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Breakpoints are supposed to be transparent to memory accesses. For all kinds of breakpoints breakpoint_xfer_memory hides the breakpoint instructions. However, sss breakpoints aren't tracked like all other breakpoints, and nothing is taking care of hiding them from memory reads. Say, as is, a background step + disassemble will see breakpoints instructions on software step targets. E.g., stepping over this line: while (1); with s& and then "disassemble" would show sss breakpoints. Actually, that's still not be possible to see today, because: - in native Linux, you can't read memory while the program is running. - with Linux gdbserver, you can, but in the all-stop RSP you can't talk to the server while the program is running... - and with non-stop, on software step targets, we presently force the use of displaced-stepping for all single-steps, so no single-step breakpoints are used... I've been working towards making non-stop not force displaced stepping on sss targets, and I noticed the issue then. With that, I indeed see this: (gdb) set remote Z-packet off (gdb) s& (gdb) disassemble main Dump of assembler code for function main: 0x000000000040049c <+0>: push %rbp 0x000000000040049d <+1>: mov %rsp,%rbp 0x00000000004004a0 <+4>: int3 0x00000000004004a1 <+5>: (bad) End of assembler dump. Instead of the correct: (gdb) disassemble main Dump of assembler code for function main: 0x000000000040049c <+0>: push %rbp 0x000000000040049d <+1>: mov %rsp,%rbp 0x00000000004004a0 <+4>: jmp 0x4004a0 <main+4> This is actually one thing that my v1 of the recent "fix a bunch of run control bugs" series was fixing, because it made sss breakpoints be regular breakpoints in the breakpoint chain. But dropped it in the version that landed in the tree, due to some problems. So instead of making sss breakpoints regular breakpoints, go with a simpler fix (at least for now) -- make breakpoint_xfer_memory take software single-step breakpoints into account. After the patch, I get the correct disassemble output. Tested on x86_64 Fedora 17, and also on top of my "use software single-step on x86" series. Also fixes the issue pointed out by Yao at https://sourceware.org/ml/gdb-patches/2014-04/msg00045.html, where the prologue analysis/frame sniffing manages to see software step breakpoint instructions. gdb/ 2014-04-10 Pedro Alves <palves@redhat.com> * breakpoint.c (single_step_breakpoints) (single_step_gdbarch): Move up in the file. (one_breakpoint_xfer_memory): New function, factored out from ... (breakpoint_xfer_memory): ... here. Also process single-step breakpoints. |
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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.