Following an exec with "breakpoint always-inserted on" tries to insert breakpoints in the new image at the addresses the symbols had in the old image. With "always-inserted off", we see: gdb gdb.multi/multi-arch-exec -ex "set breakpoint always-inserted off" GNU gdb (GDB) 7.8.50.20140924-cvs ... (gdb) b main Breakpoint 1 at 0x400664: file gdb.multi/multi-arch-exec.c, line 24. ^^^^^^^^ (gdb) c The program is not being run. (gdb) r Starting program: testsuite/gdb.multi/multi-arch-exec Breakpoint 1, main () at gdb/testsuite/gdb.multi/multi-arch-exec.c:24 24 execl (BASEDIR "/multi-arch-exec-hello", (gdb) c Continuing. process 9212 is executing new program: gdb/testsuite/gdb.multi/multi-arch-exec-hello Breakpoint 1, main () at gdb/testsuite/gdb.multi/hello.c:40 40 bar(); (gdb) info breakpoints Num Type Disp Enb Address What 1 breakpoint keep y 0x080484e4 in main at gdb/testsuite/gdb.multi/hello.c:40 ^^^^^^^^^^ breakpoint already hit 2 times (gdb) Note how main was 0x400664 in multi-arch-exec, and 0x080484e4 in gdb.multi/hello. With "always-inserted on", we get: Breakpoint 1, main () at gdb/testsuite/gdb.multi/multi-arch-exec.c:24 24 execl (BASEDIR "/multi-arch-exec-hello", (gdb) c Continuing. infrun: target_wait (-1, status) = infrun: 9444 [process 9444], infrun: status->kind = execd infrun: infwait_normal_state infrun: TARGET_WAITKIND_EXECD Warning: Cannot insert breakpoint 1. Cannot access memory at address 0x400664 (gdb) That is, GDB is trying to insert a breakpoint at 0x400664, after the exec, and then that address happens to not be mapped at all in the new image. The problem is that update_breakpoints_after_exec is creating breakpoints, which ends up in update_global_location_list immediately inserting breakpoints if "breakpoints always-inserted" is "on". update_breakpoints_after_exec is called very early when we see an exec event. At that point, we haven't loaded the symbols of the new post-exec image yet, and thus haven't reset breakpoint's addresses to whatever they may be in the new image. All we should be doing in update_breakpoints_after_exec is deleting breakpoints that no longer make sense after an exec. So the fix removes those breakpoint creations. The question is then, if not here, where are those breakpoints re-created? Turns out we don't need to do anything else, because at the end of follow_exec, we call breakpoint_re_set, whose tail is also creating exactly the same breakpoints update_breakpoints_after_exec is currently creating: breakpoint_re_set (void) { ... create_overlay_event_breakpoint (); create_longjmp_master_breakpoint (); create_std_terminate_master_breakpoint (); create_exception_master_breakpoint (); } A new test is added to exercise this. Tested on x86_64 Fedora 20. gdb/ 2014-10-02 Pedro Alves <palves@redhat.com> PR breakpoints/17431 * breakpoint.c (update_breakpoints_after_exec): Don't create overlay, longjmp, std terminate nor exception breakpoints here. gdb/testsuite/ 2014-10-02 Pedro Alves <palves@redhat.com> PR breakpoints/17431 * gdb.base/execl-update-breakpoints.c: New file. * gdb.base/execl-update-breakpoints.exp: New file. |
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binutils | ||
config | ||
cpu | ||
elfcpp | ||
etc | ||
gas | ||
gdb | ||
gold | ||
gprof | ||
include | ||
intl | ||
ld | ||
libdecnumber | ||
libiberty | ||
opcodes | ||
readline | ||
sim | ||
texinfo | ||
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COPYING | ||
COPYING.LIB | ||
COPYING.LIBGLOSS | ||
COPYING.NEWLIB | ||
COPYING3 | ||
COPYING3.LIB | ||
ChangeLog | ||
MAINTAINERS | ||
Makefile.def | ||
Makefile.in | ||
Makefile.tpl | ||
README | ||
README-maintainer-mode | ||
compile | ||
config-ml.in | ||
config.guess | ||
config.rpath | ||
config.sub | ||
configure | ||
configure.ac | ||
depcomp | ||
djunpack.bat | ||
install-sh | ||
libtool.m4 | ||
ltgcc.m4 | ||
ltmain.sh | ||
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ltsugar.m4 | ||
ltversion.m4 | ||
lt~obsolete.m4 | ||
makefile.vms | ||
missing | ||
mkdep | ||
mkinstalldirs | ||
move-if-change | ||
setup.com | ||
src-release.sh | ||
symlink-tree | ||
ylwrap |
README
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.