[rfc] longjmp breakpoints (Re: [00/19] Eliminate some more current_gdbarch uses)
Pedro Alves
pedro@codesourcery.com
Wed Jun 24 15:02:00 GMT 2009
On Tuesday 23 June 2009 19:04:13, Ulrich Weigand wrote:
> Pedro Alves wrote:
> > On Monday 08 June 2009 15:38:39, Ulrich Weigand wrote:
> > > and/or
> > > - keeping them always disabled, but installing momentary clones in
> > > =A0 threads that are stepping
> >
> > Yeah, sounds sort of good too. I've added a momentary breakpoint
> > cloning function just a few days ago. This requires looking up which
> > threads in the same address space are stepping. I'm not certain which
> > version would be uglier. Currently, it's the address lookup part
> > that's ineficient. We could tackle that with per-objfile data, without
> > making the breakpoints module much aware of stepping.
>
> This patch implements the idea of maintaining "master copies" of the
> longjmp breakpoints that are created at the same places where overlay
> event breakpoints are created today, and then installing momentary
> clones while we want them to be active within a thread.
>
> What do you think?
Looks good to me. Thanks!
>
> Tested on spu-elf.
>
> Bye,
> Ulrich
>
>
> ChangeLog:
>
> * breakpoint.h (set_longjmp_breakpoint): Add THREAD argument.
> (enum bptype): Add bp_longjmp_master.
>
> * breakpoint.c (create_longjmp_master_breakpoint): New function.
> (update_breakpoints_after_exec): Handle bp_longjmp_master
> breakpoints. Call create_longjmp_master_breakpoint.
> (print_it_typical, bpstat_stop_status, bpstat_what,
> print_one_breakpoint_location, allocate_bp_location, mention,
> delete_command, breakpoint_re_set_one): Handle bp_longjmp_master.
> (breakpoint_re_set): Call create_longjmp_master_breakpoint.
> (create_longjmp_breakpoint): Delete.
> (set_longjmp_breakpoint): Add THREAD argument. Reimplement
> to install momentary clones of bp_longjmp_master breakpoints.
>
> * infcmd.c (step_1): Pass thread to set_longjmp_breakpoint.
>
>
> Index: gdb-head/gdb/breakpoint.c
> ===================================================================
> --- gdb-head.orig/gdb/breakpoint.c
> +++ gdb-head/gdb/breakpoint.c
> @@ -1507,6 +1507,31 @@ create_overlay_event_breakpoint (char *f
> update_global_location_list (1);
> }
>
> +static void
> +create_longjmp_master_breakpoint (char *func_name)
> +{
> + struct objfile *objfile;
> +
> + ALL_OBJFILES (objfile)
> + {
> + struct breakpoint *b;
> + struct minimal_symbol *m;
> +
> + if (!gdbarch_get_longjmp_target_p (get_objfile_arch (objfile)))
> + continue;
> +
> + m = lookup_minimal_symbol_text (func_name, objfile);
> + if (m == NULL)
> + continue;
> +
> + b = create_internal_breakpoint (SYMBOL_VALUE_ADDRESS (m),
> + bp_longjmp_master);
> + b->addr_string = xstrdup (func_name);
> + b->enable_state = bp_disabled;
> + }
> + update_global_location_list (1);
> +}
> +
> void
> update_breakpoints_after_exec (void)
> {
> @@ -1535,8 +1560,9 @@ update_breakpoints_after_exec (void)
> }
>
> /* Thread event breakpoints must be set anew after an exec(),
> - as must overlay event breakpoints. */
> - if (b->type == bp_thread_event || b->type == bp_overlay_event)
> + as must overlay event and longjmp master breakpoints. */
> + if (b->type == bp_thread_event || b->type == bp_overlay_event
> + || b->type == bp_longjmp_master)
> {
> delete_breakpoint (b);
> continue;
> @@ -1608,6 +1634,10 @@ update_breakpoints_after_exec (void)
> }
> /* FIXME what about longjmp breakpoints? Re-create them here? */
> create_overlay_event_breakpoint ("_ovly_debug_event");
> + create_longjmp_master_breakpoint ("longjmp");
> + create_longjmp_master_breakpoint ("_longjmp");
> + create_longjmp_master_breakpoint ("siglongjmp");
> + create_longjmp_master_breakpoint ("_siglongjmp");
> }
>
> int
> @@ -2426,6 +2456,12 @@ print_it_typical (bpstat bs)
> result = PRINT_NOTHING;
> break;
>
> + case bp_longjmp_master:
> + /* These should never be enabled. */
> + printf_filtered (_("Longjmp Master Breakpoint: gdb should not stop!\n"));
> + result = PRINT_NOTHING;
> + break;
> +
> case bp_watchpoint:
> case bp_hardware_watchpoint:
> annotate_watchpoint (b->number);
> @@ -3119,7 +3155,8 @@ bpstat_stop_status (CORE_ADDR bp_addr, p
> if (!bs->stop)
> continue;
>
> - if (b->type == bp_thread_event || b->type == bp_overlay_event)
> + if (b->type == bp_thread_event || b->type == bp_overlay_event
> + || b->type == bp_longjmp_master)
> /* We do not stop for these. */
> bs->stop = 0;
> else
> @@ -3403,6 +3440,7 @@ bpstat_what (bpstat bs)
> break;
> case bp_thread_event:
> case bp_overlay_event:
> + case bp_longjmp_master:
> bs_class = bp_nostop;
> break;
> case bp_catchpoint:
> @@ -3529,6 +3567,7 @@ print_one_breakpoint_location (struct br
> {bp_shlib_event, "shlib events"},
> {bp_thread_event, "thread events"},
> {bp_overlay_event, "overlay events"},
> + {bp_longjmp_master, "longjmp master"},
> {bp_catchpoint, "catchpoint"},
> {bp_tracepoint, "tracepoint"},
> };
> @@ -3657,6 +3696,7 @@ print_one_breakpoint_location (struct br
> case bp_shlib_event:
> case bp_thread_event:
> case bp_overlay_event:
> + case bp_longjmp_master:
> case bp_tracepoint:
> if (opts.addressprint)
> {
> @@ -4274,6 +4314,7 @@ allocate_bp_location (struct breakpoint
> case bp_shlib_event:
> case bp_thread_event:
> case bp_overlay_event:
> + case bp_longjmp_master:
> loc->loc_type = bp_loc_software_breakpoint;
> break;
> case bp_hardware_breakpoint:
> @@ -4428,32 +4469,26 @@ make_breakpoint_permanent (struct breakp
> bl->inserted = 1;
> }
>
> -static void
> -create_longjmp_breakpoint (char *func_name)
> -{
> - struct minimal_symbol *m;
> -
> - m = lookup_minimal_symbol_text (func_name, NULL);
> - if (m == NULL)
> - return;
> - set_momentary_breakpoint_at_pc (SYMBOL_VALUE_ADDRESS (m), bp_longjmp);
> - update_global_location_list (1);
> -}
> -
> /* Call this routine when stepping and nexting to enable a breakpoint
> - if we do a longjmp(). When we hit that breakpoint, call
> + if we do a longjmp() in THREAD. When we hit that breakpoint, call
> set_longjmp_resume_breakpoint() to figure out where we are going. */
>
> void
> -set_longjmp_breakpoint (void)
> +set_longjmp_breakpoint (int thread)
> {
> - if (gdbarch_get_longjmp_target_p (current_gdbarch))
> - {
> - create_longjmp_breakpoint ("longjmp");
> - create_longjmp_breakpoint ("_longjmp");
> - create_longjmp_breakpoint ("siglongjmp");
> - create_longjmp_breakpoint ("_siglongjmp");
> - }
> + struct breakpoint *b, *temp;
> +
> + /* To avoid having to rescan all objfile symbols at every step,
> + we maintain a list of continually-inserted but always disabled
> + longjmp "master" breakpoints. Here, we simply create momentary
> + clones of those and enable them for the requested thread. */
> + ALL_BREAKPOINTS_SAFE (b, temp)
> + if (b->type == bp_longjmp_master)
> + {
> + struct breakpoint *clone = clone_momentary_breakpoint (b);
> + b->type = bp_longjmp;
> + b->thread = thread;
> + }
> }
>
> /* Delete all longjmp breakpoints from THREAD. */
> @@ -5164,6 +5199,7 @@ mention (struct breakpoint *b)
> case bp_shlib_event:
> case bp_thread_event:
> case bp_overlay_event:
> + case bp_longjmp_master:
> break;
> }
>
> @@ -7432,6 +7468,7 @@ delete_command (char *arg, int from_tty)
> && b->type != bp_shlib_event
> && b->type != bp_thread_event
> && b->type != bp_overlay_event
> + && b->type != bp_longjmp_master
> && b->number >= 0)
> {
> breaks_to_delete = 1;
> @@ -7449,6 +7486,7 @@ delete_command (char *arg, int from_tty)
> && b->type != bp_shlib_event
> && b->type != bp_thread_event
> && b->type != bp_overlay_event
> + && b->type != bp_longjmp_master
> && b->number >= 0)
> delete_breakpoint (b);
> }
> @@ -7743,9 +7781,10 @@ breakpoint_re_set_one (void *bint)
> default:
> printf_filtered (_("Deleting unknown breakpoint type %d\n"), b->type);
> /* fall through */
> - /* Delete overlay event breakpoints; they will be reset later by
> - breakpoint_re_set. */
> + /* Delete overlay event and longjmp master breakpoints; they will be
> + reset later by breakpoint_re_set. */
> case bp_overlay_event:
> + case bp_longjmp_master:
> delete_breakpoint (b);
> break;
>
> @@ -7797,6 +7836,10 @@ breakpoint_re_set (void)
> input_radix = save_input_radix;
>
> create_overlay_event_breakpoint ("_ovly_debug_event");
> + create_longjmp_master_breakpoint ("longjmp");
> + create_longjmp_master_breakpoint ("_longjmp");
> + create_longjmp_master_breakpoint ("siglongjmp");
> + create_longjmp_master_breakpoint ("_siglongjmp");
> }
>
> /* Reset the thread number of this breakpoint:
> Index: gdb-head/gdb/breakpoint.h
> ===================================================================
> --- gdb-head.orig/gdb/breakpoint.h
> +++ gdb-head/gdb/breakpoint.h
> @@ -110,6 +110,13 @@ enum bptype
>
> bp_overlay_event,
>
> + /* Master copies of longjmp breakpoints. These are always installed
> + as soon as an objfile containing longjmp is loaded, but they are
> + always disabled. While necessary, temporary clones of bp_longjmp
> + type will be created and enabled. */
> +
> + bp_longjmp_master,
> +
> bp_catchpoint,
>
> bp_tracepoint,
> @@ -765,7 +772,7 @@ extern void update_breakpoints_after_exe
> inferior_ptid. */
> extern int detach_breakpoints (int);
>
> -extern void set_longjmp_breakpoint (void);
> +extern void set_longjmp_breakpoint (int thread);
> extern void delete_longjmp_breakpoint (int thread);
>
> extern void enable_overlay_breakpoints (void);
> Index: gdb-head/gdb/infcmd.c
> ===================================================================
> --- gdb-head.orig/gdb/infcmd.c
> +++ gdb-head/gdb/infcmd.c
> @@ -831,7 +831,7 @@ step_1 (int skip_subroutines, int single
> if (in_thread_list (inferior_ptid))
> thread = pid_to_thread_id (inferior_ptid);
>
> - set_longjmp_breakpoint ();
> + set_longjmp_breakpoint (thread);
>
> make_cleanup (delete_longjmp_breakpoint_cleanup, &thread);
> }
>
--
Pedro Alves
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