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5c5019c27c
On GNU/Linux, if a pthreaded program has a thread call clone(CLONE_VM) directly, and then that clone LWP hits a debug event (breakpoint, etc.) GDB internal errors. Threaded programs shouldn't really be calling clone directly, but GDB shouldn't crash either. The crash looks like this: (gdb) break clone_fn Breakpoint 2 at 0x4007d8: file clone-thread_db.c, line 35. (gdb) r ... [Thread debugging using libthread_db enabled] ... src/gdb/linux-nat.c:1030: internal-error: lin_lwp_attach_lwp: Assertion `lwpid > 0' failed. A problem internal to GDB has been detected, further debugging may prove unreliable. The problem is that 'clone' ends up clearing the parent thread's tid field in glibc's thread data structure. For x86_64, the glibc code in question is here: sysdeps/unix/sysv/linux/x86_64/clone.S: ... testq $CLONE_THREAD, %rdi jne 1f testq $CLONE_VM, %rdi movl $-1, %eax <---- jne 2f movl $SYS_ify(getpid), %eax syscall 2: movl %eax, %fs:PID movl %eax, %fs:TID <---- 1: When GDB refreshes the thread list out of libthread_db, it finds a thread with LWP with pid -1 (the clone's parent), which naturally isn't yet on the thread list. GDB then tries to attach to that bogus LWP id, which is caught by that assertion. The fix is to detect the bad PID early. Tested on x86-64 Fedora 20. GDBserver doesn't need any fix. gdb/ChangeLog: 2015-02-20 Pedro Alves <palves@redhat.com> PR threads/18006 * linux-thread-db.c (thread_get_info_callback): Return early if the thread's lwp id is -1. gdb/testsuite/ChangeLog: 2015-02-20 Pedro Alves <palves@redhat.com> PR threads/18006 * gdb.threads/clone-thread_db.c: New file. * gdb.threads/clone-thread_db.exp: New file. |
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bfd | ||
binutils | ||
config | ||
cpu | ||
elfcpp | ||
etc | ||
gas | ||
gdb | ||
gold | ||
gprof | ||
include | ||
intl | ||
ld | ||
libdecnumber | ||
libiberty | ||
opcodes | ||
readline | ||
sim | ||
texinfo | ||
.cvsignore | ||
.gitattributes | ||
.gitignore | ||
ChangeLog | ||
compile | ||
config-ml.in | ||
config.guess | ||
config.rpath | ||
config.sub | ||
configure | ||
configure.ac | ||
COPYING | ||
COPYING.LIB | ||
COPYING.LIBGLOSS | ||
COPYING.NEWLIB | ||
COPYING3 | ||
COPYING3.LIB | ||
depcomp | ||
djunpack.bat | ||
install-sh | ||
libtool.m4 | ||
ltgcc.m4 | ||
ltmain.sh | ||
ltoptions.m4 | ||
ltsugar.m4 | ||
ltversion.m4 | ||
lt~obsolete.m4 | ||
MAINTAINERS | ||
Makefile.def | ||
Makefile.in | ||
Makefile.tpl | ||
makefile.vms | ||
missing | ||
mkdep | ||
mkinstalldirs | ||
move-if-change | ||
README | ||
README-maintainer-mode | ||
setup.com | ||
src-release.sh | ||
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.