Re: Teach gdbserver to step over internal breakpoints

Pedro Alves
2010-03-24T00:05:48Z

On Tuesday 16 March 2010 18:39:52, Pedro Alves wrote:
> This tests cleanly on x86_64-linux, native gdbserver, with
> a small hack to force it to use the thread event breakpoint.
> I'll confirm this doesn't break software-single-step archs
> before commiting, although I don't expect to, since I had
> tested an earlier version of this patch on ARM.

I've now tested this on arm-none-linux-gnueabi,
and there were no regressions. I've also re-tested this
on x86_64-linux. It's now checked in.

> 2010-03-16 Pedro Alves <pedro@codesourcery.com>
>
> gdb/gdbserver/
> * linux-low.c (can_hardware_single_step): New.
> (supports_breakpoints): New.
> (handle_extended_wait): If stopping threads, read the stop pc of
> the new cloned LWP.
> (get_pc): New.
> (get_stop_pc): Add `lwp' parameter. Handle it. Bail out if the
> low target doesn't support retrieving the PC.
> (add_lwp): Set last_resume_kind to resume_continue.
> (linux_attach_lwp_1): Adjust comments. Always set stop_expected.
> (linux_attach): Don't clear stop_expected. Set the lwp's
> last_resume_kind to resume_stop.
> (linux_detach_one_lwp): Don't check for removed breakpoints.
> (check_removed_breakpoint): Delete.
> (status_pending_p): Rename to ...
> (status_pending_p_callback): ... this. Don't check for removed
> breakpoints. Don't consider threads that are stopped from GDB's
> perspective.
> (linux_wait_for_lwp): Always read the stop_pc here.
> (cancel_breakpoint): New.
> (step_over_bkpt): New global.
> (linux_wait_for_event_1): Implement stepping over breakpoints.
> (gdb_wants_lwp_stopped): New.
> (gdb_wants_all_stopped): New.
> (linux_wait_1): Tag threads as gdb-wants-stopped. Cancel finished
> single-step traps here. Store the thread's last reported target
> wait status.
> (send_sigstop): Don't clear stop_expected. Always set it,
> instead.
> (mark_lwp_dead): Remove reference to pending_is_breakpoint.
> (cancel_finished_single_step): New.
> (cancel_finished_single_steps): New.
> (wait_for_sigstop): Don't cancel finished single-step traps here.
> (linux_resume_one_lwp): Don't check for removed breakpoints.
> Don't set `step' on non-hardware step archs.
> (linux_set_resume_request): Ignore resume_stop requests if already
> stopping or stopped. Set the lwp's last_resume_kind.
> (resume_status_pending_p): Don't check for removed breakpoints.
> (need_step_over_p): New.
> (start_step_over): New.
> (finish_step_over): New.
> (linux_resume_one_thread): Always queue a sigstop for resume_stop
> requests. Clear the thread's last reported target waitstatus.
> Don't use the `suspended' flag. Don't consider pending breakpoints.
> (linux_resume): Start a step-over if necessary.
> (proceed_one_lwp): New.
> (proceed_all_lwps): New.
> (unstop_all_lwps): New.
> * linux-low.h (struct lwp_info): Rewrite comment for the
> `suspended' flag. Add the `stop_pc' field. Delete the
> `pending_stop_pc' field. Tweak the `stepping' flag's comment.
> Add `'last_resume_kind' and `need_step_over' fields.
> * inferiors.c (struct thread_info): Delete, moved elsewhere.
> * mem-break.c (struct breakpoint): Delete `reinserting' flag.
> Delete `breakpoint_to_reinsert' field. New flag `inserted'.
> (set_raw_breakpoint_at): New.
> (set_breakpoint_at): Rewrite to use it.
> (reinsert_breakpoint_handler): Delete.
> (set_reinsert_breakpoint): New.
> (reinsert_breakpoint_by_bp): Delete.
> (delete_reinsert_breakpoints): New.
> (uninsert_breakpoint): Rewrite.
> (uninsert_breakpoints_at): New.
> (reinsert_breakpoint): Rewrite.
> (reinsert_breakpoints_at): New.
> (check_breakpoints): Rewrite.
> (breakpoint_here): New.
> (breakpoint_inserted_here): New.
> (check_mem_read): Adjust.
> * mem-break.h (breakpoints_supported, breakpoint_here)
> (breakpoint_inserted_here, set_reinsert_breakpoint): Declare.
> (reinsert_breakpoint_by_bp): Delete declaration.
> (delete_reinsert_breakpoints): Declare.
> (reinsert_breakpoint): Delete declaration.
> (reinsert_breakpoints_at): Declare.
> (uninsert_breakpoint): Delete declaration.
> (uninsert_breakpoints_at): Declare.
> (check_breakpoints): Adjust prototype.
> * server.h: Adjust include order.
> (struct thread_info): Declare here. Add a `last_status' field.

--
Pedro Alves