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.
Record targets behave as if scheduler-locking were on in replay mode. Add a
new scheduler-locking option "replay" to make this implicit behaviour explicit.
It behaves like "on" in replay mode and like "off" in record mode.
By making the current behaviour a scheduler-locking option, we allow the user
to change it. Since it is the current behaviour, this new option is also
the new default.
One caveat is that when resuming a thread that is at the end of its execution
history, record btrace implicitly stops replaying other threads and resumes
the entire process. This is a convenience feature to not require the user
to explicitly move all other threads to the end of their execution histories
before being able to resume the process.
We mimick this behaviour with scheduler-locking replay and move it from
record-btrace into infrun. With all-stop on top of non-stop, we can't do
this in record-btrace anymore.
Record full does not really support multi-threading and is therefore not
impacted. If it were extended to support multi-threading, it would 'benefit'
from this change. The good thing is that all record targets will behave the
same with respect to scheduler-locking.
I put the code for this into clear_proceed_status. It also sends the
about_to_proceed notification.
gdb/
* NEWS: Announce new scheduler-locking mode.
* infrun.c (schedlock_replay): New.
(scheduler_enums): Add schedlock_replay.
(scheduler_mode): Change default to schedlock_replay.
(user_visible_resume_ptid): Handle schedlock_replay.
(clear_proceed_status_thread): Stop replaying if resumed thread is
not replaying.
(schedlock_applies): Handle schedlock_replay.
(_initialize_infrun): Document new scheduler-locking mode.
* record-btrace.c (record_btrace_resume): Remove code to stop other
threads when not replaying the resumed thread.
doc/
* gdb.texinfo (All-Stop Mode): Describe new scheduler-locking mode.
A thread that runs out of its execution history is stopped. We already set
stop_pc and call stop_waiting. But we do not switch to the stopped thread.
In normal_stop, we call finish_thread_state_cleanup to set a thread's running
state. In all-stop mode, we call it with minus_one_ptid; in non-stop mode, we
only call it for inferior_ptid.
If in non-stop mode normal_stop is called on behalf of a thread that is not
inferior_ptid, that other thread will still be reported as running. If it is
actually stopped it can't be resumed again.
Record targets traditionally don't support non-stop and only resume
inferior_ptid. So this has not been a problem, so far.
Switch to the eventing thread for NO_HISTORY events as preparation to support
non-stop for the record btrace target.
gdb/
* infrun.c (handle_inferior_event_1): Switch to the eventing thread
in the TARKET_WAITKIND_NO_HISTORY case.
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 patch implements support for exec events on extended-remote Linux
targets. Follow-exec-mode and rerun behave as expected. Catchpoints and
test updates are implemented in subsequent patches.
This patch was derived from a patch posted last October:
https://sourceware.org/ml/gdb-patches/2014-10/msg00877.html.
It was originally based on some work done by Luis Machado in 2013.
IMPLEMENTATION
----------------
Exec events are enabled via ptrace options.
When an exec event is detected by gdbserver, the existing process
data, along with all its associated lwp and thread data, is deleted
and replaced by data for a new single-threaded process. The new
process data is initialized with the appropriate parts of the state
of the execing process. This approach takes care of several potential
pitfalls, including:
* deleting the data for an execing non-leader thread before any
wait/sigsuspend occurs
* correctly initializing the architecture of the execed process
We then report the exec event using a new RSP stop reason, "exec".
When GDB receives an "exec" event, it saves the status in the event
structure's target_waitstatus field, like what is done for remote fork
events. Because the original and execed programs may have different
architectures, we skip parsing the section of the stop reply packet
that contains register data. The register data will be retrieved
later after the inferior's architecture has been set up by
infrun.c:follow_exec.
At that point the exec event is handled by the existing event handling
in GDB. However, a few changes were necessary so that
infrun.c:follow_exec could accommodate the remote target.
* Where follow-exec-mode "new" is handled, we now call
add_inferior_with_spaces instead of add_inferior with separate calls
to set up the program and address spaces. The motivation for this
is that add_inferior_with_spaces also sets up the initial architecture
for the inferior, which is needed later by target_find_description
when it calls target_gdbarch.
* We call a new target function, target_follow_exec. This function
allows us to store the execd_pathname in the inferior, instead of
using the static string remote_exec_file from remote.c. The static
string didn't work for follow-exec-mode "new", since once you switched
to the execed program, the original remote exec-file was lost. The
execd_pathname is now stored in the inferior's program space as a
REGISTRY field. All of the requisite mechanisms for this are
defined in remote.c.
gdb/gdbserver/ChangeLog:
* linux-low.c (linux_mourn): Static declaration.
(linux_arch_setup): Move in front of
handle_extended_wait.
(linux_arch_setup_thread): New function.
(handle_extended_wait): Handle exec events. Call
linux_arch_setup_thread. Make event_lwp argument a
pointer-to-a-pointer.
(check_zombie_leaders): Do not check stopped threads.
(linux_low_ptrace_options): Add PTRACE_O_TRACEEXEC.
(linux_low_filter_event): Add lwp and thread for exec'ing
non-leader thread if leader thread has been deleted.
Refactor code into linux_arch_setup_thread and call it.
Pass child lwp pointer by reference to handle_extended_wait.
(linux_wait_for_event_filtered): Update comment.
(linux_wait_1): Prevent clobbering exec event status.
(linux_supports_exec_events): New function.
(linux_target_ops) <supports_exec_events>: Initialize new member.
* lynx-low.c (lynx_target_ops) <supports_exec_events>: Initialize
new member.
* remote-utils.c (prepare_resume_reply): New stop reason 'exec'.
* server.c (report_exec_events): New global variable.
(handle_query): Handle qSupported query for exec-events feature.
(captured_main): Initialize report_exec_events.
* server.h (report_exec_events): Declare new global variable.
* target.h (struct target_ops) <supports_exec_events>: New
member.
(target_supports_exec_events): New macro.
* win32-low.c (win32_target_ops) <supports_exec_events>:
Initialize new member.
gdb/ChangeLog:
* infrun.c (follow_exec): Use process-style ptid for
exec message. Call add_inferior_with_spaces and
target_follow_exec.
* nat/linux-ptrace.c (linux_supports_traceexec): New function.
* nat/linux-ptrace.h (linux_supports_traceexec): Declare.
* remote.c (remote_pspace_data): New static variable.
(remote_pspace_data_cleanup): New function.
(get_remote_exec_file): New function.
(set_remote_exec_file_1): New function.
(set_remote_exec_file): New function.
(show_remote_exec_file): New function.
(remote_exec_file): Delete static variable.
(anonymous enum) <PACKET_exec_event_feature> New
enumeration constant.
(remote_protocol_features): Add entry for exec-events feature.
(remote_query_supported): Add client side of qSupported query
for exec-events feature.
(remote_follow_exec): New function.
(remote_parse_stop_reply): Handle 'exec' stop reason.
(extended_remote_run, extended_remote_create_inferior): Call
get_remote_exec_file and set_remote_exec_file_1.
(init_extended_remote_ops) <to_follow_exec>: Initialize new
member.
(_initialize_remote): Call
register_program_space_data_with_cleanup. Call
add_packet_config_cmd for remote exec-events feature.
Modify call to add_setshow_string_noescape_cmd for exec-file
to use new functions set_remote_exec_file and
show_remote_exec_file.
* target-debug.h, target-delegates.c: Regenerated.
* target.c (target_follow_exec): New function.
* target.h (struct target_ops) <to_follow_exec>: New member.
(target_follow_exec): Declare new function.
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.
This patch fixes a segmentation fault in native GDB when
handling an exec event with follow-exec-mode set to "new".
The stack trace from the segfault was this:
0 0x0000000000669594 in gdbarch_data (gdbarch=0x0, data=0x20da7a0)
at /scratch/dbreazea/sandbox/exec-nat/binutils-gdb/gdb/gdbarch.c:4847
1 0x00000000004d430e in get_remote_arch_state ()
at /scratch/dbreazea/sandbox/exec-nat/binutils-gdb/gdb/remote.c:603
2 0x00000000004d431e in get_remote_state ()
at /scratch/dbreazea/sandbox/exec-nat/binutils-gdb/gdb/remote.c:616
3 0x00000000004dda8b in discard_pending_stop_replies (inf=0x217c710)
at /scratch/dbreazea/sandbox/exec-nat/binutils-gdb/gdb/remote.c:5775
4 0x00000000006a5928 in observer_inferior_exit_notification_stub (
data=0x4dda7a <discard_pending_stop_replies>, args_data=0x7fff12c258f0)
at ./observer.inc:1137
5 0x00000000006a419a in generic_observer_notify (subject=0x21dfbe0,
args=0x7fff12c258f0)
at /scratch/dbreazea/sandbox/exec-nat/binutils-gdb/gdb/observer.c:167
6 0x00000000006a59ba in observer_notify_inferior_exit (inf=0x217c710)
at ./observer.inc:1162
7 0x00000000007981d5 in exit_inferior_1 (inftoex=0x217c710, silent=1)
at /scratch/dbreazea/sandbox/exec-nat/binutils-gdb/gdb/inferior.c:244
8 0x00000000007982f2 in exit_inferior_num_silent (num=1)
at /scratch/dbreazea/sandbox/exec-nat/binutils-gdb/gdb/inferior.c:286
9 0x000000000062f93d in follow_exec (ptid=...,
execd_pathname=0x7fff12c259a0 "/scratch/dbreazea/sandbox/exec-nat/build/gdb/testsuite/gdb.base/execd-prog")
at /scratch/dbreazea/sandbox/exec-nat/binutils-gdb/gdb/infrun.c:1195
In follow_exec we were creating a new inferior for the execd program,
as required by the exec mode, but we were doing it before calling
exit_inferior_num_silent on the original inferior. So on entry to
exit_inferior_num_silent we had two inferiors with the same ptid.
In the calls made by exit_inferior_num_silent, the current inferior
is temporarily saved and replaced in order to make use of functions
that only operate on the current inferior (for example, in
do_all_continuations, called while deleting the threads of the original
inferior). When we restored the original inferior, we just took the
first inferior that matched the ptid of the original and got the new
(wrong) one. It hadn't been initialized yet and had no gdbarch
pointer, and GDB segfaulted.
The fix for that is to call exit_inferior_num_silent before adding the new
inferior, so that we never have two inferiors with the same ptid. Then
exit_inferior_num_silent uses the original inferior as the current inferior
throughout, and can find a valid gdbarch pointer.
Once we have finished with the exit of the old inferior and added the
new one, we need to create a new thread for the new inferior. In the
function that called follow_exec, handle_inferior_event_1,
ecs->event_thread now points to the thread that was deleted with the
exit of the original inferior. To remedy this we create the new thread,
and once we return from follow_exec we reset ecs->event_thread.
Note that we are guaranteed that we can reset ecs->event_thread
safely using inferior_thread because we have set the current
inferior in follow_exec, and inferior_ptid was set by the call
to context_switch at the beginning of exec event handling.
gdb/ChangeLog:
* infrun.c (follow_exec): Re-order operations for
handling follow-exec-mode "new".
(handle_inferior_event_1): Assign ecs->event_thread
to the current thread.
* remote.c (get_remote_arch_state): Add an assertion.
GDB's current behavior when dealing with non-local references in the
context of nested fuctions is approximative:
- code using valops.c:value_of_variable read the first available stack
frame that holds the corresponding variable (whereas there can be
multiple candidates for this);
- code directly relying on read_var_value will instead read non-local
variables in frames where they are not even defined.
This change adds the necessary context to symbol reads (to get the block
they belong to) and to blocks (the static link property, if any) so that
GDB can make the proper decisions when dealing with non-local varibale
references.
gdb/ChangeLog:
* ada-lang.c (ada_read_var_value): Add a var_block argument
and pass it to default_read_var_value.
* block.c (block_static_link): New accessor.
* block.h (block_static_link): Declare it.
* buildsym.c (finish_block_internal): Add a static_link
argument. If there is a static link, associate it to the new
block.
(finish_block): Add a static link argument and pass it to
finish_block_internal.
(end_symtab_get_static_block): Update calls to finish_block and
to finish_block_internal.
(end_symtab_with_blockvector): Update call to
finish_block_internal.
* buildsym.h: Forward-declare struct dynamic_prop.
(struct context_stack): Add a static_link field.
(finish_block): Add a static link argument.
* c-exp.y: Remove an obsolete comment (evaluation of variables
already start from the selected frame, and now they climb *up*
the call stack) and propagate the block information to the
produced expression.
* d-exp.y: Likewise.
* f-exp.y: Likewise.
* go-exp.y: Likewise.
* jv-exp.y: Likewise.
* m2-exp.y: Likewise.
* p-exp.y: Likewise.
* coffread.c (coff_symtab_read): Update calls to finish_block.
* dbxread.c (process_one_symbol): Likewise.
* xcoffread.c (read_xcoff_symtab): Likewise.
* compile/compile-c-symbols.c (convert_one_symbol): Promote the
"sym" parameter to struct block_symbol, update its uses and pass
its block to calls to read_var_value.
(convert_symbol_sym): Update the calls to convert_one_symbol.
* compile/compile-loc2c.c (do_compile_dwarf_expr_to_c): Update
call to read_var_value.
* dwarf2loc.c (block_op_get_frame_base): New.
(dwarf2_block_frame_base_locexpr_funcs): Implement the
get_frame_base method.
(dwarf2_block_frame_base_loclist_funcs): Likewise.
(dwarf2locexpr_baton_eval): Add a frame argument and use it
instead of the selected frame in order to evaluate the
expression.
(dwarf2_evaluate_property): Add a frame argument. Update call
to dwarf2_locexpr_baton_eval to provide a frame in available and
to handle the absence of address stack.
* dwarf2loc.h (dwarf2_evaluate_property): Add a frame argument.
* dwarf2read.c (attr_to_dynamic_prop): Add a forward
declaration.
(read_func_scope): Record any available static link description.
Update call to finish_block.
(read_lexical_block_scope): Update call to finish_block.
* findvar.c (follow_static_link): New.
(get_hosting_frame): New.
(default_read_var_value): Add a var_block argument. Use
get_hosting_frame to handle non-local references.
(read_var_value): Add a var_block argument and pass it to the
LA_READ_VAR_VALUE method.
* gdbtypes.c (resolve_dynamic_range): Update calls to
dwarf2_evaluate_property.
(resolve_dynamic_type_internal): Likewise.
* guile/scm-frame.c (gdbscm_frame_read_var): Update call to
read_var_value, passing it the block coming from symbol lookup.
* guile/scm-symbol.c (gdbscm_symbol_value): Update call to
read_var_value (TODO).
* infcmd.c (finish_command_continuation): Update call to
read_var_value, passing it the block coming from symbol lookup.
* infrun.c (insert_exception_resume_breakpoint): Likewise.
* language.h (struct language_defn): Add a var_block argument to
the LA_READ_VAR_VALUE method.
* objfiles.c (struct static_link_htab_entry): New.
(static_link_htab_entry_hash): New.
(static_link_htab_entry_eq): New.
(objfile_register_static_link): New.
(objfile_lookup_static_link): New.
(free_objfile): Free the STATIC_LINKS hashed map if needed.
* objfiles.h: Include hashtab.h.
(struct objfile): Add a static_links field.
(objfile_register_static_link): New.
(objfile_lookup_static_link): New.
* printcmd.c (print_variable_and_value): Update call to
read_var_value.
* python/py-finishbreakpoint.c (bpfinishpy_init): Likewise.
* python/py-frame.c (frapy_read_var): Update call to
read_var_value, passing it the block coming from symbol lookup.
* python/py-framefilter.c (extract_sym): Add a sym_block
parameter and set the pointed value to NULL (TODO).
(enumerate_args): Update call to extract_sym.
(enumerate_locals): Update calls to extract_sym and to
read_var_value.
* python/py-symbol.c (sympy_value): Update call to
read_var_value (TODO).
* stack.c (read_frame_local): Update call to read_var_value.
(read_frame_arg): Likewise.
(return_command): Likewise.
* symtab.h (struct symbol_block_ops): Add a get_frame_base
method.
(struct symbol): Add a block field.
(SYMBOL_BLOCK): New accessor.
* valops.c (value_of_variable): Remove frame/block handling and
pass the block argument to read_var_value, which does this job
now.
(value_struct_elt_for_reference): Update calls to
read_var_value.
(value_of_this): Pass the block found to read_var_value.
* value.h (read_var_value): Add a var_block argument.
(default_read_var_value): Likewise.
gdb/testsuite/ChangeLog:
* gdb.base/nested-subp1.exp: New file.
* gdb.base/nested-subp1.c: New file.
* gdb.base/nested-subp2.exp: New file.
* gdb.base/nested-subp2.c: New file.
* gdb.base/nested-subp3.exp: New file.
* gdb.base/nested-subp3.c: New file.
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.
The ppc64 displaced step code can't handle atomic sequences. Fallback
to stepping over the breakpoint in-line if we detect one.
gdb/ChangeLog:
2015-08-07 Pedro Alves <palves@redhat.com>
* infrun.c (displaced_step_prepare_throw): Return -1 if
gdbarch_displaced_step_copy_insn returns NULL. Update intro
comment.
* rs6000-tdep.c (LWARX_MASK, LWARX_INSTRUCTION, LDARX_INSTRUCTION)
(STWCX_MASK, STWCX_INSTRUCTION, STDCX_INSTRUCTION): Move higher up
in file.
(ppc_displaced_step_copy_insn): New function.
(ppc_displaced_step_fixup): Update comment.
(rs6000_gdbarch_init): Install ppc_displaced_step_copy_insn as
gdbarch_displaced_step_copy_insn hook.
* gdbarch.sh (displaced_step_copy_insn): Document what happens on
NULL return.
* gdbarch.h: Regenerate.
gdb/testsuite/ChangeLog:
2015-08-07 Pedro Alves <palves@redhat.com>
* gdb.arch/ppc64-atomic-inst.exp (do_test): New procedure, move
tests here.
(top level): Run do_test with and without displaced stepping.
Running the testsuite with "maint set target-non-stop on" shows:
(gdb) PASS: gdb.base/valgrind-infcall.exp: continue #98 (false warning)
continue
Continuing.
dl_main (phdr=<optimized out>..., auxv=<optimized out>) at rtld.c:2302
2302 LIBC_PROBE (init_complete, 2, LM_ID_BASE, r);
Cannot access memory at address 0x400532
(gdb) PASS: gdb.base/valgrind-infcall.exp: continue #99 (false warning)
p gdb_test_infcall ()
$1 = 1
(gdb) FAIL: gdb.base/valgrind-infcall.exp: p gdb_test_infcall ()
Even though that was a native GNU/Linux test run, this test spawns
Valgrind and connects to it with "target remote". The error above is
actually orthogonal to target-non-stop. The real issue is that that
enables displaced stepping, and displaced stepping doesn't work with
Valgrind, because we can't write to the inferior memory (thus can't
copy the instruction to the scratch pad area).
I'm sure there will be other targets with the same issue, so trying to
identify Valgrind wouldn't be sufficient. The fix is to try setting
up the displaced step anyway. If we get a MEMORY_ERROR, we disable
displaced stepping for that inferior, and fall back to doing an
in-line step-over. If "set displaced-stepping" is "on" (as opposed to
"auto), GDB warns displaced stepping failed ("on" is mainly useful for
the testsuite, not for users).
Tested on x86_64 Fedora 20.
gdb/ChangeLog:
2015-08-07 Pedro Alves <palves@redhat.com>
* inferior.h (struct inferior) <displaced_stepping_failed>: New
field.
* infrun.c (use_displaced_stepping_now_p): New parameter 'inf'.
Return false if dispaced stepping failed before.
(resume): Pass the current inferior to
use_displaced_stepping_now_p. Wrap displaced_step_prepare in
TRY/CATCH. If we get a MEMORY_ERROR, set the inferior's
displaced_stepping_failed flag, and fall back to an in-line
step-over.
gdb/testsuite/ChangeLog:
2015-08-07 Pedro Alves <palves@redhat.com>
* gdb.base/valgrind-disp-step.c: New file.
* gdb.base/valgrind-disp-step.exp: New file.
This finally implements user-visible all-stop mode running with the
target_ops backend always in non-stop mode. This is a stepping stone
towards finer-grained control of threads, being able to do interesting
things like thread groups, associating groups with breakpoints, etc.
From the user's perspective, all-stop mode is really just a special
case of being able to stop and resume specific sets of threads, so it
makes sense to do this step first.
With this, even in all-stop, the target is no longer in charge of
stopping all threads before reporting an event to the core -- the core
takes care of it when it sees fit. For example, when "next"- or
"step"-ing, we can avoid stopping and resuming all threads at each
internal single-step, and instead only stop all threads when we're
about to present the stop to the user.
The implementation is almost straight forward, as the heavy lifting
has been done already in previous patches. Basically, we replace
checks for "set non-stop on/off" (the non_stop global), with calls to
a new target_is_non_stop_p function. In a few places, if "set
non-stop off", we stop all threads explicitly, and in a few other
places we resume all threads explicitly, making use of existing
methods that were added for teaching non-stop to step over breakpoints
without displaced stepping.
This adds a new "maint set target-non-stop on/off/auto" knob that
allows both disabling the feature if we find problems, and
force-enable it for development (useful when teaching a target about
this. The default is "auto", which means the feature is enabled if a
new target method says it should be enabled. The patch implements the
method in linux-nat.c, just for illustration, because it still returns
false. We'll need a few follow up fixes before turning it on by
default. This is a separate target method from indicating regular
non-stop support, because e.g., while e.g., native linux-nat.c is
close to regression free with all-stop-non-stop (with following
patches will fixing the remaining regressions), remote.c+gdbserver
will still need more fixing, even though it supports "set non-stop
on".
Tested on x86_64 Fedora 20, native, with and without "set displaced
off", and with and without "maint set target-non-stop on"; and also
against gdbserver.
gdb/ChangeLog:
2015-08-07 Pedro Alves <palves@redhat.com>
* NEWS: Mention "maint set/show target-non-stop".
* breakpoint.c (update_global_location_list): Check
target_is_non_stop_p instead of non_stop.
* infcmd.c (attach_command_post_wait, attach_command): Likewise.
* infrun.c (show_can_use_displaced_stepping)
(can_use_displaced_stepping_p, start_step_over_inferior):
Likewise.
(internal_resume_ptid): New function.
(resume): Use it.
(proceed): Check target_is_non_stop_p instead of non_stop. If in
all-stop mode but the target is always in non-stop mode, start all
the other threads that are implicitly resumed too.
(for_each_just_stopped_thread, fetch_inferior_event)
(adjust_pc_after_break, stop_all_threads): Check
target_is_non_stop_p instead of non_stop.
(handle_inferior_event): Likewise. Handle detach-fork in all-stop
with the target always in non-stop mode.
(handle_signal_stop) <random signal>: Check target_is_non_stop_p
instead of non_stop.
(switch_back_to_stepped_thread): Check target_is_non_stop_p
instead of non_stop.
(keep_going_stepped_thread): Use internal_resume_ptid.
(stop_waiting): If in all-stop mode, and the target is in non-stop
mode, stop all threads.
(keep_going_pass): Likewise, when starting a new in-line step-over
sequence.
* linux-nat.c (get_pending_status, select_event_lwp)
(linux_nat_filter_event, linux_nat_wait_1, linux_nat_wait): Check
target_is_non_stop_p instead of non_stop.
(linux_nat_always_non_stop_p): New function.
(linux_nat_stop): Check target_is_non_stop_p instead of non_stop.
(linux_nat_add_target): Install linux_nat_always_non_stop_p.
* target-delegates.c: Regenerate.
* target.c (target_is_non_stop_p): New function.
(target_non_stop_enabled, target_non_stop_enabled_1): New globals.
(maint_set_target_non_stop_command)
(maint_show_target_non_stop_command): New functions.
(_initilize_target): Install "maint set/show target-non-stop"
commands.
* target.h (struct target_ops) <to_always_non_stop_p>: New field.
(target_non_stop_enabled): New declaration.
(target_is_non_stop_p): New declaration.
gdb/doc/ChangeLog:
2015-08-07 Pedro Alves <palves@redhat.com>
* gdb.texinfo (Maintenance Commands): Document "maint set/show
target-non-stop".
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.
Just a code refactor, no funcionality change intended.
gdb/ChangeLog:
2015-08-07 Pedro Alves <palves@redhat.com>
* infrun.c (keep_going_stepped_thread): New function, factored out
from ...
(switch_back_to_stepped_thread): ... here.
Clarify that currently_stepping works at a higher level than
target_resume.
gdb/ChangeLog:
2015-08-07 Pedro Alves <palves@redhat.com>
* infrun.c (currently_stepping): Extend intro comment.
* target.h (target_resume): Extend intro comment.
Several misc cleanups that prepare the tail end of this function, the
part that actually re-resumes the stepped thread.
The most non-obvious would be the currently_stepping change, I guess.
That's because it isn't ever correct to pass step=1 to target_resume
on software single-step targets, and currently_stepping works at a
conceptual higher level, it returns step=true even on software step
targets. It doesn't really matter on hardware step targets, as the
breakpoint will be hit immediately, but it's just wrong on software
step targets. I tested it against my x86 software single-step branch,
and it indeed fixes failed assertions (that catch spurious
PTRACE_SINGLESTEP requests) there.
gdb/ChangeLog:
2015-08-07 Pedro Alves <palves@redhat.com>
* infrun.c (switch_back_to_stepped_thread): Use ecs->ptid instead
of inferior_ptid. If the stepped thread vanished, return 0
instead of resuming here. Use reset_ecs. Print the prev_pc and
the current stop_pc in log message. Clear trap_expected if the
thread advanced. Don't pass currently_stepping to
do_target_resume.
The main motivation of this patch is sharing more code between the
proceed (starting the inferior for the first time) and keep_going
(restarting the inferior after handling an event) paths and using the
step_over_chain queue now embedded in the thread_info object for
pending in-line step-overs too (instead of just for displaced
stepping).
So this commit:
- splits out a new keep_going_pass_signal function out of keep_going
that is just like keep_going except for the bits that clear the
signal to pass if the signal is set to "handle nopass".
- makes proceed use keep_going too.
- Makes start_step_over use keep_going_pass_signal instead of lower
level displaced stepping things.
One user visible change: if inserting breakpoints while trying to
proceed fails, we now get:
(gdb) si
Warning:
Could not insert hardware watchpoint 7.
Could not insert hardware breakpoints:
You may have requested too many hardware breakpoints/watchpoints.
Command aborted.
(gdb)
while before we only saw warnings with no indication that the command
was cancelled:
(gdb) si
Warning:
Could not insert hardware watchpoint 7.
Could not insert hardware breakpoints:
You may have requested too many hardware breakpoints/watchpoints.
(gdb)
Tested on x86_64-linux-gnu, ppc64-linux-gnu and s390-linux-gnu.
gdb/ChangeLog:
2015-08-07 Pedro Alves <palves@redhat.com>
* gdbthread.h (struct thread_info) <prev_pc>: Extend comment.
* infrun.c (struct execution_control_state): Move higher up in the
file.
(reset_ecs): New function.
(start_step_over): Now returns int. Rewrite to use
keep_going_pass_signal instead of manually starting a displaced step.
(resume): Don't call set_running here. If displaced stepping
can't start now, clear trap_expected.
(find_thread_needs_step_over): Delete function.
(proceed): Set up finish_thread_state_cleanup. Call set_running.
If the current thread needs a step over, push it in the step-over
chain. Don't set insert breakpoints nor call resume directly
here. Instead rewrite to use start_step_over and
keep_going_pass_signal.
(finish_step_over): New function.
(handle_signal_stop): Call finish_step_over instead of
start_step_over.
(switch_back_to_stepped_thread): If the event thread needs another
step-over do that first. Use start_step_over.
(keep_going_pass_signal): New function, factored out from ...
(keep_going): ... here.
(_initialize_infrun): Comment moved here.
* thread.c (set_running_thread): New function.
(set_running, finish_thread_state): Use set_running_thread.
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.
I noticed that even though keep_going knows to start a step over for a
watchpoint, thread_still_needs_step_over forgets it.
gdb/ChangeLog:
2015-08-07 Pedro Alves <palves@redhat.com>
* infrun.c (thread_still_needs_step_over): Rename to ...
(thread_still_needs_step_over_bp): ... this.
(enum step_over_what): New.
(thread_still_needs_step_over): Reimplement.
Prepare to use it in contexts without an ecs handy. Follow up patches
will make use of this.
gdb/ChangeLog:
2015-08-07 Pedro Alves <pedro@codesourcery.com>
* infrun.c (adjust_pc_after_break): Now takes thread_info and
waitstatus pointers instead of an ecs. Adjust.
(handle_inferior_event): Adjust caller.
Letting a "checkpoint" run to exit with "set non-stop on" behaves
differently compared to the default all-stop mode ("set non-stop
off").
Currently, in non-stop mode:
(gdb) start
Temporary breakpoint 1 at 0x40086b: file src/gdb/testsuite/gdb.base/checkpoint.c, line 28.
Starting program: build/gdb/testsuite/gdb.base/checkpoint
Temporary breakpoint 1, main () at src/gdb/testsuite/gdb.base/checkpoint.c:28
28 char *tmp = &linebuf[0];
(gdb) checkpoint
checkpoint 1: fork returned pid 24948.
(gdb) c
Continuing.
Copy complete.
Deleting copy.
[Inferior 1 (process 24944) exited normally]
[Switching to process 24948]
(gdb) info threads
Id Target Id Frame
1 process 24948 "checkpoint" (running)
No selected thread. See `help thread'.
(gdb) c
The program is not being run.
(gdb)
Two issues above:
1. Thread 1 got stuck in "(running)" state (it isn't really running)
2. While checkpoints try to preserve the illusion that the thread is
still the same when the process exits, GDB switched to "No thread
selected." instead of staying with thread 1 selected.
Problem #1 is caused by handle_inferior_event and normal_stop not
considering that when a
TARGET_WAITKIND_SIGNALLED/TARGET_WAITKIND_EXITED event is reported,
and the inferior is mourned, the target may still have execution.
Problem #2 is caused by the make_cleanup_restore_current_thread
cleanup installed by fetch_inferior_event not being able to find the
original thread 1's ptid in the thread list, thus not being able to
restore thread 1 as selected thread. The fix is to make the cleanup
installed by make_cleanup_restore_current_thread aware of thread ptid
changes, by installing a thread_ptid_changed observer that adjusts the
cleanup's data.
After the patch, we get the same in all-stop and non-stop modes:
(gdb) c
Continuing.
Copy complete.
Deleting copy.
[Inferior 1 (process 25109) exited normally]
[Switching to process 25113]
(gdb) info threads
Id Target Id Frame
* 1 process 25113 "checkpoint" main () at src/gdb/testsuite/gdb.base/checkpoint.c:28
(gdb)
Turns out the whole checkpoints.exp file can run in non-stop mode
unmodified. I thought of moving most of the test file's contents to a
procedure that can be called twice, once in non-stop mode and another
in all-stop mode. But then, the test already takes close to 30
seconds to run on my machine, so I thought it'd be nicer to run
all-stop and non-stop mode in parallel. Thus I added a new
checkpoint-ns.exp file that just appends "set non-stop on" to GDBFLAGS
and sources checkpoint.exp.
gdb/ChangeLog:
2015-08-07 Pedro Alves <palves@redhat.com>
* infrun.c (handle_inferior_event): If we get
TARGET_WAITKIND_SIGNALLED or TARGET_WAITKIND_EXITED in non-stop
mode, mark all threads of the exiting process as not-executing.
(normal_stop): If we get TARGET_WAITKIND_SIGNALLED or
TARGET_WAITKIND_EXITED in non-stop mode, finish all threads of the
exiting process, if inferior_ptid still points at a process.
* thread.c (struct current_thread_cleanup) <next>: New field.
(current_thread_cleanup_chain): New global.
(restore_current_thread_ptid_changed): New function.
(restore_current_thread_cleanup_dtor): Remove the cleanup from the
current_thread_cleanup_chain list.
(make_cleanup_restore_current_thread): Add the cleanup data to the
current_thread_cleanup_chain list.
(_initialize_thread): Install restore_current_thread_ptid_changed
as thread_ptid_changed observer.
gdb/testsuite/ChangeLog:
2015-08-07 Pedro Alves <palves@redhat.com>
* gdb.base/checkpoint-ns.exp: New file.
* gdb.base/checkpoint.exp: Pass explicit "checkpoint.c" to
standard_testfile.
This patch is mostly extracted from Pedro's C++ branch. It adds explicit
casts from integer to enum types, where it is really the intention to do
so. This could be because we are ...
* iterating on enum values (we need to iterate on an equivalent integer)
* converting from a value read from bytes (dwarf attribute, agent
expression opcode) to the equivalent enum
* reading the equivalent integer value from another language (Python/Guile)
An exception to that is the casts in regcache.c. It seems to me like
struct regcache's register_status field could be a pointer to an array of
enum register_status. Doing so would waste a bit of memory (4 bytes
used by the enum vs 1 byte used by the current signed char, for each
register). If we switch to C++11 one day, we can define the underlying
type of an enum type, so we could have the best of both worlds.
gdb/ChangeLog:
* arm-tdep.c (set_fp_model_sfunc): Add cast from integer to enum.
(arm_set_abi): Likewise.
* ax-general.c (ax_print): Likewise.
* c-exp.y (exp : string_exp): Likewise.
* compile/compile-loc2c.c (compute_stack_depth_worker): Likewise.
(do_compile_dwarf_expr_to_c): Likewise.
* cp-name-parser.y (demangler_special : DEMANGLER_SPECIAL start):
Likewise.
* dwarf2expr.c (execute_stack_op): Likewise.
* dwarf2loc.c (dwarf2_compile_expr_to_ax): Likewise.
(disassemble_dwarf_expression): Likewise.
* dwarf2read.c (dwarf2_add_member_fn): Likewise.
(read_array_order): Likewise.
(abbrev_table_read_table): Likewise.
(read_attribute_value): Likewise.
(skip_unknown_opcode): Likewise.
(dwarf_decode_macro_bytes): Likewise.
(dwarf_decode_macros): Likewise.
* eval.c (value_f90_subarray): Likewise.
* guile/scm-param.c (gdbscm_make_parameter): Likewise.
* i386-linux-tdep.c (i386_canonicalize_syscall): Likewise.
* infrun.c (handle_command): Likewise.
* memory-map.c (memory_map_start_memory): Likewise.
* osabi.c (set_osabi): Likewise.
* parse.c (operator_length_standard): Likewise.
* ppc-linux-tdep.c (ppc_canonicalize_syscall): Likewise, and use
single return point.
* python/py-frame.c (gdbpy_frame_stop_reason_string): Likewise.
* python/py-symbol.c (gdbpy_lookup_symbol): Likewise.
(gdbpy_lookup_global_symbol): Likewise.
* record-full.c (record_full_restore): Likewise.
* regcache.c (regcache_register_status): Likewise.
(regcache_raw_read): Likewise.
(regcache_cooked_read): Likewise.
* rs6000-tdep.c (powerpc_set_vector_abi): Likewise.
* symtab.c (initialize_ordinary_address_classes): Likewise.
* target-debug.h (target_debug_print_signals): Likewise.
* utils.c (do_restore_current_language): Likewise.
As Pedro suggested on gdb-patches@ (see
https://sourceware.org/ml/gdb-patches/2015-05/msg00714.html), this
change makes symbol lookup functions return a structure that includes
both the symbol found and the block in which it was found. This makes
it possible to get rid of the block_found global variable and thus makes
block hunting explicit.
gdb/
* ada-exp.y (write_object_renaming): Replace struct
ada_symbol_info with struct block_symbol. Update field
references accordingly.
(block_lookup, select_possible_type_sym): Likewise.
(find_primitive_type): Likewise. Also update call to
ada_lookup_symbol to extract the symbol itself.
(write_var_or_type, write_name_assoc): Likewise.
* ada-lang.h (struct ada_symbol_info): Remove.
(ada_lookup_symbol_list): Replace struct ada_symbol_info with
struct block_symbol.
(ada_lookup_encoded_symbol, user_select_syms): Likewise.
(ada_lookup_symbol): Return struct block_symbol instead of a
mere symbol.
* ada-lang.c (defns_collected): Replace struct ada_symbol_info
with struct block_symbol.
(resolve_subexp, ada_resolve_function, sort_choices,
user_select_syms, is_nonfunction, add_defn_to_vec,
num_defns_collected, defns_collected,
symbols_are_identical_enums, remove_extra_symbols,
remove_irrelevant_renamings, add_lookup_symbol_list_worker,
ada_lookup_symbol_list, ada_iterate_over_symbols,
ada_lookup_encoded_symbol, get_var_value): Likewise.
(ada_lookup_symbol): Return a block_symbol instead of a mere
symbol. Replace struct ada_symbol_info with struct
block_symbol.
(ada_lookup_symbol_nonlocal): Likewise.
(standard_lookup): Make block passing explicit through
lookup_symbol_in_language.
* ada-tasks.c (get_tcb_types_info): Update the calls to
lookup_symbol_in_language to extract the mere symbol out of the
returned value.
(ada_tasks_inferior_data_sniffer): Likewise.
* ax-gdb.c (gen_static_field): Likewise for the call to
lookup_symbol.
(gen_maybe_namespace_elt): Deal with struct symbol_in_block from
lookup functions.
(gen_expr): Likewise.
* c-exp.y: Likewise. Remove uses of block_found.
(lex_one_token, classify_inner_name, c_print_token): Likewise.
(classify_name): Likewise. Rename the "sym" local variable to
"bsym".
* c-valprint.c (print_unpacked_pointer): Likewise.
* compile/compile-c-symbols.c (convert_symbol_sym): Promote the
"sym" parameter from struct symbol * to struct block_symbol.
Use it to remove uses of block_found. Deal with struct
symbol_in_block from lookup functions.
(gcc_convert_symbol): Likewise. Update the call to
convert_symbol_sym.
* compile/compile-object-load.c (compile_object_load): Deal with
struct symbol_in_block from lookup functions.
* cp-namespace.c (cp_lookup_nested_symbol_1,
cp_lookup_nested_symbol, cp_lookup_bare_symbol,
cp_search_static_and_baseclasses,
cp_lookup_symbol_in_namespace, cp_lookup_symbol_via_imports,
cp_lookup_symbol_imports_or_template,
cp_lookup_symbol_via_all_imports, cp_lookup_symbol_namespace,
lookup_namespace_scope, cp_lookup_nonlocal,
find_symbol_in_baseclass): Return struct symbol_in_block instead
of mere symbols and deal with struct symbol_in_block from lookup
functions.
* cp-support.c (inspect_type, replace_typedefs,
cp_lookup_rtti_type): Deal with struct symbol_in_block from
lookup functions.
* cp-support.h (cp_lookup_symbol_nonlocal,
cp_lookup_symbol_from_namespace,
cp_lookup_symbol_imports_or_template, cp_lookup_nested_symbol):
Return struct symbol_in_block instead of mere symbols.
* d-exp.y (d_type_from_name, d_module_from_name, push_variable,
push_module_name):
Deal with struct symbol_in_block from lookup functions. Remove
uses of block_found.
* eval.c (evaluate_subexp_standard): Update call to
cp_lookup_symbol_namespace.
* f-exp.y: Deal with struct symbol_in_block from lookup
functions. Remove uses of block_found.
(yylex): Likewise.
* gdbtypes.c (lookup_typename, lookup_struct, lookup_union,
lookup_enum, lookup_template_type, check_typedef): Deal with
struct symbol_in_block from lookup functions.
* guile/scm-frame.c (gdbscm_frame_read_var): Likewise.
* guile/scm-symbol.c (gdbscm_lookup_symbol): Likewise.
(gdbscm_lookup_global_symbol): Likewise.
* gnu-v3-abi.c (gnuv3_get_typeid_type): Likewise.
* go-exp.y: Likewise. Remove uses of block_found.
(package_name_p, classify_packaged_name, classify_name):
Likewise.
* infrun.c (insert_exception_resume_breakpoint): Likewise.
* jv-exp.y (push_variable): Likewise.
* jv-lang.c (java_lookup_class, get_java_object_type): Likewise.
* language.c (language_bool_type): Likewise.
* language.h (struct language_defn): Update
la_lookup_symbol_nonlocal to return a struct symbol_in_block
rather than a mere symbol.
* linespec.c (find_label_symbols): Deal with struct
symbol_in_block from lookup functions.
* m2-exp.y: Likewise. Remove uses of block_found.
(yylex): Likewise.
* mi/mi-cmd-stack.c (list_args_or_locals): Likewise.
* objc-lang.c (lookup_struct_typedef, find_imps): Likewise.
* p-exp.y: Likewise. Remove uses of block_found.
(yylex): Likewise.
* p-valprint.c (pascal_val_print): Likewise.
* parse.c (write_dollar_variable): Likewise. Remove uses of
block_found.
* parser-defs.h (struct symtoken): Turn the SYM field into a
struct symbol_in_block.
* printcmd.c (address_info): Deal with struct symbol_in_block
from lookup functions.
* python/py-frame.c (frapy_read_var): Likewise.
* python/py-symbol.c (gdbpy_lookup_symbol,
gdbpy_lookup_global_symbol): Likewise.
* skip.c (skip_function_command): Likewise.
* solib-darwin.c (darwin_lookup_lib_symbol): Return a struct
symbol_in_block instead of a mere symbol.
* solib-spu.c (spu_lookup_lib_symbol): Likewise.
* solib-svr4.c (elf_lookup_lib_symbol): Likewise.
* solib.c (solib_global_lookup): Likewise.
* solist.h (solib_global_lookup): Likewise.
(struct target_so_ops): Update lookup_lib_global_symbol to
return a struct symbol_in_block rather than a mere symbol.
* source.c (select_source_symtab): Deal with struct
symbol_in_block from lookup functions.
* stack.c (print_frame_args, iterate_over_block_arg_vars):
Likewise.
* symfile.c (set_initial_language): Likewise.
* symtab.c (SYMBOL_LOOKUP_FAILED): Turn into a struct
symbol_in_block.
(SYMBOL_LOOKUP_FAILED_P): New predicate as a macro.
(struct symbol_cache_slot): Turn the FOUND field into a struct
symbol_in_block.
(block_found): Remove.
(eq_symbol_entry): Update to deal with struct symbol_in_block in
cache slots.
(symbol_cache_lookup): Return a struct symbol_in_block rather
than a mere symbol.
(symbol_cache_mark_found): Add a BLOCK parameter to fill
appropriately the cache slots. Update callers.
(symbol_cache_dump): Update cache slots handling to the type
change.
(lookup_symbol_in_language, lookup_symbol, lookup_language_this,
lookup_symbol_aux, lookup_local_symbol,
lookup_symbol_in_objfile, lookup_global_symbol_from_objfile,
lookup_symbol_in_objfile_symtabs,
lookup_symbol_in_objfile_from_linkage_name,
lookup_symbol_via_quick_fns, basic_lookup_symbol_nonlocal,
lookup_symbol_in_static_block, lookup_static_symbol,
lookup_global_symbol):
Return a struct symbol_in_block rather than a mere symbol. Deal
with struct symbol_in_block from other lookup functions. Remove
uses of block_found.
(lookup_symbol_in_block): Remove uses of block_found.
(struct global_sym_lookup_data): Turn the RESULT field into a
struct symbol_in_block.
(lookup_symbol_global_iterator_cb): Update references to the
RESULT field.
(search_symbols): Deal with struct symbol_in_block from lookup
functions.
* symtab.h (struct symbol_in_block): New structure.
(block_found): Remove.
(lookup_symbol_in_language, lookup_symbol,
basic_lookup_symbol_nonlocal, lookup_symbol_in_static_block,
looku_static_symbol, lookup_global_symbol,
lookup_symbol_in_block, lookup_language_this,
lookup_global_symbol_from_objfile): Return a struct
symbol_in_block rather than just a mere symbol. Update comments
to remove mentions of block_found.
* valops.c (find_function_in_inferior,
value_struct_elt_for_reference, value_maybe_namespace_elt,
value_of_this): Deal with struct symbol_in_block from lookup
functions.
* value.c (value_static_field, value_fn_field): Likewise.
Refs:
https://sourceware.org/ml/gdb/2015-03/msg00024.htmlhttps://sourceware.org/ml/gdb/2015-06/msg00005.html
On GNU/Linux, if an infcall spawns a thread, that thread ends up with
stuck running state. This happens because:
- when linux-nat.c detects a new thread, it marks them as running,
and does not report anything to the core.
- we skip finish_thread_state when the thread that is running the
infcall stops.
As result, that new thread ends up with stuck "running" state, even
though it really is stopped.
On Windows, _all_ threads end up stuck in running state, not just the
one that was spawned. That happens because when a new thread is
detected, unlike linux-nat.c, windows-nat.c reports
TARGET_WAITKIND_SPURIOUS to infrun. It's the fact that that event
does not cause a user-visible stop that triggers the problem. When
the target is re-resumed, we call set_running with a wildcard ptid,
which marks all thread as running. That set_running is not suppressed
because the (leader) thread being resumed does not have in_infcall
set. Later, when the infcall finally finishes successfully, nothing
marks all threads back to stopped.
We can trigger the same problem on all targets by having a thread
other than the one that is running the infcall report a breakpoint hit
to infrun, and then have that breakpoint not cause a stop. That's
what the included test does.
The fix is to stop GDB from suppressing the set_running calls while
doing an infcall, and then set the threads back to stopped when the
call finishes, iff they were originally stopped before the infcall
started. (Note the MI *running/*stopped event suppression isn't
affected.)
Tested on x86_64 GNU/Linux.
gdb/ChangeLog:
2015-06-29 Pedro Alves <palves@redhat.com>
PR threads/18127
* infcall.c (run_inferior_call): On infcall success, if the thread
was marked stopped before, reset it back to stopped.
* infrun.c (resume): Don't suppress the set_running calls when
doing an infcall.
(normal_stop): Only discard the finish_thread_state cleanup if the
infcall succeeded.
gdb/testsuite/ChangeLog:
2015-06-29 Pedro Alves <palves@redhat.com>
PR threads/18127
* gdb.threads/hand-call-new-thread.c: New file.
* gdb.threads/hand-call-new-thread.c: New file.
This patch fixes a couple of failures in gdb.base/foll-vfork.exp for
extended-remote targets. The failures were the result of the
verbose/debug "Detaching..." messages in infrun.c:follow_fork_inferior
not matching what was expected in the extended-remote case.
The path modifies the ptids used in the messages to ensure that they
print "process nnn" instead of (possibly) "Thread nnn.nnn". The
detach is a process-wide operation, so we need to use a process-
style ptid regardless of what type of ptid target_pid_to_str returns.
Tested on x86_64 GNU/Linux, native, remote, extended-remote.
gdb/
* infrun.c (follow_fork_inferior): Ensure the use of
process-style ptids (pid,0,0) in verbose/debug "Detaching"
messages.
When using a conditional breakpoint where the condition evaluated
to false a large number of times before the program stopped,
a user reported that GDB's memory consumption was growing very
quickly until it ran out of memory.
The problem was tracked down to temporary struct values being created
each time the program stops and handles an inferior event. Because
the breakpoint condition usually evaluates to false, there can be
a fairly large number of such events to be handled before we eventually
return the prompt to the user (which is when we would normally purge
such values).
This patch fixes the issue by making sure that handle_inferior_event
releases all new values created during its execution.
gdb/ChangeLog:
* infrun.c (handle_inferior_event_1): Renames handle_inferior_event.
(handle_inferior_event): New function.
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.
This commit allows NULL to be passed as the int *fd argument
to exec_file_find and solib_find to simplify use cases where
the caller does not require the file to be opened.
gdb/ChangeLog:
* solib.c (solib_find_1): Allow fd argument to be NULL.
(exec_file_find): Update comment.
(solib_find): Likewise.
* exec.c (exec_file_locate_attach): Use NULL as fd
argument to exec_file_find to avoid having to close
the opened file.
* infrun.c (follow_exec): Likewise.
This commit updates follow_exec to use exec_file_find to prefix
the new executable's filename with gdb_sysroot rather than doing
it longhand.
gdb/ChangeLog:
* infrun.c (solist.h): New include.
(follow_exec): Use exec_file_find to prefix execd_pathname
with gdb_sysroot.
Hi,
When I run gdb.threads/non-stop-fair-events.exp on arm-linux target,
I see the following message in the debugging log,
displaced: breakpoint is gone: Thread 22518, step(1)^M
Sending packet: $vCont;s:p57f3.57f6#9d...
^^^^^^^^^
GDB sends vCont;s by mistake, and GDBserver fails on assert. GDB
doesn't consider software single step in infrun.c:displaced_step_fixup,
/* Go back to what we were trying to do. */
step = currently_stepping (tp);
if (debug_displaced)
fprintf_unfiltered (gdb_stdlog,
"displaced: breakpoint is gone: %s, step(%d)\n",
target_pid_to_str (tp->ptid), step);
target_resume (ptid, step, GDB_SIGNAL_0);
The patch is to let GDB consider software single step here. It fixes
fails in gdb.threads/non-stop-fair-events.exp on arm.
gdb:
2015-04-16 Yao Qi <yao.qi@linaro.org>
* infrun.c (maybe_software_singlestep): Declare.
(displaced_step_fixup): Call maybe_software_singlestep.
Pedro Alves:
The commands that enables aren't even documented in the manual.
Judging from that, I assume that only wdb users would ever really
be using the --xdb switch.
I think it's time to drop "support" for the --xdb switch too. I
looked through the commands that that exposes, the only that looked
potentially interesting was "go", but then it's just an alias
for "tbreak+jump", which can easily be done with "define go...end".
I'd rather free up the "go" name for something potentially
more interesting (either run control, or maybe even unrelated,
e.g., for golang).
gdb/ChangeLog
2015-04-11 Jan Kratochvil <jan.kratochvil@redhat.com>
* NEWS (Changes since GDB 7.9): Add removed -xdb.
* breakpoint.c (command_line_is_silent): Remove xdb_commands
conditional.
(_initialize_breakpoint): Remove xdb_commands for bc, ab, sb, db, ba
and lb.
* cli/cli-cmds.c (_initialize_cli_cmds): Remove xdb_commands for v and
va.
* cli/cli-decode.c (find_command_name_length): Remove xdb_commands
conditional.
* defs.h (xdb_commands): Remove declaration.
* f-valprint.c (_initialize_f_valprint): Remove xdb_commands for lc.
* guile/scm-cmd.c (command_classes): Remove xdb from comment.
* infcmd.c (run_no_args_command, go_command): Remove.
(_initialize_infcmd): Remove xdb_commands for S, go, g, R and lr.
* infrun.c (xdb_handle_command): Remove.
(_initialize_infrun): Remove xdb_commands for lz and z.
* main.c (xdb_commands): Remove variable.
(captured_main): Remove "xdb" from long_options.
(print_gdb_help): Remove --xdb from help.
* python/py-cmd.c (gdbpy_initialize_commands): Remove xdb from comment.
* source.c (_initialize_source): Remove xdb_commands for D, ld, / and ?.
* stack.c (backtrace_full_command, args_plus_locals_info)
(current_frame_command): Remove.
(_initialize_stack): Remove xdb_commands for t, T and l.
* symtab.c (_initialize_symtab): Remove xdb_commands for lf and lg.
* thread.c (_initialize_thread): Remove xdb_commands condition.
* tui/tui-layout.c (tui_toggle_layout_command)
(tui_toggle_split_layout_command, tui_handle_xdb_layout): Remove.
(_initialize_tui_layout): Remove xdb_commands for td and ts.
* tui/tui-regs.c (tui_scroll_regs_forward_command)
(tui_scroll_regs_backward_command): Remove.
(_initialize_tui_regs): Remove xdb_commands for fr, gr, sr, +r and -r.
* tui/tui-win.c (tui_xdb_set_win_height_command): Remove.
(_initialize_tui_win): Remove xdb_commands for U and w.
* utils.c (pagination_on_command, pagination_off_command): Remove.
(initialize_utils): Remove xdb_commands for am and sm.
gdb/doc/ChangeLog
2015-04-11 Jan Kratochvil <jan.kratochvil@redhat.com>
* gdb.texinfo (Mode Options): Remove -xdb.
PPC64 currently fails this test like:
FAIL: gdb.threads/step-over-trips-on-watchpoint.exp: displaced=on: no thread-specific bp: step: step
FAIL: gdb.threads/step-over-trips-on-watchpoint.exp: displaced=on: no thread-specific bp: next: next
FAIL: gdb.threads/step-over-trips-on-watchpoint.exp: displaced=on: no thread-specific bp: continue: continue (the program exited)
FAIL: gdb.threads/step-over-trips-on-watchpoint.exp: displaced=on: with thread-specific bp: step: step
FAIL: gdb.threads/step-over-trips-on-watchpoint.exp: displaced=on: with thread-specific bp: next: next
FAIL: gdb.threads/step-over-trips-on-watchpoint.exp: displaced=on: with thread-specific bp: continue: continue (the program exited)
The problem is that PPC is a non-continuable watchpoints architecture
and the displaced stepping code isn't coping with that correctly. On
such targets/architectures, a watchpoint traps _before_ the
instruction executes/completes. On a watchpoint trap, the PC points
at the instruction that triggers the watchpoint (side effects haven't
happened yet). In order to move past the watchpoint, GDB needs to
remove the watchpoint, single-step, and reinsert the watchpoint, just
like when stepping past a breakpoint.
The trouble is that if GDB is stepping over a breakpoint with
displaced stepping, and the instruction under the breakpoint triggers
a watchpoint, we get the watchpoint SIGTRAP, expecting a finished
(hard or software) step trap. Even though the thread's PC hasn't
advanced yet (must remove watchpoint for that), since we get a
SIGTRAP, displaced_step_fixup thinks the single-step finished
successfuly anyway, and calls gdbarch_displaced_step_fixup, which then
adjusts the thread's registers incorrectly.
The fix is to cancel the displaced step if we trip on a watchpoint.
handle_inferior_event then processes the watchpoint event, and starts
a new step-over, here:
...
/* At this point, we are stopped at an instruction which has
attempted to write to a piece of memory under control of
a watchpoint. The instruction hasn't actually executed
yet. If we were to evaluate the watchpoint expression
now, we would get the old value, and therefore no change
would seem to have occurred.
...
ecs->event_thread->stepping_over_watchpoint = 1;
keep_going (ecs);
return;
...
but this time, since we have a watchpoint to step over, watchpoints
are removed from the target, so the step-over succeeds.
The keep_going/resume changes are necessary because if we're stepping
over a watchpoint, we need to remove it from the target - displaced
stepping doesn't help, the copy of the instruction in the scratch pad
reads/writes to the same addresses, thus triggers the watchpoint
too... So without those changes we keep triggering the watchpoint
forever, never making progress. With non-stop that means we'll need
to pause all threads momentarily, which we can't today. We could
avoid that by removing the watchpoint _only_ from the thread that is
moving past the watchpoint, but GDB is not prepared for that today
either. For remote targets, that would need new packets, so good to
be able to step over it in-line as fallback anyway.
gdb/ChangeLog:
2015-04-10 Pedro Alves <palves@redhat.com>
* infrun.c (displaced_step_fixup): Switch to the event ptid
earlier. If the thread stopped for a watchpoint and the
target/arch has non-continuable watchpoints, cancel the displaced
step.
(resume): Don't start a displaced step if in-line step-over info
is valid.
TL;DR:
When stepping over a breakpoint with displaced stepping, the core must
be notified of all signals, otherwise the displaced step fixup code
confuses a breakpoint trap in the signal handler for the expected trap
indicating the displaced instruction was single-stepped
normally/successfully.
Detailed version:
Running sigstep.exp with displaced stepping on, against my x86
software single-step branch, I got:
FAIL: gdb.base/sigstep.exp: step on breakpoint, to handler: performing step
FAIL: gdb.base/sigstep.exp: next on breakpoint, to handler: performing next
FAIL: gdb.base/sigstep.exp: continue on breakpoint, to handler: performing continue
Turning on debug logs, we see:
(gdb) step
infrun: clear_proceed_status_thread (process 32147)
infrun: proceed (addr=0xffffffffffffffff, signal=GDB_SIGNAL_DEFAULT)
infrun: resume (step=1, signal=GDB_SIGNAL_0), trap_expected=1, current thread [process 32147] at 0x400842
displaced: stepping process 32147 now
displaced: saved 0x400622: 49 89 d1 5e 48 89 e2 48 83 e4 f0 50 54 49 c7 c0
displaced: %rip-relative addressing used.
displaced: using temp reg 2, old value 0x3615eafd37, new value 0x40084c
displaced: copy 0x400842->0x400622: c7 81 1c 08 20 00 00 00 00 00
displaced: displaced pc to 0x400622
displaced: run 0x400622: c7 81 1c 08
LLR: Preparing to resume process 32147, 0, inferior_ptid process 32147
LLR: PTRACE_CONT process 32147, 0 (resume event thread)
linux_nat_wait: [process -1], [TARGET_WNOHANG]
LLW: enter
LNW: waitpid(-1, ...) returned 32147, No child processes
LLW: waitpid 32147 received Alarm clock (stopped)
LLW: PTRACE_CONT process 32147, Alarm clock (preempt 'handle')
LNW: waitpid(-1, ...) returned 0, No child processes
LLW: exit (ignore)
sigchld
infrun: target_wait (-1.0.0, status) =
infrun: -1.0.0 [process -1],
infrun: status->kind = ignore
infrun: TARGET_WAITKIND_IGNORE
infrun: prepare_to_wait
linux_nat_wait: [process -1], [TARGET_WNOHANG]
LLW: enter
LNW: waitpid(-1, ...) returned 32147, No child processes
LLW: waitpid 32147 received Trace/breakpoint trap (stopped)
CSBB: process 32147 stopped by software breakpoint
LNW: waitpid(-1, ...) returned 0, No child processes
LLW: trap ptid is process 32147.
LLW: exit
infrun: target_wait (-1.0.0, status) =
infrun: 32147.32147.0 [process 32147],
infrun: status->kind = stopped, signal = GDB_SIGNAL_TRAP
infrun: TARGET_WAITKIND_STOPPED
displaced: restored process 32147 0x400622
displaced: fixup (0x400842, 0x400622), insn = 0xc7 0x81 ...
displaced: restoring reg 2 to 0x3615eafd37
displaced: relocated %rip from 0x400717 to 0x400937
infrun: stop_pc = 0x400937
infrun: delayed software breakpoint trap, ignoring
infrun: no line number info
infrun: stop_waiting
0x0000000000400937 in __dso_handle ()
1: x/i $pc
=> 0x400937: and %ah,0xa0d64(%rip) # 0x4a16a1
(gdb) FAIL: gdb.base/sigstep.exp: displaced=on: step on breakpoint, to handler: performing step
What should have happened is that the breakpoint hit in the signal
handler should have been presented to the user. But note that
"preempt 'handle'" -- what happened instead is that
displaced_step_fixup confused the breakpoint in the signal handler for
the expected SIGTRAP indicating the displaced instruction was
single-stepped normally/successfully.
This should be affecting all software single-step targets in the same
way.
The fix is to make sure the core sees all signals when displaced
stepping, just like we already must see all signals when doing an
stepping over a breakpoint in-line. We now get:
infrun: target_wait (-1.0.0, status) =
infrun: 570.570.0 [process 570],
infrun: status->kind = stopped, signal = GDB_SIGNAL_ALRM
infrun: TARGET_WAITKIND_STOPPED
displaced: restored process 570 0x400622
infrun: stop_pc = 0x400842
infrun: random signal (GDB_SIGNAL_ALRM)
infrun: signal arrived while stepping over breakpoint
infrun: inserting step-resume breakpoint at 0x400842
infrun: resume (step=0, signal=GDB_SIGNAL_ALRM), trap_expected=0, current thread [process 570] at 0x400842
LLR: Preparing to resume process 570, Alarm clock, inferior_ptid process 570
LLR: PTRACE_CONT process 570, Alarm clock (resume event thread)
infrun: prepare_to_wait
linux_nat_wait: [process -1], [TARGET_WNOHANG]
LLW: enter
LNW: waitpid(-1, ...) returned 0, No child processes
LLW: exit (ignore)
infrun: target_wait (-1.0.0, status) =
infrun: -1.0.0 [process -1],
infrun: status->kind = ignore
sigchld
infrun: TARGET_WAITKIND_IGNORE
infrun: prepare_to_wait
linux_nat_wait: [process -1], [TARGET_WNOHANG]
LLW: enter
LNW: waitpid(-1, ...) returned 570, No child processes
LLW: waitpid 570 received Trace/breakpoint trap (stopped)
CSBB: process 570 stopped by software breakpoint
LNW: waitpid(-1, ...) returned 0, No child processes
LLW: trap ptid is process 570.
LLW: exit
infrun: target_wait (-1.0.0, status) =
infrun: 570.570.0 [process 570],
infrun: status->kind = stopped, signal = GDB_SIGNAL_TRAP
infrun: TARGET_WAITKIND_STOPPED
infrun: stop_pc = 0x400717
infrun: BPSTAT_WHAT_STOP_NOISY
infrun: stop_waiting
Breakpoint 3, handler (sig=14) at /home/pedro/gdb/mygit/src/gdb/testsuite/gdb.base/sigstep.c:35
35 done = 1;
Hardware single-step targets already behave this way, because the
Linux backends (both native and gdbserver) always report signals to
the core if the thread was single-stepping.
As mentioned in the new comment in do_target_resume, we can't fix this
by instead making the displaced_step_fixup phase skip fixing up the PC
if the single step stopped somewhere we didn't expect. Here's what
the backtrace would look like if we did that:
Breakpoint 3, handler (sig=14) at /home/pedro/gdb/mygit/src/gdb/testsuite/gdb.base/sigstep.c:35
35 done = 1;
1: x/i $pc
=> 0x400717 <handler+7>: movl $0x1,0x200943(%rip) # 0x601064 <done>
(gdb) bt
#0 handler (sig=14) at /home/pedro/gdb/mygit/src/gdb/testsuite/gdb.base/sigstep.c:35
#1 <signal handler called>
#2 0x0000000000400622 in _start ()
(gdb) FAIL: gdb.base/sigstep.exp: displaced=on: step on breakpoint, to handler: backtrace
gdb/ChangeLog:
2015-04-10 Pedro Alves <palves@redhat.com>
* infrun.c (displaced_step_in_progress): New function.
(do_target_resume): Advise target to report all signals if
displaced stepping.
gdb/testsuite/ChangeLog:
2015-04-10 Pedro Alves <palves@redhat.com>
* gdb.base/sigstep.exp (breakpoint_to_handler)
(breakpoint_to_handler_entry): New parameter 'displaced'. Use it.
Test "backtrace" in handler.
(breakpoint_over_handler): New parameter 'displaced'. Use it.
(top level): Add new "displaced" test axis to
breakpoint_to_handler, breakpoint_to_handler_entry and
breakpoint_over_handler.
The problem is that with hardware step targets and displaced stepping,
"signal FOO" when stopped at a breakpoint steps the breakpoint
instruction at the same time it delivers a signal. This results in
tp->stepped_breakpoint set, but no step-resume breakpoint set. When
the next stop event arrives, GDB crashes. Irrespective of whether we
should do something more/different to step past the breakpoint in this
scenario (e.g., PR 18225), it's just wrong to assume there'll be a
step-resume breakpoint set (and was not the original intention).
gdb/ChangeLog:
2015-04-10 Pedro Alves <palves@redhat.com>
PR gdb/18216
* infrun.c (process_event_stop_test): Don't assume a step-resume
is set if tp->stepped_breakpoint is true.
gdb/testsuite/ChangeLog:
2015-04-10 Pedro Alves <palves@redhat.com>
PR gdb/18216
* gdb.threads/multiple-step-overs.exp: Remove expected eof.
On GNU/Linux, if the running kernel supports clone events, then
linux-thread-db.c defers thread listing to the target beneath:
static void
thread_db_update_thread_list (struct target_ops *ops)
{
...
if (target_has_execution && !thread_db_use_events ())
ops->beneath->to_update_thread_list (ops->beneath);
else
thread_db_update_thread_list_td_ta_thr_iter (ops);
...
}
However, when live debugging, the target beneath, linux-nat.c, does
not implement the to_update_thread_list method. The result is that if
a thread is marked exited (because it can't be deleted right now,
e.g., it was the selected thread), then it won't ever be deleted,
until the process exits or is killed/detached.
A similar thing happens with the remote.c target. Because its
target_update_thread_list implementation skips exited threads when it
walks the current thread list looking for threads that no longer exits
on the target side, using ALL_NON_EXITED_THREADS_SAFE, stale exited
threads are never deleted.
This is not a big deal -- I can't think of any way this might be user
visible, other than gdb's memory growing a tiny bit whenever a thread
gets stuck in exited state. Still, might as well clean things up
properly.
All other targets use prune_threads, so are unaffected.
The fix adds a ALL_THREADS_SAFE macro, that like
ALL_NON_EXITED_THREADS_SAFE, walks the thread list and allows deleting
the iterated thread, and uses that in places that are walking the
thread list in order to delete threads. Actually, after converting
linux-nat.c and remote.c to use this, we find the only other user of
ALL_NON_EXITED_THREADS_SAFE is also walking the list to delete
threads. So we convert that too, and end up deleting
ALL_NON_EXITED_THREADS_SAFE.
Tested on x86_64 Fedora 20, native and gdbserver.
gdb/ChangeLog
2015-04-07 Pedro Alves <palves@redhat.com>
* gdbthread.h (ALL_NON_EXITED_THREADS_SAFE): Rename to ...
(ALL_THREADS_SAFE): ... this, and don't skip exited threads.
(delete_exited_threads): New declaration.
* infrun.c (follow_exec): Use ALL_THREADS_SAFE.
* linux-nat.c (linux_nat_update_thread_list): New function.
(linux_nat_add_target): Install it.
* remote.c (remote_update_thread_list): Use ALL_THREADS_SAFE.
* thread.c (prune_threads): Use ALL_THREADS_SAFE.
(delete_exited_threads): New function.
Although not currently possible in practice when we get here,
'resume_ptid' can also be a wildcard throughout this function. It's
clearer to fetch the regcache using the thread's ptid.
gdb/ChangeLog:
2015-04-07 Pedro Alves <pedro@codesourcery.com>
* infrun.c (resume) <displaced stepping debug output>: Get the
leader thread's regcache, not resume_ptid's.
My all-stop-on-top-of-non-stop series manages to shows regressions due
to this latent bug. currently_stepping returns true if
stepped_breakpoint is set. Obviously we should clear
it before checking currently_stepping, not after.
Tested on x86_64 Fedora 20.
gdb/ChangeLog:
2015-04-01 Pedro Alves <palves@redhat.com>
* infrun.c (resume): Check currently_stepping after clearing
stepped_breakpoint, not before.
By inspection, I noticed a path where we return without discarding the
cleanups.
gdb/ChangeLog:
2015-04-01 Pedro Alves <palves@redhat.com>
* infrun.c (keep_going): Also discard cleanups if inserting
breakpoints fails.
Pedro Alves
Simon Marchi
Markus Metzger
Don Breazeal
Pierre-Marie de Rodat
Joel Brobecker
Gary Benson
Doug Evans
Jan Kratochvil
Yao Qi