <yao@codesourcery.com>
* configure.ac: Don't invoke AC_FUNC_ALLOCA.
(AC_CHECK_HEADERS): Remove malloc.h.
* configure: Re-generated.
* config.in: Re-generated.
* server.h: Don't include alloca.h and malloc.h.
* gdbreplay.c: Don't check HAVE_ALLOCA_H is defined.
Don't include malloc.h.
gnulib's alloca module was imported to gdb, and alloca is used. This
patch is to explicitly import it.
gdb:
* gnulib/update-gnulib.sh (IMPORTED_GNULIB_MODULE): Add
alloca.
* gnulib/import/Makefile.am: Re-generated.
* gnulib/import/Makefile.in: Likewise..
* gnulib/import/m4/gnulib-cache.m4: Likewise.
Since we'll add more modules in this list, better to keep them in
alphabetical order.
gdb:
* gnulib/update-gnulib.sh: Make IMPORTED_GNULIB_MODULES in
alphabetical order.
Consider the following variable declaration:
type Array_Type is array (Integer range <>) of Integer;
Var: Array_Type (0 .. -1);
"ptype var" prints the wrong upper bound for that array:
(gdb) ptype var
type = array (0 .. 4294967295) of integer
The debugging info for the type of variable "Var" is as follow:
<2><cf>: Abbrev Number: 13 (DW_TAG_structure_type)
<d0> DW_AT_name : foo__var___PAD
<3><db>: Abbrev Number: 14 (DW_TAG_member)
<dc> DW_AT_name : F
<e0> DW_AT_type : <0xa5>
This is just an artifact from code generation, which is just
a wrapper that we should ignore. The real type is the type of
field "F" in that PAD type, which is described as:
<2><a5>: Abbrev Number: 10 (DW_TAG_array_type)
<a6> DW_AT_name : foo__TvarS
<3><b6>: Abbrev Number: 11 (DW_TAG_subrange_type)
<b7> DW_AT_type : <0xc1>
<bb> DW_AT_lower_bound : 0
<bc> DW_AT_upper_bound : 0xffffffff
Trouble occurs because DW_AT_upper_bound is encoded using
a DW_FORM_data4, which is ambiguous regarding signedness.
In that case, dwarf2read.c::dwarf2_get_attr_constant_value
reads the value as unsigned, which is not what we want
in this case.
As it happens, we already have code dealing with this situation
in dwarf2read.c::read_subrange_type which checks whether
the subrange's type is signed or not, and if it is, fixes
the bound's value by sign-extending it:
if (high.kind == PROP_CONST
&& !TYPE_UNSIGNED (base_type) && (high.data.const_val & negative_mask))
high.data.const_val |= negative_mask;
Unfortunately, what happens in our case is that the base type
of the array's subrange type is marked as being unsigned, and
so we never get to apply the sign extension. Following the DWARF
trail, the range's base type is described as another subrange type...
<2><c1>: Abbrev Number: 12 (DW_TAG_subrange_type)
<c7> DW_AT_name : foo__TTvarSP1___XDLU_0__1m
<cb> DW_AT_type : <0x2d>
... whose base type is, (finally), a basic type (signed):
<1><2d>: Abbrev Number: 2 (DW_TAG_base_type)
<2e> DW_AT_byte_size : 4
<2f> DW_AT_encoding : 5 (signed)
<30> DW_AT_name : integer
The reason why GDB thinks that foo__TTvarSP1___XDLU_0__1m
(the base type of the array's range type) is an unsigned type
is found in gdbtypes.c::create_range_type. We consider that
a range type is unsigned iff its lower bound is >= 0:
if (low_bound->kind == PROP_CONST && low_bound->data.const_val >= 0)
TYPE_UNSIGNED (result_type) = 1;
That is normally sufficient, as one would expect the upper bound to
always be greater or equal to the lower bound. But Ada actually
allows the declaration of empty range types where the upper bound
is less than the lower bound. In this case, the upper bound is
negative, so we should not be marking the type as unsigned.
This patch fixes the issue by simply checking the upper bound as well
as the lower bound, and clears the range type's unsigned flag when
it is found to be constant and negative.
gdb/ChangeLog:
* gdbtypes.c (create_range_type): Unset RESULT_TYPE's
flag_unsigned if HIGH_BOUND is constant and negative.
gdb/testsuite/ChangeLog:
* gdb.ada/n_arr_bound: New testcase.
Tested on x86_64-linux.
In the previous commit, I forgot to adjust the prototypes of the
functions inside gdb/xml-syscall.c for the case when GDB is compiled
without XML support.
gdb/
2014-11-20 Sergio Durigan Junior <sergiodj@redhat.com>
PR breakpoints/10737
* xml-syscall.c (set_xml_syscall_file_name): Remove "const"
modifier from "struct gdbarch" when compiling without Expat (XML)
support.
(get_syscall_by_number): Likewise.
(get_syscall_by_name): Likewise.
(get_syscall_names): Likewise.
This patch intends to partially fix PR breakpoints/10737, which is
about making the syscall information (for the "catch syscall" command)
be per-arch, instead of global. This is not a full fix because of the
other issues pointed by Pedro here:
<https://sourceware.org/bugzilla/show_bug.cgi?id=10737#c5>
However, I consider it a good step towards the real fix. It will also
help me fix <https://sourceware.org/bugzilla/show_bug.cgi?id=17402>.
What this patch does, basically, is move the "syscalls_info"
struct to gdbarch. Currently, the syscall information is stored in a
global variable inside gdb/xml-syscall.c, which means that there is no
easy way to correlate this info with the current target or
architecture being used, for example. This causes strange behaviors,
because the syscall info is not re-read when the arch changes. For
example, if you put a syscall catchpoint in syscall 5 on i386 (syscall
open), and then load a x86_64 program on GDB and put the same syscall
5 there (fstat on x86_64), you will still see that GDB tells you that
it is catching "open", even though it is not. With this patch, GDB
correctly says that it will be catching fstat syscalls.
(gdb) set architecture i386
The target architecture is assumed to be i386
(gdb) catch syscall 5
Catchpoint 1 (syscall 'open' [5])
(gdb) set architecture i386:x86-64
The target architecture is assumed to be i386:x86-64
(gdb) catch syscall 5
Catchpoint 2 (syscall 'open' [5])
But with the patch:
(gdb) set architecture i386
The target architecture is assumed to be i386
(gdb) catch syscall 5
Catchpoint 1 (syscall 'open' [5])
(gdb) set architecture i386:x86-64
The target architecture is assumed to be i386:x86-64
(gdb) catch syscall 5
Catchpoint 2 (syscall 'fstat' [5])
As I said, there are still some problems on the "catch syscall"
mechanism, because (for example) the user should be able to "catch
syscall open" on i386, and then expect "open" to be caught also on
x86_64. Currently, it doesn't work. I intend to work on this later.
gdb/
2014-11-20 Sergio Durigan Junior <sergiodj@redhat.com>
PR breakpoints/10737
* amd64-linux-tdep.c (amd64_linux_init_abi_common): Adjust call to
set_xml_syscall_file_name to provide gdbarch.
* arm-linux-tdep.c (arm_linux_init_abi): Likewise.
* bfin-linux-tdep.c (bfin_linux_init_abi): Likewise.
* breakpoint.c (print_it_catch_syscall): Adjust call to
get_syscall_by_number to provide gdbarch.
(print_one_catch_syscall): Likewise.
(print_mention_catch_syscall): Likewise.
(print_recreate_catch_syscall): Likewise.
(catch_syscall_split_args): Adjust calls to get_syscall_by_number
and get_syscall_by_name to provide gdbarch.
(catch_syscall_completer): Adjust call to get_syscall_names to
provide gdbarch.
* gdbarch.c: Regenerate.
* gdbarch.h: Likewise.
* gdbarch.sh: Forward declare "struct syscalls_info".
(xml_syscall_file): New variable.
(syscalls_info): Likewise.
* i386-linux-tdep.c (i386_linux_init_abi): Adjust call to
set_xml_syscall_file_name to provide gdbarch.
* mips-linux-tdep.c (mips_linux_init_abi): Likewise.
* ppc-linux-tdep.c (ppc_linux_init_abi): Likewise.
* s390-linux-tdep.c (s390_gdbarch_init): Likewise.
* sparc-linux-tdep.c (sparc32_linux_init_abi): Likewise.
* sparc64-linux-tdep.c (sparc64_linux_init_abi): Likewise.
* xml-syscall.c: Include gdbarch.h.
(set_xml_syscall_file_name): Accept gdbarch parameter.
(get_syscall_by_number): Likewise.
(get_syscall_by_name): Likewise.
(get_syscall_names): Likewise.
(my_gdb_datadir): Delete global variable.
(struct syscalls_info) <my_gdb_datadir>: New variable.
(struct syscalls_info) <sysinfo>: Rename variable to
"syscalls_info".
(sysinfo): Delete global variable.
(have_initialized_sysinfo): Likewise.
(xml_syscall_file): Likewise.
(sysinfo_free_syscalls_desc): Rename to...
(syscalls_info_free_syscalls_desc): ... this.
(free_syscalls_info): Rename "sysinfo" to "syscalls_info". Adjust
code to the new layout of "struct syscalls_info".
(make_cleanup_free_syscalls_info): Rename parameter "sysinfo" to
"syscalls_info".
(syscall_create_syscall_desc): Likewise.
(syscall_start_syscall): Likewise.
(syscall_parse_xml): Likewise.
(xml_init_syscalls_info): Likewise. Drop "const" from return value.
(init_sysinfo): Rename to...
(init_syscalls_info): ...this. Add gdbarch as a parameter.
Adjust function to deal with gdbarch.
(xml_get_syscall_number): Delete parameter sysinfo. Accept
gdbarch as a parameter. Adjust code.
(xml_get_syscall_name): Likewise.
(xml_list_of_syscalls): Likewise.
(set_xml_syscall_file_name): Accept gdbarch as parameter.
(get_syscall_by_number): Likewise.
(get_syscall_by_name): Likewise.
(get_syscall_names): Likewise.
* xml-syscall.h (set_xml_syscall_file_name): Likewise.
(get_syscall_by_number): Likewise.
(get_syscall_by_name): Likewise.
(get_syscall_names): Likewise.
gdb/testsuite/
2014-11-20 Sergio Durigan Junior <sergiodj@redhat.com>
PR breakpoints/10737
* gdb.base/catch-syscall.exp (do_syscall_tests): Call
test_catch_syscall_multi_arch.
(test_catch_syscall_multi_arch): New function.
Currently "symtabs" in gdb are stored as a single linked list of
struct symtab that contains both symbol symtabs (the blockvectors)
and file symtabs (the linetables).
This has led to confusion, bugs, and performance issues.
This patch is conceptually very simple: split struct symtab into
two pieces: one part containing things common across the entire
compilation unit, and one part containing things specific to each
source file.
Example.
For the case of a program built out of these files:
foo.c
foo1.h
foo2.h
bar.c
foo1.h
bar.h
Today we have a single list of struct symtabs:
objfile -> foo.c -> foo1.h -> foo2.h -> bar.c -> foo1.h -> bar.h -> NULL
where "->" means the "next" pointer in struct symtab.
With this patch, that turns into:
objfile -> foo.c(cu) -> bar.c(cu) -> NULL
| |
v v
foo.c bar.c
| |
v v
foo1.h foo1.h
| |
v v
foo2.h bar.h
| |
v v
NULL NULL
where "foo.c(cu)" and "bar.c(cu)" are struct compunit_symtab objects,
and the files foo.c, etc. are struct symtab objects.
So now, for example, when we want to iterate over all blockvectors
we can now just iterate over the compunit_symtab list.
Plus a lot of the data that was either unused or replicated for each
symtab in a compilation unit now lives in struct compunit_symtab.
E.g., the objfile pointer, the producer string, etc.
I thought of moving "language" out of struct symtab but there is
logic to try to compute the language based on previously seen files,
and I think that's best left as is for now.
With my standard monster benchmark with -readnow (which I can't actually
do, but based on my calculations), whereas today the list requires
77MB to store all the struct symtabs, it now only requires 37MB.
A modest space savings given the gigabytes needed for all the debug info,
etc. Still, it's nice. Plus, whereas today we create a copy of dirname
for each source file symtab in a compilation unit, we now only create one
for the compunit.
So this patch is basically just a data structure reorg,
I don't expect significant performance improvements from it.
Notes:
1) A followup patch can do a similar split for struct partial_symtab.
I have left that until after I get the changes I want in to
better utilize .gdb_index (it may affect how we do partial syms).
2) Another followup patch *could* rename struct symtab.
The term "symtab" is ambiguous and has been a source of confusion.
In this patch I'm leaving it alone, calling it the "historical" name
of "filetabs", which is what they are now: just the file-name + line-table.
gdb/ChangeLog:
Split struct symtab into two: struct symtab and compunit_symtab.
* amd64-tdep.c (amd64_skip_xmm_prologue): Fetch producer from compunit.
* block.c (blockvector_for_pc_sect): Change "struct symtab *" argument
to "struct compunit_symtab *". All callers updated.
(set_block_compunit_symtab): Renamed from set_block_symtab. Change
"struct symtab *" argument to "struct compunit_symtab *".
All callers updated.
(get_block_compunit_symtab): Renamed from get_block_symtab. Change
result to "struct compunit_symtab *". All callers updated.
(find_iterator_compunit_symtab): Renamed from find_iterator_symtab.
Change result to "struct compunit_symtab *". All callers updated.
* block.h (struct global_block) <compunit_symtab>: Renamed from symtab.
hange type to "struct compunit_symtab *". All uses updated.
(struct block_iterator) <d.compunit_symtab>: Renamed from "d.symtab".
Change type to "struct compunit_symtab *". All uses updated.
* buildsym.c (struct buildsym_compunit): New struct.
(subfiles, buildsym_compdir, buildsym_objfile, main_subfile): Delete.
(buildsym_compunit): New static global.
(finish_block_internal): Update to fetch objfile from
buildsym_compunit.
(make_blockvector): Delete objfile argument.
(start_subfile): Rewrite to use buildsym_compunit. Don't initialize
debugformat, producer.
(start_buildsym_compunit): New function.
(free_buildsym_compunit): Renamed from free_subfiles_list.
All callers updated.
(patch_subfile_names): Rewrite to use buildsym_compunit.
(get_compunit_symtab): New function.
(get_macro_table): Delete argument comp_dir. All callers updated.
(start_symtab): Change result to "struct compunit_symtab *".
All callers updated. Create the subfile of the main source file.
(watch_main_source_file_lossage): Rewrite to use buildsym_compunit.
(reset_symtab_globals): Update.
(end_symtab_get_static_block): Update to use buildsym_compunit.
(end_symtab_without_blockvector): Rewrite.
(end_symtab_with_blockvector): Change result to
"struct compunit_symtab *". All callers updated.
Update to use buildsym_compunit. Don't set symtab->dirname,
instead set it in the compunit.
Explicitly make sure main symtab is first in its list.
Set debugformat, producer, blockvector, block_line_section, and
macrotable in the compunit.
(end_symtab_from_static_block): Change result to
"struct compunit_symtab *". All callers updated.
(end_symtab, end_expandable_symtab): Ditto.
(set_missing_symtab): Change symtab argument to
"struct compunit_symtab *". All callers updated.
(augment_type_symtab): Ditto.
(record_debugformat): Update to use buildsym_compunit.
(record_producer): Update to use buildsym_compunit.
* buildsym.h (struct subfile) <dirname>: Delete.
<producer, debugformat>: Delete.
<buildsym_compunit>: New member.
(get_compunit_symtab): Declare.
* dwarf2read.c (struct type_unit_group) <compunit_symtab>: Renamed
from primary_symtab. Change type to "struct compunit_symtab *".
All uses updated.
(dwarf2_start_symtab): Change result to "struct compunit_symtab *".
All callers updated.
(dwarf_decode_macros): Delete comp_dir argument. All callers updated.
(struct dwarf2_per_cu_quick_data) <compunit_symtab>: Renamed from
symtab. Change type to "struct compunit_symtab *". All uses updated.
(dw2_instantiate_symtab): Change result to "struct compunit_symtab *".
All callers updated.
(dw2_find_last_source_symtab): Ditto.
(dw2_lookup_symbol): Ditto.
(recursively_find_pc_sect_compunit_symtab): Renamed from
recursively_find_pc_sect_symtab. Change result to
"struct compunit_symtab *". All callers updated.
(dw2_find_pc_sect_compunit_symtab): Renamed from
dw2_find_pc_sect_symtab. Change result to
"struct compunit_symtab *". All callers updated.
(get_compunit_symtab): Renamed from get_symtab. Change result to
"struct compunit_symtab *". All callers updated.
(recursively_compute_inclusions): Change type of immediate_parent
argument to "struct compunit_symtab *". All callers updated.
(compute_compunit_symtab_includes): Renamed from
compute_symtab_includes. All callers updated. Rewrite to compute
includes of compunit_symtabs and not symtabs.
(process_full_comp_unit): Update to work with struct compunit_symtab.
(process_full_type_unit): Ditto.
(dwarf_decode_lines_1): Delete argument comp_dir. All callers updated.
(dwarf_decode_lines): Remove special case handling of main subfile.
(macro_start_file): Delete argument comp_dir. All callers updated.
(dwarf_decode_macro_bytes): Ditto.
* guile/scm-block.c (bkscm_print_block_syms_progress_smob): Update to
use struct compunit_symtab.
* i386-tdep.c (i386_skip_prologue): Fetch producer from compunit.
* jit.c (finalize_symtab): Build compunit_symtab.
* jv-lang.c (get_java_class_symtab): Change result to
"struct compunit_symtab *". All callers updated.
* macroscope.c (sal_macro_scope): Fetch macro table from compunit.
* macrotab.c (struct macro_table) <compunit_symtab>: Renamed from
comp_dir. Change type to "struct compunit_symtab *".
All uses updated.
(new_macro_table): Change comp_dir argument to cust,
"struct compunit_symtab *". All callers updated.
* maint.c (struct cmd_stats) <nr_compunit_symtabs>: Renamed from
nr_primary_symtabs. All uses updated.
(count_symtabs_and_blocks): Update to handle compunits.
(report_command_stats): Update output, "primary symtabs" renamed to
"compunits".
* mdebugread.c (new_symtab): Change result to
"struct compunit_symtab *". All callers updated.
(parse_procedure): Change type of search_symtab argument to
"struct compunit_symtab *". All callers updated.
* objfiles.c (objfile_relocate1): Loop over blockvectors in a
separate loop.
* objfiles.h (struct objfile) <compunit_symtabs>: Renamed from
symtabs. Change type to "struct compunit_symtab *". All uses updated.
(ALL_OBJFILE_FILETABS): Renamed from ALL_OBJFILE_SYMTABS.
All uses updated.
(ALL_OBJFILE_COMPUNITS): Renamed from ALL_OBJFILE_PRIMARY_SYMTABS.
All uses updated.
(ALL_FILETABS): Renamed from ALL_SYMTABS. All uses updated.
(ALL_COMPUNITS): Renamed from ALL_PRIMARY_SYMTABS. All uses updated.
* psympriv.h (struct partial_symtab) <compunit_symtab>: Renamed from
symtab. Change type to "struct compunit_symtab *". All uses updated.
* psymtab.c (psymtab_to_symtab): Change result type to
"struct compunit_symtab *". All callers updated.
(find_pc_sect_compunit_symtab_from_partial): Renamed from
find_pc_sect_symtab_from_partial. Change result type to
"struct compunit_symtab *". All callers updated.
(lookup_symbol_aux_psymtabs): Change result type to
"struct compunit_symtab *". All callers updated.
(find_last_source_symtab_from_partial): Ditto.
* python/py-symtab.c (stpy_get_producer): Fetch producer from compunit.
* source.c (forget_cached_source_info_for_objfile): Fetch debugformat
and macro_table from compunit.
* symfile-debug.c (debug_qf_find_last_source_symtab): Change result
type to "struct compunit_symtab *". All callers updated.
(debug_qf_lookup_symbol): Ditto.
(debug_qf_find_pc_sect_compunit_symtab): Renamed from
debug_qf_find_pc_sect_symtab, change result type to
"struct compunit_symtab *". All callers updated.
* symfile.c (allocate_symtab): Delete objfile argument.
New argument cust.
(allocate_compunit_symtab): New function.
(add_compunit_symtab_to_objfile): New function.
* symfile.h (struct quick_symbol_functions) <lookup_symbol>:
Change result type to "struct compunit_symtab *". All uses updated.
<find_pc_sect_compunit_symtab>: Renamed from find_pc_sect_symtab.
Change result type to "struct compunit_symtab *". All uses updated.
* symmisc.c (print_objfile_statistics): Compute blockvector count in
separate loop.
(dump_symtab_1): Update test for primary source symtab.
(maintenance_info_symtabs): Update to handle compunit symtabs.
(maintenance_check_symtabs): Ditto.
* symtab.c (set_primary_symtab): Delete.
(compunit_primary_filetab): New function.
(compunit_language): New function.
(iterate_over_some_symtabs): Change type of arguments "first",
"after_last" to "struct compunit_symtab *". All callers updated.
Update to loop over symtabs in each compunit.
(error_in_psymtab_expansion): Rename symtab argument to cust,
and change type to "struct compunit_symtab *". All callers updated.
(find_pc_sect_compunit_symtab): Renamed from find_pc_sect_symtab.
Change result type to "struct compunit_symtab *". All callers updated.
(find_pc_compunit_symtab): Renamed from find_pc_symtab.
Change result type to "struct compunit_symtab *". All callers updated.
(find_pc_sect_line): Only loop over symtabs within selected compunit
instead of all symtabs in the objfile.
* symtab.h (struct symtab) <blockvector>: Moved to compunit_symtab.
<compunit_symtab> New member.
<block_line_section>: Moved to compunit_symtab.
<locations_valid>: Ditto.
<epilogue_unwind_valid>: Ditto.
<macro_table>: Ditto.
<dirname>: Ditto.
<debugformat>: Ditto.
<producer>: Ditto.
<objfile>: Ditto.
<call_site_htab>: Ditto.
<includes>: Ditto.
<user>: Ditto.
<primary>: Delete
(SYMTAB_COMPUNIT): New macro.
(SYMTAB_BLOCKVECTOR): Update definition.
(SYMTAB_OBJFILE): Update definition.
(SYMTAB_DIRNAME): Update definition.
(struct compunit_symtab): New type. Common members among all source
symtabs within a compilation unit moved here. All uses updated.
(COMPUNIT_OBJFILE): New macro.
(COMPUNIT_FILETABS): New macro.
(COMPUNIT_DEBUGFORMAT): New macro.
(COMPUNIT_PRODUCER): New macro.
(COMPUNIT_DIRNAME): New macro.
(COMPUNIT_BLOCKVECTOR): New macro.
(COMPUNIT_BLOCK_LINE_SECTION): New macro.
(COMPUNIT_LOCATIONS_VALID): New macro.
(COMPUNIT_EPILOGUE_UNWIND_VALID): New macro.
(COMPUNIT_CALL_SITE_HTAB): New macro.
(COMPUNIT_MACRO_TABLE): New macro.
(ALL_COMPUNIT_FILETABS): New macro.
(compunit_symtab_ptr): New typedef.
(DEF_VEC_P (compunit_symtab_ptr)): New vector type.
gdb/testsuite/ChangeLog:
* gdb.base/maint.exp: Update expected output.
Jan noticed that gdb.ada/arrayidx.exp regressed after I applied
the following patch:
commit 8908fca577
Author: Joel Brobecker <brobecker@adacore.com>
Date: Sat Sep 27 09:09:34 2014 -0700
Subject: [Ada] Ignore __XA types when redundant.
What happens is that we're trying to print the value of
r_two_three, which is defined as follow:
type Index is (One, Two, Three);
type RTable is array (Index range Two .. Three) of Integer;
R_Two_Three : RTable := (2, 3);
The expected output is:
(gdb) p r_two_three
$1 = (two => 2, 3)
But after the patch above was applied, with the program program
compiled using gcc-gnat-4.9.2-1.fc21.x86_64 (x86_64-linux),
the output becomes:
(gdb) p r_two_three
$1 = (2, 3)
(the name of the first bound is missing). The problem comes from
the fact that the compiler described the array's index type as
a plain base type, instead of as a subrange of the enumerated type.
More particularly, this is what gcc-gnat-4.9.2-1.fc21.x86_64
generated:
<3><7ce>: Abbrev Number: 9 (DW_TAG_array_type)
<7cf> DW_AT_name : (indirect string, offset: 0xc13): p__rtable
[...]
<7d7> DW_AT_GNAT_descriptive_type: <0x98a>
[...]
<4><7df>: Abbrev Number: 8 (DW_TAG_subrange_type)
<7e0> DW_AT_type : <0xa79>
where DIE 0xa79 is:
<1><a79>: Abbrev Number: 2 (DW_TAG_base_type)
<a7a> DW_AT_byte_size : 8
<a7b> DW_AT_encoding : 7 (unsigned)
<a7c> DW_AT_name : (indirect string, offset: 0xfc): sizetype
The actual array subrange type can be found in the array's
parallel XA type (the DW_AT_GNAT_descriptive_type).
The recent commit correctly found that that bounds taken from
the descriptive type are the same as bounds of our array's index
type. But it failed to notice that ignoring this descriptive
type would make us lose the actual array index type, making us
think that we're printing an array indexed by integers.
I hadn't seen that problem, because the compiler I used produced
debugging info where the array's index type is correctly described:
<3><79f>: Abbrev Number: 10 (DW_TAG_array_type)
<7a0> DW_AT_name : (indirect string, offset: 0xb3d): p__rtable
[...]
<4><7b0>: Abbrev Number: 8 (DW_TAG_subrange_type)
<7b1> DW_AT_type : <0x9b2>
<7b5> DW_AT_upper_bound : 2
... where DIE 0x9b2 leads us to ...
<3><9b2>: Abbrev Number: 9 (DW_TAG_subrange_type)
[...]
<9b8> DW_AT_type : <0x962>
<2><962>: Abbrev Number: 22 (DW_TAG_enumeration_type)
<963> DW_AT_name : (indirect string, offset: 0xb34): p__index
[...]
This patch fixes the issue by also making sure that the subtype
of the original range type does match the subtype found in the
descriptive type.
gdb/ChangeLog:
* ada-lang.c (ada_is_redundant_range_encoding): Return 0
if the TYPE_CODE of range_type's base type does not match
the TYPE_CODE of encoding_type's base type.
Using the example in gdb.ada/complete.exp, the following command
on x86_64-windows returns one unwanted completion choice :
(gdb) complete p pck
p <pck_E>>
[all following completions entries snipped, all expected]
I tracked down this suprising entry to a minimal symbol whose name
is ".refptr.pck_E". The problem occurs while trying to see if
this symbol matches "pck" when doing wild-matching as we are doing
here:
/* Second: Try wild matching... */
if (!match && wild_match_p)
{
/* Since we are doing wild matching, this means that TEXT
may represent an unqualified symbol name. We therefore must
also compare TEXT against the unqualified name of the symbol. */
sym_name = ada_unqualified_name (ada_decode (sym_name));
if (strncmp (sym_name, text, text_len) == 0)
match = 1;
}
What happens is that ada_decode correctly identifies the fact that
SYM_NAME (".refptr.pck_E") is not following any GNAT encoding, and
therefore returns that same name, but bracketed: "<.refptr.pck_E>".
This is the convention we use for telling GDB that the decoded name
is not a real Ada name - and therefore should not be encoded for
operations such as name matching, symbol lookups, etc. So far, so good.
Next is the call to ada_unqualified_name, which unfortunately does
not notice that the decoded name it is being given isn't a natural
symbol, and just blindly strips everything up to the last do, returning
"pck_E>". And of course, "pck_E>" matches "pck" now, and so we end
up accepting this symbol as a match.
This patch fixes the problem by making ada_unqualified_name a little
smarter by making sure that the given decoded symbol name does not
start with '<'.
gdb/ChangeLog:
* ada-lang.c (ada_unqualified_name): Return DECODED_NAME if
it starts with '<'.
Tested on x86_64-windows using AdaCore's testsuite as well as
on x86_64-linux.
Consider the following code which declares a variable A2 which
is an array of arrays of integers.
type Array2_First is array (24 .. 26) of Integer;
type Array2_Second is array (1 .. 2) of Array2_First;
A1 : Array1_Second := ((10, 11, 12), (13, 14, 15));
Trying to print the type of that variable currently yields:
(gdb) ptype A2
type = array (1 .. 2, 24 .. 26) of integer
This is not correct, as this is the description of a two-dimension
array, which is different from an array of arrays. The expected
output is:
(gdb) ptype a2
type = array (1 .. 2) of foo_n926_029.array2_first
GDB's struct type currently handles multi-dimension arrays the same
way arrays of arrays, where each dimension is stored as a sub-array.
The ada-valprint module considers that consecutive array layers
are in fact multi-dimension arrays. For array of arrays, a typedef
layer is introduced between the two arrays, creating a break between
each array type.
In our situation, A2 is a described as a typedef of an array type...
.uleb128 0x8 # (DIE (0x125) DW_TAG_variable)
.ascii "a2\0" # DW_AT_name
.long 0xfc # DW_AT_type
.uleb128 0x4 # (DIE (0xfc) DW_TAG_typedef)
.long .LASF5 # DW_AT_name: "foo__array2_second"
.long 0x107 # DW_AT_type
.uleb128 0x5 # (DIE (0x107) DW_TAG_array_type)
.long .LASF5 # DW_AT_name: "foo__array2_second"
.long 0xb4 # DW_AT_type
.uleb128 0x6 # (DIE (0x114) DW_TAG_subrange_type)
.long 0x11b # DW_AT_type
.byte 0x2 # DW_AT_upper_bound
.byte 0 # end of children of DIE 0x107
... whose element type is, as expected, a typedef to the sub-array
type:
.uleb128 0x4 # (DIE (0xb4) DW_TAG_typedef)
.long .LASF4 # DW_AT_name: "foo__array2_first"
.long 0xbf # DW_AT_type
.uleb128 0x9 # (DIE (0xbf) DW_TAG_array_type)
.long .LASF4 # DW_AT_name: "foo__array2_first"
.long 0xd8 # DW_AT_GNAT_descriptive_type
.long 0x1c5 # DW_AT_type
.uleb128 0xa # (DIE (0xd0) DW_TAG_subrange_type)
.long 0xf0 # DW_AT_type
.byte 0x18 # DW_AT_lower_bound
.byte 0x1a # DW_AT_upper_bound
.byte 0 # end of children of DIE 0xbf
The reason why things fails is that, during expression evaluation,
GDB tries to "fix" A1's type. Because the sub-array has a parallel
(descriptive) type (DIE 0xd8), GDB thinks that our array's index
type must be dynamic and therefore needs to be fixed. This in turn
causes the sub-array to be "fixed", which itself results in the
typedef layer to be stripped.
However, looking closer at the parallel type, we see...
.uleb128 0xb # (DIE (0xd8) DW_TAG_structure_type)
.long .LASF8 # DW_AT_name: "foo__array2_first___XA"
[...]
.uleb128 0xc # (DIE (0xe4) DW_TAG_member)
.long .LASF10 # DW_AT_name: "foo__Tarray2_firstD1___XDLU_24__26"
... that all it tells us is that the array bounds are 24 and 26,
which is already correctly provided by the array's DW_TAG_subrange_type
bounds, meaning that this parallel type is just redundant.
Parallel types in general are slowly being removed in favor of
standard DWARF constructs. But in the meantime, this patch kills
two birds with one stone:
1. It recognizes this situation where the XA type is useless,
and saves an unnecessary range-type fixing;
2. It fixes the issue at hand because ignoring the XA type results
in no type fixing being required, which allows the typedef layer
to be preserved.
gdb/ChangeLog:
* ada-lang.c (ada_is_redundant_range_encoding): New function.
(ada_is_redundant_index_type_desc): New function.
(to_fixed_array_type): Ignore parallel XA type if redundant.
gdb/testsuite/ChangeLog:
* gdb.ada/arr_arr: New testcase.
Tested on x86_64-linux.
... when that packed array is part of a discriminated record and
one of the bounds is a discriminant.
Consider the following code:
type FUNNY_CHAR_T is (NUL, ' ', '"', '#', [etc]);
type FUNNY_STR_T is array (POSITIVE range <>) of FUNNY_CHAR_T;
pragma PACK (FUNNY_STR_T);
type FUNNY_STRING_T (SIZE : NATURAL := 1) is
record
STR : FUNNY_STR_T (1 .. SIZE) := (others => '0');
LENGTH : NATURAL := 4;
end record;
TEST: FUNNY_STRING_T(100);
GDB is able to print the value of variable "test" and "test.str".
But not "test.str(1)":
(gdb) p test
$1 = (size => 100, str => (33 'A', nul <repeats 99 times>), length => 1)
(gdb) p test.str
$2 = (33 'A', nul <repeats 99 times>)
(gdb) p test.str(1)
object size is larger than varsize-limit
The problem occurs during the phase where we are trying to resolve
the expression subscript operation. On the one hand of the subscript
operator, we have the result of the evaluation of "test.str", which
is our packed array. We have the following code to handle packed
arrays in particular:
if (ada_is_constrained_packed_array_type
(desc_base_type (value_type (argvec[0]))))
argvec[0] = ada_coerce_to_simple_array (argvec[0]);
This eventually leads to a call to constrained_packed_array_type
to return the "simple array". This function relies on a parallel
___XA type, when available, to determine the bounds. In our case,
we find type...
failure__funny_string_t__T4b___XA"
... which has one field describing the bounds of our array as:
failure__funny_string_t__T3b___XDLU_1__size
The part that interests us is after the ___XD suffix or,
in other words: "LU_1__size". What this means in GNAT encoding
parlance is that the lower bound is 1, and that the upper bound
is the value of "size". "size" is our discriminant in this case.
Normally, we would access the record's discriminant in order to
get the upper bound's value, but we do not have that information,
here. We are in a mode where we are just trying to "fix" the type
without an actual value. This is what the call to to_fixed_range_type
is doing, and because the fix'ing fails, it ends up returning
the ___XDLU type unmodified as our index type.
This shouldn't be a problem, except that the later part of
constrained_packed_array_type then uses that index_type to
determine the array size, via a call to get_discrete_bounds.
The problem is that the upper bound of the ___XDLU type is
dynamic (in the DWARF sense) while get_discrete_bounds implicitly
assumes that the bounds are static, and therefore accesses
them using macros that assume the bounds values are constants:
case TYPE_CODE_RANGE:
*lowp = TYPE_LOW_BOUND (type);
*highp = TYPE_HIGH_BOUND (type);
This therefore returns a bogus value for the upper bound,
leading to an unexpectedly large size for our array, which
later triggers the varsize-limit guard we've seen above.
This patch avoids the problem by adding special handling
of dynamic range types. It also extends the documentation
of the constrained_packed_array_type function to document
what happens in this situation.
gdb/ChangeLog:
* ada-lang.c (constrained_packed_array_type): Set the length
of the return array as if both bounds where zero if that
returned array's index type is dynamic.
gdb/testsuite/ChangeLog:
* gdb.ada/pkd_arr_elem: New Testcase.
Tested on x86_64-linux.
I cross-compile gdb for msdosdjgpp (both target and host is
i586-pc-msdosdjgpp), so the CC should be i586-pc-msdosdjgpp-gcc.
However, CC is set incorrectly to gcc after config/i386/go32.mh is inlined
into the Makefile.
This patch is to remove the CC setting in config/i386/go32.mh.
gdb:
2014-11-19 Yao Qi <yao@codesourcery.com>
* config/i386/go32.mh (CC): Remove.
This patch is conceptually quite simple.
If you look at end_symtab_from_static_block you'll see
that the static_block == NULL case is completely different
than the non-NULL case.
There's a lot of complexity to handle the NULL case but it seems
entirely unnecessary. For example, whether blockvector is NULL
is decided at the start, before this for loop:
for (subfile = subfiles; subfile; subfile = nextsub)
Secondly, after the for loop, we test symtab for non-NULL here:
/* Set this for the main source file. */
if (symtab)
but symtab will only ever be non-NULL if blockvector was non-NULL.
And if blockvector was non_NULL so will symtab.
The other case to consider is these lines of code executed before
the for loop:
/* Read the line table if it has to be read separately.
This is only used by xcoffread.c. */
if (objfile->sf->sym_read_linetable != NULL)
objfile->sf->sym_read_linetable (objfile);
/* Handle the case where the debug info specifies a different path
for the main source file. It can cause us to lose track of its
line number information. */
watch_main_source_file_lossage ();
From my reading of the code, neither of these is useful
in the static_block == NULL case.
Thus we can make the code more readable by splitting these two cases up,
which is what this patch does.
gdb/ChangeLog:
* buildsym.c (main_subfile): New static global.
(free_subfiles_list): New function.
(start_symtab): Set main_subfile.
(restart_symtab): Replace init of subfiles, current_subfile with
call to free_subfiles_list.
(watch_main_source_file_lossage): Use main_subfile.
(reset_symtab_globals): Replace init of current_subfile with call
to free_subfiles_list.
(end_symtab_without_blockvector, end_symtab_with_blockvector): New
functions, split out from ...
(end_symtab_from_static_block): ... here. Rewrite to call them.
gdb/ChangeLog:
* dwarf2read.c (dw2_instantiate_symtab): Add assert.
(dw2_lookup_symbol): Remove unnecessary test for primary symbol table.
* psymtab.c (lookup_symbol_aux_psymtabs): Ditto.
(psymtab_to_symtab): Add comment and assert.
(map_matching_symbols_psymtab): Remove unnecessary test for
non-primary symtab.
Basically the problem is that "symtab" is ambiguous.
Is it the primary symtab (where we canonically think of
blockvectors as being stored) or is it for a specific file
(where each file's line table is stored) ?
gdb_disassembly wants the symtab that contains the line table
but is instead getting the primary symtab.
gdb/ChangeLog:
PR symtab/17559
* symtab.c (find_pc_line_symtab): New function.
* symtab.h (find_pc_line_symtab): Declare.
* disasm.c (gdb_disassembly): Call find_pc_line_symtab instead of
find_pc_symtab.
* tui/tui-disasm.c (tui_set_disassem_content): Ditto.
* tui/tui-hooks.c (tui_selected_frame_level_changed_hook): Ditto.
* tui/tui-source.c (tui_vertical_source_scroll): Ditto.
* tui/tui-win.c (make_visible_with_new_height): Ditto.
* tui/tui-winsource.c (tui_horizontal_source_scroll): Ditto.
(tui_display_main): Call find_pc_line_symtab instead of find_pc_line.
gdb/testsuite/ChangeLog:
PR symtab/17559
* gdb.base/line-symtabs.exp: New file.
* gdb.base/line-symtabs.c: New file.
* gdb.base/line-symtabs.h: New file.
This patch just renames one function.
Its only caller is in stack.c where we're printing a backtrace
with non-zero info_verbose and we want to make sure all the needed
symtabs are expanded before printing the backtrace
so that debug symbol reading messages don't pollute the backtrace.
I think the new name of the function makes clearer to the reader
what is going on.
gdb/ChangeLog:
* symtab.c (expand_symtab_containing_pc): Renamed from
find_pc_sect_symtab_via_partial. All callers updated.
One parenthesis is missing, and it causes a compilation error. This
patch is to fix it.
gdb:
2014-11-15 Yao Qi <yao@codesourcery.com>
* go32-nat.c (go32_create_inferior): Add missing parenthesis.
When trying to build gdbserver on ppc-lynx178, the compiler reports
while trying to compile gdbserver/ax.c that vsprintf is not declared.
Looking at my C99 reference manual (a draft), I see the following
synopsis:
#include <stdarg.h>
#include <stdio.h>
int vsprintf(char * restrict s, [etc]);
Looking at stdio.h on LynxOS-178, if found where vsprintf gets
declared:
#if defined(__varargs_h) || defined(__stdarg_h) \
|| defined(_VARARGS_H) || defined(_STDARG_H)
extern int vsprintf _AP((char *, const char *, va_list));
#endif
Digging further, I noticed that common-defs.h, which is included
via server.h, includes stdarg.h after including stdio, explaining
why vsprintf does not get declared in this case.
This patch fixes the problem by including stdarg.h before stdio.h.
gdb/ChangeLog:
* common/common-defs.h: Move <stdarg.h> #include ahead of
<stdio.h> #include.
Tested on x86_64-linux.
We're currently pulling gnulib's errno module as a dependency of some
other module. That provides an errno.h that defines EILSEQ to a
distinct value if the system's errno.h doesn't define it already.
However, GNU iconv does this:
/* Get errno declaration and values. */
#include <errno.h>
/* Some systems, like SunOS 4, don't have EILSEQ. Some systems, like BSD/OS,
have EILSEQ in a different header. On these systems, define EILSEQ
ourselves. */
#ifndef EILSEQ
#define EILSEQ @EILSEQ@
#endif
That's in:
http://git.savannah.gnu.org/cgit/libiconv.git/tree/include/iconv.h.in
The "different header" mentioned is wchar.h. This is handled in:
http://git.savannah.gnu.org/cgit/libiconv.git/tree/m4/eilseq.m4
which defines @EILSEQ@ to ENOENT if EILSEQ isn't found in either
errno.h or wchar.h.
So if iconv sets errno to EILSEQ on such system's, it's really setting
it to ENOENT. And when we check for EILSEQ, we're checking for
gnulib's value. The result is we won't detect the error correctly.
As we dropped support for both SunOS 4 or old BSD/OS, maybe we don't
need to care about the wchar.h issue anymore. Still, AFAICS, gnulib's
m4/errno_h.m4 doesn't know that EILSEQ may be defined in wchar.h, and
so on such systems, ISTM gnulib ends up defining an incompatible
EILSEQ itself, but I think that should be fixed on the gnulib side, by
making it extract the EILSEQ value out of the system's wchar.h, like
GNU iconv does.
So that leaves handling the case of gnulib making up a EILSEQ value,
which we take as meaning the system really doesn't really define it,
which will be the same systems GNU iconv sets errno to ENOENT instead
of EILSEQ.
Looking at glibc's iconv it seems that ENOENT is never used there.
It seems it's safe to always treat ENOENT the same as EILSEQ.
The current EILSEQ definition under PHONY_ICONV is obviously stale as
gnulib garantees there's always a EILSEQ defined.
Tested on x86_64 Fedora 20.
gdb/
2014-11-14 Pedro Alves <palves@redhat.com>
* charset.c [PHONY_ICONV && !EILSEQ] (EILSEQ): Don't define.
[!PHONY_ICONV] (gdb_iconv): New function.
[!PHONY_ICONV] (iconv): Redefine to gdb_iconv.
No longer used since the non-continuable watchpoints handling rework.
gdb/
2014-11-12 Pedro Alves <palves@redhat.com>
* infrun.c (enum infwait_states, infwait_state): Delete.
The gdb.arch/i386-bp_permanent.exp test is currently failing an
assertion recently added:
(gdb) stepi
../../src/gdb/infrun.c:2237: internal-error: resume: Assertion `sig != GDB_SIGNAL_0' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.
Quit this debugging session? (y or n)
FAIL: gdb.arch/i386-bp_permanent.exp: Single stepping past permanent breakpoint. (GDB internal error)
The assertion expects that the only reason we currently need to step a
breakpoint instruction is when we have a signal to deliver. But when
stepping a permanent breakpoint (with or without a signal) we also
reach this code.
The assertion is correct and the permanent breakpoints skipping code
is wrong.
Consider the case of the user doing "step/stepi" when stopped at a
permanent breakpoint. GDB's `resume' calls the
gdbarch_skip_permanent_breakpoint hook and then happily continues
stepping:
/* Normally, by the time we reach `resume', the breakpoints are either
removed or inserted, as appropriate. The exception is if we're sitting
at a permanent breakpoint; we need to step over it, but permanent
breakpoints can't be removed. So we have to test for it here. */
if (breakpoint_here_p (aspace, pc) == permanent_breakpoint_here)
{
gdbarch_skip_permanent_breakpoint (gdbarch, regcache);
}
But since gdbarch_skip_permanent_breakpoint already advanced the PC
manually, this ends up executing the instruction that is _after_ the
breakpoint instruction. The user-visible result is that a single-step
steps two instructions.
The gdb.arch/i386-bp_permanent.exp test is actually ensuring that
that's indeed how things work. It runs to an int3 instruction, does
"stepi", and checks that "leave" was executed with that "stepi". Like
this:
(gdb) b *0x0804848c
Breakpoint 2 at 0x804848c
(gdb) c
Continuing.
Breakpoint 2, 0x0804848c in standard ()
(gdb) disassemble
Dump of assembler code for function standard:
0x08048488 <+0>: push %ebp
0x08048489 <+1>: mov %esp,%ebp
0x0804848b <+3>: push %edi
=> 0x0804848c <+4>: int3
0x0804848d <+5>: leave
0x0804848e <+6>: ret
0x0804848f <+7>: nop
(gdb) si
0x0804848e in standard ()
(gdb) disassemble
Dump of assembler code for function standard:
0x08048488 <+0>: push %ebp
0x08048489 <+1>: mov %esp,%ebp
0x0804848b <+3>: push %edi
0x0804848c <+4>: int3
0x0804848d <+5>: leave
=> 0x0804848e <+6>: ret
0x0804848f <+7>: nop
End of assembler dump.
(gdb)
One would instead expect that a stepi at 0x0804848c stops at
0x0804848d, _before_ the "leave" is executed. This commit changes GDB
this way. Care is taken to make stepping into a signal handler when
the step starts at a permanent breakpoint instruction work correctly.
The patch adjusts gdb.arch/i386-bp_permanent.exp in this direction,
and also makes it work on x86_64 (currently it only works on i*86).
The patch also adds a new gdb.base/bp-permanent.exp test that
exercises many different code paths related to stepping permanent
breakpoints, including the stepping with signals cases. The test uses
"hack/trick" to make it work on all (or most) platforms -- it doesn't
really hard code a breakpoint instruction.
Tested on x86_64 Fedora 20, native and gdbserver.
gdb/
2014-11-12 Pedro Alves <palves@redhat.com>
* infrun.c (resume): Clear the thread's 'stepped_breakpoint' flag.
Rewrite stepping over a permanent breakpoint.
(thread_still_needs_step_over, proceed): Don't set
stepping_over_breakpoint for permanent breakpoints.
(handle_signal_stop): Don't clear stepped_breakpoint. Also pull
single-step breakpoints out of the target on hardware step
targets.
(process_event_stop_test): If stepping a permanent breakpoint
doesn't hit the step-resume breakpoint, delete the step-resume
breakpoint.
(switch_back_to_stepped_thread): Also check if the stepped thread
has advanced already on hardware step targets.
(currently_stepping): Return true if the thread stepped a
breakpoint.
gdb/testsuite/
2014-11-12 Pedro Alves <palves@redhat.com>
* gdb.arch/i386-bp_permanent.c: New file.
* gdb.arch/i386-bp_permanent.exp: Don't skip on x86_64.
(srcfile): Set to i386-bp_permanent.c.
(top level): Adjust to work in both 32-bit and 64-bit modes. Test
that stepi does not execute the 'leave' instruction, instead of
testing it does execute.
* gdb.base/bp-permanent.c: New file.
* gdb.base/bp-permanent.exp: New file.
"permanent"-ness is currently a property of the breakpoint. But, it
should actually be an implementation detail of a _location_. Consider
this bit in infrun.c:
/* Normally, by the time we reach `resume', the breakpoints are either
removed or inserted, as appropriate. The exception is if we're sitting
at a permanent breakpoint; we need to step over it, but permanent
breakpoints can't be removed. So we have to test for it here. */
if (breakpoint_here_p (aspace, pc) == permanent_breakpoint_here)
{
if (gdbarch_skip_permanent_breakpoint_p (gdbarch))
gdbarch_skip_permanent_breakpoint (gdbarch, regcache);
else
error (_("\
The program is stopped at a permanent breakpoint, but GDB does not know\n\
how to step past a permanent breakpoint on this architecture. Try using\n\
a command like `return' or `jump' to continue execution."));
}
This will wrongly skip a non-breakpoint instruction if we have a
multiple location breakpoint where the whole breakpoint was set to
"permanent" because one of the locations happened to be permanent,
even if the one GDB is resuming from is not.
Related, because the permanent breakpoints are only marked as such in
init_breakpoint_sal, we currently miss marking momentary breakpoints
as permanent. A test added by a following patch trips on that.
Making permanent-ness be per-location, and marking locations as such
in add_location_to_breakpoint, the natural place to do this, fixes
this issue...
... and then exposes a latent issue with mark_breakpoints_out. It's
clearing the inserted flag of permanent breakpoints. This results in
assertions failing like this:
Breakpoint 1, main () at testsuite/gdb.base/callexit.c:32
32 return 0;
(gdb) call callexit()
[Inferior 1 (process 15849) exited normally]
gdb/breakpoint.c:12854: internal-error: allegedly permanent breakpoint is not actually inserted
A problem internal to GDB has been detected,
further debugging may prove unreliable.
The call dummy breakpoint, which is a momentary breakpoint, is set on
top of a manually inserted breakpoint instruction, and so is now
rightfully marked as a permanent breakpoint. See "Write a legitimate
instruction at the point where the infcall breakpoint is going to be
inserted." comment in infcall.c.
Re. make_breakpoint_permanent. That's only called by solib-pa64.c.
Permanent breakpoints were actually originally invented for HP-UX [1].
I believe that that call (the only one in the tree) is unnecessary
nowadays, given that nowadays the core breakpoints code analyzes the
instruction under the breakpoint to automatically detect whether it's
setting a breakpoint on top of a breakpoint instruction in the
program. I know close to nothing about HP-PA/HP-UX, though.
[1] https://sourceware.org/ml/gdb-patches/1999-q3/msg00245.html, and
https://sourceware.org/ml/gdb-patches/1999-q3/msg00242.html
In addition to the per-location issue, "permanent breakpoints" are
currently always displayed as enabled=='n':
(gdb) b main
Breakpoint 3 at 0x40053c: file ../../../src/gdb/testsuite/gdb.arch/i386-permbkpt.S, line 29.
(gdb) info breakpoints
Num Type Disp Enb Address What
3 breakpoint keep n 0x000000000040053c ../../../src/gdb/testsuite/gdb.arch/i386-permbkpt.S:29
But OTOH they're always enabled; there's no way to disable them...
In turn, this means that if one adds commands to such a breakpoint,
they're _always_ run:
(gdb) start
Starting program: /home/pedro/gdb/mygit/build/gdb/testsuite/gdb.arch/i386-permbkpt
...
Temporary breakpoint 1, main () at ../../../src/gdb/testsuite/gdb.arch/i386-permbkpt.S:29
29 int3
(gdb) b main
Breakpoint 2 at 0x40053c: file ../../../src/gdb/testsuite/gdb.arch/i386-permbkpt.S, line 29.
(gdb) info breakpoints
Num Type Disp Enb Address What
2 breakpoint keep n 0x000000000040053c ../../../src/gdb/testsuite/gdb.arch/i386-permbkpt.S:29
(gdb) commands
Type commands for breakpoint(s) 2, one per line.
End with a line saying just "end".
>echo "hello!"
>end
(gdb) disable 2
(gdb) start
The program being debugged has been started already.
Start it from the beginning? (y or n) y
Temporary breakpoint 3 at 0x40053c: file ../../../src/gdb/testsuite/gdb.arch/i386-permbkpt.S, line 29.
Starting program: /home/pedro/gdb/mygit/build/gdb/testsuite/gdb.arch/i386-permbkpt
Breakpoint 2, main () at ../../../src/gdb/testsuite/gdb.arch/i386-permbkpt.S:29
29 int3
"hello!"(gdb)
IMO, one should be able to disable such a breakpoint, and GDB should
then behave just like if the user hadn't created the breakpoint in the
first place (that is, report a SIGTRAP).
By making permanent-ness a property of the location, and eliminating
the bp_permanent enum enable_state state ends up fixing that as well.
No tests are added for these changes yet; they'll be added in a follow
up patch, as skipping permanent breakpoints is currently broken and
trips on an assertion in infrun.
Tested on x86_64 Fedora 20, native and gdbserver.
gdb/ChangeLog:
2014-11-12 Pedro Alves <palves@redhat.com>
Mark locations as permanent, not the whole breakpoint.
* breakpoint.c (remove_breakpoint_1, remove_breakpoint): Adjust.
(mark_breakpoints_out): Don't mark permanent breakpoints as
uninserted.
(breakpoint_init_inferior): Use mark_breakpoints_out.
(breakpoint_here_p): Adjust.
(bpstat_stop_status, describe_other_breakpoints): Remove handling
of permanent breakpoints.
(make_breakpoint_permanent): Mark each location as permanent,
instead of marking the breakpoint.
(add_location_to_breakpoint): If the location is permanent, mark
it as such, and as inserted.
(init_breakpoint_sal): Don't make the breakpoint permanent here.
(bp_location_compare, update_global_location_list): Adjust.
(update_breakpoint_locations): Don't make the breakpoint permanent
here.
(disable_breakpoint, enable_breakpoint_disp): Don't skip permanent
breakpoints.
* breakpoint.h (enum enable_state) <bp_permanent>: Delete field.
(struct bp_location) <permanent>: New field.
* guile/scm-breakpoint.c (bpscm_enable_state_to_string): Remove
reference to bp_permanent.
breakpoint.c uses gdbarch_breakpoint_from_pc to determine whether a
breakpoint location points at a permanent breakpoint:
static int
bp_loc_is_permanent (struct bp_location *loc)
{
...
addr = loc->address;
bpoint = gdbarch_breakpoint_from_pc (loc->gdbarch, &addr, &len);
...
if (target_read_memory (loc->address, target_mem, len) == 0
&& memcmp (target_mem, bpoint, len) == 0)
retval = 1;
...
So I think we should default the gdbarch_skip_permanent_breakpoint
hook to advancing the PC by the length of the breakpoint instruction,
as determined by gdbarch_breakpoint_from_pc. I believe that simple
implementation does the right thing for most architectures. If
there's an oddball architecture where that doesn't work, then it
should override the hook, just like it should be overriding the hook
if there was no default anyway.
The only two implementation of skip_permanent_breakpoint are
i386_skip_permanent_breakpoint, for x86, and
hppa_skip_permanent_breakpoint, for PA-RISC/HP-UX
The x86 implementation is trivial, and can clearly be replaced by the
new default.
I don't know about the HP-UX one though, I know almost nothing about
PA. It may well be advancing the PC ends up being equivalent.
Otherwise, it must be that "jump $pc_after_bp" doesn't work either...
Tested on x86_64 Fedora 20 native and gdbserver.
gdb/
2014-11-12 Pedro Alves <palves@redhat.com>
* arch-utils.c (default_skip_permanent_breakpoint): New function.
* arch-utils.h (default_skip_permanent_breakpoint): New
declaration.
* gdbarch.sh (skip_permanent_breakpoint): Now an 'f' function.
Install default_skip_permanent_breakpoint as default method.
* i386-tdep.c (i386_skip_permanent_breakpoint): Delete function.
(i386_gdbarch_init): Don't install it.
* infrun.c (resume): Assume there's always a
gdbarch_skip_permanent_breakpoint implementation.
* gdbarch.h, gdbarch.c: Regenerate.
Linux supports multiple "PID namespaces". Processes in different PID
namespaces have different views of the system process list. Sometimes,
a single process can appear in more than one PID namespace, but with a
different PID in each. When GDB and its target are in different PID
namespaces, various features can break due to the mismatch between
what the target believes its PID to be and what GDB believes its PID
to be. The most visible broken functionality is thread enumeration
silently failing.
This patch explicitly warns users against trying to debug across PID
namespaces.
The patch introduced no new failures in my test suite run on an x86_64
installation of Ubuntu 14.10. It doesn't include a test: writing an
automated test that exercises this code would be very involved because
CLONE_NEWNS requires CAP_SYS_ADMIN; the easier way to reproduce the
problem is to start a new lxc container.
gdb/
2014-11-11 Daniel Colascione <dancol@dancol.org>
Warn about cross-PID-namespace debugging.
* nat/linux-procfs.h (linux_proc_pid_get_ns): New prototype.
* nat/linux-procfs.c (linux_proc_pid_get_ns): New function.
* linux-thread-db.c (check_pid_namespace_match): New function.
(thread_db_inferior_created): Call it.
When searching static symbols, gdb would search over all
expanded symtabs of all objfiles, and if that fails only then
would it search all partial/gdb_index tables of all objfiles.
This means that the user could get a random instance of the
symbol depending on what symtabs have been previously expanded.
Now the search is consistent, searching each objfile completely
before proceeding to the next one.
gdb/ChangeLog:
PR symtab/17564
* symtab.c (lookup_symbol_in_all_objfiles): Delete.
(lookup_static_symbol): Move definition to new location and rewrite.
(lookup_symbol_in_objfile): New function.
(lookup_symbol_global_iterator_cb): Call it.
gdb/testsuite/ChangeLog:
PR symtab/17564
* gdb.base/symtab-search-order.exp: New file.
* gdb.base/symtab-search-order.c: New file.
* gdb.base/symtab-search-order-1.c: New file.
* gdb.base/symtab-search-order-shlib-1.c: New file.
A recent change to eval.c triggered a GCC bug that causes a false positive
"may be used uninitialized" warning in evaluate_subexp_standard. This seems
to be triggered by a specific CFG constructed via setjmp and gotos.
While the GCC bug is in the process of being fixed, there are released
compiler versions (in particular GCC 4.9) in the field that show this
problem. In order to allow compiling GDB with one of those compilers,
this commit slightly reworks the CFG (in an equivalent way) of the
affected function, so that the GCC bug is no longer triggered.
gdb/ChangeLog:
* eval.c (evaluate_subexp_standard): Work around GCC bug 63748.
The in_prologue check in the nexti code is obsolete; this commit
removes that, and then removes the in_prologue function as nothing
else uses it.
Looking at the code in GDB that makes use in_prologue, all we find is
this one caller:
if ((ecs->event_thread->control.step_over_calls == STEP_OVER_NONE)
|| ((ecs->event_thread->control.step_range_end == 1)
&& in_prologue (gdbarch, ecs->event_thread->prev_pc,
ecs->stop_func_start)))
{
/* I presume that step_over_calls is only 0 when we're
supposed to be stepping at the assembly language level
("stepi"). Just stop. */
/* Also, maybe we just did a "nexti" inside a prolog, so we
thought it was a subroutine call but it was not. Stop as
well. FENN */
/* And this works the same backward as frontward. MVS */
end_stepping_range (ecs);
return;
}
This was added by:
commit 100a02e1de
...
From Fernando Nasser:
* infrun.c (handle_inferior_event): Handle "nexti" inside function
prologues.
The mailing list thread is here:
https://sourceware.org/ml/gdb-patches/2001-01/msg00047.html
Not much discussion there, and no test, but looking at the code around
what was patched in that revision, we see that the checks that detect
whether the program has just stepped into a subroutine didn't rely on
the unwinders at all back then.
From 'git show 100a02e1:gdb/infrun.c':
if (stop_pc == ecs->stop_func_start /* Quick test */
|| (in_prologue (stop_pc, ecs->stop_func_start) &&
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
!IN_SOLIB_RETURN_TRAMPOLINE (stop_pc, ecs->stop_func_name))
|| IN_SOLIB_CALL_TRAMPOLINE (stop_pc, ecs->stop_func_name)
|| ecs->stop_func_name == 0)
{
/* It's a subroutine call. */
if ((step_over_calls == STEP_OVER_NONE)
|| ((step_range_end == 1)
&& in_prologue (prev_pc, ecs->stop_func_start)))
{
/* I presume that step_over_calls is only 0 when we're
supposed to be stepping at the assembly language level
("stepi"). Just stop. */
/* Also, maybe we just did a "nexti" inside a prolog,
so we thought it was a subroutine call but it was not.
Stop as well. FENN */
stop_step = 1;
print_stop_reason (END_STEPPING_RANGE, 0);
stop_stepping (ecs);
return;
}
Stripping the IN_SOLIB_RETURN_TRAMPOLINE checks for simplicity, we had:
if (stop_pc == ecs->stop_func_start /* Quick test */
|| in_prologue (stop_pc, ecs->stop_func_start)
|| ecs->stop_func_name == 0)
{
/* It's a subroutine call. */
That is, detecting a subroutine call was based on prologue detection
back then. So the in_prologue check in the current tree only made
sense back then as it was undoing a bad decision the in_prologue check
that used to exist above did.
Today, the check for a subroutine call relies on frame ids instead,
which are stable throughout the function. So we can just remove the
in_prologue check for nexti, and the whole in_prologue function along
with it.
Tested on x86_64 Fedora 20, and also by nexti-ing manually a prologue.
gdb/
2014-11-07 Pedro Alves <palves@redhat.com>
* infrun.c (process_event_stop_test) <subroutine check>: Don't
check if we did a "nexti" inside a prologue.
* symtab.c (in_prologue): Delete function.
* symtab.h (in_prologue): Delete declaration.
"aux" doesn't contribute anything to the name, and it makes the
reader wonder what it's supposed to mean.
gdb/ChangeLog:
* symtab.c (lookup_local_symbol): Renamed from lookup_symbol_aux_local.
All callers updated.
(lookup_symbol_in_all_objfiles): Renamed from
lookup_symbol_aux_symtabs. All callers updated.
(lookup_symbol_via_quick_fns): Renamed from lookup_symbol_aux_quick.
All callers updated.
(lookup_symbol_in_objfile_symtabs): Renamed from
lookup_symbol_aux_objfile. All callers updated.
and lookup_static_symbol_aux to lookup_static_symbol.
gdb/ChangeLog:
* symtab.c (lookup_static_symbol): Renamed from
lookup_static_symbol_aux. All callers updated.
(lookup_symbol_in_static_block): Renamed from lookup_symbol_static.
All callers updated.
gdb/ChangeLog:
* block.h (ALL_BLOCK_SYMBOLS_WITH_NAME): New macro.
* block.c (block_lookup_symbol): Use it.
* cp-support.c (make_symbol_overload_list_block): Use it.
* symtab.c (iterate_over_symbols): Use it.
There is another function, lookup_symbol_aux_block, and
the names lookup_block_symbol and lookup_symbol_aux_block don't
convey any real difference between them.
The difference is that lookup_block_symbol lives in the lower level
block API, and lookup_symbol_aux_block lives in the higher level symtab API.
This patch makes this distinction clear.
gdb/ChangeLog:
* symtab.c (lookup_block_symbol): Moved to ...
* block.c (block_lookup_symbol): ... here and renamed.
All callers updated.
* block.h (block_lookup_symbol): Declare.
* symtab.h (lookup_block_symbol): Delete.
Non-primary symtabs share the block vector with their primary symtabs.
In these cases there's no need to use ALL_SYMTABS.
gdb/ChangeLog:
* ada-lang.c (ada_make_symbol_completion_list): Use
ALL_PRIMARY_SYMTABS instead of ALL_SYMTABS.
* symtab.c (lookup_objfile_from_block): Ditto.
obstack_next_free is supposed to return a void*, rather than a char*
as it does currently. Avoid warning on void* arithmetic when
obstack_next_free gets it proper return type.
* cp-valprint.c (cp_print_value_fields): Cast obstack_next_free
to char* before doing pointer arithmetic.
obstack_blank isn't the correct macro to call for shrinking obstacks
since it does size checking.
* charset.c (convert_between_encodings): Shrink obstack using
obstack_blank_fast.
* minsyms.c (install_minimal_symbols): Likewise.
Older versions of ncurses' newterm can't take NULL for their ofp and ifp
parameters. Newer versions can, and they fall back on stdout/stdin if
that is the case.
This patch explicitly passes stdout/stdin to the call to newterm to
avoid segfaulting with older ncurses.
gdb/Changelog:
2014-11-04 Simon Marchi <simon.marchi@ericsson.com>
* tui/tui.c (tui_enable): Pass stdout and stdin to newterm.
Used to be necessary for the thread-hop code, but that's gone now.
Nothing uses this anymore.
gdb/
2014-11-04 Pedro Alves <palves@redhat.com>
* breakpoint.c (breakpoint_thread_match): Delete function.
* breakpoint.h (breakpoint_thread_match): Delete declaration.
When evaluating method calls under EVAL_SKIP, the "object" and the
arguments to the method should also be evaluated under EVAL_SKIP,
instead of skipping to evaluate them as was being done previously.
gdb/ChangeLog:
PR c++/17494
* eval.c (evaluate_subexp_standard): Evaluate the "object" and
the method args also under EVAL_SKIP when evaluating method
calls under EVAL_SKIP.
gdb/testsuite/ChangeLog:
PR c++/17494
* gdb.cp/pr17494.cc: New file.
* gdb.cp/pr17494.exp: New file.
gdb/ChangeLog:
* NEWS: Mention ability add attributes to gdb.Objfile and
gdb.Progspace objects.
* python/py-objfile.c (objfile_object): New member dict.
(objfpy_dealloc): Py_XDECREF dict.
(objfpy_initialize): Initialize dict.
(objfile_getset): Add __dict__.
(objfile_object_type): Set tp_dictoffset member.
* python/py-progspace.c (progspace_object): New member dict.
(pspy_dealloc): Py_XDECREF dict.
(pspy_initialize): Initialize dict.
(pspace_getset): Add __dict__.
(pspace_object_type): Set tp_dictoffset member.
gdb/doc/ChangeLog:
* python.texi (Progspaces In Python): Document ability to add
random attributes to gdb.Progspace objects.
(Objfiles In Python): Document ability to add random attributes to
gdb.objfile objects.
gdb/testsuite/ChangeLog:
* gdb.python/py-objfile.exp: Add tests for setting random attributes
in objfiles.
* gdb.python/py-progspace.exp: Add tests for setting random attributes
in progspaces.
In gdb/command/prompt.py:before_prompt_hook, the '\' in the new prompt
is replaced with '\\', shown as below,
> def before_prompt_hook(self, current):
> if self.value is not '':
> newprompt = gdb.prompt.substitute_prompt(self.value)
> return newprompt.replace('\\', '\\\\')
> else:
> return None
I don't see any explanations on this in comments nor email. As doc
said, "set extended-prompt \w" substitute the current working
directory, but it prints something different from what pwd or
os.getcwdu() prints on mingw32 host.
(gdb) python print os.getcwdu()^M
\\build2-lucid-cs\yqi\yqi\arm-none-eabi
(gdb) pwd^M
Working directory \\build2-lucid-cs\yqi\yqi\arm-none-eabi
(gdb) set extended-prompt \w
\\\\build2-lucid-cs\\yqi\\yqi\\arm-none-eabi
This makes me think whether the substitution in before_prompt_hook is
necessary or not. This patch is to remove this substitution.
Run gdb.python on x86_64-linux and arm-none-eabi on mingw32 host. No
regressions.
gdb:
2014-10-30 Yao Qi <yao@codesourcery.com>
* python/lib/gdb/command/prompt.py (before_prompt_hook): Don't
replace '\\' with '\\\\'.
infrun.c:
5392 /* Did we find the stepping thread? */
5393 if (tp->control.step_range_end)
5394 {
5395 /* Yep. There should only one though. */
5396 gdb_assert (stepping_thread == NULL);
5397
5398 /* The event thread is handled at the top, before we
5399 enter this loop. */
5400 gdb_assert (tp != ecs->event_thread);
5401
5402 /* If some thread other than the event thread is
5403 stepping, then scheduler locking can't be in effect,
5404 otherwise we wouldn't have resumed the current event
5405 thread in the first place. */
5406 gdb_assert (!schedlock_applies (currently_stepping (tp)));
5407
5408 stepping_thread = tp;
5409 }
Like:
gdb/infrun.c:5406: internal-error: switch_back_to_stepped_thread: Assertion `!schedlock_applies (1)' failed.
The way the assertion is written is assuming that with schedlock=step
we'll always leave threads other than the one with the stepping range
locked, while that's not true with the "next" command. With schedlock
"step", other threads still run unlocked when "next" detects a
function call and steps over it. Whether that makes sense or not,
still, it's documented that way in the manual. If another thread hits
an event that doesn't cause a stop while the nexting thread steps over
a function call, we'll get here and fail the assertion.
The fix is just to adjust the assertion. Even though we found the
stepping thread, we'll still step-over the breakpoint that just
triggered correctly.
Surprisingly, gdb.threads/schedlock.exp doesn't have any test that
steps over a function call. This commits fixes that. This ensures
that "next" doesn't switch focus to another thread, and checks whether
other threads run locked or not, depending on scheduler locking mode
and command. There's a lot of duplication in that file that this ends
cleaning up. There's more that could be cleaned up, but that would
end up an unrelated change, best done separately.
This new coverage in schedlock.exp happens to trigger the internal
error in question, like so:
FAIL: gdb.threads/schedlock.exp: schedlock=step: cmd=next: call_function=1: next to increment (1) (GDB internal error)
FAIL: gdb.threads/schedlock.exp: schedlock=step: cmd=next: call_function=1: next to increment (3) (GDB internal error)
FAIL: gdb.threads/schedlock.exp: schedlock=step: cmd=next: call_function=1: next to increment (5) (GDB internal error)
FAIL: gdb.threads/schedlock.exp: schedlock=step: cmd=next: call_function=1: next to increment (7) (GDB internal error)
FAIL: gdb.threads/schedlock.exp: schedlock=step: cmd=next: call_function=1: next to increment (9) (GDB internal error)
FAIL: gdb.threads/schedlock.exp: schedlock=step: cmd=next: call_function=1: next does not change thread (switched to thread 0)
FAIL: gdb.threads/schedlock.exp: schedlock=step: cmd=next: call_function=1: current thread advanced - unlocked (wrong amount)
That's because we have more than one thread running the same loop, and
while one thread is stepping over a function call, the other thread
hits the step-resume breakpoint of the first, which needs to be
stepped over, and we end up in switch_back_to_stepped_thread exactly
in the problem case.
I think a simpler and more directed test is also useful, to not rely
on internal breakpoint magics. So this commit also adds a test that
has a thread trip on a conditional breakpoint that doesn't cause a
user-visible stop while another thread is stepping over a call. That
currently fails like this:
FAIL: gdb.threads/next-bp-other-thread.exp: schedlock=step: next over function call (GDB internal error)
Tested on x86_64 Fedora 20.
gdb/
2014-10-29 Pedro Alves <palves@redhat.com>
PR gdb/17408
* infrun.c (switch_back_to_stepped_thread): Use currently_stepping
instead of assuming a thread with a stepping range is always
stepping.
gdb/testsuite/
2014-10-29 Pedro Alves <palves@redhat.com>
PR gdb/17408
* gdb.threads/schedlock.c (some_function): New function.
(call_function): New global.
(MAYBE_CALL_SOME_FUNCTION): New macro.
(thread_function): Call it.
* gdb.threads/schedlock.exp (get_args): Add description parameter,
and use it instead of a global counter. Adjust all callers.
(get_current_thread): Use "find current thread" for test message
here rather than having all callers pass down the same string.
(goto_loop): New procedure, factored out from ...
(my_continue): ... this.
(step_ten_loops): Change parameter from test message to command to
use. Adjust.
(list_count): Delete global.
(check_result): New procedure, factored out from duplicate top
level code.
(continue tests): Wrap in with_test_prefix.
(test_step): New procedure, factored out from duplicate top level
code.
(top level): Test "step" in combination with all scheduler-locking
modes. Test "next" in combination with all scheduler-locking
modes, and in combination with stepping over a function call or
not.
* gdb.threads/next-bp-other-thread.c: New file.
* gdb.threads/next-bp-other-thread.exp: New file.
This is more of a readline/terminal issue than a Python one.
PR17372 is a regression in 7.8 caused by the fix for PR17072:
commit 0017922d02
Author: Pedro Alves <palves@redhat.com>
Date: Mon Jul 14 19:55:32 2014 +0100
Background execution + pagination aborts readline/gdb
gdb_readline_wrapper_line removes the handler after a line is
processed. Usually, we'll end up re-displaying the prompt, and that
reinstalls the handler. But if the output is coming out of handling
a stop event, we don't re-display the prompt, and nothing restores the
handler. So the next input wakes up the event loop and calls into
readline, which aborts.
...
gdb/
2014-07-14 Pedro Alves <palves@redhat.com>
PR gdb/17072
* top.c (gdb_readline_wrapper_line): Tweak comment.
(gdb_readline_wrapper_cleanup): If readline is enabled, reinstall
the input handler callback.
The problem is that installing the input handler callback also preps
the terminal, putting it in raw mode and with echo disabled, which is
bad if we're going to call a command that assumes cooked/canonical
mode, and echo enabled, like in the case of the PR, Python's
interactive shell. Another example I came up with that doesn't depend
on Python is starting a subshell with "(gdb) shell /bin/sh" from a
multi-line command. Tests covering both these examples are added.
The fix is to revert the original fix for PR gdb/17072, and instead
restore the callback handler after processing an asynchronous target
event.
Furthermore, calling rl_callback_handler_install when we already have
some input in readline's line buffer discards that input, which is
obviously a bad thing to do while the user is typing. No specific
test is added for that, because I first tried calling it even if the
callback handler was still installed and that resulted in hundreds of
failures in the testsuite.
gdb/
2014-10-29 Pedro Alves <palves@redhat.com>
PR python/17372
* event-top.c (change_line_handler): Call
gdb_rl_callback_handler_remove instead of
rl_callback_handler_remove.
(callback_handler_installed): New global.
(gdb_rl_callback_handler_remove, gdb_rl_callback_handler_install)
(gdb_rl_callback_handler_reinstall): New functions.
(display_gdb_prompt): Call gdb_rl_callback_handler_remove and
gdb_rl_callback_handler_install instead of
rl_callback_handler_remove and rl_callback_handler_install.
(gdb_disable_readline): Call gdb_rl_callback_handler_remove
instead of rl_callback_handler_remove.
* event-top.h (gdb_rl_callback_handler_remove)
(gdb_rl_callback_handler_install)
(gdb_rl_callback_handler_reinstall): New declarations.
* infrun.c (reinstall_readline_callback_handler_cleanup): New
cleanup function.
(fetch_inferior_event): Install it.
* top.c (gdb_readline_wrapper_line) Call
gdb_rl_callback_handler_remove instead of
rl_callback_handler_remove.
(gdb_readline_wrapper_cleanup): Don't call
rl_callback_handler_install.
gdb/testsuite/
2014-10-29 Pedro Alves <palves@redhat.com>
PR python/17372
* gdb.python/python.exp: Test a multi-line command that spawns
interactive Python.
* gdb.base/multi-line-starts-subshell.exp: New file.
While running GDB under Valgrind, I noticed that if the very first
command entered is just <RET>, GDB accesses an uninitialized value:
$ valgrind ./gdb -q -nx
==26790== Memcheck, a memory error detector
==26790== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al.
==26790== Using Valgrind-3.9.0 and LibVEX; rerun with -h for copyright info
==26790== Command: ./gdb -q -nx
==26790==
(gdb)
==26790== Conditional jump or move depends on uninitialised value(s)
==26790== at 0x619DFC: command_line_handler (event-top.c:588)
==26790== by 0x7813D5: rl_callback_read_char (callback.c:220)
==26790== by 0x6194B4: rl_callback_read_char_wrapper (event-top.c:166)
==26790== by 0x61988A: stdin_event_handler (event-top.c:372)
==26790== by 0x61847D: handle_file_event (event-loop.c:762)
==26790== by 0x617964: process_event (event-loop.c:339)
==26790== by 0x617A2B: gdb_do_one_event (event-loop.c:403)
==26790== by 0x617A7B: start_event_loop (event-loop.c:428)
==26790== by 0x6194E6: cli_command_loop (event-top.c:181)
==26790== by 0x60F86B: current_interp_command_loop (interps.c:317)
==26790== by 0x610A34: captured_command_loop (main.c:321)
==26790== by 0x60C728: catch_errors (exceptions.c:237)
==26790==
(gdb)
It's this check here:
/* If we just got an empty line, and that is supposed to repeat the
previous command, return the value in the global buffer. */
if (repeat && p == linebuffer && *p != '\\')
{
The problem is that linebuffer's contents were never initialized at
this point.
gdb/
2014-10-29 Pedro Alves <palves@redhat.com>
* event-top.c (command_line_handler): Clear the first byte of
linebuffer, when it is first allocated.
exiting instead of throwing an error. E.g.:
$ TERM=foo gdb
(gdb) layout asm
Error opening terminal: foo.
$
The problem is that we're calling initscr to initialize the screen.
As mentioned in
http://pubs.opengroup.org/onlinepubs/7908799/xcurses/initscr.html:
If errors occur, initscr() writes an appropriate error message to
standard error and exits.
^^^^^
Instead, we should use newterm:
"A program that needs an indication of error conditions, so it can
continue to run in a line-oriented mode if the terminal cannot support
a screen-oriented program, would also use this function."
After the patch:
$ TERM=foo gdb -q -nx
(gdb) layout asm
Cannot enable the TUI: error opening terminal [TERM=foo]
(gdb)
And then PR tui/17519 is about GDB not validating whether the terminal
has the necessary capabilities when enabling the TUI. If one tries to
enable the TUI with TERM=dumb (and e.g., from a shell within emacs),
GDB ends up with a clear screen, the cursor is placed at the
bottom/right corner of the screen, there's no prompt, typing shows no
echo, and there's no indication of what's going on. c-x,a gets you
out of the TUI, but it's completely non-obvious.
After the patch, we get:
$ TERM=dumb gdb -q -nx
(gdb) layout asm
Cannot enable the TUI: terminal doesn't support cursor addressing [TERM=dumb]
(gdb)
While at it, I've moved all the tui_allowed_p validation to
tui_enable, and expanded the error messages. Previously we'd get:
$ gdb -q -nx -i=mi
(gdb)
layout asm
&"layout asm\n"
&"TUI mode not allowed\n"
^error,msg="TUI mode not allowed"
and:
$ gdb -q -nx -ex "layout asm" > foo
TUI mode not allowed
While now we get:
$ gdb -q -nx -i=mi
(gdb)
layout asm
&"layout asm\n"
&"Cannot enable the TUI when the interpreter is 'mi'\n"
^error,msg="Cannot enable the TUI when the interpreter is 'mi'"
(gdb)
and:
$ gdb -q -nx -ex "layout asm" > foo
Cannot enable the TUI when output is not a terminal
Tested on x86_64 Fedora 20.
gdb/
2014-10-29 Pedro Alves <palves@redhat.com>
PR tui/16138
PR tui/17519
* tui/tui-interp.c (tui_is_toplevel): Delete global.
(tui_allowed_p): Delete function.
* tui/tui.c: Include "interps.h".
(tui_enable): Don't use tui_allowed_p. Error out here with
detailed error messages if the TUI is the top level interpreter,
or if output is not a terminal. Use newterm instead of initscr,
and error out if initializing the terminal fails. Also error out if
the terminal doesn't support cursor addressing.
* tui/tui.h (tui_allowed_p): Delete declaration.
I noticed that with:
$ TERM=dumb ./gdb -q -nx
<c-x,a>
Cannot enable the TUI: terminal doesn't support cursor addressing [TERM=dumb]
(gdb)
The next key the user types is silently eaten.
The problem is that we're throwing an exception while in a readline
callback that isn't prepared for that:
(top-gdb) bt
#0 tui_enable () at /home/pedro/gdb/mygit/build/../src/gdb/tui/tui.c:388
#1 0x000000000051f47b in tui_rl_switch_mode (notused1=1, notused2=1) at /home/pedro/gdb/mygit/build/../src/gdb/tui/tui.c:101
#2 0x0000000000768d6f in _rl_dispatch_subseq (key=1, map=0xd069c0 <emacs_ctlx_keymap>, got_subseq=0) at /home/pedro/gdb/mygit/build/../src/readline/readline.c:774
#3 0x0000000000768acb in _rl_dispatch_callback (cxt=0x1ce6190) at /home/pedro/gdb/mygit/build/../src/readline/readline.c:686
#4 0x000000000078120b in rl_callback_read_char () at /home/pedro/gdb/mygit/build/../src/readline/callback.c:170
#5 0x0000000000619445 in rl_callback_read_char_wrapper (client_data=0x0) at /home/pedro/gdb/mygit/build/../src/gdb/event-top.c:166
#6 0x000000000061981b in stdin_event_handler (error=0, client_data=0x0) at /home/pedro/gdb/mygit/build/../src/gdb/event-top.c:372
#7 0x000000000061840e in handle_file_event (data=...) at /home/pedro/gdb/mygit/build/../src/gdb/event-loop.c:762
#8 0x00000000006178f5 in process_event () at /home/pedro/gdb/mygit/build/../src/gdb/event-loop.c:339
#9 0x00000000006179bc in gdb_do_one_event () at /home/pedro/gdb/mygit/build/../src/gdb/event-loop.c:403
#10 0x0000000000617a0c in start_event_loop () at /home/pedro/gdb/mygit/build/../src/gdb/event-loop.c:428
Here, in _rl_dispatch_subseq:
769
770 rl_executing_keymap = map;
771
772 rl_dispatching = 1;
773 RL_SETSTATE(RL_STATE_DISPATCHING);
774 (*map[key].function)(rl_numeric_arg * rl_arg_sign, key);
775 RL_UNSETSTATE(RL_STATE_DISPATCHING);
776 rl_dispatching = 0;
777
778 /* If we have input pending, then the last command was a prefix
779 command. Don't change the state of rl_last_func. Otherwise,
GDB is called from line 774, but longjmp'ing at that point leaves
rl_dispatching and RL_STATE_DISPATCHING set.
Fix this by wrapping tui_rl_switch_mode in a TRY_CATCH.
gdb/
2014-10-29 Pedro Alves <palves@redhat.com>
* tui/tui.c (tui_rl_switch_mode): Wrap tui_enable/tui_disable in
TRY_CATCH.
We are trying to insert a breakpoint on line 4 for the following
Ada code.
3 procedure STR is
4 XX : String (1 .. Blocks.Sz) := (others => 'X'); -- STOP
5 K : Integer;
6 begin
7 K := 13;
The code generated on ARM (-march=armv7-m) starts like this:
(gdb) disass str'address
Dump of assembler code for function _ada_str:
--# Line str.adb:3
0x08000014 <+0>: push {r4, r7, lr}
0x08000016 <+2>: sub sp, #28
0x08000018 <+4>: add r7, sp, #0
0x0800001a <+6>: mov r3, sp
0x0800001c <+8>: mov r4, r3
--# Line str.adb:4
0x0800001e <+10>: ldr r3, [pc, #84] ; (0x8000074 <_ada_str+96>)
0x08000020 <+12>: ldr r3, [r3, #0]
0x08000022 <+14>: str r3, [r7, #20]
0x08000024 <+16>: ldr r3, [r7, #20]
[...]
When computing the address related to str.adb:4, GDB correctly
resolves it to 0x0800001e first, but then considers the next
3 instructions as being part of the prologue because it thinks
they are part of stack-protector code. As a result, instead
of inserting the breakpoint at line 4, it skips those instruction
and consequently the rest of the instructions until the start
of the next line, which his line 7.
The stack-protector code is expected to start like this...
ldr Rn, .Label
....
.Lable:
.word __stack_chk_guard
... but the implementation actually accepts a sequence where
the ldr location points to an address for which there is no symbol.
It only aborts if the address points to a symbol which is not
__stack_chk_guard.
Since the __stack_chk_guard symbol is always expected to exist
when used (it lives in .dynsym), this patch fixes the issue by
requiring that the ldr gets the address of the __stack_chk_guard
symbol. If the address could not be resolved, then it rejects
the sequence as being stack-protector code.
gdb/ChangeLog:
* arm-tdep.c (arm_skip_stack_protector): Return early if
address loaded by first "ldr" instruction does not have
a corresponding minimal symbol. Update comment.
Tested on arm-eabi using AdaCore's testsuite.
Tested on arm-linux-gnueabi by Yao as well.
This patch fixes the bug in my patch skipping stack protector
https://www.sourceware.org/ml/gdb-patches/2010-12/msg00110.html
In my skipping stack protector patch, I misunderstood the constant vs.
immediate on instruction encodings, and treated immediate as constant
by mistake. The instruction 'ldr Rd, [PC, #immed]' loads the
address of __stack_chk_guard to Rd, and #immed is an offset from PC.
We should get the __stack_chk_guard from *(pc + #immed).
As a result of this mistake, arm_analyze_load_stack_chk_guard returns
the wrong address of __stack_chk_guard, and the symbol
__stack_chk_guard can't be found. However, we continue to match the
following instructions when symbol isn't found, so the code still
works. In other words, the code just matches the instruction pattern
without checking __stack_chk_guard symbol correctly.
Joel's patch <https://sourceware.org/ml/gdb-patches/2014-10/msg00605.html>
makes the heuristics stricter that we stop matching instructions if
symbol __stack_chk_guard isn't found. Then the bug is exposed. This
patch is to correct the load address computation for ldr instruction,
and it fixes some fails in gdb.mi/gdb792.exp on armv4t both arm and
thumb mode.
Regression tested on arm-linux-gnueabi target with
{armv4t, armv7-a} x {marm, mthumb} x {-fstack-protector,-fno-stack-protector}
gdb:
2014-10-29 Yao Qi <yao@codesourcery.com>
* arm-tdep.c (arm_analyze_load_stack_chk_guard): Compute the
loaded address correctly of ldr instruction.
TL;DR - if we step an instruction that is as long as
decr_pc_after_break (1-byte on x86) right after removing the
breakpoint at PC, in non-stop mode, adjust_pc_after_break adjusts the
PC, but it shouldn't.
In non-stop mode, when a breakpoint is removed, it is moved to the
"moribund locations" list. This is because other threads that are
running may have tripped on that breakpoint as well, and we haven't
heard about it. When a trap is reported, we check if perhaps it was
such a deleted breakpoint that caused the trap. If so, we also need
to adjust the PC (decr_pc_after_break).
Now, say that, on x86:
- a breakpoint was placed at an address where we have an instruction
of the same length as decr_pc_after_break on this arch (1 on x86).
- the breakpoint is removed, and thus put on the moribund locations
list.
- the thread is single-stepped.
As there's no breakpoint inserted at PC anymore, the single-step
actually executes the 1-byte instruction normally. GDB should _not_
adjust the PC for the resulting SIGTRAP. But, adjust_pc_after_break
confuses the step SIGTRAP reported for this single-step as being a
SIGTRAP for the moribund location of the breakpoint that used to be at
the previous PC, and so infrun applies the decr_pc_after_break
adjustment incorrectly.
The confusion comes from the special case mentioned in the comment:
static void
adjust_pc_after_break (struct execution_control_state *ecs)
{
...
As a special case, we could have hardware single-stepped a
software breakpoint. In this case (prev_pc == breakpoint_pc),
we also need to back up to the breakpoint address. */
if (thread_has_single_step_breakpoints_set (ecs->event_thread)
|| !ptid_equal (ecs->ptid, inferior_ptid)
|| !currently_stepping (ecs->event_thread)
|| (ecs->event_thread->stepped_breakpoint
&& ecs->event_thread->prev_pc == breakpoint_pc))
regcache_write_pc (regcache, breakpoint_pc);
The condition that incorrectly triggers is the
"ecs->event_thread->prev_pc == breakpoint_pc" one.
Afterwards, the next resume resume re-executes an instruction that had
already executed, which if you're lucky, results in the inferior
crashing. If you're unlucky, you'll get silent bad behavior...
The fix is to remember that we stepped a breakpoint. Turns out the
only case we step a breakpoint instruction today isn't covered by the
testsuite. It's the case of a 'handle nostop" signal arriving while a
step is in progress _and_ we have a software watchpoint, which forces
always single-stepping. This commit extends sigstep.exp to cover
that, and adds a new test for the adjust_pc_after_break issue.
Tested on x86_64 Fedora 20, native and gdbserver.
gdb/
2014-10-28 Pedro Alves <palves@redhat.com>
PR gdb/12623
* gdbthread.h (struct thread_info) <stepped_breakpoint>: New
field.
* infrun.c (resume) <stepping breakpoint instruction>: Set the
thread's stepped_breakpoint field. Skip if reverse debugging.
Add comment.
(init_thread_stepping_state, handle_signal_stop): Clear the
thread's stepped_breakpoint field.
gdb/testsuite/
2014-10-28 Pedro Alves <palves@redhat.com>
PR gdb/12623
* gdb.base/sigstep.c (no_handler): New global.
(main): If 'no_handler is true, set the signal handlers to
SIG_IGN.
* gdb.base/sigstep.exp (breakpoint_over_handler): Add
with_sw_watch and no_handler parameters. Handle them.
(top level) <stepping over handler when stopped at a breakpoint
test>: Add a test axis for testing with a software watchpoint, and
another for testing with the signal handler set to SIG_IGN.
* gdb.base/step-sw-breakpoint-adjust-pc.c: New file.
* gdb.base/step-sw-breakpoint-adjust-pc.exp: New file.
In https://sourceware.org/ml/gdb-patches/2014-10/msg00652.html, Sandra
shows a target that was broken by the recent update_thread_list
optimization:
(gdb) target remote qa8-centos32-cs:10514
...
(gdb) continue
Continuing.
Cannot execute this command without a live selected thread.
(gdb)
The error means that the current thread is in "exited" state when the
continue command is processed. The root of the problem was found
here:
> Sending packet: $Hg0#df...Packet received:
...
> Sending packet: $?#3f...Packet received: S00
> Sending packet: $qfThreadInfo#bb...Packet received: l
> Sending packet: $Hc-1#09...Packet received:
> Sending packet: $qC#b4...Packet received: unset
This target doesn't really support threads (no thread indication in
stop reply packets; no support for qC), but then supports
qfThreadInfo, and returns an empty thread list to GDB.
See https://sourceware.org/ml/gdb-patches/2014-10/msg00665.html for
why the target does that.
As remote_update_thread_list deletes threads from GDB's list that are
not found in the thread list that the target reports, the result is
that GDB deletes the "fake" main thread that GDB added itself. (As
that thread is currently selected, it is marked "exited" instead of
being deleted straight away.)
This commit avoids deleting the main thread in this scenario.
gdb/
2014-10-27 Pedro Alves <palves@redhat.com>
* remote.c (remote_thread_alive): New, factored out from ...
(remote_thread_alive): ... this.
(remote_update_thread_list): Bail out before deleting threads if
the target returned an empty list, and, the current thread has a
magic/fake ptid.
I noticed that "si" behaves differently when a "handle nostop" signal
arrives while the step is in progress, depending on whether the
program was stopped at a breakpoint when "si" was entered.
Specifically, in case GDB needs to step off a breakpoint, the handler
is skipped and the program stops in the next "mainline" instruction.
Otherwise, the "si" stops in the first instruction of the signal
handler.
I was surprised the testsuite doesn't catch this difference. Turns
out gdb.base/sigstep.exp covers a bunch of cases related to stepping
and signal handlers, but does not test stepi nor nexti, only
step/next/continue.
My first reaction was that stopping in the signal handler was the
correct thing to do, as it's where the next user-visible instruction
that is executed is. I considered then "nexti" -- a signal handler
could be reasonably considered a subroutine call to step over, it'd
seem intuitive to me that "nexti" would skip it.
But then, I realized that signals that arrive while a plain/line
"step" is in progress _also_ have their handler skipped. A user might
well be excused for being confused by this, given:
(gdb) help step
Step program until it reaches a different source line.
And the signal handler's sources will be in different source lines,
after all.
I think that having to explain that "stepi" steps into handlers, (and
that "nexti" wouldn't according to my reasoning above), while "step"
does not, is a sign of an awkward interface.
E.g., if a user truly is interested in stepping into signal handlers,
then it's odd that she has to either force the signal to "handle
stop", or recall to do "stepi" whenever such a signal might be
delivered. For that use case, it'd seem nicer to me if "step" also
stepped into handlers.
This suggests to me that we either need a global "step-into-handlers"
setting, or perhaps better, make "handle pass/nopass stop/nostop
print/noprint" have have an additional axis - "handle
stepinto/nostepinto", so that the user could configure whether
handlers for specific signals should be stepped into.
In any case, I think it's simpler (and thus better) for all step
commands to behave the same. This commit thus makes "si/ni" skip
handlers for "handle nostop" signals that arrive while the command was
already in progress, like step/next do.
To be clear, nothing changes if the program was stopped for a signal,
and the user enters a stepping command _then_ -- GDB still steps into
the handler. The change concerns signals that don't cause a stop and
that arrive while the step is in progress.
Tested on x86_64 Fedora 20, native and gdbserver.
gdb/
2014-10-27 Pedro Alves <palves@redhat.com>
* infrun.c (handle_signal_stop): Also skip handlers when a random
signal arrives while handling a "stepi" or a "nexti". Set the
thread's 'step_after_step_resume_breakpoint' flag.
gdb/doc/
2014-10-27 Pedro Alves <palves@redhat.com>
* gdb.texinfo (Continuing and Stepping): Add cross reference to
info on stepping and signal handlers.
(Signals): Explain stepping and signal handlers. Add context
index entry, and cross references.
gdb/testsuite/
2014-10-27 Pedro Alves <palves@redhat.com>
* gdb.base/sigstep.c (dummy): New global.
(main): Issue a couple writes to the new global.
* gdb.base/sigstep.exp (get_next_pc, test_skip_handler): New
procedures.
(skip_over_handler): Use test_skip_handler.
(top level): Call skip_over_handler for stepi and nexti too.
(breakpoint_over_handler): Use test_skip_handler.
(top level): Call breakpoint_over_handler for stepi and nexti too.
When running GDB's reverse debugging testsuite against a few ARM
multilibs, i noticed failures in the machinestate* testcases.
Further investigation showed that push and pop instruction encodings
A1 and A2 were not being handled properly, thus we missed saving
important contents from registers and memory. When going backwards,
such contents were not restored and thus we ended up with a corrupted
state that did not correspond to the real values we had at a
particular point in time.
Attached is a patch that fixes around 36 failures for both
gdb.reverse/machinestate.exp and
gdb.reverse/machinestate-precsave.exp testcases, making them fully
pass. This is for both armv7 and armv4. I still see failures for
armv4 thumb though, so it needs a bit more investigation.
I see no regressions due to this patch for armv7, armv7 thumb, armv4
and armv4 thumb.
gdb/ChangeLog:
* arm-tdep.c (INSN_S_L_BIT_NUM): Document.
(arm_record_ld_st_imm_offset): Reimplement to cover all
load/store cases for ARM opcode 010.
(arm_record_ld_st_multiple): Reimplement to cover all
load/store cases for ARM opcode 100.
