Using the 'catch-signal' test from the testsuite, on x86_64 Cygwin:
$ ./gdb testsuite/outputs/gdb.base/catch-signal/catch-signal.exe
[...]
(gdb) catch signal
Catchpoint 1 (standard signals)
(gdb) r
[...]
Catchpoint 1 (signal SIGHUP), main () at
../../../gdb/testsuite/gdb.base/catch-signal.c:40
40 raise (SIGHUP); /* second HUP */
(gdb) c
Continuing.
main () at ../../../gdb/testsuite/gdb.base/catch-signal.c:40
40 raise (SIGHUP); /* second HUP */
Failed to resume program execution (ContinueDebugEvent failed, error 87)
(gdb)
This error occurs because when handle_output_debug_string processes a Cygwin
signal message, it re-writes current_event.dwThreadId to reflect the thread that
the signal will be delivered to, which can be different to the thread reporting
the signal.
Altering current_event.dwThreadId() will cause ContinueDebugEvent() to be
applied to the wrong thread and fail.
So, rather than re-writing the thread id in current_event, use the thread
id by returning it.
With this patch applied this test now yields the expected result:
$ ./gdb testsuite/outputs/gdb.base/catch-signal/catch-signal.exe
[...]
(gdb) catch signal
Catchpoint 1 (standard signals)
(gdb) r
[...]
Catchpoint 1 (signal SIGHUP), main () at
../../../gdb/testsuite/gdb.base/catch-signal.c:40
40 raise (SIGHUP); /* second HUP */
(gdb) c
Continuing.
Catchpoint 1 (signal SIGHUP), main () at
../../../gdb/testsuite/gdb.base/catch-signal.c:42
42 raise (SIGHUP); /* third HUP */
(gdb)
gdb/ChangeLog:
2015-04-22 Jon Turney <jon.turney@dronecode.org.uk>
* windows-nat.c (handle_output_debug_string): Don't change
current_event.dwThreadId.
(get_windows_debug_event): Use thread_id, rather than relying on
current_event.dwThreadId being changed.
Using the 'catch-signal' test from the testsuite, on x86_64 Cygwin:
$ ./gdb testsuite/outputs/gdb.base/catch-signal/catch-signal.exe
[...]
(gdb) catch signal
Catchpoint 1 (standard signals)
(gdb) r
[...]
Catchpoint 1 (signal SIGHUP), main () at
../../../gdb/testsuite/gdb.base/catch-signal.c:40
40 raise (SIGHUP); /* second HUP */
(gdb) c
Continuing.
[hangs]
This is due to a defect in the way Cygwin signals are handled: When
handle_output_debug_string processes a Cygwin signal message, it re-writes
current_event.dwThreadId to reflect the thread that the signal will be delivered
to.
Subsequently, the call to ContinueDebugEvent will fail, because we're trying to
resume the wrong thread. GDB is then stuck waiting forever for another event
that will never come.
This patch doesn't fix the problem, it just adds appropriate error handling.
Using error() seems appropriate here, if ContinueDebugEvent() fails, the
inferior is in an unknown state and we will probably not be debugging it
anymore.
With this patch applied, resuming the execution of the program now yields:
$ ./gdb testsuite/outputs/gdb.base/catch-signal/catch-signal.exe
[...]
(gdb) catch signal
Catchpoint 1 (standard signals)
(gdb) r
[...]
Catchpoint 1 (signal SIGHUP), main () at
../../../gdb/testsuite/gdb.base/catch-signal.c:40
40 raise (SIGHUP); /* second HUP */
(gdb) c
Continuing.
main () at ../../../gdb/testsuite/gdb.base/catch-signal.c:40
40 raise (SIGHUP); /* second HUP */
Failed to resume program execution (ContinueDebugEvent failed, error 87)
(gdb)
gdb/ChangeLog:
2015-04-22 Jon Turney <jon.turney@dronecode.org.uk>
* windows-nat.c (windows_continue): Report an error if
ContinueDebugEvent() fails.
Problem reported as PR pascal/17815
Part 1/3: Remember the case pattern that allowed finding a field of this.
File gdb/p-exp.y modified
This is the fix in the pascal parser (p-exp.y),
to avoid the error that GDB does find normal variables
case insensitively, but not fields of this,
inside a class or object method.
Part 2/3: Add "class" option for pascal compiler
File gdb/testsuite/lib/pascal.exp
This part of the patch series is unchanged.
It adds class option to pascal compiler
which adds the required command line option to
accept pascal class types.
Part 3/3:
New file: gdb/testsuite/gdb.pascal/case-insensitive-symbols.exp
New file: gdb/testsuite/gdb.pascal/case-insensitive-symbols.pas
Here is an updated version of this test, using Pedro's suggestions.
Test to check that PR 17815 is fixed.
This patch extends the rl78 prologue analyzer so that it can recognize
this kind of prologue:
0x119f <main>: movw ax, sp
0x11a1 <main+2>: subw ax, #0x1fa6
0x11a4 <main+5>: movw sp, ax
The test case for gdb.base/miscexprs.exp is now compiled to generate
that sequence instead of a much longer and more inefficient sequence.
gdb/ChangeLog:
* rl78-tdep.c (RL78_SP_ADDR): Define.
(opc_reg_to_gdb_regnum): New static function.
(rl78_analyze_prologue): Recognize instructions forming slightly
more interesting prologues.
Code in update_dprintf_command_list performed a duplicated memory
allocation which caused an obvious memory leak. This removes the
duplication.
gdb/
2015-04-19 Gabriel Krisman Bertazi <gabriel@krisman.be>
* breakpoint.c (update_dprintf_command_list): Remove duplicated
xmalloc.
gdb/
* reply_mig_hack.awk: Don't bother to declare an intermediate
function pointer variable.
... allowing us to simplify the parsing a little bit. And, instead of
"warning: initialization from incompatible pointer type", we now get "warning:
function called through a non-compatible type". Oh well.
gdb/ChangeLog:
* solib-svr4.c (svr4_exec_displacement): Rename outer "displacement"
to "exec_displacement" to avoid confusion with inner use of the name.
This patch is to cherry-pick part of Pedro's patch here
https://sourceware.org/ml/gdb-patches/2015-04/msg00527.html in which
zero is returned if the HW point isn't supported.
In arm-linux native gdb testing on a board doesn't support HW breakpoint,
without this patch, the output in gdb.base/breakpoint-in-ro-region.exp is like:
(gdb) hbreak *0x83bc^M
Hardware breakpoints used exceeds limit.^M
(gdb) PASS: gdb.base/breakpoint-in-ro-region.exp: probe hbreak support (support)
with this patch, the output becomes:
(gdb) hbreak *0x83bc^M
No hardware breakpoint support in the target.^M
(gdb) PASS: gdb.base/breakpoint-in-ro-region.exp: probe hbreak support (no support)
As a result, the following fails are fixed.
-FAIL: gdb.base/breakpoint-in-ro-region.exp: always-inserted off: auto-hw on: step in ro region (cannot insert hw break)
-FAIL: gdb.base/breakpoint-in-ro-region.exp: always-inserted off: auto-hw on: thread advanced
-FAIL: gdb.base/breakpoint-in-ro-region.exp: always-inserted on: auto-hw on: step in ro region (cannot insert hw break)
-FAIL: gdb.base/breakpoint-in-ro-region.exp: always-inserted on: auto-hw on: thread advanced
gdb:
2015-04-17 Pedro Alves <palves@redhat.com>
* arm-linux-nat.c (arm_linux_can_use_hw_breakpoint): Return zero
if HW point of TYPE isn't supported.
The return value of target_can_use_hardware_watchpoint isn't well
documented, so this patch is to update the comments to reflect the
fact. This patch also removes a trailing ";" which is picked up
from Pedro's patch https://sourceware.org/ml/gdb-patches/2015-04/msg00527.html
gdb:
2015-04-17 Yao Qi <yao.qi@linaro.org>
Pedro Alves <palves@redhat.com>
* target.h (target_can_use_hardware_watchpoint): Update comments.
Remove trailing ";".
This commit modifies remote_add_inferior to take an extra argument
try_open_exec. If this is nonzero, remote_add_inferior will attempt
to open this inferior's executable as the main executable if no main
executable is open already. Callers are updated appropriately.
With this commit, remote debugging can now be initiated using only a
"target remote" or "target extended-remote" command; no "set sysroot"
or "file" commands are required, e.g.
bash$ gdb -q
(gdb) target remote | gdbserver - /bin/sh
Remote debugging using | gdbserver - /bin/sh
Process /bin/sh created; pid = 32166
stdin/stdout redirected
Remote debugging using stdio
Reading symbols from target:/bin/bash...
One testcase required updating as a result of this commit. The test
checked that GDB's "info files" command does not crash if no main
executable is open, and relied on GDB's inability to access the main
executable over the remote protocol. The test was updated to inhibit
this new behavior.
gdb/ChangeLog:
* remote.c (remote_add_inferior): New argument try_open_exec.
If nonzero, attempt to open the inferior's executable file as
the main executable if no main executable is open already.
All callers updated.
* NEWS: Mention that GDB now supports automatic location and
retrieval of executable + files from remote targets.
gdb/doc/ChangeLog:
* gdb.texinfo (Connecting to a Remote Target): Mention that
GDB can access program files from remote targets that support
qXfer:exec-file:read and Host I/O packets.
gdb/testsuite/ChangeLog:
* gdb.server/server-exec-info.exp: Inhibit GDB from accessing
the main executable over the remote protocol.
This commit adds a new packet "qXfer:exec-file:read" to the remote
protocol that can be used to obtain the pathname of the file that
was executed to create a process on the remote system. Support for
this packet is added to GDB and remote_ops.to_pid_to_exec_file is
implemented using it.
gdb/ChangeLog:
* target.h (TARGET_OBJECT_EXEC_FILE): New enum value.
* remote.c (PACKET_qXfer_exec_file): Likewise.
(remote_protocol_features): Register the
"qXfer:exec-file:read" feature.
(remote_xfer_partial): Handle TARGET_OBJECT_EXEC_FILE.
(remote_pid_to_exec_file): New function.
(init_remote_ops): Initialize to_pid_to_exec_file.
(_initialize_remote): Register new "set/show remote
pid-to-exec-file-packet" command.
* NEWS: Announce new qXfer:exec-file:read packet.
gdb/doc/ChangeLog:
* gdb.texinfo (Remote Configuration): Document the "set/show
remote pid-to-exec-file-packet" command.
(General Query Packets): Document the qXfer:exec-file:read
qSupported features. Document the qXfer:exec-file:read packet.
This commit introduces a new function linux_proc_pid_to_exec_file
that shared Linux code can use to discover the filename of the
executable that was run to create a process on the system.
gdb/ChangeLog:
* nat/linux-procfs.h (linux_proc_pid_to_exec_file):
New declaration.
* nat/linux-procfs.c (linux_proc_pid_to_exec_file):
New function, factored out from...
* linux-nat.c (linux_child_pid_to_exec_file): ...here.
This commit updates exec_file_locate_attach to use exec_file_find
to compute the full pathname of the main executable in some cases.
The net effect of this is that the main executable's path will be
prefixed with gdb_sysroot in the same way that shared library paths
currently are.
gdb/ChangeLog:
* exec.c (solist.h): New include.
(exec_file_locate_attach): Prefix absolute executable
paths with gdb_sysroot if set.
* NEWS: Mention that executable paths may be prepended
with sysroot.
gdb/doc/ChangeLog:
* gdb.texinfo (set sysroot): Document that "set sysroot" also
applies to executable paths if supplied to GDB as absolute.
This commit adds a new function, exec_file_find, which computes the
full pathname of the main executable in much the same way solib_find
does for pathnames of shared libraries. The bulk of the existing
solib_find was moved into a new static function solib_find_1, with
exec_file_find and solib_find being small wrappers for solib_find_1.
gdb/ChangeLog:
* solist.h (exec_file_find): New declaration.
* solib.c (solib_find_1): New function, factored out from...
(solib_find): ...here.
(exec_file_find): New function.
This commit adds a new function, exec_file_locate_attach, which works
like exec_file_attach except that, instead of a filename argument, it
takes an integer process ID and attempts to determine the executable
filename from that.
gdb/ChangeLog:
* gdbcore.h (exec_file_locate_attach): New declaration.
* exec.c (exec_file_locate_attach): New function, factored
out from...
* infcmd.c (attach_command_post_wait): ...here.
Hi,
When I run gdb.threads/non-stop-fair-events.exp on arm-linux target,
I see the following message in the debugging log,
displaced: breakpoint is gone: Thread 22518, step(1)^M
Sending packet: $vCont;s:p57f3.57f6#9d...
^^^^^^^^^
GDB sends vCont;s by mistake, and GDBserver fails on assert. GDB
doesn't consider software single step in infrun.c:displaced_step_fixup,
/* Go back to what we were trying to do. */
step = currently_stepping (tp);
if (debug_displaced)
fprintf_unfiltered (gdb_stdlog,
"displaced: breakpoint is gone: %s, step(%d)\n",
target_pid_to_str (tp->ptid), step);
target_resume (ptid, step, GDB_SIGNAL_0);
The patch is to let GDB consider software single step here. It fixes
fails in gdb.threads/non-stop-fair-events.exp on arm.
gdb:
2015-04-16 Yao Qi <yao.qi@linaro.org>
* infrun.c (maybe_software_singlestep): Declare.
(displaced_step_fixup): Call maybe_software_singlestep.
"info fun foo" can be a pain when it's not interruptable,
especially if you're not exactly sure of what you're looking for
and provide something that matches too much.
gdb/ChangeLog:
* dwarf2read.c (dw2_expand_symtabs_matching): Add some QUIT calls.
Some missing parentheses and one itertools.imap (Py2) vs map (Py3) issue.
gdb/ChangeLog:
* python/lib/gdb/command/unwinders.py: Add parentheses.
gdb/testsuite/ChangeLog:
* gdb.python/py-framefilter.py (ErrorFilter.filter): Use map function
if itertools.imap is not present.
* gdb.python/py-objfile.exp: Add parentheses.
* gdb.python/py-type.exp: Same.
* gdb.python/py-unwind-maint.py: Same.
When I "set debug displaced 1" to fix fail in
gdb.base/disp-step-syscall.exp, the debug message is wrong. This
patch is to fix it.
gdb:
2015-04-15 Yao Qi <yao.qi@linaro.org>
* arm-linux-tdep.c (arm_linux_copy_svc): Update debug message.
Hi,
I see this fail on arm-linux target,
FAIL: gdb.base/disp-step-syscall.exp: fork: single step over fork final pc
which is caused by the PC isn't expected after displaced stepping the
svc instruction. The code is:
=> 0xb6ead9a4 <__libc_do_syscall+4>: svc 0
0xb6ead9a6 <__libc_do_syscall+6>: pop {r7, pc}
0xb6ead9a8: nop.w^M
0xb6ead9ac: nop.w
after single step svc instruction, pc should be 0xb6ead9a6, but the
actual value of pc is 0xb6ead9a8. The problem is illustrated by
turning on debug message of displaced stepping,
stepi^M
displaced: stepping Thread 12031 now^M
displaced: saved 0x8574: 02 bc 6a 46 04 b4 01 b4 df f8 10 c0 4d f8 04 cd 03 48 04 4b ff f7 d2 ef ff f7 e8 ef 0d 87 00 00 ^M
displaced: process thumb insn df00 at b6ead9a4^M
displaced: copying svc insn df00^M
displaced: read r7 value 00000078^M
displaced: sigreturn/rt_sigreturn SVC call not in signal trampoline frame^M
displaced: writing insn df00 at 00008574^M
displaced: copy 0xb6ead9a4->0x8574: displaced: check mode of b6ead9a4 instead of 00008574^M
displaced: displaced pc to 0x8574^M
displaced: run 0x8574: 00 df 01 de ^M
displaced: restored Thread 12031 0x8574^M
displaced: PC is apparently 00008576 after SVC step (within scratch space)^M
displaced: writing pc b6ead9a8 <----- WRONG ADDRESS
GDB writes the wrong address back to pc because GDB thinks the
instruction size is 4, which isn't true for thumb instruction.
This patch is to replace 4 with dsc->insn_size.
gdb:
2015-04-15 Yao Qi <yao.qi@linaro.org>
* arm-linux-tdep.c (arm_linux_cleanup_svc): Use
dsc->insn_size instead of 4.
GDB has five places where it pretends to stat for bfd_openr_iovec.
Four of these only set the incoming buffer's st_size, leaving the
other fields unchanged, which is to say very likely populated with
random values from the stack. remote_bfd_iovec_stat was fixed in
0a93529c56714b1da3d7106d3e0300764f8bb81c; this commit fixes the
other four.
gdb/ChangeLog:
* jit.c (mem_bfd_iovec_stat): Zero supplied buffer.
* minidebug.c (lzma_stat): Likewise.
* solib-spu.c (spu_bfd_iovec_stat): Likewise.
* spu-linux-nat.c (spu_bfd_iovec_stat): Likewise.
Recognize NT_X86_XSTATE notes in FreeBSD process cores. Recent
FreeBSD versions include a note containing the XSAVE state for each
thread in the process when XSAVE is in use. The note stores a copy of
the current XSAVE mask in a reserved section of the machine-defined
XSAVE state at the same offset as Linux's NT_X86_XSTATE note.
For native processes, use the PT_GETXSTATE_INFO ptrace request to
determine if XSAVE is enabled, and if so the active XSAVE state mask
(that is, the value of %xcr0 for the target process) as well as the
size of XSAVE state area. Use the PT_GETXSTATE and PT_SETXSTATE requests
to fetch and store the XSAVE state, respectively, in the BSD x86
native targets.
In addition, the FreeBSD amd64 and i386 native targets now include
"read_description" target methods to determine the correct x86 target
description for the current XSAVE mask. On FreeBSD amd64 this also
properly returns an i386 target description for 32-bit binaries which
allows the 64-bit GDB to run 32-bit binaries.
Note that the ptrace changes are in the BSD native targets, not the
FreeBSD-specific native targets since that is where the other ptrace
register accesses occur. Of the other BSDs, NetBSD and DragonFly use
XSAVE in the kernel but do not currently export the extended state via
ptrace(2). OpenBSD does not currently support XSAVE.
bfd/ChangeLog:
* elf.c (elfcore_grok_note): Recognize NT_X86_XSTATE on
FreeBSD.
(elfcore_write_xstatereg): Use correct note name on FreeBSD.
gdb/ChangeLog:
* amd64-tdep.c (amd64_target_description): New function.
* amd64-tdep.h: Export amd64_target_description and tdesc_amd64.
* amd64bsd-nat.c [PT_GETXSTATE_INFO]: New variable amd64bsd_xsave_len.
(amd64bsd_fetch_inferior_registers) [PT_GETXSTATE_INFO]: Handle
x86 extended save area.
(amd64bsd_store_inferior_registers) [PT_GETXSTATE_INFO]: Likewise.
* amd64bsd-nat.h: Export amd64bsd_xsave_len.
* amd64fbsd-nat.c (amd64fbsd_read_description): New function.
(_initialize_amd64fbsd_nat): Set "to_read_description" to
"amd64fbsd_read_description".
* amd64fbsd-tdep.c (amd64fbsd_core_read_description): New function.
(amd64fbsd_supply_xstateregset): New function.
(amd64fbsd_collect_xstateregset): New function.
Add "amd64fbsd_xstateregset".
(amd64fbsd_iterate_over_regset_sections): New function.
(amd64fbsd_init_abi): Set "xsave_xcr0_offset" to
"I386_FBSD_XSAVE_XCR0_OFFSET".
Add "iterate_over_regset_sections" gdbarch method.
Add "core_read_description" gdbarch method.
* i386-tdep.c (i386_target_description): New function.
* i386-tdep.h: Export i386_target_description and tdesc_i386.
* i386bsd-nat.c [PT_GETXSTATE_INFO]: New variable i386bsd_xsave_len.
(i386bsd_fetch_inferior_registers) [PT_GETXSTATE_INFO]: Handle
x86 extended save area.
(i386bsd_store_inferior_registers) [PT_GETXSTATE_INFO]: Likewise.
* i386bsd-nat.h: Export i386bsd_xsave_len.
* i386fbsd-nat.c (i386fbsd_read_description): New function.
(_initialize_i386fbsd_nat): Set "to_read_description" to
"i386fbsd_read_description".
* i386fbsd-tdep.c (i386fbsd_core_read_xcr0): New function.
(i386fbsd_core_read_description): New function.
(i386fbsd_supply_xstateregset): New function.
(i386fbsd_collect_xstateregset): New function.
Add "i386fbsd_xstateregset".
(i386fbsd_iterate_over_regset_sections): New function.
(i386fbsd4_init_abi): Set "xsave_xcr0_offset" to
"I386_FBSD_XSAVE_XCR0_OFFSET".
Add "iterate_over_regset_sections" gdbarch method.
Add "core_read_description" gdbarch method.
* i386fbsd-tdep.h: New file.
Pedro Alves:
The commands that enables aren't even documented in the manual.
Judging from that, I assume that only wdb users would ever really
be using the --xdb switch.
I think it's time to drop "support" for the --xdb switch too. I
looked through the commands that that exposes, the only that looked
potentially interesting was "go", but then it's just an alias
for "tbreak+jump", which can easily be done with "define go...end".
I'd rather free up the "go" name for something potentially
more interesting (either run control, or maybe even unrelated,
e.g., for golang).
gdb/ChangeLog
2015-04-11 Jan Kratochvil <jan.kratochvil@redhat.com>
* NEWS (Changes since GDB 7.9): Add removed -xdb.
* breakpoint.c (command_line_is_silent): Remove xdb_commands
conditional.
(_initialize_breakpoint): Remove xdb_commands for bc, ab, sb, db, ba
and lb.
* cli/cli-cmds.c (_initialize_cli_cmds): Remove xdb_commands for v and
va.
* cli/cli-decode.c (find_command_name_length): Remove xdb_commands
conditional.
* defs.h (xdb_commands): Remove declaration.
* f-valprint.c (_initialize_f_valprint): Remove xdb_commands for lc.
* guile/scm-cmd.c (command_classes): Remove xdb from comment.
* infcmd.c (run_no_args_command, go_command): Remove.
(_initialize_infcmd): Remove xdb_commands for S, go, g, R and lr.
* infrun.c (xdb_handle_command): Remove.
(_initialize_infrun): Remove xdb_commands for lz and z.
* main.c (xdb_commands): Remove variable.
(captured_main): Remove "xdb" from long_options.
(print_gdb_help): Remove --xdb from help.
* python/py-cmd.c (gdbpy_initialize_commands): Remove xdb from comment.
* source.c (_initialize_source): Remove xdb_commands for D, ld, / and ?.
* stack.c (backtrace_full_command, args_plus_locals_info)
(current_frame_command): Remove.
(_initialize_stack): Remove xdb_commands for t, T and l.
* symtab.c (_initialize_symtab): Remove xdb_commands for lf and lg.
* thread.c (_initialize_thread): Remove xdb_commands condition.
* tui/tui-layout.c (tui_toggle_layout_command)
(tui_toggle_split_layout_command, tui_handle_xdb_layout): Remove.
(_initialize_tui_layout): Remove xdb_commands for td and ts.
* tui/tui-regs.c (tui_scroll_regs_forward_command)
(tui_scroll_regs_backward_command): Remove.
(_initialize_tui_regs): Remove xdb_commands for fr, gr, sr, +r and -r.
* tui/tui-win.c (tui_xdb_set_win_height_command): Remove.
(_initialize_tui_win): Remove xdb_commands for U and w.
* utils.c (pagination_on_command, pagination_off_command): Remove.
(initialize_utils): Remove xdb_commands for am and sm.
gdb/doc/ChangeLog
2015-04-11 Jan Kratochvil <jan.kratochvil@redhat.com>
* gdb.texinfo (Mode Options): Remove -xdb.
PPC64 currently fails this test like:
FAIL: gdb.threads/step-over-trips-on-watchpoint.exp: displaced=on: no thread-specific bp: step: step
FAIL: gdb.threads/step-over-trips-on-watchpoint.exp: displaced=on: no thread-specific bp: next: next
FAIL: gdb.threads/step-over-trips-on-watchpoint.exp: displaced=on: no thread-specific bp: continue: continue (the program exited)
FAIL: gdb.threads/step-over-trips-on-watchpoint.exp: displaced=on: with thread-specific bp: step: step
FAIL: gdb.threads/step-over-trips-on-watchpoint.exp: displaced=on: with thread-specific bp: next: next
FAIL: gdb.threads/step-over-trips-on-watchpoint.exp: displaced=on: with thread-specific bp: continue: continue (the program exited)
The problem is that PPC is a non-continuable watchpoints architecture
and the displaced stepping code isn't coping with that correctly. On
such targets/architectures, a watchpoint traps _before_ the
instruction executes/completes. On a watchpoint trap, the PC points
at the instruction that triggers the watchpoint (side effects haven't
happened yet). In order to move past the watchpoint, GDB needs to
remove the watchpoint, single-step, and reinsert the watchpoint, just
like when stepping past a breakpoint.
The trouble is that if GDB is stepping over a breakpoint with
displaced stepping, and the instruction under the breakpoint triggers
a watchpoint, we get the watchpoint SIGTRAP, expecting a finished
(hard or software) step trap. Even though the thread's PC hasn't
advanced yet (must remove watchpoint for that), since we get a
SIGTRAP, displaced_step_fixup thinks the single-step finished
successfuly anyway, and calls gdbarch_displaced_step_fixup, which then
adjusts the thread's registers incorrectly.
The fix is to cancel the displaced step if we trip on a watchpoint.
handle_inferior_event then processes the watchpoint event, and starts
a new step-over, here:
...
/* At this point, we are stopped at an instruction which has
attempted to write to a piece of memory under control of
a watchpoint. The instruction hasn't actually executed
yet. If we were to evaluate the watchpoint expression
now, we would get the old value, and therefore no change
would seem to have occurred.
...
ecs->event_thread->stepping_over_watchpoint = 1;
keep_going (ecs);
return;
...
but this time, since we have a watchpoint to step over, watchpoints
are removed from the target, so the step-over succeeds.
The keep_going/resume changes are necessary because if we're stepping
over a watchpoint, we need to remove it from the target - displaced
stepping doesn't help, the copy of the instruction in the scratch pad
reads/writes to the same addresses, thus triggers the watchpoint
too... So without those changes we keep triggering the watchpoint
forever, never making progress. With non-stop that means we'll need
to pause all threads momentarily, which we can't today. We could
avoid that by removing the watchpoint _only_ from the thread that is
moving past the watchpoint, but GDB is not prepared for that today
either. For remote targets, that would need new packets, so good to
be able to step over it in-line as fallback anyway.
gdb/ChangeLog:
2015-04-10 Pedro Alves <palves@redhat.com>
* infrun.c (displaced_step_fixup): Switch to the event ptid
earlier. If the thread stopped for a watchpoint and the
target/arch has non-continuable watchpoints, cancel the displaced
step.
(resume): Don't start a displaced step if in-line step-over info
is valid.
TL;DR:
When stepping over a breakpoint with displaced stepping, the core must
be notified of all signals, otherwise the displaced step fixup code
confuses a breakpoint trap in the signal handler for the expected trap
indicating the displaced instruction was single-stepped
normally/successfully.
Detailed version:
Running sigstep.exp with displaced stepping on, against my x86
software single-step branch, I got:
FAIL: gdb.base/sigstep.exp: step on breakpoint, to handler: performing step
FAIL: gdb.base/sigstep.exp: next on breakpoint, to handler: performing next
FAIL: gdb.base/sigstep.exp: continue on breakpoint, to handler: performing continue
Turning on debug logs, we see:
(gdb) step
infrun: clear_proceed_status_thread (process 32147)
infrun: proceed (addr=0xffffffffffffffff, signal=GDB_SIGNAL_DEFAULT)
infrun: resume (step=1, signal=GDB_SIGNAL_0), trap_expected=1, current thread [process 32147] at 0x400842
displaced: stepping process 32147 now
displaced: saved 0x400622: 49 89 d1 5e 48 89 e2 48 83 e4 f0 50 54 49 c7 c0
displaced: %rip-relative addressing used.
displaced: using temp reg 2, old value 0x3615eafd37, new value 0x40084c
displaced: copy 0x400842->0x400622: c7 81 1c 08 20 00 00 00 00 00
displaced: displaced pc to 0x400622
displaced: run 0x400622: c7 81 1c 08
LLR: Preparing to resume process 32147, 0, inferior_ptid process 32147
LLR: PTRACE_CONT process 32147, 0 (resume event thread)
linux_nat_wait: [process -1], [TARGET_WNOHANG]
LLW: enter
LNW: waitpid(-1, ...) returned 32147, No child processes
LLW: waitpid 32147 received Alarm clock (stopped)
LLW: PTRACE_CONT process 32147, Alarm clock (preempt 'handle')
LNW: waitpid(-1, ...) returned 0, No child processes
LLW: exit (ignore)
sigchld
infrun: target_wait (-1.0.0, status) =
infrun: -1.0.0 [process -1],
infrun: status->kind = ignore
infrun: TARGET_WAITKIND_IGNORE
infrun: prepare_to_wait
linux_nat_wait: [process -1], [TARGET_WNOHANG]
LLW: enter
LNW: waitpid(-1, ...) returned 32147, No child processes
LLW: waitpid 32147 received Trace/breakpoint trap (stopped)
CSBB: process 32147 stopped by software breakpoint
LNW: waitpid(-1, ...) returned 0, No child processes
LLW: trap ptid is process 32147.
LLW: exit
infrun: target_wait (-1.0.0, status) =
infrun: 32147.32147.0 [process 32147],
infrun: status->kind = stopped, signal = GDB_SIGNAL_TRAP
infrun: TARGET_WAITKIND_STOPPED
displaced: restored process 32147 0x400622
displaced: fixup (0x400842, 0x400622), insn = 0xc7 0x81 ...
displaced: restoring reg 2 to 0x3615eafd37
displaced: relocated %rip from 0x400717 to 0x400937
infrun: stop_pc = 0x400937
infrun: delayed software breakpoint trap, ignoring
infrun: no line number info
infrun: stop_waiting
0x0000000000400937 in __dso_handle ()
1: x/i $pc
=> 0x400937: and %ah,0xa0d64(%rip) # 0x4a16a1
(gdb) FAIL: gdb.base/sigstep.exp: displaced=on: step on breakpoint, to handler: performing step
What should have happened is that the breakpoint hit in the signal
handler should have been presented to the user. But note that
"preempt 'handle'" -- what happened instead is that
displaced_step_fixup confused the breakpoint in the signal handler for
the expected SIGTRAP indicating the displaced instruction was
single-stepped normally/successfully.
This should be affecting all software single-step targets in the same
way.
The fix is to make sure the core sees all signals when displaced
stepping, just like we already must see all signals when doing an
stepping over a breakpoint in-line. We now get:
infrun: target_wait (-1.0.0, status) =
infrun: 570.570.0 [process 570],
infrun: status->kind = stopped, signal = GDB_SIGNAL_ALRM
infrun: TARGET_WAITKIND_STOPPED
displaced: restored process 570 0x400622
infrun: stop_pc = 0x400842
infrun: random signal (GDB_SIGNAL_ALRM)
infrun: signal arrived while stepping over breakpoint
infrun: inserting step-resume breakpoint at 0x400842
infrun: resume (step=0, signal=GDB_SIGNAL_ALRM), trap_expected=0, current thread [process 570] at 0x400842
LLR: Preparing to resume process 570, Alarm clock, inferior_ptid process 570
LLR: PTRACE_CONT process 570, Alarm clock (resume event thread)
infrun: prepare_to_wait
linux_nat_wait: [process -1], [TARGET_WNOHANG]
LLW: enter
LNW: waitpid(-1, ...) returned 0, No child processes
LLW: exit (ignore)
infrun: target_wait (-1.0.0, status) =
infrun: -1.0.0 [process -1],
infrun: status->kind = ignore
sigchld
infrun: TARGET_WAITKIND_IGNORE
infrun: prepare_to_wait
linux_nat_wait: [process -1], [TARGET_WNOHANG]
LLW: enter
LNW: waitpid(-1, ...) returned 570, No child processes
LLW: waitpid 570 received Trace/breakpoint trap (stopped)
CSBB: process 570 stopped by software breakpoint
LNW: waitpid(-1, ...) returned 0, No child processes
LLW: trap ptid is process 570.
LLW: exit
infrun: target_wait (-1.0.0, status) =
infrun: 570.570.0 [process 570],
infrun: status->kind = stopped, signal = GDB_SIGNAL_TRAP
infrun: TARGET_WAITKIND_STOPPED
infrun: stop_pc = 0x400717
infrun: BPSTAT_WHAT_STOP_NOISY
infrun: stop_waiting
Breakpoint 3, handler (sig=14) at /home/pedro/gdb/mygit/src/gdb/testsuite/gdb.base/sigstep.c:35
35 done = 1;
Hardware single-step targets already behave this way, because the
Linux backends (both native and gdbserver) always report signals to
the core if the thread was single-stepping.
As mentioned in the new comment in do_target_resume, we can't fix this
by instead making the displaced_step_fixup phase skip fixing up the PC
if the single step stopped somewhere we didn't expect. Here's what
the backtrace would look like if we did that:
Breakpoint 3, handler (sig=14) at /home/pedro/gdb/mygit/src/gdb/testsuite/gdb.base/sigstep.c:35
35 done = 1;
1: x/i $pc
=> 0x400717 <handler+7>: movl $0x1,0x200943(%rip) # 0x601064 <done>
(gdb) bt
#0 handler (sig=14) at /home/pedro/gdb/mygit/src/gdb/testsuite/gdb.base/sigstep.c:35
#1 <signal handler called>
#2 0x0000000000400622 in _start ()
(gdb) FAIL: gdb.base/sigstep.exp: displaced=on: step on breakpoint, to handler: backtrace
gdb/ChangeLog:
2015-04-10 Pedro Alves <palves@redhat.com>
* infrun.c (displaced_step_in_progress): New function.
(do_target_resume): Advise target to report all signals if
displaced stepping.
gdb/testsuite/ChangeLog:
2015-04-10 Pedro Alves <palves@redhat.com>
* gdb.base/sigstep.exp (breakpoint_to_handler)
(breakpoint_to_handler_entry): New parameter 'displaced'. Use it.
Test "backtrace" in handler.
(breakpoint_over_handler): New parameter 'displaced'. Use it.
(top level): Add new "displaced" test axis to
breakpoint_to_handler, breakpoint_to_handler_entry and
breakpoint_over_handler.
The problem is that with hardware step targets and displaced stepping,
"signal FOO" when stopped at a breakpoint steps the breakpoint
instruction at the same time it delivers a signal. This results in
tp->stepped_breakpoint set, but no step-resume breakpoint set. When
the next stop event arrives, GDB crashes. Irrespective of whether we
should do something more/different to step past the breakpoint in this
scenario (e.g., PR 18225), it's just wrong to assume there'll be a
step-resume breakpoint set (and was not the original intention).
gdb/ChangeLog:
2015-04-10 Pedro Alves <palves@redhat.com>
PR gdb/18216
* infrun.c (process_event_stop_test): Don't assume a step-resume
is set if tp->stepped_breakpoint is true.
gdb/testsuite/ChangeLog:
2015-04-10 Pedro Alves <palves@redhat.com>
PR gdb/18216
* gdb.threads/multiple-step-overs.exp: Remove expected eof.
Recent patch series "V2 All-stop on top of non-stop" causes a SIGSEGV
in the test case,
> -PASS: gdb.base/info-shared.exp: continue to breakpoint: library function #4
> +FAIL: gdb.base/info-shared.exp: continue to breakpoint: library function #4
>
> continue^M
> Continuing.^M
> ^M
> Program received signal SIGSEGV, Segmentation fault.^M
> 0x40021564 in ?? () gdb/testsuite/gdb.base/info-shared-solib1.so^M
> (gdb) FAIL: gdb.base/info-shared.exp: continue to breakpoint: library function #4
and an ARM displaced stepping bug is exposed. It can be reproduced by
the modified gdb.arch/arm-disp-step.exp as below,
continue^M
Continuing.^M
^M
Program received signal SIGSEGV, Segmentation fault.^M
0xa713cfcc in ?? ()^M
(gdb) FAIL: gdb.arch/arm-disp-step.exp: continue to breakpoint: continue to test_add_rn_pc_end
This patch is to fix it.
gdb:
2015-04-10 Yao Qi <yao.qi@linaro.org>
* arm-tdep.c (install_alu_reg): Update comment.
(thumb_copy_alu_reg): Remove local variable rn. Update
debugging message. Use r2 instead of r1 in the modified
instruction.
gdb/testsuite:
2015-04-10 Yao Qi <yao.qi@linaro.org>
* gdb.arch/arm-disp-step.S (main): Call test_add_rn_pc.
(test_add_rn_pc): New function.
* gdb.arch/arm-disp-step.exp (test_add_rn_pc): New proc.
(top level): Invoke test_add_rn_pc.
Running break-interp.exp with the target always in non-stop mode trips
on PR13858, as enabling non-stop also enables displaced stepping.
The problem is that when GDB doesn't know where the entry point is, it
doesn't know where to put the displaced stepping scratch pad. The
test added by this commit exercises this. Without the fix, we get:
(gdb) PASS: gdb.base/step-over-no-symbols.exp: displaced=on: break *$pc
set displaced-stepping on
(gdb) PASS: gdb.base/step-over-no-symbols.exp: displaced=on: set displaced-stepping on
stepi
0x00000000004005be in ?? ()
Entry point address is not known.
(gdb) PASS: gdb.base/step-over-no-symbols.exp: displaced=on: stepi
p /x $pc
$2 = 0x4005be
(gdb) PASS: gdb.base/step-over-no-symbols.exp: displaced=on: get after PC
FAIL: gdb.base/step-over-no-symbols.exp: displaced=on: advanced
The fix switches all GNU/Linux ports to get the entry point from
AT_ENTRY in the target auxiliary vector instead of from symbols. This
is currently only done by PPC when Cell debugging is enabled, but I
think all archs should be able to do the same. Note that
ppc_linux_displaced_step_location cached the result, I'm guessing to
avoid constantly re-fetching the auxv out of remote targets, but
that's no longer necessary nowadays, as the auxv blob is itself cached
in the inferior object. The ppc_linux_entry_point_addr global is
obviously bad for multi-process too nowadays.
Tested on x86-64 (-m64/-m32), PPC64 (-m64/-m32) and S/390 GNU/Linux.
Yao tested the new test on ARM as well.
gdb/ChangeLog:
2015-04-10 Pedro Alves <palves@redhat.com>
PR gdb/13858
* amd64-linux-tdep.c (amd64_linux_init_abi_common): Install
linux_displaced_step_location as gdbarch_displaced_step_location
hook.
* arm-linux-tdep.c (arm_linux_init_abi): Likewise.
* i386-linux-tdep.c (i386_linux_init_abi): Likewise.
* linux-tdep.c (linux_displaced_step_location): New function,
based on ppc_linux_displaced_step_location.
* linux-tdep.h (linux_displaced_step_location): New declaration.
* ppc-linux-tdep.c (ppc_linux_entry_point_addr): Delete.
(ppc_linux_inferior_created, ppc_linux_displaced_step_location):
Delete.
(ppc_linux_init_abi): Install linux_displaced_step_location as
gdbarch_displaced_step_location hook, even without Cell/B.E..
(_initialize_ppc_linux_tdep): Don't install
ppc_linux_inferior_created as inferior_created observer.
* s390-linux-tdep.c (s390_gdbarch_init): Install
linux_displaced_step_location as gdbarch_displaced_step_location
hook.
gdb/testsuite/
2015-04-10 Pedro Alves <palves@redhat.com>
PR gdb/13858
* gdb.base/step-over-no-symbols.exp: New file.
This commit introduces a new shared function to replace three
identical functions in various places in the codebase.
gdb/ChangeLog:
* common/common-remote-fileio.h (remote_fileio_to_fio_error):
New declaration.
* common/common-remote-fileio.c (remote_fileio_to_fio_error):
New function, factored out the named functions below.
* inf-child.c (gdb/fileio.h): Remove include.
(common-remote-fileio.h): New include.
(inf_child_errno_to_fileio_error): Remove function. Update
all callers to use remote_fileio_to_fio_error.
* remote-fileio.c (remote_fileio_errno_to_target): Likewise.
gdb/gdbserver/ChangeLog:
* hostio-errno.c (errno_to_fileio_error): Remove function.
Update caller to use remote_fileio_to_fio_error.
gdb/ChangeLog:
2015-04-09 Pedro Alves <palves@redhat.com>
* gnulib/update-gnulib.sh (aclocal version check): Filter out
"called too early to check prototype".
This patch is related to PR python/16699, and is an improvement over the
patch posted here:
<https://sourceware.org/ml/gdb-patches/2014-03/msg00301.html>
Keith noticed that, when using the "complete" command on GDB to complete
a Python command, some strange things could happen. In order to
understand what can go wrong, I need to explain how the Python
completion mechanism works.
When the user requests a completion of a Python command by using TAB,
GDB will first try to determine the right set of "brkchars" that will be
used when doing the completion. This is done by actually calling the
"complete" method of the Python class. Then, when we already know the
"brkchars" that will be used, we call the "complete" method again, for
the same values.
If you read the thread mentioned above, you will see that one of the
design decisions was to make the "cmdpy_completer_helper" (which is the
function the does the actual calling of the "complete" method) cache the
first result of the completion, since this result will be used in the
second call, to do the actual completion.
The problem is that the "complete" command does not process the
brkchars, and the current Python completion mechanism (improved by the
patch mentioned above) relies on GDB trying to determine the brkchars,
and then doing the completion itself. Therefore, when we use the
"complete" command instead of doing a TAB-completion on GDB, there is a
scenario where we can use the invalid cache of a previous Python command
that was completed before. For example:
(gdb) A <TAB>
(gdb) complete B
B value1
B value10
B value2
B value3
B value4
B value5
B value6
B value7
B value8
B value9
(gdb) B <TAB>
comp1 comp2 comp4 comp6 comp8
comp10 comp3 comp5 comp7 comp9
Here, we see that "complete B " gave a different result than "B <TAB>".
The reason for that is because "A <TAB>" was called before, and its
completion results were "value*", so when GDB tried to "complete B " it
wrongly answered with the results for A. The problem here is using a
wrong cache (A's cache) for completing B.
We tried to come up with a solution that would preserve the caching
mechanism, but it wasn't really possible. So I decided to completely
remove the cache, and doing the method calling twice for every
completion. This is not optimal, but I do not think it will impact
users noticeably.
It is worth mentioning another small issue that I found. The code was
doing:
wordobj = PyUnicode_Decode (word, sizeof (word), host_charset (), NULL);
which is totally wrong, because using "sizeof" here will lead to always
the same result. So I changed this to use "strlen". The testcase also
catches this problem.
Keith kindly expanded the existing testcase to cover the problem
described above, and everything is passing.
gdb/ChangeLog:
2015-04-08 Sergio Durigan Junior <sergiodj@redhat.com>
PR python/16699
* python/py-cmd.c (cmdpy_completer_helper): Adjust function to not
use a caching mechanism. Adjust comments and code to reflect
that. Replace 'sizeof' by 'strlen' when fetching 'wordobj'.
(cmdpy_completer_handle_brkchars): Adjust call to
cmdpy_completer_helper. Call Py_XDECREF for 'resultobj'.
(cmdpy_completer): Likewise.
gdb/testsuite/ChangeLog:
2015-04-08 Keith Seitz <keiths@redhat.com>
PR python/16699
* gdb.python/py-completion.exp: New tests for completion.
* gdb.python/py-completion.py (CompleteLimit1): New class.
(CompleteLimit2): Likewise.
(CompleteLimit3): Likewise.
(CompleteLimit4): Likewise.
(CompleteLimit5): Likewise.
(CompleteLimit6): Likewise.
(CompleteLimit7): Likewise.
Nowadays, in infrun.c:resume, the setting to 'step' variable is like:
if (use_displaced_stepping (gdbarch)
&& tp->control.trap_expected
&& sig == GDB_SIGNAL_0
&& !current_inferior ()->waiting_for_vfork_done)
{
}
/* Do we need to do it the hard way, w/temp breakpoints? */
else if (step)
step = maybe_software_singlestep (gdbarch, pc); <-- [1]
...
if (execution_direction != EXEC_REVERSE
&& step && breakpoint_inserted_here_p (aspace, pc))
{
...
if (gdbarch_cannot_step_breakpoint (gdbarch)) <-- [2]
step = 0;
}
spu doesn't have displaced stepping and uses software single step,
so 'step' is set to zero in [1], and [2] becomes unreachable as a
result. So don't have to call set_gdbarch_cannot_step_breakpoint
in spu_gdbarch_init.
gdb:
2015-04-08 Yao Qi <yao.qi@linaro.org>
* spu-tdep.c (spu_gdbarch_init): Don't call
set_gdbarch_cannot_step_breakpoint.
On GNU/Linux, if the running kernel supports clone events, then
linux-thread-db.c defers thread listing to the target beneath:
static void
thread_db_update_thread_list (struct target_ops *ops)
{
...
if (target_has_execution && !thread_db_use_events ())
ops->beneath->to_update_thread_list (ops->beneath);
else
thread_db_update_thread_list_td_ta_thr_iter (ops);
...
}
However, when live debugging, the target beneath, linux-nat.c, does
not implement the to_update_thread_list method. The result is that if
a thread is marked exited (because it can't be deleted right now,
e.g., it was the selected thread), then it won't ever be deleted,
until the process exits or is killed/detached.
A similar thing happens with the remote.c target. Because its
target_update_thread_list implementation skips exited threads when it
walks the current thread list looking for threads that no longer exits
on the target side, using ALL_NON_EXITED_THREADS_SAFE, stale exited
threads are never deleted.
This is not a big deal -- I can't think of any way this might be user
visible, other than gdb's memory growing a tiny bit whenever a thread
gets stuck in exited state. Still, might as well clean things up
properly.
All other targets use prune_threads, so are unaffected.
The fix adds a ALL_THREADS_SAFE macro, that like
ALL_NON_EXITED_THREADS_SAFE, walks the thread list and allows deleting
the iterated thread, and uses that in places that are walking the
thread list in order to delete threads. Actually, after converting
linux-nat.c and remote.c to use this, we find the only other user of
ALL_NON_EXITED_THREADS_SAFE is also walking the list to delete
threads. So we convert that too, and end up deleting
ALL_NON_EXITED_THREADS_SAFE.
Tested on x86_64 Fedora 20, native and gdbserver.
gdb/ChangeLog
2015-04-07 Pedro Alves <palves@redhat.com>
* gdbthread.h (ALL_NON_EXITED_THREADS_SAFE): Rename to ...
(ALL_THREADS_SAFE): ... this, and don't skip exited threads.
(delete_exited_threads): New declaration.
* infrun.c (follow_exec): Use ALL_THREADS_SAFE.
* linux-nat.c (linux_nat_update_thread_list): New function.
(linux_nat_add_target): Install it.
* remote.c (remote_update_thread_list): Use ALL_THREADS_SAFE.
* thread.c (prune_threads): Use ALL_THREADS_SAFE.
(delete_exited_threads): New function.
