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with the following code...
12 Nested; -- break #1
13 return I; -- break #2
14 end;
(line 12 is a call to function Nested)
... we have noticed the following errorneous behavior on ppc-aix,
where, after having inserted a breakpoint at line 12 and line 13,
and continuing from the breakpoint at line 12, the program never
stops at line 13, running away until the program terminates:
% gdb -q func
(gdb) b func.adb:12
Breakpoint 1 at 0x10000a24: file func.adb, line 12.
(gdb) b func.adb:13
Breakpoint 2 at 0x10000a28: file func.adb, line 13.
(gdb) run
Starting program: /[...]/func
Breakpoint 1, func () at func.adb:12
12 Nested; -- break #1
(gdb) c
Continuing.
[Inferior 1 (process 4128872) exited with code 02]
When resuming from the first breakpoint, GDB first tries to step out
of that first breakpoint. We rely on software single-stepping on this
platform, and it just so happens that the address of the first
software single-step breakpoint is the same as the user's breakpoint
#2 (0x10000a28). So, with infrun and target traces turned on (but
uninteresting traces snip'ed off), the "continue" operation looks like
this:
(gdb) c
### First, we insert the user breakpoints (the second one is an internal
### breakpoint on __pthread_init). The first user breakpoint is not
### inserted as we need to step out of it first.
target_insert_breakpoint (0x0000000010000a28, xxx) = 0
target_insert_breakpoint (0x00000000d03f3800, xxx) = 0
### Then we proceed with the step-out-of-breakpoint...
infrun: resume (step=1, signal=GDB_SIGNAL_0), trap_expected=1, current thread [process 15335610] at 0x10000a24
### That's when we insert the SSS breakpoints...
target_insert_breakpoint (0x0000000010000a28, xxx) = 0
target_insert_breakpoint (0x00000000100009ac, xxx) = 0
### ... then let the inferior resume...
target_resume (15335610, continue, 0)
infrun: wait_for_inferior ()
target_wait (-1, status, options={}) = 15335610, status->kind = stopped, signal = GDB_SIGNAL_TRAP
infrun: target_wait (-1, status) =
infrun: 15335610 [process 15335610],
infrun: status->kind = stopped, signal = GDB_SIGNAL_TRAP
infrun: infwait_normal_state
infrun: TARGET_WAITKIND_STOPPED
infrun: stop_pc = 0x100009ac
### At this point, we stopped at the second SSS breakpoint...
target_stopped_by_watchpoint () = 0
### We remove the SSS breakpoints...
target_remove_breakpoint (0x0000000010000a28, xxx) = 0
target_remove_breakpoint (0x00000000100009ac, xxx) = 0
target_stopped_by_watchpoint () = 0
### We find that we're not done, so we resume....
infrun: no stepping, continue
### And thus insert the user breakpoints again, except we're not
### inserting the second breakpoint?!?
target_insert_breakpoint (0x0000000010000a24, xxx) = 0
infrun: resume (step=0, signal=GDB_SIGNAL_0), trap_expected=0, current thread [process 15335610] at 0x100009ac
target_resume (-1, continue, 0)
infrun: prepare_to_wait
target_wait (-1, status, options={}) = 15335610, status->kind = exited, status = 2
What happens is that the removal of the software single-step
breakpoints effectively removed the breakpoint instruction from
inferior memory. But because such breakpoints are inserted directly
as raw breakpoints rather than through the normal chain of
breakpoints, we fail to notice that one of the user breakpoints points
to the same address and that this user breakpoint is therefore
effectively un-inserted. When resuming after the single-step, GDB
thinks that the user breakpoint is still inserted and therefore does
not need to insert it again.
This patch teaches the insert and remove routines of both regular and
raw breakpoints to be aware of each other. Special care needs to be
applied in case the target supports evaluation of breakpoint
conditions or commands.
gdb/ChangeLog:
PR breakpoints/17000
* breakpoint.c (find_non_raw_software_breakpoint_inserted_here):
New function, extracted from software_breakpoint_inserted_here_p.
(software_breakpoint_inserted_here_p): Replace factored out code
by call to find_non_raw_software_breakpoint_inserted_here.
(bp_target_info_copy_insertion_state): New function.
(bkpt_insert_location): Handle the case of a single-step
breakpoint already inserted at the same address.
(bkpt_remove_location): Handle the case of a single-step
breakpoint still inserted at the same address.
(deprecated_insert_raw_breakpoint): Handle the case of non-raw
breakpoint already inserted at the same address.
(deprecated_remove_raw_breakpoint): Handle the case of a
non-raw breakpoint still inserted at the same address.
(find_single_step_breakpoint): New function, extracted from
single_step_breakpoint_inserted_here_p.
(find_single_step_breakpoint): New function,
factored out from single_step_breakpoint_inserted_here_p.
(single_step_breakpoint_inserted_here_p): Reimplement.
gdb/testsuite/ChangeLog:
PR breakpoints/17000
* gdb.base/sss-bp-on-user-bp.exp: Remove kfail.
* gdb.base/sss-bp-on-user-bp-2.exp: Remove kfail.
Tested on ppc-aix with AdaCore's testsuite. Tested on x86_64-linux,
(native and gdbserver) with the official testsuite. Also tested on
x86_64-linux through Pedro's branch enabling software single-stepping
on that platform (native and gdbserver).
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| bfd | ||
| binutils | ||
| config | ||
| cpu | ||
| elfcpp | ||
| etc | ||
| gas | ||
| gdb | ||
| gold | ||
| gprof | ||
| include | ||
| intl | ||
| ld | ||
| libdecnumber | ||
| libiberty | ||
| opcodes | ||
| readline | ||
| sim | ||
| texinfo | ||
| .cvsignore | ||
| .gitignore | ||
| ChangeLog | ||
| compile | ||
| config-ml.in | ||
| config.guess | ||
| config.rpath | ||
| config.sub | ||
| configure | ||
| configure.ac | ||
| COPYING | ||
| COPYING3 | ||
| COPYING3.LIB | ||
| COPYING.LIB | ||
| COPYING.LIBGLOSS | ||
| COPYING.NEWLIB | ||
| depcomp | ||
| djunpack.bat | ||
| install-sh | ||
| libtool.m4 | ||
| lt~obsolete.m4 | ||
| ltgcc.m4 | ||
| ltmain.sh | ||
| ltoptions.m4 | ||
| ltsugar.m4 | ||
| ltversion.m4 | ||
| MAINTAINERS | ||
| Makefile.def | ||
| Makefile.in | ||
| Makefile.tpl | ||
| makefile.vms | ||
| missing | ||
| mkdep | ||
| mkinstalldirs | ||
| move-if-change | ||
| README | ||
| README-maintainer-mode | ||
| setup.com | ||
| src-release | ||
| symlink-tree | ||
| ylwrap | ||
README for GNU development tools This directory contains various GNU compilers, assemblers, linkers, debuggers, etc., plus their support routines, definitions, and documentation. If you are receiving this as part of a GDB release, see the file gdb/README. If with a binutils release, see binutils/README; if with a libg++ release, see libg++/README, etc. That'll give you info about this package -- supported targets, how to use it, how to report bugs, etc. It is now possible to automatically configure and build a variety of tools with one command. To build all of the tools contained herein, run the ``configure'' script here, e.g.: ./configure make To install them (by default in /usr/local/bin, /usr/local/lib, etc), then do: make install (If the configure script can't determine your type of computer, give it the name as an argument, for instance ``./configure sun4''. You can use the script ``config.sub'' to test whether a name is recognized; if it is, config.sub translates it to a triplet specifying CPU, vendor, and OS.) If you have more than one compiler on your system, it is often best to explicitly set CC in the environment before running configure, and to also set CC when running make. For example (assuming sh/bash/ksh): CC=gcc ./configure make A similar example using csh: setenv CC gcc ./configure make Much of the code and documentation enclosed is copyright by the Free Software Foundation, Inc. See the file COPYING or COPYING.LIB in the various directories, for a description of the GNU General Public License terms under which you can copy the files. REPORTING BUGS: Again, see gdb/README, binutils/README, etc., for info on where and how to report problems.