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Pedro Alves 5c5019c27c PR18006: internal error if threaded program calls clone(CLONE_VM)
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.
2015-02-20 19:00:21 +00:00
bfd S390: Support new vector register sections 2015-02-20 10:39:53 +01:00
binutils S390: Support new vector register sections 2015-02-20 10:39:53 +01:00
config Fix --diable-shared --enable-plugins build breakage 2014-08-19 21:59:56 +09:30
cpu or1k: add missing l.msync, l.psync and l.psync instructions. 2014-07-20 20:26:09 +03:00
elfcpp [gold] Recognize DWARF5/GCC5 DW_LANG_Fortran03 and DW_LANG_Fortran08. 2015-02-17 08:08:24 +01:00
etc PR external/{16327,16328}: Remove etc/configure.texi and etc/standards.texi. 2014-06-27 11:33:25 +02:00
gas gas doc warning fixes 2015-02-19 14:14:51 +10:30
gdb PR18006: internal error if threaded program calls clone(CLONE_VM) 2015-02-20 19:00:21 +00:00
gold Fix gold error: hidden symbol '...' is not defined locally 2015-02-18 22:51:14 +10:30
gprof Regenerate Makeile.in file for copyright update 2015-01-02 22:27:27 +10:30
include S390: Support new vector register sections 2015-02-20 10:39:53 +01:00
intl merge from gcc 2010-09-27 21:01:18 +00:00
ld Use nm/readelf with "failif" 2015-02-19 04:45:27 -08:00
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opcodes Wrap a few opcodes headers in extern "C" for C++ 2015-02-19 22:45:47 +00:00
readline Fix executable indicator in file name completion on Windows. 2014-12-30 21:14:25 +02:00
sim sim: drop unused headers 2015-02-20 00:16:14 -05:00
texinfo * texinfo/texinfo.tex: Update to version 2009-03-28.05. 2009-04-21 12:36:46 +00:00
.cvsignore
.gitattributes Add a .gitattributes file for use with git-merge-changelog 2014-07-25 18:07:23 -04:00
.gitignore Sync the root .gitignore file with GCC's. 2013-01-11 15:17:35 +00:00
ChangeLog FT32 initial support 2015-01-28 16:25:18 +10:30
compile Update from upstream Automake 2014-11-16 13:43:48 +01:00
config-ml.in * config-ml.in: Don't handle arc-*-elf*. 2011-03-22 20:01:13 +00:00
config.guess config.sub, config.guess: Update from upstream, to 2015-01-01 version. 2015-01-02 10:40:57 +01:00
config.rpath Remove freebsd1 from libtool.m4 macros and config.rpath. 2011-02-13 21:00:14 +00:00
config.sub config.sub, config.guess: Update from upstream, to 2015-01-01 version. 2015-01-02 10:40:57 +01:00
configure FT32 initial support 2015-01-28 16:25:18 +10:30
configure.ac FT32 initial support 2015-01-28 16:25:18 +10:30
COPYING
COPYING.LIB
COPYING.LIBGLOSS 2013-01-07 Jeff Johnston <jjohnstn@redhat.com> 2013-01-07 21:39:26 +00:00
COPYING.NEWLIB 2013-10-01 Jeff Johnston <jjohnstn@redhat.com> 2013-10-01 18:14:04 +00:00
COPYING3 * COPYING3: New file. Contains version 3 of the GNU General Public License. 2007-07-17 13:50:23 +00:00
COPYING3.LIB * COPYING3: New file. Contains version 3 of the GNU General Public License. 2007-07-17 13:50:23 +00:00
depcomp Update from upstream Automake 2014-11-16 13:43:48 +01:00
djunpack.bat * djunpack.bat: Use ".." quoting in Sed command, for the sake of 2009-03-27 13:37:09 +00:00
install-sh Update from upstream Automake 2014-11-16 13:43:48 +01:00
libtool.m4 Update libtool.m4 from GCC trunk 2014-11-24 09:14:09 -08:00
ltgcc.m4 * libtool.m4: Update to libtool 2.2.6. 2008-09-29 15:28:14 +00:00
ltmain.sh PR target/59788 2014-02-06 11:01:57 +01:00
ltoptions.m4 Sync Libtool from GCC. 2010-01-09 21:11:44 +00:00
ltsugar.m4 * libtool.m4: Update to libtool 2.2.6. 2008-09-29 15:28:14 +00:00
ltversion.m4 Sync Libtool from GCC. 2010-01-09 21:11:44 +00:00
lt~obsolete.m4 Sync Libtool from GCC. 2010-01-09 21:11:44 +00:00
MAINTAINERS Update description of ownership of files in include/ 2014-11-04 16:14:14 -08:00
Makefile.def [GCC bug #63539]: libgo does not use the newly built objcopy when doing a combined build 2015-01-03 14:54:45 -08:00
Makefile.in [GCC bug #63539]: libgo does not use the newly built objcopy when doing a combined build 2015-01-03 14:54:45 -08:00
Makefile.tpl [GCC bug #63539]: libgo does not use the newly built objcopy when doing a combined build 2015-01-03 14:54:45 -08:00
makefile.vms
missing Update from upstream Automake 2014-11-16 13:43:48 +01:00
mkdep
mkinstalldirs Update from upstream Automake 2014-11-16 13:43:48 +01:00
move-if-change Update `move-if-change' from gnulib 2014-11-16 17:04:02 +01:00
README
README-maintainer-mode Cleanups after the update to Autoconf 2.64, Automake 1.11. 2009-08-22 17:08:11 +00:00
setup.com 2009-09-01 Tristan Gingold <gingold@adacore.com> 2009-09-01 13:38:26 +00:00
src-release.sh src-release.sh: configure using --target. 2014-10-15 09:50:53 +02:00
symlink-tree
ylwrap Update from upstream Automake 2014-11-16 13:43:48 +01:00

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