[patch/rfc] Fix step/next across signals
Andrew Cagney
cagney@gnu.org
Mon Aug 30 16:58:00 GMT 2004
I've checked this in.
Andrew
> Hello,
>
> The attached fixes a bug with step/next across signals. Given:
>
> Breakpoint at 10 hit
> 10 while (!done);
> (gdb) next
>
> when there was a signal pending (that set DONE), GDB would:
>
> Attempt to step of the breakpoint at "10":
> - pull all breakpoints
> - PT_STEP (to get off the BP instruction)
> - get back the signal instead
>
> Attempt to skip the signal handler:
> - add a step_resume_breakpoint at "10" the signal return addr
> - PT_STEP delivering the signal
> - insert all breakpoints (including step_resume)
> - PT_CONTINUE the inferior
> - get back SIGTRAP from the step_resume breakpoint
> - delete the step_resume bp
>
> Go back to doing the next:
> - PT_STEP the inferior (breakpoints including "10" still inserted)
> - re-hit "10"
>
> the problem is that GDB forgot that it was, at the time of the signal, trying to step off a breakpoint.
>
> The attached patch fixes this, it notes if/when it was stepping off a breakpoint, so that it can return to that task once the step-resume-breakpoint is hit.
>
> I've tested it on a my patched PPC/NetBSD kernel and it KPASSes 1757; and a vanila rhel3u2 system with no test changes.
>
> Since the 1757 KFAILs pass, I've removed them as `obvious'.
>
> comments?
> Andrew
>
>
>
> Index: testsuite/ChangeLog
> 2004-08-26 Andrew Cagney <cagney@gnu.org>
>
> * gdb.base/sigstep.exp (breakpoint_over_handler): Remove kfail
> gdb/1757.
>
> Index: ChangeLog
> 2004-08-26 Andrew Cagney <cagney@gnu.org>
>
> Fix PR breakpoints/1757.
> * infrun.c (struct execution_control_state): Replace
> remove_breakpoints_on_following_step with
> step_after_step_resume_breakpoint.
> (init_execution_control_state): Update.
> (handle_inferior_event): For signals, when stepping off a
> breakpoint, set step_after_step_resume_breakpoint. When
> BPSTAT_WHAT_STEP_RESUME, do a single-step off the breakpoint.
> (keep_going): Delete code handling
> remove_breakpoints_on_following_step.
>
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