Re: [patch/rfc] Fix step/next across signals

[Andrew Cagney <cagney@gnu.org>]

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.
>