This is the first pass at implementing support for all-stop mode
running against the remote target using the non-stop variant of the
protocol.
The trickiest part here is the initial connection setup/synching. We
need to fetch all inferiors' target descriptions etc. before stopping
threads, because stop_all_threads needs to read the threads' registers
(to record each thread's stop_pc). But OTOH, the initial inferior
setup (target_post_attach, post_create_inferior, etc.), only works
correctly if the inferior is stopped... So I've split that initial
setup part from attach_command_post_wait to a separate function, and
added a "still needs setup" flag to the inferior structure. This is
similar to gdbserver/linux-low.c's handling of discovering the
process's target description). Then if on connection all threads of
the remote inferior are running, when we go about stopping them, as
soon as they stop we call setup_inferior, from within
stop_all_threads.
Also, in all-stop, we need to process all the initial stop replies to
learn about all the pending signal the threads may already be stopped
for, and pick the one to report as current. This is exposed by
gdb.threads/reconnect-signal.exp.
gdb/
2015-11-30 Pedro Alves <palves@redhat.com>
* gdbthread.h (switch_to_thread_no_regs): Declare.
* infcmd.c (setup_inferior): New function, factored out from ...
(attach_command_post_wait): ... this. Rename to ...
(attach_post_wait): ... this. Replace parameter async_exec with
attach_post_wait_mode parameter. Adjust.
(enum attach_post_wait_mode): New enum.
(struct attach_command_continuation_args): Replace 'async_exec'
field with 'mode' field.
(attach_command_continuation): Adjust.
(attach_command): Add comment. Mark the inferior as needing
setup. Adjust to use enum attach_post_wait_mode.
(notice_new_inferior): Use switch_to_thread_no_regs. Adjust to
use enum attach_post_wait_mode.
* inferior.h (setup_inferior): Declare.
(struct inferior) <needs_setup>: New field.
* infrun.c (set_last_target_status): Make extern.
(stop_all_threads): Make extern. Setup inferior, if necessary.
* infrun.h (set_last_target_status, stop_all_threads): Declare.
* remote-notif.c (remote_async_get_pending_events_handler)
(handle_notification): Replace non_stop checks with
target_is_non_stop_p() checks.
* remote.c (remote_notice_new_inferior): Remove non_stop check.
(remote_update_thread_list): Replace non_stop check with
target_is_non_stop_p() check.
(print_one_stopped_thread): New function.
(process_initial_stop_replies): New 'from_tty' parameter.
"Notice" all new live inferiors after storing initial stops as
pending status in each corresponding thread. If all-stop, stop
all threads, try picking a signalled thread as current, and print
the status of that one thread. Record the last target status.
(remote_start_remote): Replace non_stop checks with
target_is_non_stop_p() checks. Don't query for the remote current
thread of use qOffsets here. Pass from_tty to
process_initial_stop_replies.
(extended_remote_attach): Replace non_stop checks with
target_is_non_stop_p() checks.
(extended_remote_post_attach): Send qOffsets here.
(remote_vcont_resume, remote_resume, remote_stop)
(remote_interrupt, remote_parse_stop_reply, remote_wait): Replace
non_stop checks with target_is_non_stop_p() checks.
(remote_async): If target is non-stop, mark/clear the pending
events token.
* thread.c (switch_to_thread_no_regs): New function.
This fixes a few build errors like these in C++ mode:
src/gdb/reverse.c: In function ‘void exec_reverse_once(char*, char*, int)’:
src/gdb/reverse.c:49:34: error: invalid conversion from ‘int’ to ‘exec_direction_kind’ [-fpermissive]
enum exec_direction_kind dir = execution_direction;
^
make: *** [reverse.o] Error 1
gdb/ChangeLog:
2015-10-13 Pedro Alves <palves@redhat.com>
* infrun.c (restore_execution_direction): New function.
(fetch_inferior_event): Use it instead of
make_cleanup_restore_integer.
(execution_direction): Change type to enum
exec_direction_kind.
* infrun.h (execution_direction): Likewise.
This patch, relative to a tree with
https://sourceware.org/ml/gdb-patches/2015-08/msg00295.html, fixes
issues/crashes that trigger if something unexpected happens during a
hook-stop.
E.g., if the inferior disappears while running the hook-stop, we hit
failed assertions:
(gdb) define hook-stop
Type commands for definition of "hook-stop".
End with a line saying just "end".
>kill
>end
(gdb) si
Kill the program being debugged? (y or n) [answered Y; input not from terminal]
/home/pedro/gdb/mygit/build/../src/gdb/thread.c:88: internal-error: inferior_thread: Assertion `tp' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.
Quit this debugging session? (y or n)
I noticed that if a hook-stop issues a synchronous execution command,
we print the same stop event twice:
(gdb) define hook-stop
Type commands for definition of "hook-stop".
End with a line saying just "end".
>si
>end
(gdb) si
0x000000000040074a 42 args[i] = 1; /* Init value. */ <<<<<<< once
0x000000000040074a 42 args[i] = 1; /* Init value. */ <<<<<<< twice
(gdb)
In MI:
*stopped,reason="end-stepping-range",frame={addr="0x000000000040074a",func="main",args=[],file="threads.c",fullname="/home/pedro/gdb/tests/threads.c",line="42"},thread-id="1",stopped-threads="all",core="0"
*stopped,reason="end-stepping-range",frame={addr="0x000000000040074a",func="main",args=[],file="threads.c",fullname="/home/pedro/gdb/tests/threads.c",line="42"},thread-id="1",stopped-threads="all",core="0"
(gdb)
The fix has GDB stop processing the event if the context changed. I
don't expect people to be doing crazy things from the hook-stop.
E.g., it gives me headaches to try to come up a proper behavior for
handling a thread change from a hook-stop... (E.g., imagine the
hook-stop does thread N; step, with scheduler-locing on). I think the
most important bit here is preventing crashes.
The patch adds a new hook-stop.exp test that covers the above and also
merges in the old hook-stop-continue.exp and hook-stop-frame.exp into
the same framework.
gdb/ChangeLog:
2015-09-14 Pedro Alves <palves@redhat.com>
* infrun.c (current_stop_id): New global.
(get_stop_id, new_stop_id): New functions.
(fetch_inferior_event): Handle normal_stop proceeding the target.
(struct stop_context): New.
(save_stop_context, release_stop_context_cleanup)
(stop_context_changed): New functions.
(normal_stop): Return true if the hook-stop changes the stop
context.
* infrun.h (get_stop_id): Declare.
(normal_stop): Now returns int. Add documentation.
gdb/testsuite/ChangeLog:
2015-09-14 Pedro Alves <palves@redhat.com>
* gdb.base/hook-stop-continue.c: Delete.
* gdb.base/hook-stop-continue.exp: Delete.
* gdb.base/hook-stop-frame.c: Delete.
* gdb.base/hook-stop-frame.exp: Delete.
* gdb.base/hook-stop.c: New file.
* gdb.base/hook-stop.exp: New file.
This removes infcall-specific special casing from normal_stop,
simplifying it.
Like the "finish" command's, the FSM is responsible for storing the
function's return value.
gdb/ChangeLog:
2015-09-09 Pedro Alves <palves@redhat.com>
* infcall.c: Include thread_fsm.h.
(struct call_return_meta_info): New.
(get_call_return_value): New function, factored out from
call_function_by_hand_dummy.
(struct call_thread_fsm): New.
(call_thread_fsm_ops): New global.
(new_call_thread_fsm, call_thread_fsm_should_stop)
(call_thread_fsm_should_notify_stop): New functions.
(run_inferior_call): Add 'sm' parameter. Associate the FSM with
the thread.
(call_function_by_hand_dummy): Create a new call_thread_fsm
instance, associate it with the thread, and wait for the FSM to
finish. If finished successfully, fetch the function's result
value out of the FSM.
* infrun.c (fetch_inferior_event): If the FSM says the stop
shouldn't be notified, don't call normal_stop.
(maybe_remove_breakpoints): New function, factored out from ...
(normal_stop): ... here. Simplify.
* infrun.h (maybe_remove_breakpoints): Declare.
* thread-fsm.c (thread_fsm_should_notify_stop): New function.
(thread-fsm.h) <struct thread_fsm_ops>: New field.
(thread_fsm_should_notify_stop): Declare.
This adds an object oriented replacement for the "struct continuation"
mechanism, and converts the stepping commands (step, next, stepi,
nexti) and the "finish" commands to use it.
It adds a new thread "class" (struct thread_fsm) that contains the
necessary info and callbacks to manage the state machine of a thread's
execution command.
This allows getting rid of some hacks. E.g., in fetch_inferior_event
and normal_stop we no longer need to know whether a thread is doing a
multi-step (e.g., step N). This effectively makes the
intermediate_continuations unused -- they'll be garbage collected in a
separate patch. (They were never a proper abstraction, IMO. See how
fetch_inferior_event needs to check step_multi before knowing whether
to call INF_EXEC_CONTINUE or INF_EXEC_COMPLETE.)
The target async vs !async uiout hacks in mi_on_normal_stop go away
too.
print_stop_event is no longer called from normal_stop. Instead it is
now called from within each interpreter's normal_stop observer. This
clears the path to make each interpreter print a stop event the way it
sees fit. Currently we have some hacks in common code to
differenciate CLI vs TUI vs MI around this area.
The "finish" command's FSM class stores the return value plus that
value's position in the value history, so that those can be printed to
both MI and CLI's streams. This fixes the CLI "finish" command when
run from MI -- it now also includes the function's return value in the
CLI stream:
(gdb)
~"callee3 (strarg=0x400730 \"A string argument.\") at src/gdb/testsuite/gdb.mi/basics.c:35\n"
~"35\t}\n"
+~"Value returned is $1 = 0\n"
*stopped,reason="function-finished",frame=...,gdb-result-var="$1",return-value="0",thread-id="1",stopped-threads="all",core="0"
-FAIL: gdb.mi/mi-cli.exp: CLI finish: check CLI output
+PASS: gdb.mi/mi-cli.exp: CLI finish: check CLI output
gdb/ChangeLog:
2015-09-09 Pedro Alves <palves@redhat.com>
* Makefile.in (COMMON_OBS): Add thread-fsm.o.
* breakpoint.c (handle_jit_event): Print debug output.
(bpstat_what): Split event callback handling to ...
(bpstat_run_callbacks): ... this new function.
(momentary_bkpt_print_it): No longer handle bp_finish here.
* breakpoint.h (bpstat_run_callbacks): Declare.
* gdbthread.h (struct thread_info) <step_multi>: Delete field.
<thread_fsm>: New field.
(thread_cancel_execution_command): Declare.
* infcmd.c: Include thread-fsm.h.
(struct step_command_fsm): New.
(step_command_fsm_ops): New global.
(new_step_command_fsm, step_command_fsm_prepare): New functions.
(step_1): Adjust to use step_command_fsm_prepare and
prepare_one_step.
(struct step_1_continuation_args): Delete.
(step_1_continuation): Delete.
(step_command_fsm_should_stop): New function.
(step_once): Delete.
(step_command_fsm_clean_up, step_command_fsm_async_reply_reason)
(prepare_one_step): New function, based on step_once.
(until_next_command): Remove step_multi reference.
(struct return_value_info): New.
(print_return_value): Rename to ...
(print_return_value_1): ... this. New struct return_value_info
parameter. Adjust.
(print_return_value): Reimplement as wrapper around
print_return_value_1.
(struct finish_command_fsm): New.
(finish_command_continuation): Delete.
(finish_command_fsm_ops): New global.
(new_finish_command_fsm, finish_command_fsm_should_stop): New
functions.
(finish_command_fsm_clean_up, finish_command_fsm_return_value):
New.
(finish_command_continuation_free_arg): Delete.
(finish_command_fsm_async_reply_reason): New.
(finish_backward, finish_forward): Change symbol parameter to a
finish_command_fsm. Adjust.
(finish_command): Create a finish_command_fsm. Adjust.
* infrun.c: Include "thread-fsm.h".
(clear_proceed_status_thread): Delete the thread's FSM.
(infrun_thread_stop_requested_callback): Cancel the thread's
execution command.
(clean_up_just_stopped_threads_fsms): New function.
(fetch_inferior_event): Handle the event_thread's should_stop
method saying the command isn't done yet.
(process_event_stop_test): Run breakpoint callbacks here.
(print_stop_event): Rename to ...
(print_stop_location): ... this.
(restore_current_uiout_cleanup): New function.
(print_stop_event): Reimplement.
(normal_stop): No longer notify the end_stepping_range observers
here handle "step N" nor "finish" here. No longer call
print_stop_event here.
* infrun.h (struct return_value_info): Forward declare.
(print_return_value): Declare.
(print_stop_event): Change prototype.
* thread-fsm.c: New file.
* thread-fsm.h: New file.
* thread.c: Include "thread-fsm.h".
(thread_cancel_execution_command): New function.
(clear_thread_inferior_resources): Call it.
* cli/cli-interp.c (cli_on_normal_stop): New function.
(cli_interpreter_init): Install cli_on_normal_stop as normal_stop
observer.
* mi/mi-interp.c: Include "thread-fsm.h".
(restore_current_uiout_cleanup): Delete.
(mi_on_normal_stop): If the thread has an FSM associated, and it
finished, ask it for the async-reply-reason to print. Always call
print_stop_event here, regardless of the top-level interpreter.
Check bpstat_what to tell whether an asynchronous breakpoint hit
triggered.
* tui/tui-interp.c (tui_on_normal_stop): New function.
(tui_init): Install tui_on_normal_stop as normal_stop observer.
gdb/testsuite/ChangeLog:
2015-09-09 Pedro Alves <palves@redhat.com>
* gdb.mi/mi-cli.exp: Add CLI finish tests.
This patch makes the execution control code use largely the same
mechanisms in both sync- and async-capable targets. This means using
continuations and use the event loop to react to target events on sync
targets as well. The trick is to immediately mark infrun's event loop
source after resume instead of calling wait_for_inferior. Then
fetch_inferior_event is adjusted to do a blocking wait on sync
targets.
Tested on x86_64 Fedora 20, native and gdbserver, with and without
"maint set target-async off".
gdb/ChangeLog:
2015-09-09 Pedro Alves <palves@redhat.com>
* breakpoint.c (bpstat_do_actions_1, until_break_command): Don't
check whether the target can async.
* inf-loop.c (inferior_event_handler): Only call target_async if
the target can async.
* infcall.c: Include top.h and interps.h.
(run_inferior_call): For the interpreter to sync mode while
running the infcall. Call wait_sync_command_done instead of
wait_for_inferior plus normal_stop.
* infcmd.c (prepare_execution_command): Don't check whether the
target can async when running in the foreground.
(step_1): Delete synchronous case handling.
(step_once): Always install a continuation, even in sync mode.
(until_next_command, finish_forward): Don't check whether the
target can async.
(attach_command_post_wait, notice_new_inferior): Always install a
continuation, even in sync mode.
* infrun.c (mark_infrun_async_event_handler): New function.
(proceed): In sync mode, mark infrun's event source instead of
waiting for events here.
(fetch_inferior_event): If the target can't async, do a blocking
wait.
(prepare_to_wait): In sync mode, mark infrun's event source.
(infrun_async_inferior_event_handler): No longer bail out if the
target can't async.
* infrun.h (mark_infrun_async_event_handler): New declaration.
* linux-nat.c (linux_nat_wait_1): Remove calls to
set_sigint_trap/clear_sigint_trap.
(linux_nat_terminal_inferior): No longer check whether the target
can async.
* mi/mi-interp.c (mi_on_sync_execution_done): Update and simplify
comment.
(mi_execute_command_input_handler): No longer check whether the
target is async. Update and simplify comment.
* target.c (default_target_wait): New function.
* target.h (struct target_ops) <to_wait>: Now defaults to
default_target_wait.
(default_target_wait): Declare.
* top.c (wait_sync_command_done): New function, factored out from
...
(maybe_wait_sync_command_done): ... this.
* top.h (wait_sync_command_done): Declare.
* target-delegates.c: Regenerate.
The main motivation for this is making non-stop / all-stop behave
similarly on initial connection, in order to move in the direction of
reimplementing all-stop mode with the remote target always running in
non-stop mode.
When we connect to a remote target in non-stop mode, we may find
threads either running or already stopped. The act of connecting
itself does not force threads to stop. To handle that, the remote
non-stop connection is currently roughly like this:
#1 - Fetch list of remote threads (qXfer:threads:read, qfThreadInfo,
etc). All threads are assumed to be running until the target
reports an asynchronous stop reply for them.
#2 - Fetch the initial set of threads that were already stopped, with
the '?' packet. (In non-stop, this is coupled with the vStopped
mechanism to be able to retrieve the status of more than one
thread.)
The stop replies fetched in #2 are placed in the pending stop reply
queue, and left for the regular event loop to process. That is,
"target remote" finishes and returns _before_ those stops are
processed.
That means that it's possible to have GDB process further commands
before the initial set of stopped threads is reported to the user.
E.g., before the patch, note how the prompt is printed before the
frame:
Remote debugging using :9999
(gdb)
[Thread 15296] #1 stopped.
0x0000003615a011f0 in ?? ()
Even though thread #1 was not running, for a moment, the user can see
it as such:
$ gdb a.out -ex "set non-stop 1" -ex "tar rem :9999" -ex "info threads" -ex "info registers"
Remote debugging using :9999
Id Target Id Frame
* 1 Thread 4772 (running)
Target is executing. <<<<<<< info registers
(gdb)
[Thread 4772] #1 stopped.
0x0000003615a011f0 in ?? ()
To fix that, this commit makes gdb process all threads found already
stopped at connection time, before giving the prompt to the user.
The fix takes a cue from fork-child.c:startup_inferior [1], and
processes the events locally in remote.c, avoiding the whole
wait_for_inferior/handle_inferior_event path. I decided to try this
approach after noticing that:
- several cases in handle_inferior_event miss checking stop_soon.
- we don't want to fetch the thread list in normal_stop.
and trying to fix them was resulting in sprinkling stop_soon checks in
many places, and uglifying normal_stop even more.
While with this patch, I'm avoiding changing GDB's output other than
when the prompt is printed, I think this approach is more flexible if
we do want to change it. And also, it's likely easier to get rid of
the MI *running event that is still sent for threads that are
initially found stopped, if we want to.
This happens to fix the testsuite too. All non-stop tests are racy
against "target remote" / gdbserver testing currently. That is,
sometimes the tests run, but other times they're just skipped without
any indication of PASS/FAIL. When that happens, the logs show:
target remote localhost:2346
Remote debugging using localhost:2346
(gdb)
[Thread 25418] #1 stopped.
0x0000003615a011f0 in ?? ()
^CQuit
(gdb) Remote debugging from host 127.0.0.1
Killing process(es): 25418
monitor exit
(gdb) Remote connection closed
(gdb) testcase /home/pedro/gdb/mygit/build/../src/gdb/testsuite/gdb.threads/multi-create-ns-info-thr.exp completed in 61 seconds
The trouble here is that there's output after the prompt, and the
regex in question doesn't expect that:
-re "Remote debugging using .*$serialport_re.*$gdb_prompt $" {
verbose "Set target to $targetname"
return 0
}
[1] - before startup_inferior was added, we'd go through
wait_for_inferior/handle_inferior_event while going through the shell,
and that turned out problematic.
Tested on x86_64 Fedora 20, gdbserver.
gdb/ChangeLog:
2015-08-20 Pedro Alves <palves@redhat.com>
* infrun.c (print_target_wait_results): Make extern.
* infrun.h (print_target_wait_results): Declare.
* remote.c (set_stop_requested_callback): Delete.
(process_initial_stop_replies): New function.
(remote_start_remote): Use it.
(stop_reply_queue_length): New function.
gdb/testsuite/ChangeLog:
2015-08-20 Pedro Alves <palves@redhat.com>
* gdb.server/connect-stopped-target.c: New file.
* gdb.server/connect-stopped-target.exp: New file.
That is, step past breakpoints by:
- pausing all threads
- removing breakpoint at PC
- single-step
- reinsert breakpoint
- restart threads
similarly to all-stop (with displaced stepping disabled). This allows
non-stop to work on targets/architectures without displaced stepping
support. That is, it makes displaced stepping an optimization instead
of a requirement. For example, in principle, all GNU/Linux ports
support non-stop mode at the target_ops level, but not all
corresponding gdbarch's implement displaced stepping. This should
make non-stop work for all (albeit, not as efficiently). And then
there are scenarios where even if the architecture supports displaced
stepping, we can't use it, because we e.g., don't find a usable
address to use as displaced step scratch pad. It should also fix
stepping past watchpoints on targets that have non-continuable
watchpoints in non-stop mode (e.g., PPC, untested). Running the
instruction out of line in the displaced stepping scratch pad doesn't
help that case, as the copied instruction reads/writes the same
watched memory... We can fix that too by teaching GDB to only remove
the watchpoint from the thread that we want to move past the
watchpoint (currently, removing a watchpoint always removes it from
all threads), but again, that can be considered an optimization; not
all targets would support it.
For those familiar with the gdb and gdbserver Linux target_ops
backends, the implementation should look similar, except it is done on
the core side. When we pause threads, we may find they stop with an
interesting event that should be handled later when the thread is
re-resumed, thus we store such events in the thread object, and mark
the event as pending. We should only consume pending events if the
thread is indeed resumed, thus we add a new "resumed" flag to the
thread object. At a later stage, we might add new target methods to
accelerate some of this, like "pause all threads", with corresponding
RSP packets, but we'd still need a fallback method for remote targets
that don't support such packets, so, again, that can be deferred as
optimization.
My _real_ motivation here is making it possible to reimplement
all-stop mode on top of the target always working on non-stop mode, so
that e.g., we can send RSP packets to a remote target even while the
target is running -- can't do that in the all-stop RSP variant, by
design).
Tested on x86_64 Fedora 20, with and without "set displaced off"
forced. The latter forces the new code paths whenever GDB needs to
step past a breakpoint.
gdb/ChangeLog:
2015-08-07 Pedro Alves <pedro@codesourcery.com>
* breakpoint.c (breakpoints_should_be_inserted_now): If any thread
has a pending status, return true.
* gdbthread.h: Include target/waitstatus.h.
(struct thread_suspend_state) <stop_reason, waitstatus_pending_p,
stop_pc>: New fields.
(struct thread_info) <resumed>: New field.
(set_resumed): Declare.
* infrun.c: Include "event-loop.h".
(infrun_async_inferior_event_token, infrun_is_async): New globals.
(infrun_async): New function.
(clear_step_over_info): Add debug output.
(displaced_step_in_progress_any_inferior): New function.
(displaced_step_fixup): New returns int.
(start_step_over): Handle in-line step-overs too. Assert the
thread is marked resumed.
(resume_cleanups): Clear the thread's resumed flag.
(resume): Set the thread's resumed flag. Return early if the
thread has a pending status. Allow stepping a breakpoint with no
signal.
(proceed): Adjust to check 'resumed' instead of 'executing'.
(clear_proceed_status_thread): If the thread has a pending status,
and that status is a finished step, discard the pending status.
(clear_proceed_status): Don't clear step_over_info here.
(random_pending_event_thread, do_target_wait): New functions.
(prepare_for_detach, wait_for_inferior, fetch_inferior_event): Use
do_target_wait.
(wait_one): New function.
(THREAD_STOPPED_BY): New macro.
(thread_stopped_by_watchpoint, thread_stopped_by_sw_breakpoint)
(thread_stopped_by_hw_breakpoint): New functions.
(switch_to_thread_cleanup, save_waitstatus, stop_all_threads): New
functions.
(handle_inferior_event): Also call set_resumed(false) on all
threads implicitly stopped by the event.
(restart_threads, resumed_thread_with_pending_status): New
functions.
(finish_step_over): If we were doing an in-line step-over before,
and no longer are after trying to start a new step-over, restart
all threads. If we have multiple threads with pending events,
save the current event and go through the event loop again.
(handle_signal_stop): Return early if finish_step_over returns
false.
<random signal>: If we get a signal while stepping over a
breakpoint in-line in non-stop mode, restart all threads. Clear
step_over_info before delivering the signal.
(keep_going_stepped_thread): Use internal_error instead of
gdb_assert. Mark the thread as resumed.
(keep_going_pass_signal): Assert the thread isn't already resumed.
If some other thread is doing an in-line step-over, defer the
resume. If we just started a new in-line step-over, stop all
threads. Don't clear step_over_info.
(infrun_async_inferior_event_handler): New function.
(_initialize_infrun): Create async event handler with
infrun_async_inferior_event_handler as callback.
(infrun_async): New declaration.
* target.c (target_async): New function.
* target.h (target_async): Declare macro and readd as function
declaration.
* target/waitstatus.h (enum target_stop_reason)
<TARGET_STOPPED_BY_SINGLE_STEP>: New value.
* thread.c (new_thread): Clear the new waitstatus field.
(set_resumed): New function.
In order to teach non-stop mode to do in-line step-overs (pause all
threads, remove breakpoint, single-step, reinsert breakpoint, restart
threads), we'll need to be able to queue in-line step over requests,
much like we queue displaced stepping (out-of-line) requests.
Actually, the queue should be the same -- threads wait for their turn
to step past something (breakpoint, watchpoint), doesn't matter what
technique we end up using when the step over actually starts.
I found that the queue management ends up simpler and more efficient
if embedded in the thread objects themselves. This commit converts
the existing displaced stepping queue to that. Later patches will
make the in-line step-overs code paths use it too.
gdb/ChangeLog:
2015-08-07 Pedro Alves <palves@redhat.com>
* gdbthread.h (struct thread_info) <step_over_prev,
step_over_next>: New fields.
(thread_step_over_chain_enqueue, thread_step_over_chain_remove)
(thread_step_over_chain_next, thread_is_in_step_over_chain): New
declarations.
* infrun.c (struct displaced_step_request): Delete.
(struct displaced_step_inferior_state) <step_request_queue>:
Delete field.
(displaced_step_prepare): Assert that trap_expected is set. Use
thread_step_over_chain_enqueue. Split starting a new displaced
step to ...
(start_step_over): ... this new function.
(resume): Assert the thread isn't waiting for a step over already.
(proceed): Assert the thread isn't waiting for a step over
already.
(infrun_thread_stop_requested): Adjust to remove threads from the
embedded step-over chain.
(handle_inferior_event) <fork/vfork>: Call start_step_over after
displaced_step_fixup.
(handle_signal_stop): Call start_step_over after
displaced_step_fixup.
* infrun.h (step_over_queue_head): New declaration.
* thread.c (step_over_chain_enqueue, step_over_chain_remove)
(thread_step_over_chain_next, thread_is_in_step_over_chain)
(thread_step_over_chain_enqueue)
(thread_step_over_chain_remove): New functions.
(delete_thread_1): Remove thread from the step-over chain.
Now stop_registers are no longer used and it can be removed.
I am not much sure what 'proceed_to_finish' really means now so I make a wild
guess while updating comments about it.
gdb/ChangeLog
2015-05-13 Jan Kratochvil <jan.kratochvil@redhat.com>
* gdbthread.h (struct thread_control_state): Update comment for
proceed_to_finish.
* infcall.c (run_inferior_call): Update comment about
proceed_to_finish.
* infcmd.c (get_return_value): Update comment about stop_registers.
(finish_forward): Update comment about proceed_to_finish.
* infrun.c (stop_registers): Remove.
(clear_proceed_status, normal_stop): Remove stop_registers handling.
* infrun.h (stop_registers): Remove.
... and move comment to declaration.
gdb/ChangeLog:
2015-03-24 Pedro Alves <palves@redhat.com>
* infrun.c (user_visible_resume_ptid): Rewrite going from
most-locked to unlocked instead of the opposite. Move comment ...
* infrun.h (user_visible_resume_ptid): ... here.
The "step" parameters of 'proceed' and 'resume' aren't really useful
as indication of whether run control wants to single-step the target,
as that information must already be retrievable from
currently_stepping. In fact, if currently_stepping disagrees with
whether we single-stepped the target, then things break. Thus instead
of having the same information in two places, this patch removes those
parameters.
Setting 'step_start_function' is the only user of proceed's 'step'
argument, other than passing the 'step' argument down to 'resume' and
debug log output. Move that instead to set_step_frame, where we
already set other related fields.
clear_proceed_status keeps its "step" parameter for now because it
needs to know which set of threads should have their state cleared,
and is called before the "stepping_command" flag is set.
Tested on x86_64 Fedora 20, native and gdbserver.
gdb/ChangeLog:
2015-03-24 Pedro Alves <palves@redhat.com>
* breakpoint.c (until_break_command): Adjust call to proceed.
* gdbthread.h (struct thread_control_state) <stepping_command>:
New field.
* infcall.c (run_inferior_call): Adjust call to proceed.
* infcmd.c (run_command_1, proceed_thread_callback, continue_1):
Adjust calls to proceed.
(set_step_frame): Set the current thread's step_start_function
here.
(step_once): Adjust calls to proceed.
(jump_command, signal_command, until_next_command)
(finish_backward, finish_forward, proceed_after_attach_callback)
(attach_command_post_wait): Adjust calls to proceed.
* infrun.c (proceed_after_vfork_done): Adjust call to proceed.
(do_target_resume): New function, factored out from ...
(resume): ... here. Remove 'step' parameter. Instead, check
currently_stepping to determine whether the thread should be
single-stepped.
(proceed): Remove 'step' parameter and don't set the thread's
step_start_function here. Adjust call to 'resume'.
(handle_inferior_event): Adjust calls to 'resume'.
(switch_back_to_stepped_thread): Use do_target_resume instead of
'resume'.
(keep_going): Adjust calls to 'resume'.
* infrun.h (proceed): Remove 'step' parameter.
(resume): Likewise.
* windows-nat.c (do_initial_windows_stuff): Adjust call to
'resume'.
* mi/mi-main.c (proceed_thread): Adjust call to 'proceed'.
When GDB finds out the target triggered a watchpoint, and the target
has non-continuable watchpoints, GDB sets things up to step past the
instruction that triggered the watchpoint. This is just like stepping
past a breakpoint, but goes through a different mechanism - it resumes
only the thread that needs to step past the watchpoint, but also
switches a "infwait state" global, that has the effect that the next
target_wait only wait for events only from that thread.
This forcing of a ptid to pass to target_wait obviously becomes a
bottleneck if we ever support stepping past different watchpoints
simultaneously (in separate processes).
It's also unnecessary -- the target should only return events for
threads that have been resumed; if no other thread than the one we're
stepping past the watchpoint has been resumed, then those other
threads should not report events. If we couldn't assume that, then
stepping past regular breakpoints would be broken for not likewise
forcing a similar infwait_state.
So this patch eliminates infwait_state, and instead teaches keep_going
to mark step_over_info in a way that has the breakpoints module skip
inserting watchpoints (because we're stepping past one), like it skips
breakpoints when we're stepping past one.
Tested on:
- x86_64 Fedora 20 (continuable watchpoints)
- PPC64 Fedora 18 (non-steppable watchpoints)
gdb/
2014-10-15 Pedro Alves <palves@redhat.com>
* breakpoint.c (should_be_inserted): Don't insert watchpoints if
trying to step past a non-steppable watchpoint.
* gdbthread.h (struct thread_info) <stepping_over_watchpoint>: New
field.
* infrun.c (struct step_over_info): Add new field
'nonsteppable_watchpoint_p' and adjust comments.
(set_step_over_info): New 'nonsteppable_watchpoint_p' parameter.
Adjust.
(clear_step_over_info): Clear nonsteppable_watchpoint_p as well.
(stepping_past_nonsteppable_watchpoint): New function.
(step_over_info_valid_p): Also return true if stepping past a
nonsteppable watchpoint.
(proceed): Adjust call to set_step_over_info. Remove reference to
init_infwait_state.
(init_wait_for_inferior): Remove reference to init_infwait_state.
(waiton_ptid): Delete global.
(struct execution_control_state)
<stepped_after_stopped_by_watchpoint>: Delete field.
(wait_for_inferior, fetch_inferior_event): Always pass
minus_one_ptid to target_wait.
(init_thread_stepping_state): Clear 'stepping_over_watchpoint'
field.
(init_infwait_state): Delete function.
(handle_inferior_event): Remove infwait_state handling.
(handle_signal_stop) <watchpoints handling>: Adjust after
stepped_after_stopped_by_watchpoint removal. Don't remove
breakpoints here nor set infwait_state. Set the thread's
stepping_over_watchpoint flag, and call keep_going instead.
(keep_going): Handle stepping_over_watchpoint. Adjust
set_step_over_info calls.
* infrun.h (stepping_past_nonsteppable_watchpoint): Declare
function.
This patch reorganizes the code that implements follow-fork and
detach-on-fork in preparation for implementation of those features for the
extended-remote target. The function linux-nat.c:linux_child_follow_fork
contained target-independent code mixed in with target-dependent code. The
target-independent pieces need to be accessible for the host-side
implementation of follow-fork for extended-remote Linux targets.
The changes are fairly mechanical. A new routine, follow_fork_inferior,
is implemented in infrun.c, containing those parts of
linux_child_follow_fork that manage inferiors and the inferior list. The
parts of linux_child_follow_fork that deal with LWPs and target-specifics
were left in-place. Although the order of some operations was changed, the
resulting functionality was not.
Modifications were made to the other native target follow-fork functions,
inf_ttrace_follow_fork and inf_ptrace_follow_fork, that should allow them
to work with follow_fork_inferior. Some other adjustments were necessary
in inf-ttrace.c. The changes to inf-ttrace.c and inf-ptrace.c were not
tested.
gdb/ChangeLog:
* inf-ptrace.c (inf_ptrace_follow_fork): Remove target-independent
code so as to work with follow_fork_inferior.
* inf-ttrace.c (inf_ttrace_follow_fork): Ditto.
(inf_ttrace_create_inferior): Remove reference to
inf_ttrace_vfork_ppid.
(inf_ttrace_attach): Ditto.
(inf_ttrace_detach): Ditto.
(inf_ttrace_kill): Use current_inferior instead of
inf_ttrace_vfork_ppid.
(inf_ttrace_wait): Eliminate use of inf_ttrace_vfork_ppid, report
TARGET_WAITKIND_VFORK_DONE event, delete HACK that switched the
inferior away from the parent.
* infrun.c (follow_fork): Call follow_fork_inferior instead of
target_follow_fork.
(follow_fork_inferior): New function.
(follow_inferior_reset_breakpoints): Make function static.
* infrun.h (follow_inferior_reset_breakpoints): Remove declaration.
* linux-nat.c (linux_child_follow_fork): Move target-independent
code to infrun.c:follow_fork_inferior.
This commit moves the inclusion of ptid.h to common-defs.h and removes
all other inclusions.
gdb/
2014-08-07 Gary Benson <gbenson@redhat.com>
* common/common-defs.h: Include ptid.h.
* defs.h: Do not include ptid.h.
* inferior.h: Likewise.
* infrun.h: Likewise.
* nat/linux-btrace.h: Likewise.
* nat/linux-osdata.h: Likewise.
* target/waitstatus.h: Likewise.
gdb/gdbserver/
2014-08-07 Gary Benson <gbenson@redhat.com>
* server.h: Do not include ptid.h.
* notif.h: Likewise.
Currently, GDB can pass a signal to the wrong thread in several
different but related scenarios.
E.g., if thread 1 stops for signal SIGFOO, the user switches to thread
2, and then issues "continue", SIGFOO is actually delivered to thread
2, not thread 1. This obviously messes up programs that use
pthread_kill to send signals to specific threads.
This has been a known issue for a long while. Back in 2008 when I
made stop_signal be per-thread (2020b7ab), I kept the behavior -- see
code in 'proceed' being removed -- wanting to come back to it later.
The time has finally come now.
The patch fixes this -- on resumption, intercepted signals are always
delivered to the thread that had intercepted them.
Another example: if thread 1 stops for a breakpoint, the user switches
to thread 2, and then issues "signal SIGFOO", SIGFOO is actually
delivered to thread 1, not thread 2, because 'proceed' first switches
to thread 1 to step over its breakpoint... If the user deletes the
breakpoint before issuing "signal FOO", then the signal is delivered
to thread 2 (the current thread).
"signal SIGFOO" can be used for two things: inject a signal in the
program while the program/thread had stopped for none, bypassing
"handle nopass"; or changing/suppressing a signal the program had
stopped for. These scenarios are really two faces of the same coin,
and GDB can't really guess what the user is trying to do. GDB might
have intercepted signals in more than one thread even (see the new
signal-command-multiple-signals-pending.exp test). At least in the
inject case, it's obviously clear to me that the user means to deliver
the signal to the currently selected thread, so best is to make the
command's behavior consistent and easy to explain.
Then, if the user is trying to suppress/change a signal the program
had stopped for instead of injecting a new signal, but, the user had
changed threads meanwhile, then she will be surprised that with:
(gdb) continue
Thread 1 stopped for signal SIGFOO.
(gdb) thread 2
(gdb) signal SIGBAR
... GDB actually delivers SIGFOO to thread 1, and SIGBAR to thread 2
(with scheduler-locking off, which is the default, because then
"signal" or any other resumption command resumes all threads).
So the patch makes GDB detect that, and ask for confirmation:
(gdb) thread 1
[Switching to thread 1 (Thread 10979)]
(gdb) signal SIGUSR2
Note:
Thread 3 previously stopped with signal SIGUSR2, User defined signal 2.
Thread 2 previously stopped with signal SIGUSR1, User defined signal 1.
Continuing thread 1 (the current thread) with specified signal will
still deliver the signals noted above to their respective threads.
Continue anyway? (y or n)
All these scenarios are covered by the new tests.
Tested on x86_64 Fedora 20, native and gdbserver.
gdb/
2014-07-25 Pedro Alves <palves@redhat.com>
* NEWS: Mention signal passing and "signal" command changes.
* gdbthread.h (struct thread_suspend_state) <stop_signal>: Extend
comment.
* breakpoint.c (until_break_command): Adjust clear_proceed_status
call.
* infcall.c (run_inferior_call): Adjust clear_proceed_status call.
* infcmd.c (proceed_thread_callback, continue_1, step_once)
(jump_command): Adjust clear_proceed_status call.
(signal_command): Warn if other thread that are resumed have
signals that will be delivered. Adjust clear_proceed_status call.
(until_next_command, finish_command)
(proceed_after_attach_callback, attach_command_post_wait)
(attach_command): Adjust clear_proceed_status call.
* infrun.c (proceed_after_vfork_done): Likewise.
(proceed_after_attach_callback): Adjust comment.
(clear_proceed_status_thread): Clear stop_signal if not in pass
state.
(clear_proceed_status_callback): Delete.
(clear_proceed_status): New 'step' parameter. Only clear the
proceed status of threads the command being prepared is about to
resume.
(proceed): If passed in an explicit signal, override stop_signal
with it. Don't pass the last stop signal to the thread we're
resuming.
(init_wait_for_inferior): Adjust clear_proceed_status call.
(switch_back_to_stepped_thread): Clear the signal if it should not
be passed.
* infrun.h (clear_proceed_status): New 'step' parameter.
(user_visible_resume_ptid): Add comment.
* linux-nat.c (linux_nat_resume_callback): Don't check whether the
signal is in pass state.
* remote.c (append_pending_thread_resumptions): Likewise.
* mi/mi-main.c (proceed_thread): Adjust clear_proceed_status call.
gdb/doc/
2014-07-25 Pedro Alves <palves@redhat.com>
Eli Zaretskii <eliz@gnu.org>
* gdb.texinfo (Signaling) <signal command>: Explain what happens
with multi-threaded programs.
gdb/testsuite/
2014-07-25 Pedro Alves <palves@redhat.com>
* gdb.threads/signal-command-handle-nopass.c: New file.
* gdb.threads/signal-command-handle-nopass.exp: New file.
* gdb.threads/signal-command-multiple-signals-pending.c: New file.
* gdb.threads/signal-command-multiple-signals-pending.exp: New file.
* gdb.threads/signal-delivered-right-thread.c: New file.
* gdb.threads/signal-delivered-right-thread.exp: New file.
Ignoring expected and desired differences like whether the prompt is
output after *stoppped records, GDB MI output is still different in
sync and async modes.
In sync mode, when a CLI execution command is entered, the "reason"
field is missing in the *stopped async record. And in async mode, for
some events, like program exits, the corresponding CLI output is
missing in the CLI channel.
Vis, diff between sync vs async modes:
run
^running
*running,thread-id="1"
(gdb)
...
- ~"[Inferior 1 (process 15882) exited normally]\n"
=thread-exited,id="1",group-id="i1"
=thread-group-exited,id="i1",exit-code="0"
- *stopped
+ *stopped,reason="exited-normally"
si
...
(gdb)
~"0x000000000045e033\t29\t memset (&args, 0, sizeof args);\n"
- *stopped,frame=...,thread-id="1",stopped-threads="all",core="0"
+ *stopped,reason="end-stepping-range",frame=...,thread-id="1",stopped-threads="all",core="0"
(gdb)
In addition, in both cases, when a MI execution command is entered,
and a breakpoint triggers, the event is sent to the console too. But
some events like program exits have the CLI output missing in the CLI
channel:
-exec-run
^running
*running,thread-id="1"
(gdb)
...
=thread-exited,id="1",group-id="i1"
=thread-group-exited,id="i1",exit-code="0"
- *stopped
+ *stopped,reason="exited-normally"
We'll want to make background commands always possible by default.
IOW, make target-async be the default. But, in order to do that,
we'll need to emulate MI sync on top of an async target. That means
we'll have yet another combination to care for in the testsuite.
Rather than making the testsuite cope with all these differences, I
thought it better to just fix GDB to always have the complete output,
no matter whether it's in sync or async mode.
This is all related to interpreter-exec, and the corresponding uiout
switching. (Typing a CLI command directly in MI is shorthand for
running it through -interpreter-exec console.)
In sync mode, when a CLI command is active, normal_stop is called when
the current interpreter and uiout are CLI's. So print_XXX_reason
prints the stop reason to CLI uiout (only), and we don't show it in
MI.
In async mode the stop event is processed when we're back in the MI
interpreter, so the stop reason is printed directly to the MI uiout.
Fix this by making run control event printing roughly independent of
whatever is the current interpreter or uiout. That is, move these
prints to interpreter observers, that know whether to print or be
quiet, and if printing, which uiout to print to. In the case of the
console/tui interpreters, only print if the top interpreter. For MI,
always print.
Breakpoint hits / normal stops are already handled similarly -- MI has
a normal_stop observer that prints the event to both MI and the CLI,
though that could be cleaned up further in the direction of this
patch.
This also makes all of:
(gdb) foo
and
(gdb) interpreter-exec MI "-exec-foo"
and
(gdb)
-exec-foo
and
(gdb)
-interpreter-exec console "foo"
print as expected.
Tested on x86_64 Fedora 20, sync and async modes.
gdb/
2014-05-29 Pedro Alves <palves@redhat.com>
PR gdb/13860
* cli/cli-interp.c: Include infrun.h and observer.h.
(cli_uiout, cli_interp): New globals.
(cli_on_signal_received, cli_on_end_stepping_range)
(cli_on_signal_exited, cli_on_exited, cli_on_no_history): New
functions.
(cli_interpreter_init): Install them as 'end_stepping_range',
'signal_received' 'signal_exited', 'exited' and 'no_history'
observers.
(_initialize_cli_interp): Remove cli_interp local.
* infrun.c (handle_inferior_event): Call the several stop reason
observers instead of printing the stop reason directly.
(end_stepping_range): New function.
(print_end_stepping_range_reason, print_signal_exited_reason)
(print_exited_reason, print_signal_received_reason)
(print_no_history_reason): Make static, and add an uiout
parameter. Print to that instead of to CURRENT_UIOUT.
* infrun.h (print_end_stepping_range_reason)
(print_signal_exited_reason, print_exited_reason)
(print_signal_received_reason print_no_history_reason): New
declarations.
* mi/mi-common.h (struct mi_interp): Rename 'uiout' field to
'mi_uiout'.
<cli_uiout>: New field.
* mi/mi-interp.c (mi_interpreter_init): Adjust. Create the new
uiout for CLI output. Install 'signal_received',
'end_stepping_range', 'signal_exited', 'exited' and 'no_history'
observers.
(find_mi_interpreter, mi_interp_data, mi_on_signal_received)
(mi_on_end_stepping_range, mi_on_signal_exited, mi_on_exited)
(mi_on_no_history): New functions.
(ui_out_free_cleanup): Delete function.
(mi_on_normal_stop): Don't allocate a new uiout for CLI output,
instead use the one already stored in the MI interpreter data.
(mi_ui_out): Adjust.
* tui/tui-interp.c: Include infrun.h and observer.h.
(tui_interp): New global.
(tui_on_signal_received, tui_on_end_stepping_range)
(tui_on_signal_exited, tui_on_exited)
(tui_on_no_history): New functions.
(tui_init): Install them as 'end_stepping_range',
'signal_received' 'signal_exited', 'exited' and 'no_history'
observers.
(_initialize_tui_interp): Delete tui_interp local.
gdb/doc/
2014-05-29 Pedro Alves <palves@redhat.com>
PR gdb/13860
* observer.texi (signal_received, end_stepping_range)
(signal_exited, exited, no_history): New observer subjects.
gdb/testsuite/
2014-05-29 Pedro Alves <palves@redhat.com>
PR gdb/13860
* gdb.mi/mi-cli.exp: Always expect "end-stepping-range" stop
reason, even in sync mode.
Move infrun.c declarations out of inferior.h to a new infrun.h file.
Tested by building on:
i686-w64-mingw32, enable-targets=all
x86_64-linux, enable-targets=all
i586-pc-msdosdjgpp
And also grepped the whole tree for each symbol moved to find where
infrun.h might be necessary.
gdb/
2014-05-22 Pedro Alves <palves@redhat.com>
* inferior.h (debug_infrun, debug_displaced, stop_on_solib_events)
(sync_execution, sched_multi, step_stop_if_no_debug, non_stop)
(disable_randomization, enum exec_direction_kind)
(execution_direction, stop_registers, start_remote)
(clear_proceed_status, proceed, resume, user_visible_resume_ptid)
(wait_for_inferior, normal_stop, get_last_target_status)
(prepare_for_detach, fetch_inferior_event, init_wait_for_inferior)
(insert_step_resume_breakpoint_at_sal)
(follow_inferior_reset_breakpoints, stepping_past_instruction_at)
(set_step_info, print_stop_event, signal_stop_state)
(signal_print_state, signal_pass_state, signal_stop_update)
(signal_print_update, signal_pass_update)
(update_signals_program_target, clear_exit_convenience_vars)
(displaced_step_dump_bytes, update_observer_mode)
(signal_catch_update, gdb_signal_from_command): Move
declarations ...
* infrun.h: ... to this new file.
* amd64-tdep.c: Include infrun.h.
* annotate.c: Include infrun.h.
* arch-utils.c: Include infrun.h.
* arm-linux-tdep.c: Include infrun.h.
* arm-tdep.c: Include infrun.h.
* break-catch-sig.c: Include infrun.h.
* breakpoint.c: Include infrun.h.
* common/agent.c: Include infrun.h instead of inferior.h.
* corelow.c: Include infrun.h.
* event-top.c: Include infrun.h.
* go32-nat.c: Include infrun.h.
* i386-tdep.c: Include infrun.h.
* inf-loop.c: Include infrun.h.
* infcall.c: Include infrun.h.
* infcmd.c: Include infrun.h.
* infrun.c: Include infrun.h.
* linux-fork.c: Include infrun.h.
* linux-nat.c: Include infrun.h.
* linux-thread-db.c: Include infrun.h.
* monitor.c: Include infrun.h.
* nto-tdep.c: Include infrun.h.
* procfs.c: Include infrun.h.
* record-btrace.c: Include infrun.h.
* record-full.c: Include infrun.h.
* remote-m32r-sdi.c: Include infrun.h.
* remote-mips.c: Include infrun.h.
* remote-notif.c: Include infrun.h.
* remote-sim.c: Include infrun.h.
* remote.c: Include infrun.h.
* reverse.c: Include infrun.h.
* rs6000-tdep.c: Include infrun.h.
* s390-linux-tdep.c: Include infrun.h.
* solib-irix.c: Include infrun.h.
* solib-osf.c: Include infrun.h.
* solib-svr4.c: Include infrun.h.
* target.c: Include infrun.h.
* top.c: Include infrun.h.
* windows-nat.c: Include infrun.h.
* mi/mi-interp.c: Include infrun.h.
* mi/mi-main.c: Include infrun.h.
* python/py-threadevent.c: Include infrun.h.
Joel Brobecker
Pedro Alves
Jan Kratochvil
Don Breazeal
Gary Benson