"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.
The problem here is that if a thread other than gdb's main thread
gets a SIGCHLD (it's an asynchronous signal so the kernel will
essentially pick a random thread) then gdb will hang if it is
in sigsuspend when the SIGCHLD is delivered. The other thread
will see the signal and the sigsuspend won't "wake up".
Guile and libgc should be blocking SIGCHLD in their threads,
but we need to work with Guile 2.0 and libgc 7.4.
The problem first shows up in libgc 7.4 because it is the first
release that enables multiple marker threads by default.
gdb/ChangeLog:
PR 17247
* guile.c: #include <signal.h>.
(_initialize_guile): Block SIGCHLD while initializing Guile.
Replaces the following, which is reverted.
2014-07-26 Doug Evans <xdje42@gmail.com>
PR 17185
* configure.ac: Add check for header gc/gc.h.
Add check for function setenv.
* configure: Regenerate.
* config.in: Regenerate.
* guile/guile.c (_initialize_guile): Add workaround for libgc 7.4.0.
gdb/ChangeLog:
* guile/scm-cmd.c (gdbscm_parse_command_name): Replace magic number
with named constant. Fix style of pointer comparison.
* python/py-cmd.c (gdbpy_parse_command_name): Ditto.
This commit moves the inclusion of stdarg.h to common-defs.h and
removes all other inclusions.
gdb/
2014-08-07 Gary Benson <gbenson@redhat.com>
* common/common-defs.h: Include stdarg.h.
* defs.h: Do not include stdarg.h.
* ada-lang.c: Likewise.
* common/common-utils.h: Likewise.
* guile/scm-string.c: Likewise.
* guile/scm-utils.c: Likewise.
* m32c-tdep.c: Likewise.
gdb/gdbserver/
2014-08-07 Gary Benson <gbenson@redhat.com>
* server.h: Do not include stdarg.h.
* nto-low.c: Likewise.
* guile/scm-param.c (pascm_parameter_defined_p): New function.
(gdbscm_register_parameter_x): Call it. Raise error for pre-existing
parameters.
testsuite/
* gdb.guile/scm-parameter.exp: Add tests for trying to create
previously existing parameter, and previously ambiguously spelled
parameter.
* acinclude.m4 (GDB_GUILE_PROGRAM_NAMES): New macro.
(GDB_GUILD_TARGET_FLAG, GDB_TRY_GUILD): New macros.
* configure.ac: Try to use guild to compile an scm file, if it fails
then disable guile support.
* configure: Regenerate.
* data-directory/Makefile.in (GUILE_SOURCE_FILES): Renamed from
GUILE_FILE_LIST.
(GUILE_COMPILED_FILES): New variable.
(GUILE_FILES) Update.
(GUILD, GUILD_TARGET_FLAG, GUILD_COMPILE_FLAGS): New variables.
(stamp-guile): Compile scm files.
* guile/guile.c (boot_guile_support): New function.
(standard_throw_args_p): New function.
(print_standard_throw_error, print_throw_error): New functions.
(handle_boot_error): New function.
(initialize_scheme_side): Rewrite to call boot_guile_support.
* guile/lib/gdb/boot.scm: Update %load-compiled-path. Load gdb.go.
* guile/lib/gdb/init.scm (%silence-compiler-warnings%): New function.
* data-directory/Makefile.in (GUILE_FILES): Add support.scm.
* guile/lib/gdb/support.scm: New file.
* guile/guile.c (gdbscm_init_module_name): Change to "gdb".
* guile/lib/gdb.scm: Load gdb/init.scm as an include file.
All uses updated.
* guile/lib/gdb/init.scm (SCM_ARG1, SCM_ARG2): Moved to support.scm.
All uses updated.
(%assert-type): Ditto, and renamed to assert-type.
(%exception-print-style): Delete.
testsuite/
* gdb.guile/types-module.exp: Add tests for wrong type arguments.
PR 17185 describes a problem with using gdb+guile with libgc 7.4.0.
The symptom is a hang in sigsuspend.
[The thread referenced in the PR has the details.]
It's not clear what the right fix is, or even where the bug is yet.
This patch applies the same workaround Guile has applied.
There is no functionality or real performance loss with this,
and Guile has been using it for awhile.
* configure.ac: Add check for header gc/gc.h.
Add check for function setenv.
* configure: Regenerate.
* config.in: Regenerate.
* guile/guile.c (_initialize_guile): Add workaround for libgc 7.4.0.
Currently there are many calls to help_list that pass the constant -1
as the "class" value. However, the parameter is declared as being of
type enum command_class, and uses of the constant violate this
abstraction.
This patch fixes the error everywhere it occurs in the gdb sources.
Tested by rebuilding.
2014-06-13 Tom Tromey <tromey@redhat.com>
* cp-support.c (maint_cplus_command): Pass all_commands, not -1,
to help_list.
* guile/guile.c (info_guile_command): Pass all_commands, not -1,
to help_list.
* tui/tui-win.c (tui_command): Pass all_commands, not -1, to
help_list.
* tui/tui-regs.c (tui_reg_command): Pass all_commands, not -1, to
help_list.Pass all_commands, not -1, to help_list.
* cli/cli-dump.c (dump_command, append_command)
(srec_dump_command, ihex_dump_command, tekhex_dump_command)
(binary_dump_command, binary_append_command): Pass all_commands,
not -1, to help_list.
* cli/cli-cmds.c (info_command, set_debug): Pass all_commands, not
-1, to help_list.
* valprint.c (set_print, set_print_raw): Pass all_commands, not
-1, to help_list.
* typeprint.c (set_print_type): Pass all_commands, not -1, to
help_list.
* top.c (set_history): Pass all_commands, not -1, to help_list.
* target-descriptions.c (set_tdesc_cmd, unset_tdesc_cmd): Pass
all_commands, not -1, to help_list.
* symfile.c (overlay_command): Pass all_commands, not -1, to
help_list.
* spu-tdep.c (info_spu_command): Pass all_commands, not -1, to
help_list.
* serial.c (serial_set_cmd): Pass all_commands, not -1, to
help_list.
* ser-tcp.c (set_tcp_cmd, show_tcp_cmd): Pass all_commands, not
-1, to help_list.
* remote.c (remote_command, set_remote_cmd): Pass all_commands,
not -1, to help_list.
* ravenscar-thread.c (set_ravenscar_command): Pass all_commands,
not -1, to help_list.
* maint.c (maintenance_command, maintenance_info_command)
(maintenance_print_command, maintenance_set_cmd): Pass
all_commands, not -1, to help_list.
* macrocmd.c (macro_command): Pass all_commands, not -1, to
help_list.
* language.c (set_check): Pass all_commands, not -1, to help_list.
* infcmd.c (unset_command): Pass all_commands, not -1, to
help_list.
* frame.c (set_backtrace_cmd): Pass all_commands, not -1, to
help_list.
* dwarf2read.c (set_dwarf2_cmd): Pass all_commands, not -1, to
help_list.
* dcache.c (set_dcache_command): Pass all_commands, not -1, to
help_list.
* breakpoint.c (save_command): Pass all_commands, not -1, to
help_list.
* ada-lang.c (maint_set_ada_cmd, set_ada_command): Pass
all_commands, not -1, to help_list.
gdb/
2014-06-01 Ludovic Courtès <ludo@gnu.org>
* configure.ac: When Guile is available, check for the
availability of 'scm_new_smob'.
* configure, config.h.in: Regenerate.
* guile/guile-internal.h (scm_new_smob) [!HAVE_SCM_NEW_SMOB]: New
function.
https://sourceware.org/ml/gdb-patches/2014-05/msg00737.html
Currently a MEMORY_ERROR raised during unwinding a frame will cause the
unwind to stop with an error message, for example:
(gdb) bt
#0 breakpt () at amd64-invalid-stack-middle.c:27
#1 0x00000000004008f0 in func5 () at amd64-invalid-stack-middle.c:32
#2 0x0000000000400900 in func4 () at amd64-invalid-stack-middle.c:38
#3 0x0000000000400910 in func3 () at amd64-invalid-stack-middle.c:44
#4 0x0000000000400928 in func2 () at amd64-invalid-stack-middle.c:50
Cannot access memory at address 0x2aaaaaab0000
However, frame #4 is marked as being the end of the stack unwind, so a
subsequent request for the backtrace looses the error message, such as:
(gdb) bt
#0 breakpt () at amd64-invalid-stack-middle.c:27
#1 0x00000000004008f0 in func5 () at amd64-invalid-stack-middle.c:32
#2 0x0000000000400900 in func4 () at amd64-invalid-stack-middle.c:38
#3 0x0000000000400910 in func3 () at amd64-invalid-stack-middle.c:44
#4 0x0000000000400928 in func2 () at amd64-invalid-stack-middle.c:50
When fetching the backtrace, or requesting the stack depth using the MI
interface the situation is even worse, the first time a request is made
we encounter the memory error and so the MI returns an error instead of
the correct result, for example:
(gdb) -stack-info-depth
^error,msg="Cannot access memory at address 0x2aaaaaab0000"
Or,
(gdb) -stack-list-frames
^error,msg="Cannot access memory at address 0x2aaaaaab0000"
However, once one of these commands has been used gdb has, internally,
walked the stack and figured that out that frame #4 is the bottom of the
stack, so the second time an MI command is tried you'll get the "expected"
result:
(gdb) -stack-info-depth
^done,depth="5"
Or,
(gdb) -stack-list-frames
^done,stack=[frame={level="0", .. snip lots .. }]
After this patch the MEMORY_ERROR encountered during the frame unwind is
attached to frame #4 as the stop reason, and is displayed in the CLI each
time the backtrace is requested. In the MI, catching the error means that
the "expected" result is returned the first time the MI command is issued.
So, from the CLI the results of the backtrace will be:
(gdb) bt
#0 breakpt () at amd64-invalid-stack-middle.c:27
#1 0x00000000004008f0 in func5 () at amd64-invalid-stack-middle.c:32
#2 0x0000000000400900 in func4 () at amd64-invalid-stack-middle.c:38
#3 0x0000000000400910 in func3 () at amd64-invalid-stack-middle.c:44
#4 0x0000000000400928 in func2 () at amd64-invalid-stack-middle.c:50
Backtrace stopped: Cannot access memory at address 0x2aaaaaab0000
Each and every time that the backtrace is requested, while the MI output
will similarly be consistently:
(gdb) -stack-info-depth
^done,depth="5"
Or,
(gdb) -stack-list-frames
^done,stack=[frame={level="0", .. snip lots .. }]
gdb/ChangeLog:
* frame.c (struct frame_info): Add stop_string field.
(get_prev_frame_always_1): Renamed from get_prev_frame_always.
(get_prev_frame_always): Old content moved into
get_prev_frame_always_1. Call get_prev_frame_always_1 inside
TRY_CATCH, handle MEMORY_ERROR exceptions.
(frame_stop_reason_string): New function definition.
* frame.h (unwind_stop_reason_to_string): Extend comment to
mention frame_stop_reason_string.
(frame_stop_reason_string): New function declaration.
* stack.c (frame_info): Switch to frame_stop_reason_string.
(backtrace_command_1): Switch to frame_stop_reason_string.
* unwind_stop_reason.def: Add UNWIND_MEMORY_ERROR.
(LAST_ENTRY): Changed to UNWIND_MEMORY_ERROR.
* guile/lib/gdb.scm: Add FRAME_UNWIND_MEMORY_ERROR to export list.
gdb/doc/ChangeLog:
* guile.texi (Frames In Guile): Mention FRAME_UNWIND_MEMORY_ERROR.
* python.texi (Frames In Python): Mention
gdb.FRAME_UNWIND_MEMORY_ERROR.
gdb/testsuite/ChangeLog:
* gdb.arch/amd64-invalid-stack-middle.exp: Update expected results.
* gdb.arch/amd64-invalid-stack-top.exp: Likewise.
https://sourceware.org/ml/gdb-patches/2014-05/msg00721.html
This function is confusingly named, the "frame_" in the name implies it
somehow is frame dependent, when in reality the function just converts an
'enum unwind_stop_reason' value to a string.
gdb/ChangeLog:
* frame.c (frame_stop_reason_string): Rename to ...
(unwind_stop_reason_to_string): this.
* frame.h (frame_stop_reason_string): Rename to ...
(unwind_stop_reason_to_string): this.
* stack.c (frame_info): Update call to frame_stop_reason_string.
(backtrace_command_1): Likewise.
* guile/scm-frame.c (gdbscm_unwind_stop_reason_string): Likewise.
* python/py-frame.c (gdbpy_frame_stop_reason_string): Likewise.
* guile/scm-value.c (gdbscm_value_dynamic_type): Use coerce_ref to
dereference TYPE_CODE_REF values.
testsuite/
* gdb.guile/scm-value.c: Improve test case.
* gdb.guile/scm-value.exp: Add new test.
* guile/scm-type.c (tyscm_copy_type_recursive): Move type to its
new eq?-hashtab.
testsuite/
* gdb.guile/scm-value.ep (test_value_after_death): Do a garbage
collect after discarding symbols.
Pedro Alves
Doug Evans
Gary Benson
Tom Tromey
Ludovic Courtès
Andrew Burgess
Andy Wingo