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multi-threaded.
On Linux, we need to explicitly ptrace attach to all lwps of a
process. Because GDB might not be connected yet when an attach is
requested, and thus it may not be possible to activate thread_db, as
that requires access to symbols (IOW, gdbserver --attach), a while ago
we make linux_attach loop over the lwps as listed by /proc/PID/task to
find the lwps to attach to.
linux_attach_lwp_1 has:
...
if (initial)
/* If lwp is the tgid, we handle adding existing threads later.
Otherwise we just add lwp without bothering about any other
threads. */
ptid = ptid_build (lwpid, lwpid, 0);
else
{
/* Note that extracting the pid from the current inferior is
safe, since we're always called in the context of the same
process as this new thread. */
int pid = pid_of (current_inferior);
ptid = ptid_build (pid, lwpid, 0);
}
That "safe" comment referred to linux_attach_lwp being called by
thread-db.c. But this was clearly missed when a new call to
linux_attach_lwp_1 was added to linux_attach. As a result,
current_inferior will be set to some random process, and non-initial
lwps of the second inferior get assigned the pid of the wrong
inferior. E.g., in the case of attaching to two inferiors, for the
second inferior (and so on), non-initial lwps of the second inferior
get assigned the pid of the first inferior. This doesn't trigger on
the first inferior, when current_inferior is NULL, add_thread switches
the current inferior to the newly added thread.
Rather than making linux_attach switch current_inferior temporarily
(thus avoiding further reliance on global state), or making
linux_attach_lwp_1 get the tgid from /proc, which add extra syscalls,
and will be wrong in case of the user having originally attached
directly to a non-tgid lwp, and then that lwp spawning new clones (the
ptid.pid field of further new clones should be the same as the
original lwp's pid, which is not the tgid), we note that callers of
linux_attach_lwp/linux_attach_lwp_1 always have the right pid handy
already, so they can pass it down along with the lwpid.
The only other reason for the "initial" parameter is to error out
instead of warn in case of attach failure, when we're first attaching
to a process. There are only three callers of
linux_attach_lwp/linux_attach_lwp_1, and each wants to print a
different warn/error string, so we can just move the error/warn out of
linux_attach_lwp_1 to the callers, thus getting rid of the "initial"
parameter.
There really nothing gdbserver-specific about attaching to two
threaded processes, so this adds a new test under gdb.multi/. The
test passes cleanly against the native GNU/Linux target, but
fails/triggers the bug against GDBserver (before the patch), with the
native-extended-remote board (as plain remote doesn't support
multi-process).
Tested on x86_64 Fedora 17, with the native-extended-gdbserver board.
gdb/gdbserver/
2014-04-25 Pedro Alves <palves@redhat.com>
PR server/16255
* linux-low.c (linux_attach_fail_reason_string): New function.
(linux_attach_lwp): Delete.
(linux_attach_lwp_1): Rename to ...
(linux_attach_lwp): ... this. Take a ptid instead of a pid as
argument. Remove "initial" parameter. Return int instead of
void. Don't error or warn here.
(linux_attach): Adjust to call linux_attach_lwp. Call error on
failure to attach to the tgid. Call warning when failing to
attach to an lwp.
* linux-low.h (linux_attach_lwp): Take a ptid instead of a pid as
argument. Remove "initial" parameter. Return int instead of
void. Don't error or warn here.
(linux_attach_fail_reason_string): New declaration.
* thread-db.c (attach_thread): Adjust to linux_attach_lwp's
interface change. Use linux_attach_fail_reason_string.
gdb/
2014-04-25 Pedro Alves <palves@redhat.com>
PR server/16255
* common/linux-ptrace.c (linux_ptrace_attach_warnings): Rename to ...
(linux_ptrace_attach_fail_reason): ... this. Remove "warning: "
and newline from built string.
* common/linux-ptrace.h (linux_ptrace_attach_warnings): Rename to ...
(linux_ptrace_attach_fail_reason): ... this.
* linux-nat.c (linux_nat_attach): Adjust to use
linux_ptrace_attach_fail_reason.
gdb/testsuite/
2014-04-25 Simon Marchi <simon.marchi@ericsson.com>
Pedro Alves <palves@redhat.com>
PR server/16255
* gdb.multi/multi-attach.c: New file.
* gdb.multi/multi-attach.exp: New file.
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gdbserver use it.
gdb/
* Makefile.in (HFILES_NO_SRCDIR): Add nat/linux-nat.h and
nat/linux-waitpid.h.
(linux-waitpid.o): New object file rule.
* common/linux-ptrace.c: Include nat/linux-waitpid.h.
(current_ptrace_options): Moved from linux-nat.c.
(linux_ptrace_test_ret_to_nx): Use type casts for ptrace
parameters.
(linux_fork_to_function): New function.
(linux_grandchild_function): Likewise.
(linux_child_function): Likewise.
(linux_check_ptrace_features): New function, heavily
based on linux-nat.c:linux_test_for_tracefork.
(linux_enable_event_reporting): New function.
(ptrace_supports_feature): Likewise.
(linux_supports_tracefork): Likewise.
(linux_supports_traceclone): Likewise.
(linux_supports_tracevforkdone): Likewise.
(linux_supports_tracesysgood): Likewise.
* common/linux-ptrace.h (HAS_NOMMU): Moved from
gdbserver/linux-low.c.
(linux_enable_event_reporting): New declaration.
(linux_supports_tracefork): Likewise.
(linux_supports_traceclone): Likewise.
(linux_supports_tracevforkdone): Likewise.
(linux_supports_tracesysgood): Likewise.
* config.in (PTRACE_TYPE_ARG4): Regenerate.
* config/aarch64/linux.mh (NATDEPFILES): Add linux-waitpid.o.
* config/alpha/alpha-linux.mh (NATDEPFILES): Likewise.
* config/arm/linux.mh (NATDEPFILES): Likewise.
* config/i386/linux.mh (NATDEPFILES): Likewise.
* config/i386/linux64.mh (NATDEPFILES): Likewise.
* config/ia64/linux.mh (NATDEPFILES): Likewise.
* config/m32r/linux.mh (NATDEPFILES): Likewise.
* config/m68k/linux.mh (NATDEPFILES): Likewise.
* config/mips/linux.mh (NATDEPFILES): Likewise.
* config/pa/linux.mh (NATDEPFILES): Likewise..
* config/powerpc/linux.mh (NATDEPFILES): Likewise..
* config/powerpc/ppc64-linux.mh (NATDEPFILES): Likewise.
* config/powerpc/spu-linux.mh (NATDEPFILES): Likewise.
* config/sparc/linux.mh (NATDEPFILES): Likewise.
* config/sparc/linux64.mh (NATDEPFILES): Likewise.
* config/tilegx/linux.mh (NATDEPFILES): Likewise.
* config/xtensa/linux.mh (NATDEPFILES): Likewise.
* configure.ac (AC_CACHE_CHECK): Add void * to the list of
ptrace's 4th argument's types.
Check the type of PTRACE_TYPE_ARG4.
* configure: Regenerate.
* linux-nat.c: Include nat/linux-nat.h and nat/linux-waitpid.h.
(SYSCALL_SIGTRAP): Moved to nat/linux-nat.h.
(linux_supports_tracefork_flag): Remove.
(linux_supports_tracesysgood_flag): Likewise.
(linux_supports_tracevforkdone_flag): Likewise.
(current_ptrace_options): Moved to
common/linux-ptrace.c.
(linux_tracefork_child): Remove.
(my_waitpid): Remove.
(linux_test_for_tracefork): Renamed to
linux_check_ptrace_features and moved to common/linux-ptrace.c.
(linux_test_for_tracesysgood): Remove.
(linux_supports_tracesysgood): Remove.
(linux_supports_tracefork): Remove.
(linux_supports_tracevforkdone): Remove.
(linux_enable_tracesysgood): Remove.
(linux_enable_event_reporting): Remove.
(linux_init_ptrace): New function.
(linux_child_post_attach): Call linux_init_ptrace.
(linux_child_post_startup_inferior): Call linux_init_ptrace.
(linux_child_follow_fork): Call linux_supports_tracefork
and linux_supports_tracevforkdone.
(linux_child_insert_fork_catchpoint): Call
linux_supports_tracefork.
(linux_child_insert_vfork_catchpoint): Likewise.
(linux_child_set_syscall_catchpoint): Call
linux_supports_tracesysgood.
(lin_lwp_attach_lwp): Call linux_supports_tracefork.
* nat/linux-nat.h: New file.
* nat/linux-waitpid.c: New file.
* nat/linux-waitpid.h: New file.
gdb/gdbserver/
* Makefile.in: Explain why ../target and ../nat are not
listed as include file search paths.
(linux-waitpid.o): New object file rule.
* configure.srv (srv_native_linux_obj): New variable.
Replace all occurrences of linux native object files with
$srv_native_linux_obj.
* linux-low.c: Include nat/linux-nat.h and nat/linux-waitpid.h.
(HAS_NOMMU): Move defining logic to common/linux-ptrace.c.
(linux_enable_event_reporting): Remove declaration.
(my_waitpid): Moved to common/linux-waitpid.c.
(linux_wait_for_event): Pass ptid when calling
linux_enable_event_reporting.
(linux_supports_tracefork_flag): Remove.
(linux_enable_event_reporting): Likewise.
(linux_tracefork_grandchild): Remove.
(STACK_SIZE): Moved to common/linux-ptrace.c.
(linux_tracefork_child): Remove.
(linux_test_for_tracefork): Remove.
(linux_look_up_symbols): Call linux_supports_traceclone.
(initialize_low): Remove call to linux_test_for_tracefork.
* linux-low.h (PTRACE_TYPE_ARG3): Move to
common/linux-ptrace.h.
(PTRACE_TYPE_ARG4): Likewise.
Include linux-ptrace.h.
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Two modifications:
1. The addition of 2013 to the copyright year range for every file;
2. The use of a single year range, instead of potentially multiple
year ranges, as approved by the FSF.
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* common/linux-ptrace.c: Include gdb_assert.h.
<__i386__> (linux_ptrace_test_ret_to_nx_instr): New declaration.
<__i386__>: Include sys/reg.h, sys/mman.h, signal.h, sys/wait.h and
stdint.h.
(linux_ptrace_test_ret_to_nx, linux_ptrace_init_warnings): New
functions.
* common/linux-ptrace.h (linux_ptrace_init_warnings): New declarations.
* linux-nat.c (linux_child_post_attach)
(linux_child_post_startup_inferior): Call linux_ptrace_init_warnings.
gdb/gdbserver/
* gdbserver/linux-low.c (initialize_low): Call
linux_ptrace_init_warnings.
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* common/linux-procfs.c (linux_proc_get_int): New, from
linux_proc_get_tgid, change its LWPID type to pid_t, add parameter
field.
(linux_proc_get_tgid): Only call linux_proc_get_int.
(linux_proc_get_tracerpid): New.
(linux_proc_pid_has_state): New, from linux_proc_pid_is_zombie.
(linux_proc_pid_is_stopped, linux_proc_pid_is_zombie): Only call
linux_proc_pid_has_state.
* common/linux-procfs.h (linux_proc_get_tracerpid): New declaration.
* common/linux-ptrace.c: Include linux-procfs.h and buffer.h.
(linux_ptrace_attach_warnings): New.
* common/linux-ptrace.h (struct buffer, linux_ptrace_attach_warnings):
New declaration.
* linux-nat.c: Include exceptions.h, linux-ptrace.h and buffer.h.
(linux_nat_attach): New variables ex, buffer, message and message_s.
Wrap to_attach by TRY_CATCH and call linux_ptrace_attach_warnings.
gdb/gdbserver/
* linux-low.c (linux_attach_lwp_1): New variable buffer. Call
linux_ptrace_attach_warnings.
gdb/testsuite/
* gdb.base/attach-twice.c: New files.
* gdb.base/attach-twice.exp: New files.
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gdb/ChangeLog:
Copyright year update in most files of the GDB Project.
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The DSBT support is very close to the FDPIC code, so extend the existing
loadmap support to work with FDPIC loadmaps too.
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
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* common/linux-ptrace.h: Remove include <sys/wait.h>.
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* linux-nat.c: Move common macros to ...
Include linux-ptrace.h.
* common/linux-ptrace.h: ... here. New.
gdb/gdbserver/
* linux-low.c: Move common macros to linux-ptrace.h.
Include linux-ptrace.h.
* Makefile.in (linux_ptrace_h): New.
(linux-low.o): Depends on linux-ptrace.h.
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