A sanity-check in my release scripts caught something: After having
created the tarballs, I verify that no checked-in file disappeared
in the process, and lo and behod, it found that the following file
got wiped:
- gdb/testsuite/dg-extract-results.py:
And it's not part of the tarball either.
I don't understand while we delete all *.py files in gdb/testsuite,
since I don't see a rule that expected to create one. A run of the
testsuite also doesn't seem to be creating .py files there.
I traced this to the following commit, which unfortunately provided
no explanation. Perhaps we used to run some tests in the gdb/testsuite
directory and caused files to be left behind there. Perhaps we still
do today?
In the meantime, Executive Decision: In order to allow me to create
tarballs without losing files, I removed it. It's easy to put something
back if we find out why it might still be needed.
gdb/testsuite/ChangeLog:
* Makefile.in (clean mostlyclean): Do not delete *.py.
Tested on x86_64-linux by running the src-release.sh script again,
and this time, dg-extract-results.py no longer gets wiped.
Now that the GDB 7.9 branch has been created, we can
bump the version number.
gdb/ChangeLog:
GDB 7.9 branch created (92fc2e6978):
* version.in: Bump version to 7.9.50.DATE-cvs.
bfd/ChangeLog
2015-01-13 Thomas Preud'homme <thomas.preudhomme@arm.com>
* elfnn-aarch64.c (elfNN_aarch64_final_link_relocate): Use
SYMBOLIC_BIND to check if a symbol should be bound symbolically.
ld/testsuite/ChangeLog
2015-01-13 Thomas Preud'homme <thomas.preudhomme@arm.com>
* ld-aarch64/aarch64-elf.exp: Added relocs-257-symbolic-func test.
* ld-aarch64/relocs-257-symbolic-func.d: New file.
* ld-aarch64/relocs-257-symbolic-func.s: Likewise.
bfd/
* elfnn-aarch64.c: (elfNN_aarch64_howto_table): Enable overflow check for
TLSLE_MOVW_TPREL_G2.
ld/testsuite/
* ld-aarch64/tprel_g2_overflow.s: New testcase.
* ld-aarch64/tprel_g2_overflow.d: New expectation file.
* ld-aarch64/aarch64-elf.exp: Run new testcase.
bfd/
PR ld/17415
* elfnn-aarch64.c (elfNN_aarch64_howto_table): Mark
R_AARCH64_TLSLE_ADD_TPREL_HI12 as complain_overflow_unsigned.
* elfxx-aarch64.c (_bfd_aarch64_elf_resolve_relocation): Correct the bit
mask.
ld/testsuite/
PR ld/17415
* ld-aarch64/pr17415.s: Source file for new test.
* ld-aarch64/pr17415.d: Expect file for new test.
* ld-aarch64/aarch64-elf.exp: Run the new test.
The following change...
commit 1994afbf19
Date: Tue Dec 23 07:55:39 2014 -0800
Subject: Look up primitive types as symbols.
... caused the following regression:
% gdb
(gdb) set lang ada
(gdb) python print gdb.lookup_type('character')
Traceback (most recent call last):
File "<string>", line 1, in <module>
gdb.error: No type named character.
Error while executing Python code.
This is because the language_lookup_primitive_type_as_symbol call
was moved to the la_lookup_symbol_nonlocal hook. A couple of
implementations have been upated accordingly, but the Ada version
has not. This patch fixes this omission.
gdb/ChangeLog:
* ada-lang.c (ada_lookup_symbol_nonlocal): If name not found
in static block, then try searching for primitive types.
gdb/testsuite/ChangeLog:
* gdb.python/py-lookup-type.exp: New file.
This patch makes readline append new history lines to the GDB history
file on exit instead of overwriting the entire history file on exit.
This change allows us to run multiple simultaneous GDB sessions without
having each session overwrite the added history of each other session on
exit.
Care must be taken to ensure that the history file doesn't get corrupted
when multiple GDB processes are trying to simultaneously append to and
then truncate it. Safety is achieved in such a situation by using an
intermediate local history file to mutually exclude multiple processes
from simultaneously performing write operations on the global history
file.
gdb/ChangeLog:
* top.h (gdb_add_history): Declare.
* top.c (command_count): New variable.
(gdb_add_history): New function.
(gdb_safe_append_history): New static function.
(quit_force): Call it.
(command_line_input): Use gdb_add_history instead of
add_history.
* event-top.c (command_line_handler): Likewise.
abbrev_base is independent of abbrev_size. We should use abbrev_base +
abbrev_size to check abbrev section size.
* dwarf.c (process_debug_info): Properly check abbrev size.
The `machine/setjmp.h' header is no longer present on OS X 10.10, and is
non-standard. Instead, `darwin-nat.c' should be using the standard
`setjmp.h' header.
gdb/ChangeLog:
2015-01-12 James Clarke <jrtc27@jrtc27.com> (tiny patch)
PR gdb/17046
* darwin-nat.c: Replace <machine/setjmp.h> #include by
<setjmp.h> #include.
The previous change to py-prompt.exp made it return without restoring
GDBFLAGS, resulting in breaking the following tests:
$ make check RUNTESTFLAGS="--target_board=native-gdbserver --directory=gdb.python"
...
Running src/gdb/testsuite/gdb.python/py-prompt.exp ...
Running src/gdb/testsuite/gdb.python/py-section-script.exp ...
ERROR: (timeout) GDB never initialized after 10 seconds.
ERROR: no fileid for gdbuild
ERROR: Couldn't send python print ('test') to GDB.
ERROR: no fileid for gdbuild
ERROR: Couldn't send python print (sys.version_info[0]) to GDB.
ERROR: no fileid for gdbuild
ERROR: Couldn't send python print (sys.version_info[1]) to GDB.
ERROR: no fileid for gdbuild
ERROR: no fileid for gdbuild
...
gdb/testsuite/
2015-01-12 Pedro Alves <palves@redhat.com>
* gdb.python/py-prompt.exp: When the board can't spawn for attach,
restore GDBFLAGS before returning.
PR binutils/17531
* dwarf.c (process_debug_info): Check for abbrev_base being larger
than the section size.
(process_cu_tu_index): Use xcalloc2 to allocate the CU and TU
arrays.
(xcalloc2): New function. Like xcalloc, but checks for overflow.
* dwarf.h (xcalloc2): Prototype.
When runtime patching code (like e.g. done by the Linux kernel) there
may be cases where the set of stack frame alterations differs between
unpatched and patched code. Consequently the corresponding unwind data
needs patching too. Locating the right places within an FDE, however,
is rather cumbersome without a way to insert labels in the resulting
section. Hence this patch introduces a new directive, .cfi_label. Note
that with the way CFI data gets emitted currently (at the end of the
assembly process) this can't support local FB- and dollar-labels.
gas/
2015-01-12 Jan Beulich <jbeulich@suse.com>
* gas/dw2gencfi.c (cfi_add_label, dot_cfi_label): New.
(cfi_pseudo_table): Add "cfi_label".
(output_cfi_insn): Handle CFI_label.
(select_cie_for_fde): Als terminate CIE when encountering
CFI_label.
* dw2gencfi.h (cfi_add_label): Declare.
(struct cfi_insn_data): New member "sym_name".
(CFI_label): New.
* read.c (read_symbol_name): Drop "static".
* read.h (read_symbol_name): Declare.
gas/testsuite/
2015-01-12 Jan Beulich <jbeulich@suse.com>
gas/cfi/cfi-label.d, gas/cfi/cfi-label.s: New.
gas/cfi/cfi.exp: Run new tests.
Keep a group containing just debug sections or the other special
sections we currently mark against garbage collection.
* elflink.c (_bfd_elf_gc_mark_debug_special_section_group): New
function.
(_bfd_elf_gc_mark_extra_sections): Use it.
PR 17817
* Makefile.am (aoutx.stamp): cp -p $srcdir/aoutx.texi to keep
timestamps so that makeinfo need not be installed.
(archive.stamp, archures.stamp, bfdt.stamp, cache.stamp,
coffcode.stamp, core.stamp, elf.stamp, elfcode.stamp, mmo.stamp,
format.stamp, libbfd.stamp, bfdio.stamp, bfdwin.stamp,
opncls.stamp, reloc.stamp, section.stamp, syms.stamp, targets.stamp,
init.stamp, hash.stamp, linker.stamp): Similarly.
(bfdver.texi): Use test rather than [ ] in commands.
* Makefile.in: Regenerate.
for x86_64 -m32 run one gets:
+FAIL: gdb.python/py-frame.exp: test Frame.read_register(rip)
I do not have x32 OS here but the %rip test should PASS there I think.
On Sun, 11 Jan 2015 14:58:06 +0100, Yao Qi wrote:
With your patch applied, this test is skipped on 'x86_64 -m32'. I
prefer to increasing the test coverage, so how about extending the test
for 'x86_64 -m32'? I mean test Frame.read_register(eip)...
gdb/testsuite/ChangeLog
2015-01-12 Jan Kratochvil <jan.kratochvil@redhat.com>
* gdb.python/py-frame.exp (test Frame.read_register(rip)): Use
is_amd64_regs_target and is_x86_like_target.
These two, other than VQSHLU, didn't have their immediates properly range
checked so far.
(Re-sending unchanged from the original v2 due to never having got an
answer to https://sourceware.org/ml/binutils/2013-04/msg00121.html.)
gas/
2015-01-12 Jan Beulich <jbeulich@suse.com>
* gas/config/tc-arm.c (do_neon_shl_imm): Check immediate range.
(do_neon_qshl_imm): Likewise.
gas/testsuite/
2015-01-12 Jan Beulich <jbeulich@suse.com>
* gas/arm/neon-addressing-bad.s: Add test for invalid VSHL,
VQSHL, and VQSHLU immediates.
* gas/arm/neon-addressing-bad.l: Update accordingly.
The C standard doesn't guarantee a function pointer can be cast to
void* and vice versa.
binutils/
* prdbg.c (print_debugging_info): Don't use void* for function
pointer param.
* budbg.h (print_debugging_info): Update prototype.
gas/
* read.c (s_altmacro, s_reloc): Make definition static.
gdb/testsuite/ChangeLog:
* lib/dwarf.exp (Dwarf): Flag an error if a numeric attribute value
is given without an explicit form.
* gdb.dwarf2/arr-subrange.exp: Specify forms for all numeric
attributes.
* gdb.dwarf/corrupt.exp: Ditto.
* gdb.dwarf2/enum-type.exp: Ditto.
* gdb.trace/entry-values.exp: Ditto.
* gdb.trace/unavailable-dwarf-piece.exp: Ditto.
clear_symtab_users calls breakpoint_re_set before
observer_notify_new_objfile(NULL), and thus symbol lookup
done during breakpoint_re_set will see a stale cache.
Presumably we just need to move the call to observer_notify_new_objfile(NULL)
to before breakpoint_re_set, but need to check for other such issues,
and 7.9 is scheduled to branch tomorrow.
Reverts commits:
b2fb95e006400678a494d98b9ccbcc77087adf50
gdb/ChangeLog:
* symtab.c (eq_symbol_entry): Use SYMBOL_SEARCH_NAME and
symbol_matches_domain for symbol comparisons.
* symtab.c (symbol_cache_mark_found): Improve function comment.
Rename parameter objfile to objfile_context.
(symbol_cache_mark_not_found): Improve function comment.
Add symbol lookup cache.
* NEWS: Document new options and commands.
* symtab.c (symbol_cache_key): New static global.
(DEFAULT_SYMBOL_CACHE_SIZE, MAX_SYMBOL_CACHE_SIZE): New macros.
(SYMBOL_LOOKUP_FAILED): New macro.
(symbol_cache_slot_state): New enum.
(block_symbol_cache): New struct.
(symbol_cache): New struct.
(new_symbol_cache_size, symbol_cache_size): New static globals.
(hash_symbol_entry, eq_symbol_entry): New functions.
(symbol_cache_byte_size, resize_symbol_cache): New functions.
(make_symbol_cache, free_symbol_cache): New functions.
(get_symbol_cache, symbol_cache_cleanup): New function.
(set_symbol_cache_size, set_symbol_cache_size_handler): New functions.
(symbol_cache_lookup, symbol_cache_clear_slot): New function.
(symbol_cache_mark_found, symbol_cache_mark_not_found): New functions.
(symbol_cache_flush, symbol_cache_dump): New functions.
(maintenance_print_symbol_cache): New function.
(maintenance_flush_symbol_cache): New function.
(symbol_cache_stats): New function.
(maintenance_print_symbol_cache_statistics): New function.
(symtab_new_objfile_observer): New function.
(symtab_free_objfile_observer): New function.
(lookup_static_symbol, lookup_global_symbol): Use symbol cache.
(_initialize_symtab): Init symbol_cache_key. New parameter
maint symbol-cache-size. New maint commands print symbol-cache,
print symbol-cache-statistics, flush-symbol-cache.
Install new_objfile, free_objfile observers.
gdb/doc/ChangeLog:
* gdb.texinfo (Symbols): Document new commands
"maint print symbol-cache", "maint print symbol-cache-statistics",
"maint flush-symbol-cache". Document new option
"maint set symbol-cache-size".
gdb/ChangeLog:
PR gdb/15830
* NEWS: The "maint demangle" command is renamed as "demangle".
* demangle.c: #include cli/cli-utils.h, language.h.
(demangle_command): New function.
(_initialize_demangle): Add new command "demangle".
* maint.c (maintenance_demangle): Stub out.
(_initialize_maint_cmds): Update help text for "maint demangle",
and mark as deprecated.
gdb/doc/ChangeLog:
* gdb.texinfo (Debugging C Plus Plus): Mention "demangle".
(Symbols): Ditto.
(Maintenance Commands): Delete docs for "maint demangle".
gdb/testsuite/ChangeLog:
* gdb.base/maint.exp: Remove references to "maint demangle".
* gdb.cp/demangle.exp: Update. "maint demangle" -> "demangle".
Add tests for explicitly specifying language to demangle.
* gdb.dlang/demangle.exp: Ditto.
When building PIE, we should only discard space for pc-relative relocs
symbols which turn out to need copy relocs.
bfd/
PR ld/17827
* elf64-x86-64.c (elf_x86_64_allocate_dynrelocs): For PIE,
only discard space for pc-relative relocs symbols which turn
out to need copy relocs.
ld/testsuite/
PR ld/17827
* ld-x86-64/pr17689.out: Updated.
* ld-x86-64/pr17689b.S: Likewise.
* ld-x86-64/pr17827.rd: New file.
* ld-x86-64/x86-64.exp: Run PR ld/17827 test.
gdb/ChangeLog:
Add symbol lookup cache.
* NEWS: Document new options and commands.
* symtab.c (symbol_cache_key): New static global.
(DEFAULT_SYMBOL_CACHE_SIZE, MAX_SYMBOL_CACHE_SIZE): New macros.
(SYMBOL_LOOKUP_FAILED): New macro.
(symbol_cache_slot_state): New enum.
(block_symbol_cache): New struct.
(symbol_cache): New struct.
(new_symbol_cache_size, symbol_cache_size): New static globals.
(hash_symbol_entry, eq_symbol_entry): New functions.
(symbol_cache_byte_size, resize_symbol_cache): New functions.
(make_symbol_cache, free_symbol_cache): New functions.
(get_symbol_cache, symbol_cache_cleanup): New function.
(set_symbol_cache_size, set_symbol_cache_size_handler): New functions.
(symbol_cache_lookup, symbol_cache_clear_slot): New function.
(symbol_cache_mark_found, symbol_cache_mark_not_found): New functions.
(symbol_cache_flush, symbol_cache_dump): New functions.
(maintenance_print_symbol_cache): New function.
(maintenance_flush_symbol_cache): New function.
(symbol_cache_stats): New function.
(maintenance_print_symbol_cache_statistics): New function.
(symtab_new_objfile_observer): New function.
(symtab_free_objfile_observer): New function.
(lookup_static_symbol, lookup_global_symbol): Use symbol cache.
(_initialize_symtab): Init symbol_cache_key. New parameter
maint symbol-cache-size. New maint commands print symbol-cache,
print symbol-cache-statistics, flush-symbol-cache.
Install new_objfile, free_objfile observers.
doc/ChangeLog:
* gdb.texinfo (Symbols): Document new commands
"maint print symbol-cache", "maint print symbol-cache-statistics",
"maint flush-symbol-cache". Document new option
"maint set symbol-cache-size".
gdb/gdbserver/ChangeLog:
* i387-fp.c (i387_cache_to_xsave): In look over
num_avx512_zmmh_high_registers, replace use of struct i387_xsave
zmmh_low_space field by use of zmmh_high_space.
Tested on x86_64-linux, using boards/native-gdbserver.exp.
When fixups are converted to a difference type within md_apply_fix, we
previously left the contents of VALP (the value that was initially
computed within write.c:fixup_segment) unchanged. This is harmless,
except that this value is used within write.c:fixup_segment once we
return from md_apply_fix to perform an overflow check.
In some cases, the value computed in write.c:fixup_segment is so wrong
that an overflow error can be triggered. These errors are incorrect.
This patch avoids the overflow errors by adjusting the value in
write.c:fixup_segment using the VALP pointer in md_apply_fix.
A test for this issue is included.
gas/ChangeLog:
* config/tc-avr.c (md_apply_fix): Update the contents of VALP for
diff fixups.
gas/testsuite/ChangeLog:
* gas/avr/large-debug-line-table.d: New file.
* gas/avr/large-debug-line-table.s: New file.
This fixes an issue where a page-aligned data section, combined with -z relro,
could lead to a gap between text and data segments larger than a page, and
we would fail to overlap the segments in the file.
gold/
* layout.cc (Layout::set_segment_offsets): Don't align start of segment
unless alignment is larger than page size.
The #line directives within GDB's autogenerated yacc files (e.g.
c-exp.c) are being incorrectly munged, causing these directives to refer
to nonexistent source files, e.g.
#line 36 "/home/patrick/binutils-gdb/gdb//home/patrick/binutils-gdb/gdb/c-exp.y"
as opposed to
#line 36 "/home/patrick/binutils-gdb/gdb/c-exp.y"
The munging happens due to a sed expression added by commit 954d8cae
whose intended purpose[1] was to work around the fact that ylwrap emitted #line
directives without any directory information, e.g.
#line 36 "c-exp.y"
So the sed expression was meant to munge such directives to refer to
absolute paths instead. But the behavior of ylwrap was changed some
years ago[2] to emit absolute paths within #line directives. And when
our local copy of ylwrap was synced by commit e30465112, the sed
expression in question became unnecessary, and indeed harmful.
This patch removes the now-obsolete sed expression. The emitted #line
directives are now correct without it.
gdb/ChangeLog:
* Makefile.in (.y.c): Don't munge yacc's #line
directives.
[1]: https://sourceware.org/ml/gdb-patches/2010-11/msg00265.html
[2]: http://git.savannah.gnu.org/cgit/automake.git/commit/lib/ylwrap?id=b6359a5f3
the X-Gene scheduling description up in the respective GCC backend.
* config/tc-arm.c (arm_cpus): Add support for APM X-Gene 1 and
X-Gene 2.
* doc/c-arm.texi (ARM Options): Mention xgene1 and xgene2.
This patch primarily rewrites defaulted_query() to use
gdb_readline_wrapper() to prompt the user for input, like
prompt_for_continue() does. The motivation for this rewrite is to be
able to reuse the default query hook in TUI, obviating the need for a
custom TUI query hook.
However, having TUI use the default query mechanism exposed a couple of
latent bugs in tui_redisplay_readline() related to the handling of
multi-line prompts, in particular GDB's multi-line quit prompt.
The first issue is an off-by-one error in the calculation of the height
of the prompt. The check in question should be col <= prev_col, not c <
prev_col, to properly account for the case when a prompt contains
multiple consecutive newlines. Failing to do so makes TUI have the
wrong idea of the vertical height of the prompt. This patch fixes the
column check.
The second issue is that cur_line does not get updated to reflect the
cursor position if the user's prompt cursor is at the end of the prompt
(i.e. if rl_point == rl_end). cur_line only gets updated if rl_point
lies between 0..rl_end-1 because that is the bounds of the for loop
responsible for updating cur_line. This patch changes the loop's bounds
to 0..rl_end so that cur_line always gets updated.
With these two bug fixes out of the way, the default query mechanism
works well in TUI even with multi-line prompts like GDB's quit prompt.
gdb/ChangeLog:
* utils.c (defaulted_query): Rewrite to use gdb_readline_wrapper
to prompt for input.
* tui/tui-hooks.c (tui_query_hook): Remove.
(tui_install_hooks): Don't set deprecated_query_hook.
* tui/tui-io.c (tui_redisplay_readline): Fix off-by-one error in
height calculation. Always update the command window's cur_line.
This commit adds a non-stop mode test originally inspired by
signal-while-stepping-over-bp-other-thread.exp, that exposes the
thread starvation issues fixed by the previous patches. It sets a set
of threads stepping in parallel, and has one of them get a signal.
Without the previous fixes, this would fail with timeouts.
gdb/testsuite/
2015-01-09 Pedro Alves <palves@redhat.com>
* gdb.threads/non-stop-fair-events.c: New file.
* gdb.threads/non-stop-fair-events.exp: New file.
This patch applies the same starvation avoidance improvements of the
previous patch to the Linux gdbserver side.
Without this, the test added by the following commit
(gdb.threads/non-stop-fair-events.exp) always fails with time outs.
gdb/gdbserver/
2015-01-09 Pedro Alves <palves@redhat.com>
* linux-low.c (step_over_bkpt): Move higher up in the file.
(handle_extended_wait): Don't store the stop_pc here.
(get_stop_pc): Adjust comments and rename to ...
(check_stopped_by_breakpoint): ... this. Record whether the LWP
stopped for a software breakpoint or hardware breakpoint.
(thread_still_has_status_pending_p): New function.
(status_pending_p_callback): Use
thread_still_has_status_pending_p. If the event is no longer
interesting, resume the LWP.
(handle_tracepoints): Add assert.
(maybe_move_out_of_jump_pad): Remove cancel_breakpoints call.
(wstatus_maybe_breakpoint): New function.
(cancel_breakpoint): Delete function.
(check_stopped_by_watchpoint): New function, factored out from
linux_low_filter_event.
(lp_status_maybe_breakpoint): Delete function.
(linux_low_filter_event): Remove filter_ptid argument.
Leave thread group exits pending here. Store the LWP's stop PC.
Always leave events pending.
(linux_wait_for_event_filtered): Pull all events out of the
kernel, and leave them all pending.
(count_events_callback, select_event_lwp_callback): Consider all
events.
(cancel_breakpoints_callback, linux_cancel_breakpoints): Delete.
(select_event_lwp): Only give preference to the stepping LWP in
all-stop mode. Adjust comments.
(ignore_event): New function.
(linux_wait_1): Delete 'retry' label. Use ignore_event. Remove
references to cancel_breakpoints. Adjust to renames. Also give
equal priority to all LWPs that have had events in non-stop mode.
If reporting a software breakpoint event, unadjust the LWP's PC.
(linux_wait): If linux_wait_1 returned an ignored event, retry.
(stuck_in_jump_pad_callback, move_out_of_jump_pad_callback):
Adjust.
(linux_resume_one_lwp): Store the LWP's PC. Adjust.
(resume_status_pending_p): Use thread_still_has_status_pending_p.
(linux_stopped_by_watchpoint): Adjust.
(linux_target_ops): Remove reference to linux_cancel_breakpoints.
* linux-low.h (enum lwp_stop_reason): New.
(struct lwp_info) <stop_pc>: Adjust comment.
<stopped_by_watchpoint>: Delete field.
<stop_reason>: New field.
* linux-x86-low.c (x86_linux_prepare_to_resume): Adjust.
* mem-break.c (software_breakpoint_inserted_here)
(hardware_breakpoint_inserted_here): New function.
* mem-break.h (software_breakpoint_inserted_here)
(hardware_breakpoint_inserted_here): Declare.
* target.h (struct target_ops) <cancel_breakpoints>: Remove field.
(cancel_breakpoints): Delete.
* tracepoint.c (clear_installed_tracepoints, stop_tracing)
(upload_fast_traceframes): Remove references to
cancel_breakpoints.
Running the testsuite with a series that reimplements user-visible
all-stop behavior on top of a target running in non-stop mode revealed
problems related to event starvation avoidance.
For example, I see
gdb.threads/signal-while-stepping-over-bp-other-thread.exp failing.
What happens is that GDB core never gets to see the signal event. It
ends up processing the events for the same threads over an over,
because Linux's waitpid(-1, ...) returns that first task in the task
list that has an event, starving threads on the tail of the task list.
So I wrote a non-stop mode test originally inspired by
signal-while-stepping-over-bp-other-thread.exp, to stress this
independently of all-stop on top of non-stop. Fixing it required the
changes described below. The test will be added in a following
commit.
1) linux-nat.c has code in place that picks an event LWP at random out
of all that have had events. This is because on the kernel side,
"waitpid(-1, ...)" just walks the task list linearly looking for the
first that had an event. But, this code is currently only used in
all-stop mode. So with a multi-threaded program that has multiple
events triggering debug events in parallel, GDB ends up starving some
threads.
To make the event randomization work in non-stop mode too, the patch
makes us pull out all the already pending events on the kernel side,
with waitpid, before deciding which LWP to report to the core.
There's some code in linux_wait that takes care of leaving events
pending if they were for LWPs the caller is not interested in. The
patch moves that to linux_nat_filter_event, so that we only have one
place that leaves events pending. With that in place, conceptually,
the flow is simpler and more normalized:
#1 - walk the LWP list looking for an LWP with a pending event to report.
#2 - if no pending event, pull events out of the kernel, and store
them in the LWP structures as pending.
#3- goto #1.
2) Then, currently the event randomization code only considers SIGTRAP
(or trap-like) events. That means that if e.g., have have multiple
threads stepping in parallel that hit a breakpoint that needs stepping
over, and one gets a signal, the signal may end up never getting
processed, because GDB will always be giving priority to the SIGTRAPs.
The patch fixes this by making the randomization code consider all
kinds of pending events.
3) If multiple threads hit a breakpoint, we report one of those, and
"cancel" the others. Cancelling means decrementing the PC, and
discarding the event. If the next time the LWP is resumed the
breakpoint is still installed, the LWP should hit it again, and we'll
report the hit then. The problem I found is that this delays threads
from advancing too much, with the kernel potentially ending up
scheduling the same threads over and over, and others not advancing.
So the patch switches away from cancelling the breakpoints, and
instead remembering that the LWP had stopped for a breakpoint. If on
resume the breakpoint is still installed, we report it. If it's no
longer installed, we discard the pending event then. This is actually
how GDBserver used to handle this before d50171e4 (Teach linux
gdbserver to step-over-breakpoints), but with the difference that back
then we'd delay adjusting the PC until resuming, which made it so that
"info threads" could wrongly see threads with unadjusted PCs.
gdb/
2015-01-09 Pedro Alves <palves@redhat.com>
* breakpoint.c (hardware_breakpoint_inserted_here_p): New
function.
* breakpoint.h (hardware_breakpoint_inserted_here_p): New
declaration.
* linux-nat.c (linux_nat_status_is_event): Move higher up in file.
(linux_resume_one_lwp): Store the thread's PC. Adjust to clear
stop_reason.
(check_stopped_by_watchpoint): New function.
(save_sigtrap): Reimplement.
(linux_nat_stopped_by_watchpoint): Adjust.
(linux_nat_lp_status_is_event): Delete.
(stop_wait_callback): Only call save_sigtrap after storing the
pending status.
(status_callback): If the thread had been stopped for a breakpoint
that has since been removed, discard the event and resume the LWP.
(count_events_callback, select_event_lwp_callback): Use
lwp_status_pending_p instead of linux_nat_lp_status_is_event.
(cancel_breakpoint): Rename to ...
(check_stopped_by_breakpoint): ... this. Record whether the LWP
stopped for a software breakpoint or hardware breakpoint.
(select_event_lwp): Only give preference to the stepping LWP in
all-stop mode. Adjust comments.
(stop_and_resume_callback): Remove references to new_pending_p.
(linux_nat_filter_event): Likewise. Leave exit events of the
leader thread pending here. Handle signal short circuiting here.
Only call save_sigtrap after storing the pending waitstatus.
(linux_nat_wait_1): Remove 'retry' label. Remove references to
new_pending. Don't handle leaving events the caller is not
interested in pending here, nor handle signal short-circuiting
here. Also give equal priority to all LWPs that have had events
in non-stop mode. If reporting a software breakpoint event,
unadjust the LWP's PC.
* linux-nat.h (enum lwp_stop_reason): New.
(struct lwp_info) <stop_pc>: New field.
(struct lwp_info) <stopped_by_watchpoint>: Delete field.
(struct lwp_info) <stop_reason>: New field.
* x86-linux-nat.c (x86_linux_prepare_to_resume): Adjust.
A subsequent patch will make the Linux backend's target_wait method
pull all events out of the kernel (with waitpid) and store them as
pending status in the LWP structure if no pending status was already
available. Then, the backend goes over the pending statuses and pick
one to report to the core.
With that, the existing thread-execl.exp test exposes a bug, like:
(gdb) set scheduler-locking on
(gdb) PASS: gdb.threads/thread-execl.exp: schedlock on: set scheduler-locking on
next
FAIL: gdb.threads/thread-execl.exp: schedlock on: get to main in new image (timeout)
Recall that when the non-leader thread execs, all threads in the
process die, the execing thread changes its pid to the tgid, and then
waitpid returns an exec event to the tgid. If GDB didn't resume the
leader LWP, then GDB sees an event for an LWP that was supposedly
stopped, and thus not marked as resumed. Because the code that picks
a pending event to report to the core ignores not-resumed LWPs:
/* Return non-zero if LP has a wait status pending. */
static int
status_callback (struct lwp_info *lp, void *data)
{
/* Only report a pending wait status if we pretend that this has
indeed been resumed. */
if (!lp->resumed)
return 0;
the event ends up pending forever, thus the timeout.
gdb/
2015-01-09 Pedro Alves <palves@redhat.com>
* linux-nat.c (linux_handle_extended_wait) <PTRACE_EVENT_EXEC>:
Set the LWP's 'resumed' flag.
Whenever we resume an LWP, we must clear a few flags and flush the
LWP's register cache. We actually currently flush the register cache
of all LWPs, but that's unnecessary. This patch makes us flush the
register cache of only the LWP that is resumed. Instead of open
coding all that in many places, we use a helper function.
Likewise, we have two fields in the LWP structure where a pending
status may be recorded. Add a helper predicate that checks both and
use it throughout instead of open coding the checks.
gdb/
2015-01-09 Pedro Alves <palves@redhat.com>
* linux-nat.c (linux_resume_one_lwp): New function.
(resume_lwp): Use lwp_status_pending_p and linux_resume_one_lwp.
(linux_nat_resume): Use lwp_status_pending_p and
linux_resume_one_lwp.
(linux_handle_syscall_trap): Use linux_resume_one_lwp.
(linux_handle_extended_wait): Use linux_resume_one_lwp.
(status_callback, running_callback): Use lwp_status_pending_p.
(lwp_status_pending_p): New function.
(stop_and_resume_callback): Use lwp_status_pending_p.
(linux_nat_filter_event): Use linux_resume_one_lwp.
(linux_nat_wait_1): Always use status_callback to look for an LWP
with a pending status. Use linux_resume_one_lwp.
(resume_stopped_resumed_lwps): Use lwp_status_pending_p and
linux_resume_one_lwp.
Factor out common code, and use the more efficient
ALL_BP_LOCATIONS_AT_ADDR.
gdb/
2015-01-09 Pedro Alves <palves@redhat.com>
* breakpoint.c (bp_location_inserted_here_p): New function,
factored out from ...
(breakpoint_inserted_here_p): ... here. Use
ALL_BP_LOCATIONS_AT_ADDR.
(software_breakpoint_inserted_here_p): Use
bp_location_inserted_here_p and ALL_BP_LOCATIONS_AT_ADDR.
