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If your target has no support for TARGET_WAITKIND_NO_RESUMED events
(and no way to support them, such as the yet-unsubmitted AMDGPU
target), and you step over thread exit with scheduler-locking on, this
is what you get:
(gdb) n
[Thread ... exited]
*hang*
Getting back the prompt by typing Ctrl-C may not even work, since no
inferior thread is running to receive the SIGINT. Even if it works,
it seems unnecessarily harsh. If you started an execution command for
which there's a clear thread of interest (step, next, until, etc.),
and that thread disappears, then I think it's more user friendly if
GDB just detects the situation and aborts the command, giving back the
prompt.
That is what this commit implements. It does this by explicitly
requesting the target to report thread exit events whenever the main
resumed thread has a thread_fsm. Note that unlike stepping over a
breakpoint, we don't need to enable clone events in this case.
With this patch, we get:
(gdb) n
[Thread 0x7ffff7d89700 (LWP 3961883) exited]
Command aborted, thread exited.
(gdb)
Reviewed-By: Andrew Burgess <aburgess@redhat.com>
Change-Id: I901ab64c91d10830590b2dac217b5264635a2b95
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This commit documents in both manual and NEWS:
- the new remote clone event stop reply,
- the new QThreadOptions packet and its current defined options,
- the associated "set/show remote thread-events-packet" command,
- and the associated QThreadOptions qSupported feature.
Approved-By: Eli Zaretskii <eliz@gnu.org>
Change-Id: Ic1c8de1fefba95729bbd242969284265de42427e
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Add new gdb.threads/step-over-thread-exit.exp and
gdb.threads/step-over-thread-exit-while-stop-all-threads.exp
testcases, exercising stepping over thread exit syscall. These make
use of lib/my-syscalls.S to define the exit syscall.
Co-authored-by: Pedro Alves <pedro@palves.net>
Reviewed-By: Andrew Burgess <aburgess@redhat.com>
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=27338
Change-Id: Ie8b2c5747db99b7023463a897a8390d9e814a9c9
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Refactor the syscall assembly code in gdb/testsuite/lib/my-syscalls.S
behind a SYSCALL macro so that it's easy to add new syscalls without
duplicating code.
Note that the way the macro is implemented, it only works correctly
for syscalls with up to 3 arguments, and, if the syscall doesn't
return (the macro doesn't bother to save/restore callee-saved
registers).
The following patch will want to use the macro to define a wrapper for
the "exit" syscall, so the limitations continue to be sufficient.
Change-Id: I8acf1463b11a084d6b4579aaffb49b5d0dea3bba
Reviewed-By: Andrew Burgess <aburgess@redhat.com>
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If GDB sets the GDB_THREAD_OPTION_EXIT option on a thread, then if the
thread disappears from the thread list, GDB expects to shortly see a
thread exit event for it. See e.g., here, in
remote_target::update_thread_list():
/* Do not remove the thread if we've requested to be
notified of its exit. For example, the thread may be
displaced stepping, infrun will need to handle the
exit event, and displaced stepping info is recorded
in the thread object. If we deleted the thread now,
we'd lose that info. */
if ((tp->thread_options () & GDB_THREAD_OPTION_EXIT) != 0)
continue;
There's one scenario that is deleting a thread from the
remote/gdbserver thread list without ever reporting a corresponding
thread exit event though -- check_zombie_leaders. This can lead to
GDB getting confused. For example, with a following patch that
enables GDB_THREAD_OPTION_EXIT whenever schedlock is enabled, we'd see
this regression:
$ make check RUNTESTFLAGS="--target_board=native-extended-gdbserver" TESTS="gdb.threads/no-unwaited-for-left.exp"
...
Running src/gdb/testsuite/gdb.threads/no-unwaited-for-left.exp ...
FAIL: gdb.threads/no-unwaited-for-left.exp: continue stops when the main thread exits (timeout)
... some more cascading FAILs ...
gdb.log shows:
(gdb) continue
Continuing.
FAIL: gdb.threads/no-unwaited-for-left.exp: continue stops when the main thread exits (timeout)
A passing run would have resulted in:
(gdb) continue
Continuing.
No unwaited-for children left.
(gdb) PASS: gdb.threads/no-unwaited-for-left.exp: continue stops when the main thread exits
note how the leader thread is not listed in the remote-reported XML
thread list below:
(gdb) set debug remote 1
(gdb) set debug infrun 1
(gdb) info threads
Id Target Id Frame
* 1 Thread 1163850.1163850 "no-unwaited-for" main () at /home/pedro/rocm/gdb/build/gdb/testsuite/../../../src/gdb/testsuite/gdb.threads/no-unwaited-for-left.c:65
3 Thread 1163850.1164130 "no-unwaited-for" [remote] Sending packet: $Hgp11c24a.11c362#39
(gdb) c
Continuing.
[infrun] clear_proceed_status_thread: 1163850.1163850.0
...
[infrun] resume_1: step=1, signal=GDB_SIGNAL_0, trap_expected=1, current thread [1163850.1163850.0] at 0x55555555534f
[remote] Sending packet: $QPassSignals:#f3
[remote] Packet received: OK
[remote] Sending packet: $QThreadOptions;3:p11c24a.11c24a#f3
[remote] Packet received: OK
...
[infrun] target_set_thread_options: [options for Thread 1163850.1163850 are now 0x3]
...
[infrun] do_target_resume: resume_ptid=1163850.1163850.0, step=0, sig=GDB_SIGNAL_0
[remote] Sending packet: $vCont;c:p11c24a.11c24a#98
[infrun] prepare_to_wait: prepare_to_wait
[infrun] reset: reason=handling event
[infrun] maybe_set_commit_resumed_all_targets: enabling commit-resumed for target extended-remote
[infrun] maybe_call_commit_resumed_all_targets: calling commit_resumed for target extended-remote
[infrun] fetch_inferior_event: exit
[infrun] fetch_inferior_event: enter
[infrun] scoped_disable_commit_resumed: reason=handling event
[infrun] random_pending_event_thread: None found.
[remote] wait: enter
[remote] Packet received: N
[remote] wait: exit
[infrun] print_target_wait_results: target_wait (-1.0.0 [process -1], status) =
[infrun] print_target_wait_results: -1.0.0 [process -1],
[infrun] print_target_wait_results: status->kind = NO_RESUMED
[infrun] handle_inferior_event: status->kind = NO_RESUMED
[remote] Sending packet: $Hgp0.0#ad
[remote] Packet received: OK
[remote] Sending packet: $qXfer:threads:read::0,1000#92
[remote] Packet received: l<threads>\n<thread id="p11c24a.11c362" core="0" name="no-unwaited-for" handle="0097d8f7ff7f0000"/>\n</threads>\n
[infrun] handle_no_resumed: TARGET_WAITKIND_NO_RESUMED (ignoring: found resumed)
...
... however, infrun decided there was a resumed thread still, so
ignored the TARGET_WAITKIND_NO_RESUMED event. Debugging GDB, we see
that the "found resumed" thread that GDB finds, is the leader thread.
Even though that thread is not on the remote-reported thread list, it
is still on the GDB thread list, due to the special case in remote.c
mentioned above.
This commit addresses the issue by fixing GDBserver to report a thread
exit event for the zombie leader too, i.e., making GDBserver respect
the "if thread has GDB_THREAD_OPTION_EXIT set, report a thread exit"
invariant. To do that, it takes a bit more code than one would
imagine off hand, due to the fact that we currently always report LWP
exit pending events as TARGET_WAITKIND_EXITED, and then decide whether
to convert it to TARGET_WAITKIND_THREAD_EXITED just before reporting
the event to GDBserver core. For the zombie leader scenario
described, we need to record early on that we want to report a
THREAD_EXITED event, and then make sure that decision isn't lost along
the way to reporting the event to GDBserver core.
Reviewed-By: Andrew Burgess <aburgess@redhat.com>
Change-Id: I1e68fccdbc9534434dee07163d3fd19744c8403b
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If scheduler-locking is in effect, e.g., with "set scheduler-locking
on", and you step over a function that spawns a new thread, the new
thread is allowed to run free, at least until some event is hit, at
which point, whether the new thread is re-resumed depends on a number
of seemingly random factors. E.g., if the target is all-stop, and the
parent thread hits a breakpoint, and GDB decides the breakpoint isn't
interesting to report to the user, then the parent thread is resumed,
but the new thread is left stopped.
I think that letting the new threads run with scheduler-locking
enabled is a defect. This commit fixes that, making use of the new
clone events on Linux, and of target_thread_events() on targets where
new threads have no connection to the thread that spawned them.
Testcase and documentation changes included.
Approved-By: Eli Zaretskii <eliz@gnu.org>
Reviewed-By: Andrew Burgess <aburgess@redhat.com>
Change-Id: Ie12140138b37534b7fc1d904da34f0f174aa11ce
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Normally, if the last resumed thread on the target exits, the server
sends a no-resumed event to GDB. If however, GDB enables the
GDB_THREAD_OPTION_EXIT option on a thread, and, that thread exits, the
server sends a thread exit event for that thread instead.
In all-stop RSP mode, since events can only be forwarded to GDB one at
a time, and the whole target stops whenever an event is reported, GDB
resumes the target again after getting a THREAD_EXITED event, and then
the server finally reports back a no-resumed event if/when
appropriate.
For non-stop RSP though, events are asynchronous, and if the server
sends a thread-exit event for the last resumed thread, the no-resumed
event is never sent. This patch makes sure that in non-stop mode, the
server queues a no-resumed event after the thread-exit event if it was
the last resumed thread that exited.
Without this, we'd see failures in step-over-thread-exit testcases
added later in the series, like so:
continue
Continuing.
- No unwaited-for children left.
- (gdb) PASS: gdb.threads/step-over-thread-exit.exp: displaced-stepping=off: non-stop=on: target-non-stop=on: schedlock=off: ns_stop_all=1: continue stops when thread exits
+ FAIL: gdb.threads/step-over-thread-exit.exp: displaced-stepping=off: non-stop=on: target-non-stop=on: schedlock=off: ns_stop_all=1: continue stops when thread exits (timeout)
(and other similar ones)
Reviewed-By: Andrew Burgess <aburgess@redhat.com>
Change-Id: I927d78b30f88236dbd5634b051a716f72420e7c7
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Running the
gdb.threads/step-over-thread-exit-while-stop-all-threads.exp testcase
added later in the series against gdbserver, after the
TARGET_WAITKIND_NO_RESUMED fix from the following patch, would run
into an infinite loop in stop_all_threads, leading to a timeout:
FAIL: gdb.threads/step-over-thread-exit-while-stop-all-threads.exp: displaced-stepping=off: target-non-stop=on: iter 0: continue (timeout)
The is really a latent bug, and it is about the fact that
stop_all_threads stops listening to events from a target as soon as it
sees a TARGET_WAITKIND_NO_RESUMED, ignoring that
TARGET_WAITKIND_NO_RESUMED may be delayed. handle_no_resumed knows
how to handle delayed no-resumed events, but stop_all_threads was
never taught to.
In more detail, here's what happens with that testcase:
#1 - Multiple threads report breakpoint hits to gdb.
#2 - gdb picks one events, and it's for thread 1. All other stops are
left pending. thread 1 needs to move past a breakpoint, so gdb
stops all threads to start an inline step over for thread 1.
While stopping threads, some of the threads that were still
running report events that are also left pending.
#2 - gdb steps thread 1
#3 - Thread 1 exits while stepping (it steps over an exit syscall),
gdbserver reports thread exit for thread 1
#4 - Thread 1 was the last resumed thread, so gdbserver also reports
no-resumed:
[remote] Notification received: Stop:w0;p3445d0.3445d3
[remote] Sending packet: $vStopped#55
[remote] Packet received: N
[remote] Sending packet: $vStopped#55
[remote] Packet received: OK
#5 - gdb processes the thread exit for thread 1, finishes the step
over and restarts threads.
#6 - gdb picks the next event to process out of one of the resumed
threads with pending events:
[infrun] random_resumed_with_pending_wait_status: Found 32 events, selecting #11
#7 - This is again a breakpoint hit and the breakpoint needs to be
stepped over too, so gdb starts a step-over dance again.
#8 - We reach stop_all_threads, which finds that some threads need to
be stopped.
#9 - wait_one finally consumes the no-resumed event queue by #4.
Seeing this, wait_one disable target async, to stop listening for
events out of the remote target.
#10 - We still haven't seen all the stops expected, so
stop_all_threads tries another iteration.
#11 - Because the remote target is no longer async, and there are no
other targets, wait_one return no-resumed immediately without
polling the remote target.
#12 - We still haven't seen all the stops expected, so
stop_all_threads tries another iteration. goto #11, looping
forever.
Fix this by explicitly enabling/re-enabling target async on targets
that can async, before waiting for stops.
Reviewed-By: Andrew Burgess <aburgess@redhat.com>
Change-Id: Ie3ffb0df89635585a6631aa842689cecc989e33f
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GDB doesn't handle correctly the case where a thread steps over a
breakpoint (using either in-line or displaced stepping), and the
executed instruction causes the thread to exit.
Using the test program included later in the series, this is what it
looks like with displaced-stepping, on x86-64 Linux, where we have two
displaced-step buffers:
$ ./gdb -q -nx --data-directory=data-directory build/binutils-gdb/gdb/testsuite/outputs/gdb.threads/step-over-thread-exit/step-over-thread-exit -ex "b my_exit_syscall" -ex r
Reading symbols from build/binutils-gdb/gdb/testsuite/outputs/gdb.threads/step-over-thread-exit/step-over-thread-exit...
Breakpoint 1 at 0x123c: file src/binutils-gdb/gdb/testsuite/lib/my-syscalls.S, line 68.
Starting program: build/binutils-gdb/gdb/testsuite/outputs/gdb.threads/step-over-thread-exit/step-over-thread-exit
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/usr/lib/../lib/libthread_db.so.1".
[New Thread 0x7ffff7c5f640 (LWP 2915510)]
[Switching to Thread 0x7ffff7c5f640 (LWP 2915510)]
Thread 2 "step-over-threa" hit Breakpoint 1, my_exit_syscall () at src/binutils-gdb/gdb/testsuite/lib/my-syscalls.S:68
68 syscall
(gdb) c
Continuing.
[New Thread 0x7ffff7c5f640 (LWP 2915524)]
[Thread 0x7ffff7c5f640 (LWP 2915510) exited]
[Switching to Thread 0x7ffff7c5f640 (LWP 2915524)]
Thread 3 "step-over-threa" hit Breakpoint 1, my_exit_syscall () at src/binutils-gdb/gdb/testsuite/lib/my-syscalls.S:68
68 syscall
(gdb) c
Continuing.
[New Thread 0x7ffff7c5f640 (LWP 2915616)]
[Thread 0x7ffff7c5f640 (LWP 2915524) exited]
[Switching to Thread 0x7ffff7c5f640 (LWP 2915616)]
Thread 4 "step-over-threa" hit Breakpoint 1, my_exit_syscall () at src/binutils-gdb/gdb/testsuite/lib/my-syscalls.S:68
68 syscall
(gdb) c
Continuing.
... hangs ...
The first two times we do "continue", we displaced-step the syscall
instruction that causes the thread to exit. When the thread exits,
the main thread, waiting on pthread_join, is unblocked. It spawns a
new thread, which hits the breakpoint on the syscall again. However,
infrun was never notified that the displaced-stepping threads are done
using the displaced-step buffer, so now both buffers are marked as
used. So when we do the third continue, there are no buffers
available to displaced-step the syscall, so the thread waits forever
for its turn.
When trying the same but with in-line step over (displaced-stepping
disabled):
$ ./gdb -q -nx --data-directory=data-directory \
build/binutils-gdb/gdb/testsuite/outputs/gdb.threads/step-over-thread-exit/step-over-thread-exit \
-ex "b my_exit_syscall" -ex "set displaced-stepping off" -ex r
Reading symbols from build/binutils-gdb/gdb/testsuite/outputs/gdb.threads/step-over-thread-exit/step-over-thread-exit...
Breakpoint 1 at 0x123c: file src/binutils-gdb/gdb/testsuite/lib/my-syscalls.S, line 68.
Starting program: build/binutils-gdb/gdb/testsuite/outputs/gdb.threads/step-over-thread-exit/step-over-thread-exit
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/usr/lib/../lib/libthread_db.so.1".
[New Thread 0x7ffff7c5f640 (LWP 2928290)]
[Switching to Thread 0x7ffff7c5f640 (LWP 2928290)]
Thread 2 "step-over-threa" hit Breakpoint 1, my_exit_syscall () at src/binutils-gdb/gdb/testsuite/lib/my-syscalls.S:68
68 syscall
(gdb) c
Continuing.
[Thread 0x7ffff7c5f640 (LWP 2928290) exited]
No unwaited-for children left.
(gdb) i th
Id Target Id Frame
1 Thread 0x7ffff7c60740 (LWP 2928285) "step-over-threa" 0x00007ffff7f7c9b7 in __pthread_clockjoin_ex () from /usr/lib/libpthread.so.0
The current thread <Thread ID 2> has terminated. See `help thread'.
(gdb) thread 1
[Switching to thread 1 (Thread 0x7ffff7c60740 (LWP 2928285))]
#0 0x00007ffff7f7c9b7 in __pthread_clockjoin_ex () from /usr/lib/libpthread.so.0
(gdb) c
Continuing.
^C^C
... hangs ...
The "continue" causes an in-line step to occur, meaning the main
thread is stopped while we step the syscall. The stepped thread exits
when executing the syscall, the linux-nat target notices there are no
more resumed threads to be waited for, so returns
TARGET_WAITKIND_NO_RESUMED, which causes the prompt to return. But
infrun never clears the in-line step over info. So if we try
continuing the main thread, GDB doesn't resume it, because it thinks
there's an in-line step in progress that we need to wait for to
finish, and we are stuck there.
To fix this, infrun needs to be informed when a thread doing a
displaced or in-line step over exits. We can do that with the new
target_set_thread_options mechanism which is optimal for only enabling
exit events of the thread that needs it; or, if that is not supported,
by using target_thread_events, which enables thread exit events for
all threads. This is done by this commit.
This patch then modifies handle_inferior_event in infrun.c to clean up
any step-over the exiting thread might have been doing at the time of
the exit. The cases to consider are:
- the exiting thread was doing an in-line step-over with an all-stop
target
- the exiting thread was doing an in-line step-over with a non-stop
target
- the exiting thread was doing a displaced step-over with a non-stop
target
The displaced-stepping buffer implementation in displaced-stepping.c
is modified to account for the fact that it's possible that we
"finish" a displaced step after a thread exit event. The buffer that
the exiting thread was using is marked as available again and the
original instructions under the scratch pad are restored. However, it
skips applying the fixup, which wouldn't make sense since the thread
does not exist anymore.
Another case that needs handling is if a displaced-stepping thread
exits, and the event is reported while we are in stop_all_threads. We
should call displaced_step_finish in the handle_one function, in that
case. It was already called in other code paths, just not the "thread
exited" path.
This commit doesn't make infrun ask the target to report the
TARGET_WAITKIND_THREAD_EXITED events yet, that'll be done later in the
series.
Note that "stop_print_frame = false;" line is moved to normal_stop,
because TARGET_WAITKIND_THREAD_EXITED can also end up with the event
transmorphed into TARGET_WAITKIND_NO_RESUMED. Moving it to
normal_stop keeps it centralized.
Co-authored-by: Simon Marchi <simon.marchi@efficios.com>
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=27338
Reviewed-By: Andrew Burgess <aburgess@redhat.com>
Change-Id: I745c6955d7ef90beb83bcf0ff1d1ac8b9b6285a5
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This implements support for the new GDB_THREAD_OPTION_EXIT thread
option for native Linux.
Reviewed-By: Andrew Burgess <aburgess@redhat.com>
Change-Id: Ia69fc0b9b96f9af7de7cefc1ddb1fba9bbb0bb90
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=27338
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This implements support for the new GDB_THREAD_OPTION_EXIT thread
option for Linux GDBserver.
Reviewed-By: Andrew Burgess <aburgess@redhat.com>
Change-Id: I96b719fdf7fee94709e98bb3a90751d8134f3a38
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=27338
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When stepping over a breakpoint with displaced stepping, GDB needs to
be informed if the stepped thread exits, otherwise the displaced
stepping buffer that was allocated to that thread leaks, and this can
result in deadlock, with other threads waiting for their turn to
displaced step, but their turn never comes.
Similarly, when stepping over a breakpoint in line, GDB also needs to
be informed if the stepped thread exits, so that is can clear the step
over state and re-resume threads.
This commit makes it possible for GDB to ask the target to report
thread exit events for a given thread, using the new "thread options"
mechanism introduced by a previous patch.
This only adds the core bits. Following patches in the series will
teach the Linux backends (native & gdbserver) to handle the
GDB_THREAD_OPTION_EXIT option, and then a later patch will make use of
these thread exit events to clean up displaced stepping and inline
stepping state properly.
Reviewed-By: Andrew Burgess <aburgess@redhat.com>
Change-Id: I96b719fdf7fee94709e98bb3a90751d8134f3a38
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=27338
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Currently, infrun assumes that when TARGET_WAITKIND_THREAD_EXITED is
reported, the corresponding GDB thread has already been removed from
the GDB thread list.
Later in the series, that will no longer work, as infrun will need to
refer to the thread's thread_info when it processes
TARGET_WAITKIND_THREAD_EXITED.
As preparation, this patch makes deleting the GDB thread
responsibility of infrun, instead of the target.
Reviewed-By: Andrew Burgess <aburgess@redhat.com>
Change-Id: I013d87f61ffc9aaca49f0d6ce2a43e3ea69274de
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gdbserver's linux_process_target::wait loops if:
- called in sync mode, and,
- wait_1 returns TARGET_WAITKIND_IGNORE, _and_,
- wait_1 also returns null_ptid.
The null_ptid check fails however when this path is taken:
ptid_t
linux_process_target::filter_exit_event (lwp_info *event_child,
target_waitstatus *ourstatus)
{
...
if (!is_leader (thread))
{
if (report_exit_events_for (thread))
ourstatus->set_thread_exited (0);
else
ourstatus->set_ignore (); <<<<<<<
delete_lwp (event_child);
}
return ptid;
}
This makes linux_process_target::wait return TARGET_WAITKIND_IGNORE in
sync mode, which is unexpected by the core and fails an assertion.
This commit fixes it by just making linux_process_target::wait loop if
it got a TARGET_WAITKIND_IGNORE, irrespective of event_ptid.
Change-Id: I39776908a6c75cbd68aa04139ffcf7be334868cf
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Currently, GDB does not understand the THREAD_EXITED stop reply in
remote all-stop mode. There's no good reason for this, it just
happened that THREAD_EXITED was only ever reported in non-stop mode so
far. This patch teaches GDB to parse that event in all-stop RSP too.
There is no need to add a qSupported feature for this, because the
server won't send a THREAD_EXITED event unless GDB explicitly asks for
it, with QThreadEvents, or with the GDB_THREAD_OPTION_EXIT
QThreadOptions option added in the next patch.
Change-Id: Ide5d12391adf432779fe4c79526801c4a5630966
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Now that gdb/19675 is fixed for both native and gdbserver GNU/Linux,
remove the gdb/19675 kfails.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=19675
Reviewed-By: Andrew Burgess <aburgess@redhat.com>
Change-Id: I95c1c38ca370100675d303cd3c8995860bef465d
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This commit extends the logic added by these two commits from a while
ago:
#1 7b961964f866 (gdbserver: hide fork child threads from GDB),
#2 df5ad102009c (gdb, gdbserver: detach fork child when detaching from fork parent)
... to handle thread clone events, which are very similar to (v)fork
events.
For #1, we want to hide clone children as well, so just update the
comments.
For #2, unlike (v)fork children, pending clone children aren't full
processes, they're just threads, so don't detach them in
handle_detach. linux-low.cc will take care of detaching them along
with all other threads of the process, there's nothing special that
needs to be done.
Reviewed-By: Andrew Burgess <aburgess@redhat.com>
Change-Id: I7f5901d07efda576a2522d03e183994e071b8ffc
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This patch teaches the Linux GDBserver backend to report clone events
to GDB, when GDB has requested them with the GDB_THREAD_OPTION_CLONE
thread option, via the new QThreadOptions packet.
This shuffles code in linux_process_target::handle_extended_wait
around to a more logical order when we now have to handle and
potentially report all of fork/vfork/clone.
Raname lwp_info::fork_relative -> lwp_info::relative as the field is
no longer only about (v)fork.
With this, gdb.threads/stepi-over-clone.exp now cleanly passes against
GDBserver, so remove the native-target-only requirement from that
testcase.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=19675
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=27830
Reviewed-By: Andrew Burgess <aburgess@redhat.com>
Change-Id: I3a19bc98801ec31e5c6fdbe1ebe17df855142bb2
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This commit teaches the native Linux target about the
GDB_THREAD_OPTION_CLONE thread option. It's actually simpler to just
continue reporting all clone events unconditionally to the core.
There's never any harm in reporting a clone event when the option is
disabled. All we need to do is to report support for the option,
otherwise GDB falls back to use target_thread_events().
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=19675
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=27830
Reviewed-By: Andrew Burgess <aburgess@redhat.com>
Change-Id: If90316e2dcd0c61d0fefa0d463c046011698acf9
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A previous patch taught GDB about a new TARGET_WAITKIND_THREAD_CLONED
event kind, and made the Linux target report clone events.
A following patch will teach Linux GDBserver to do the same thing.
However, for remote debugging, it wouldn't be ideal for GDBserver to
report every clone event to GDB, when GDB only cares about such events
in some specific situations. Reporting clone events all the time
would be potentially chatty. We don't enable thread create/exit
events all the time for the same reason. Instead we have the
QThreadEvents packet. QThreadEvents is target-wide, though.
This patch makes GDB instead explicitly request that the target
reports clone events or not, on a per-thread basis.
In order to be able to do that with GDBserver, we need a new remote
protocol feature. Since a following patch will want to enable thread
exit events on per-thread basis too, the packet introduced here is
more generic than just for clone events. It lets you enable/disable a
set of options at once, modelled on Linux ptrace's PTRACE_SETOPTIONS.
IOW, this commit introduces a new QThreadOptions packet, that lets you
specify a set of per-thread event options you want to enable. The
packet accepts a list of options/thread-id pairs, similarly to vCont,
processed left to right, with the options field being a number
interpreted as a bit mask of options. The only option defined in this
commit is GDB_THREAD_OPTION_CLONE (0x1), which ask the remote target
to report clone events. Another patch later in the series will
introduce another option.
For example, this packet sets option "1" (clone events) on thread
p1000.2345:
QThreadOptions;1:p1000.2345
and this clears options for all threads of process 1000, and then sets
option "1" (clone events) on thread p1000.2345:
QThreadOptions;0:p1000.-1;1:p1000.2345
This clears options of all threads of all processes:
QThreadOptions;0
The target reports the set of supported options by including
"QThreadOptions=<supported options>" in its qSupported response.
infrun is then tweaked to enable GDB_THREAD_OPTION_CLONE when stepping
over a breakpoint.
Unlike PTRACE_SETOPTIONS, fork/vfork/clone children do NOT inherit
their parent's thread options. This is so that GDB can send e.g.,
"QThreadOptions;0;1:TID" without worrying about threads it doesn't
know about yet.
Documentation for this new remote protocol feature is included in a
documentation patch later in the series.
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=19675
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=27830
Reviewed-By: Andrew Burgess <aburgess@redhat.com>
Change-Id: Ie41e5093b2573f14cf6ac41b0b5804eba75be37e
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Similarly to QProgramSignals and QPassSignals, avoid sending duplicate
QThreadEvents packets.
Approved-By: Andrew Burgess <aburgess@redhat.com>
Change-Id: Iaf5babb0b64e1527ba4db31aac8674d82b17e8b4
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The previous patch taught GDB about a new
TARGET_WAITKIND_THREAD_CLONED event kind, and made the Linux target
report clone events.
A following patch will teach Linux GDBserver to do the same thing.
But before we get there, we need to teach the remote protocol about
TARGET_WAITKIND_THREAD_CLONED. That's what this patch does. Clone is
very similar to vfork and fork, and the new stop reply is likewise
handled similarly. The stub reports "T05clone:...".
GDBserver core is taught to handle TARGET_WAITKIND_THREAD_CLONED and
forward it to GDB in this patch, but no backend actually emits it yet.
That will be done in a following patch.
Documentation for this new remote protocol feature is included in a
documentation patch later in the series.
Reviewed-By: Andrew Burgess <aburgess@redhat.com>
Change-Id: If271f20320d864f074d8ac0d531cc1a323da847f
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=19675
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=27830
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(A good chunk of the problem statement in the commit log below is
Andrew's, adjusted for a different solution, and for covering
displaced stepping too. The testcase is mostly Andrew's too.)
This commit addresses bugs gdb/19675 and gdb/27830, which are about
stepping over a breakpoint set at a clone syscall instruction, one is
about displaced stepping, and the other about in-line stepping.
Currently, when a new thread is created through a clone syscall, GDB
sets the new thread running. With 'continue' this makes sense
(assuming no schedlock):
- all-stop mode, user issues 'continue', all threads are set running,
a newly created thread should also be set running.
- non-stop mode, user issues 'continue', other pre-existing threads
are not affected, but as the new thread is (sort-of) a child of the
thread the user asked to run, it makes sense that the new threads
should be created in the running state.
Similarly, if we are stopped at the clone syscall, and there's no
software breakpoint at this address, then the current behaviour is
fine:
- all-stop mode, user issues 'stepi', stepping will be done in place
(as there's no breakpoint to step over). While stepping the thread
of interest all the other threads will be allowed to continue. A
newly created thread will be set running, and then stopped once the
thread of interest has completed its step.
- non-stop mode, user issues 'stepi', stepping will be done in place
(as there's no breakpoint to step over). Other threads might be
running or stopped, but as with the continue case above, the new
thread will be created running. The only possible issue here is
that the new thread will be left running after the initial thread
has completed its stepi. The user would need to manually select
the thread and interrupt it, this might not be what the user
expects. However, this is not something this commit tries to
change.
The problem then is what happens when we try to step over a clone
syscall if there is a breakpoint at the syscall address.
- For both all-stop and non-stop modes, with in-line stepping:
+ user issues 'stepi',
+ [non-stop mode only] GDB stops all threads. In all-stop mode all
threads are already stopped.
+ GDB removes s/w breakpoint at syscall address,
+ GDB single steps just the thread of interest, all other threads
are left stopped,
+ New thread is created running,
+ Initial thread completes its step,
+ [non-stop mode only] GDB resumes all threads that it previously
stopped.
There are two problems in the in-line stepping scenario above:
1. The new thread might pass through the same code that the initial
thread is in (i.e. the clone syscall code), in which case it will
fail to hit the breakpoint in clone as this was removed so the
first thread can single step,
2. The new thread might trigger some other stop event before the
initial thread reports its step completion. If this happens we
end up triggering an assertion as GDB assumes that only the
thread being stepped should stop. The assert looks like this:
infrun.c:5899: internal-error: int finish_step_over(execution_control_state*): Assertion `ecs->event_thread->control.trap_expected' failed.
- For both all-stop and non-stop modes, with displaced stepping:
+ user issues 'stepi',
+ GDB starts the displaced step, moves thread's PC to the
out-of-line scratch pad, maybe adjusts registers,
+ GDB single steps the thread of interest, [non-stop mode only] all
other threads are left as they were, either running or stopped.
In all-stop, all other threads are left stopped.
+ New thread is created running,
+ Initial thread completes its step, GDB re-adjusts its PC,
restores/releases scratchpad,
+ [non-stop mode only] GDB resumes the thread, now past its
breakpoint.
+ [all-stop mode only] GDB resumes all threads.
There is one problem with the displaced stepping scenario above:
3. When the parent thread completed its step, GDB adjusted its PC,
but did not adjust the child's PC, thus that new child thread
will continue execution in the scratch pad, invoking undefined
behavior. If you're lucky, you see a crash. If unlucky, the
inferior gets silently corrupted.
What is needed is for GDB to have more control over whether the new
thread is created running or not. Issue #1 above requires that the
new thread not be allowed to run until the breakpoint has been
reinserted. The only way to guarantee this is if the new thread is
held in a stopped state until the single step has completed. Issue #3
above requires that GDB is informed of when a thread clones itself,
and of what is the child's ptid, so that GDB can fixup both the parent
and the child.
When looking for solutions to this problem I considered how GDB
handles fork/vfork as these have some of the same issues. The main
difference between fork/vfork and clone is that the clone events are
not reported back to core GDB. Instead, the clone event is handled
automatically in the target code and the child thread is immediately
set running.
Note we have support for requesting thread creation events out of the
target (TARGET_WAITKIND_THREAD_CREATED). However, those are reported
for the new/child thread. That would be sufficient to address in-line
stepping (issue #1), but not for displaced-stepping (issue #3). To
handle displaced-stepping, we need an event that is reported to the
_parent_ of the clone, as the information about the displaced step is
associated with the clone parent. TARGET_WAITKIND_THREAD_CREATED
includes no indication of which thread is the parent that spawned the
new child. In fact, for some targets, like e.g., Windows, it would be
impossible to know which thread that was, as thread creation there
doesn't work by "cloning".
The solution implemented here is to model clone on fork/vfork, and
introduce a new TARGET_WAITKIND_THREAD_CLONED event. This event is
similar to TARGET_WAITKIND_FORKED and TARGET_WAITKIND_VFORKED, except
that we end up with a new thread in the same process, instead of a new
thread of a new process. Like FORKED and VFORKED, THREAD_CLONED
waitstatuses have a child_ptid property, and the child is held stopped
until GDB explicitly resumes it. This addresses the in-line stepping
case (issues #1 and #2).
The infrun code that handles displaced stepping fixup for the child
after a fork/vfork event is thus reused for THREAD_CLONE, with some
minimal conditions added, addressing the displaced stepping case
(issue #3).
The native Linux backend is adjusted to unconditionally report
TARGET_WAITKIND_THREAD_CLONED events to the core.
Following the follow_fork model in core GDB, we introduce a
target_follow_clone target method, which is responsible for making the
new clone child visible to the rest of GDB.
Subsequent patches will add clone events support to the remote
protocol and gdbserver.
displaced_step_in_progress_thread becomes unused with this patch, but
a new use will reappear later in the series. To avoid deleting it and
readding it back, this patch marks it with attribute unused, and the
latter patch removes the attribute again. We need to do this because
the function is static, and with no callers, the compiler would warn,
(error with -Werror), breaking the build.
This adds a new gdb.threads/stepi-over-clone.exp testcase, which
exercises stepping over a clone syscall, with displaced stepping vs
inline stepping, and all-stop vs non-stop. We already test stepping
over clone syscalls with gdb.base/step-over-syscall.exp, but this test
uses pthreads, while the other test uses raw clone, and this one is
more thorough. The testcase passes on native GNU/Linux, but fails
against GDBserver. GDBserver will be fixed by a later patch in the
series.
Co-authored-by: Andrew Burgess <aburgess@redhat.com>
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=19675
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=27830
Change-Id: I95c06024736384ae8542a67ed9fdf6534c325c8e
Reviewed-By: Andrew Burgess <aburgess@redhat.com>
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I noticed that on an Ubuntu 20.04 system, after a following patch
("Step over clone syscall w/ breakpoint,
TARGET_WAITKIND_THREAD_CLONED"), the gdb.threads/step-over-exec.exp
was passing cleanly, but still, we'd end up with four new unexpected
GDB core dumps:
=== gdb Summary ===
# of unexpected core files 4
# of expected passes 48
That said patch is making the pre-existing
gdb.threads/step-over-exec.exp testcase (almost silently) expose a
latent problem in gdb/linux-nat.c, resulting in a GDB crash when:
#1 - a non-leader thread execs
#2 - the post-exec program stops somewhere
#3 - you kill the inferior
Instead of #3 directly, the testcase just returns, which ends up in
gdb_exit, tearing down GDB, which kills the inferior, and is thus
equivalent to #3 above.
Vis (after said patch is applied):
$ gdb --args ./gdb /home/pedro/gdb/build/gdb/testsuite/outputs/gdb.threads/step-over-exec/step-over-exec-execr-thread-other-diff-text-segs-true
...
(top-gdb) r
...
(gdb) b main
...
(gdb) r
...
Breakpoint 1, main (argc=1, argv=0x7fffffffdb88) at /home/pedro/gdb/build/gdb/testsuite/../../../src/gdb/testsuite/gdb.threads/step-over-exec.c:69
69 argv0 = argv[0];
(gdb) c
Continuing.
[New Thread 0x7ffff7d89700 (LWP 2506975)]
Other going in exec.
Exec-ing /home/pedro/gdb/build/gdb/testsuite/outputs/gdb.threads/step-over-exec/step-over-exec-execr-thread-other-diff-text-segs-true-execd
process 2506769 is executing new program: /home/pedro/gdb/build/gdb/testsuite/outputs/gdb.threads/step-over-exec/step-over-exec-execr-thread-other-diff-text-segs-true-execd
Thread 1 "step-over-exec-" hit Breakpoint 1, main () at /home/pedro/gdb/build/gdb/testsuite/../../../src/gdb/testsuite/gdb.threads/step-over-exec-execd.c:28
28 foo ();
(gdb) k
...
Thread 1 "gdb" received signal SIGSEGV, Segmentation fault.
0x000055555574444c in thread_info::has_pending_waitstatus (this=0x0) at ../../src/gdb/gdbthread.h:393
393 return m_suspend.waitstatus_pending_p;
(top-gdb) bt
#0 0x000055555574444c in thread_info::has_pending_waitstatus (this=0x0) at ../../src/gdb/gdbthread.h:393
#1 0x0000555555a884d1 in get_pending_child_status (lp=0x5555579b8230, ws=0x7fffffffd130) at ../../src/gdb/linux-nat.c:1345
#2 0x0000555555a8e5e6 in kill_unfollowed_child_callback (lp=0x5555579b8230) at ../../src/gdb/linux-nat.c:3564
#3 0x0000555555a92a26 in gdb::function_view<int (lwp_info*)>::bind<int, lwp_info*>(int (*)(lwp_info*))::{lambda(gdb::fv_detail::erased_callable, lwp_info*)#1}::operator()(gdb::fv_detail::erased_callable, lwp_info*) const (this=0x0, ecall=..., args#0=0x5555579b8230) at ../../src/gdb/../gdbsupport/function-view.h:284
#4 0x0000555555a92a51 in gdb::function_view<int (lwp_info*)>::bind<int, lwp_info*>(int (*)(lwp_info*))::{lambda(gdb::fv_detail::erased_callable, lwp_info*)#1}::_FUN(gdb::fv_detail::erased_callable, lwp_info*) () at ../../src/gdb/../gdbsupport/function-view.h:278
#5 0x0000555555a91f84 in gdb::function_view<int (lwp_info*)>::operator()(lwp_info*) const (this=0x7fffffffd210, args#0=0x5555579b8230) at ../../src/gdb/../gdbsupport/function-view.h:247
#6 0x0000555555a87072 in iterate_over_lwps(ptid_t, gdb::function_view<int (lwp_info*)>) (filter=..., callback=...) at ../../src/gdb/linux-nat.c:864
#7 0x0000555555a8e732 in linux_nat_target::kill (this=0x55555653af40 <the_amd64_linux_nat_target>) at ../../src/gdb/linux-nat.c:3590
#8 0x0000555555cfdc11 in target_kill () at ../../src/gdb/target.c:911
...
The root of the problem is that when a non-leader LWP execs, it just
changes its tid to the tgid, replacing the pre-exec leader thread,
becoming the new leader. There's no thread exit event for the execing
thread. It's as if the old pre-exec LWP vanishes without trace. The
ptrace man page says:
"PTRACE_O_TRACEEXEC (since Linux 2.5.46)
Stop the tracee at the next execve(2). A waitpid(2) by the
tracer will return a status value such that
status>>8 == (SIGTRAP | (PTRACE_EVENT_EXEC<<8))
If the execing thread is not a thread group leader, the thread
ID is reset to thread group leader's ID before this stop.
Since Linux 3.0, the former thread ID can be retrieved with
PTRACE_GETEVENTMSG."
When the core of GDB processes an exec events, it deletes all the
threads of the inferior. But, that is too late -- deleting the thread
does not delete the corresponding LWP, so we end leaving the pre-exec
non-leader LWP stale in the LWP list. That's what leads to the crash
above -- linux_nat_target::kill iterates over all LWPs, and after the
patch in question, that code will look for the corresponding
thread_info for each LWP. For the pre-exec non-leader LWP still
listed, won't find one.
This patch fixes it, by deleting the pre-exec non-leader LWP (and
thread) from the LWP/thread lists as soon as we get an exec event out
of ptrace.
GDBserver does not need an equivalent fix, because it is already doing
this, as side effect of mourning the pre-exec process, in
gdbserver/linux-low.cc:
else if (event == PTRACE_EVENT_EXEC && cs.report_exec_events)
{
...
/* Delete the execing process and all its threads. */
mourn (proc);
switch_to_thread (nullptr);
The crash with gdb.threads/step-over-exec.exp is not observable on
newer systems, which postdate the glibc change to move "libpthread.so"
internals to "libc.so.6", because right after the exec, GDB traps a
load event for "libc.so.6", which leads to GDB trying to open
libthread_db for the post-exec inferior, and, on such systems that
succeeds. When we load libthread_db, we call
linux_stop_and_wait_all_lwps, which, as the name suggests, stops all
lwps, and then waits to see their stops. While doing this, GDB
detects that the pre-exec stale LWP is gone, and deletes it.
If we use "catch exec" to stop right at the exec before the
"libc.so.6" load event ever happens, and issue "kill" right there,
then GDB crashes on newer systems as well. So instead of tweaking
gdb.threads/step-over-exec.exp to cover the fix, add a new
gdb.threads/threads-after-exec.exp testcase that uses "catch exec".
The test also uses the new "maint info linux-lwps" command if testing
on Linux native, which also exposes the stale LWP problem with an
unfixed GDB.
Also tweak a comment in infrun.c:follow_exec referring to how
linux-nat.c used to behave, as it would become stale otherwise.
Reviewed-By: Andrew Burgess <aburgess@redhat.com>
Change-Id: I21ec18072c7750f3a972160ae6b9e46590376643
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This adds a maintenance command that lets you list all the LWPs under
control of the linux-nat target.
For example:
(gdb) maint info linux-lwps
LWP Ptid Thread ID
560948.561047.0 None
560948.560948.0 1.1
This shows that "560948.561047.0" LWP doesn't map to any thread_info
object, which is bogus. We'll be using this in a testcase in a
following patch.
Co-Authored-By: Pedro Alves <pedro@palves.net>
Change-Id: Ic4e9e123385976e5cd054391990124b7a20fb3f5
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When building gdb with -O2, we run into:
...
gdb/tui/tui-disasm.c: In function ‘CORE_ADDR tui_find_disassembly_address \
(gdbarch*, CORE_ADDR, int)’:
gdb/tui/tui-disasm.c:293:7: warning: ‘last_addr’ may be used uninitialized \
in this function [-Wmaybe-uninitialized]
if (last_addr < pc)
^~
...
The warning triggers since commit 72535eb14bd ("[gdb/tui] Fix segfault in
tui_find_disassembly_address").
Fix the warning by ensuring that last_addr is initialized at the point of
use:
...
+ last_addr = asm_lines.back ().addr;
if (last_addr < pc)
...
Tested on x86_64-linux.
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In tui_find_disassembly_address we find an assert:
...
if (asm_lines.size () < max_lines)
{
if (!possible_new_low.has_value ())
return new_low;
/* Take the best possible match we have. */
new_low = *possible_new_low;
next_addr = tui_disassemble (gdbarch, asm_lines, new_low, max_lines);
last_addr = asm_lines.back ().addr;
gdb_assert (asm_lines.size () >= max_lines);
}
...
The comment right above:
...
/* If we failed to disassemble the required number of lines then the
following walk forward is not going to work, it assumes that
ASM_LINES contains exactly MAX_LINES entries. Instead we should
consider falling back to a previous possible start address in
POSSIBLE_NEW_LOW. */
...
claims that the more strict asm_lines.size () == max_line is required.
Update the assert to reflect this, and move it to after the if because it's
supposed to hold in general, not just when entering the if.
Tested on x86_64-linux.
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defs.h declares re_comp, but it shouldn't. If this is needed, it
should be picked up from xregex.h via gdb_regex.h.
Tested by rebuilding.
Reviewed-by: Kevin Buettner <kevinb@redhat.com>
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Teach bfd and readelf about some recent gfx11 architectures. This code
is taken from the rocgdb 5.7.x branch [1].
[1] https://github.com/rocm-Developer-Tools/rocgdb/tree/rocm-5.7.x
bfd/ChangeLog:
* archures.c (bfd_mach_amdgcn_gfx1100, bfd_mach_amdgcn_gfx1101,
bfd_mach_amdgcn_gfx1102): New.
* bfd-in2.h (bfd_mach_amdgcn_gfx1100, bfd_mach_amdgcn_gfx1101,
bfd_mach_amdgcn_gfx1102): New.
* cpu-amdgcn.c (arch_info_struct): Add entries for
bfd_mach_amdgcn_gfx1100, bfd_mach_amdgcn_gfx1101,
bfd_mach_amdgcn_gfx1102.
binutils/ChangeLog:
* readelf.c (decode_AMDGPU_machine_flags): Handle gfx1100,
gfx1101, gfx1102.
include/ChangeLog:
* elf/amdgpu.h (EF_AMDGPU_MACH_AMDGCN_GFX1100,
EF_AMDGPU_MACH_AMDGCN_GFX1101,
EF_AMDGPU_MACH_AMDGCN_GFX1102): New.
Change-Id: I95a8a62942e359781a1c9fa2079950fbcf2a78b8
Co-Authored-By: Laurent Morichetti <laurent.morichetti@amd.com>
Cc: Lancelot Six <lancelot.six@amd.com>
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Signed-off-by: Michael J. Eager <eager@eagercon.com>
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PR 30880
* dwarf.c (read_and_display_attr_value): Fix loclist handling. (display_loclists_list): Likewise.
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executable stacks and/or executable segments.
include
* bfdlink.h (struct bfd_link_info): Update descriptions of the 'execstack', 'noexecstack' and 'warn_execstack' fields. Add 'error_exectack' and 'warn_is_error_for_rwx_segments' fields.
bfd
* elf.c (assign_file_positions_except_relocs): Turn warnings about executable segments into errors if so requested.
* elflink.c (bfd_elf_size_dynamic_sections): Turn warnings about executable stacks into errors if so requested.
ld
* ldlex.h (enum option_values): Add OPTION_ERROR_EXECSTACK, OPTION_NO_ERROR_EXECSTACK, OPTION_WARN_EXECSTACK_OBJECTS, OPTION_ERROR_RWX_SEGMENTS and OPTION_NO_ERROR_RWX_SEGMENTS. (struct ld_option): Add new long options. (parse_args): Parse new long options. (elf_static_list_options): Display the new options.
* ld.texi: Document the new command line options.
* configure.ac (error-execstack): New configuration option. (error-rwx-segments): New configuration option.
* emultempl/elf.em (_before_parse): Initialse the new linkinfo fields.
* NEWS: Mention the new features.
* config.in: Regenerate.
* configure: Regenerate.
* testsuite/ld-elf/commonpage2.d: Disable errors for RWX segments and/or executable stacks.
* testsuite/ld-elf/elf.exp: Likewise.
* testsuite/ld-elf/header.d: Likewise.
* testsuite/ld-elf/loadaddr1.d: Likewise.
* testsuite/ld-elf/loadaddr2.d: Likewise.
* testsuite/ld-elf/maxpage4.d: Likewise.
* testsuite/ld-elf/nobits-1.d: Likewise.
* testsuite/ld-elf/note-1.d: Likewise.
* testsuite/ld-elf/orphan-10.d: Likewise.
* testsuite/ld-elf/orphan-11.d: Likewise.
* testsuite/ld-elf/orphan-12.d: Likewise.
* testsuite/ld-elf/orphan-5.d: Likewise.
* testsuite/ld-elf/orphan-7.d: Likewise.
* testsuite/ld-elf/orphan-8.d: Likewise.
* testsuite/ld-elf/orphan-9.d: Likewise.
* testsuite/ld-elf/orphan-region.d: Likewise.
* testsuite/ld-elf/orphan.d: Likewise.
* testsuite/ld-elf/pr19539.d: Likewise.
* testsuite/ld-elf/pr26256-1a.d: Likewise.
* testsuite/ld-elf/pr26907.d: Likewise.
* testsuite/ld-elf/pr28597.d: Likewise.
* testsuite/ld-elf/retain2.d: Likewise.
* testsuite/ld-elf/shared.exp: Likewise.
* testsuite/ld-elf/size-1.d: Likewise.
* testsuite/ld-elf/textaddr7.d: Likewise.
* testsuite/ld-elf/warn1.d: Likewise.
* testsuite/ld-elf/warn2.d: Likewise.
* testsuite/ld-i386/discarded1.d: Likewise.
* testsuite/ld-i386/pr19175.d: Likewise.
* testsuite/ld-i386/pr19539.d: Likewise.
* testsuite/ld-i386/pr23189.d: Likewise.
* testsuite/ld-plugin/lto-3r.d: Likewise.
* testsuite/ld-plugin/lto-5r.d: Likewise.
* testsuite/ld-plugin/lto.exp: Likewise.
* testsuite/ld-powerpc/ppc476-shared.d: Likewise.
* testsuite/ld-powerpc/ppc476-shared2.d: Likewise.
* testsuite/ld-powerpc/pr28827-2.d: Likewise.
* testsuite/ld-s390/s390.exp: Likewise.
* testsuite/ld-scripts/align2a.d: Likewise.
* testsuite/ld-scripts/align2b.d: Likewise.
* testsuite/ld-scripts/align5.d: Likewise.
* testsuite/ld-scripts/alignof.exp: Likewise.
* testsuite/ld-scripts/crossref.exp: Likewise.
* testsuite/ld-scripts/defined2.d: Likewise.
* testsuite/ld-scripts/defined3.d: Likewise.
* testsuite/ld-scripts/defined5.d: Likewise.
* testsuite/ld-scripts/pr14962.d: Likewise.
* testsuite/ld-scripts/pr18963.d: Likewise.
* testsuite/ld-scripts/pr20302.d: Likewise.
* testsuite/ld-scripts/print-memory-usage.exp: Likewise.
* testsuite/ld-scripts/rgn-at1.d: Likewise.
* testsuite/ld-scripts/rgn-at10.d: Likewise.
* testsuite/ld-scripts/rgn-at4.d: Likewise.
* testsuite/ld-scripts/rgn-at6.d: Likewise.
* testsuite/ld-scripts/rgn-at8.d: Likewise.
* testsuite/ld-scripts/rgn-at9.d: Likewise.
* testsuite/ld-scripts/rgn-over1.d: Likewise.
* testsuite/ld-scripts/rgn-over2.d: Likewise.
* testsuite/ld-scripts/rgn-over4.d: Likewise.
* testsuite/ld-scripts/rgn-over5.d: Likewise.
* testsuite/ld-scripts/rgn-over6.d: Likewise.
* testsuite/ld-scripts/script.exp: Likewise.
* testsuite/ld-scripts/sizeof.exp: Likewise.
* testsuite/ld-scripts/sort-file.d: Likewise.
* testsuite/ld-x86-64/discarded1.d: Likewise.
* testsuite/ld-x86-64/pr19175.d: Likewise.
* testsuite/ld-x86-64/pr19539a.d: Likewise.
* testsuite/ld-x86-64/pr19539b.d: Likewise.
* testsuite/ld-x86-64/pr23189.d: Likewise.
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the offset-to-entry mappings are allocated in blocks, which may
become a bit wasteful in case there are extremely many small
input files or sections. This made it so that a large project
(Qt5WebEngine) didn't build anymore on x86 32bit due to address
space limits. It barely fit into address space before the new
string merging, and then got pushed over the limit by this.
So instead of leaving the waste reallocate the maps to their final
size once known. Now the link barely fits again.
bfd/
* merge.c (record_section): Reallocate offset maps to their
final size.
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as the bug report shows we had an overflow in the test if
hash table resizing is needed. Reorder the expression to avoid
that. There's still a bug somewhere in gracefully handling
failure in resizing (e.g. out of memory), but this pushes the
boundary for that occurring somewhen into the future and
immediately helps the reporter.
bfd/
PR ld/31009
* merge.c (NEEDS_RESIZE): New macro avoiding overflow.
(sec_merge_maybe_resize): Use it.
(sec_merge_hash_insert): Ditto.
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The tests are not compatible with ilp32 abi: the GNU property
note is ABI dependent (size changes) and the disasm is ABI
dependent too. Making the test portable between the ABIs is
not trivial.
For now force lp64 abi.
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The test creates a large shared library and covers a number of
BTI stub insertion cases.
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We decide to emit BTI stubs based on the instruction at the target
location. But PLT code is generated later than the stubs so we always
read 0 which is not a valid BTI.
Fix the logic to special case the PLT section: this is code the linker
generates so we know when it will have BTI.
This avoids BTI stubs in large executables where the PLTs have them
already. An alternative is to never emit BTI stubs for PLTs, instead
use BTI in the PLT if a library gets too big, however that may be
more tricky given the ordering of PLT sizing and stub insertion.
Related to bug 30957.
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BTI stub parameters were recomputed even if those were already set up.
This is unnecessary work and leaks the symbol name that is allocated
for the stub.
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Input sections are grouped together that can use the same stub area
(within reach) and these groups have a stable id.
Stubs have a name generated from the stub group id and target symbol.
When a relocation requires a stub with a name that already exists, the
stub is reused instead of adding a new one.
For an indirect branch stub another BTI stub may be inserted near the
target to provide a BTI landing pad.
The BTI stub can end up with the same stub group id and thus the same
name as the indirect stub. This happens if the target symbol is within
reach of the indirect branch stub. Then, due to the name collision,
only a single stub was emmitted which branched to itself causing an
infinite loop at runtime.
A possible solution is to just name the BTI stubs differently, but
since in the problematic case the indirect and BTI stub are in the
same stub area, a better solution is to emit a single stub with a
direct branch. The stub is still needed since the caller cannot reach
the target directly and we also want a BTI landing pad in the stub in
case other indirect stubs target the same symbol and thus need a BTI
stub.
In short we convert an indirect branch stub into a BTI stub when the
target is within reach and has no BTI. It is a hassle to change the
symbol of the stub so a BTI stub may end up with *_veneer instead of
*_bti_veneer after the conversion, but this should not matter much.
(Refactoring some of _bfd_aarch64_add_call_stub_entries would be
useful but too much for this bug fix patch.)
The same conversion to direct branch could be done even if the target
did not need a BTI. The stub groups are fixed in the current logic so
linking can fail if too many stubs are inserted and the section layout
is changed too much, but this only happens in extreme cases that can
be reasonably ignored. Because of this the target cannot go out of
reach during stub insertion so the optimization is valid, but not
implemented by this patch for the non-BTI case.
Fixes bug 30930.
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The instruction was looked up in the wrong input file (file of branch
source instead of branch target) when optimizing away BTI stubs in
commit 5834f36d93cabf1a8bcc7dd7654141aed3d296bc
bfd: aarch64: Optimize BTI stubs PR30076
This can cause adding BTI stubs when they are not necessary or removing
them when they are (the latter is a correctness issue but it is very
unlikely in practice).
Fixes bug 30957.
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