160 lines
6.0 KiB
Diff
160 lines
6.0 KiB
Diff
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http://sourceware.org/ml/gdb-patches/2010-02/msg00625.html
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Subject: RFC: fix bug with std::terminate handler
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I would appreciate comments on this patch.
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This comes from an automatically-reported bug in the Red Hat bugzilla:
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https://bugzilla.redhat.com/show_bug.cgi?id=562975
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call_function_by_hand installs a momentary breakpoint on std::terminate,
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and then deletes it later. However, this can cause a double deletion of
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the breakpoint. In the bug, the called function is dlopen, which causes
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gdb to enter solib_add, which calls breakpoint_re_set, deleting the
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momentary breakpoint.
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This fix works by creating the momentary breakpoint with an internal
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breakpoint number, and then trying to delete the breakpoint by number.
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This bug does not always manifest in a crash. In fact, I couldn't make
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it crash here, but I could observe the problem under valgrind.
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Built and regtested on x86-64 (compile farm). I also manually verified
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it using valgrind.
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I think this patch is mildly ugly, due to the introduction of
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set_momentary_breakpoint_at_pc_with_number. However, in the absence of
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comments, I plan to check it in after a reasonable waiting period.
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Tom
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2010-02-25 Tom Tromey <tromey@redhat.com>
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* infcall.c (do_delete_breakpoint_by_number): New function.
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(call_function_by_hand): Refer to momentary breakpoint by number.
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* breakpoint.h (set_momentary_breakpoint_at_pc_with_number):
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Declare.
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* breakpoint.c (set_momentary_breakpoint_at_pc_with_number): New
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function.
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Index: gdb-7.0.90.20100312/gdb/breakpoint.c
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===================================================================
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--- gdb-7.0.90.20100312.orig/gdb/breakpoint.c 2010-03-12 14:54:26.000000000 +0100
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+++ gdb-7.0.90.20100312/gdb/breakpoint.c 2010-03-12 14:54:53.000000000 +0100
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@@ -6115,6 +6115,20 @@ set_momentary_breakpoint_at_pc (struct g
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return set_momentary_breakpoint (gdbarch, sal, null_frame_id, type);
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}
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+
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+/* Like set_momentary_breakpoint_at_pc, but ensure that the new
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+ breakpoint has a number. */
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+
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+struct breakpoint *
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+set_momentary_breakpoint_at_pc_with_number (struct gdbarch *gdbarch,
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+ CORE_ADDR pc,
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+ enum bptype type)
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+{
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+ struct breakpoint *result = set_momentary_breakpoint_at_pc (gdbarch, pc,
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+ type);
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+ result->number = internal_breakpoint_number--;
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+ return result;
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+}
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/* Tell the user we have just set a breakpoint B. */
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Index: gdb-7.0.90.20100312/gdb/breakpoint.h
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===================================================================
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--- gdb-7.0.90.20100312.orig/gdb/breakpoint.h 2010-03-12 14:54:26.000000000 +0100
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+++ gdb-7.0.90.20100312/gdb/breakpoint.h 2010-03-12 14:54:53.000000000 +0100
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@@ -774,6 +774,9 @@ extern struct breakpoint *set_momentary_
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extern struct breakpoint *set_momentary_breakpoint_at_pc
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(struct gdbarch *, CORE_ADDR pc, enum bptype type);
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+extern struct breakpoint *set_momentary_breakpoint_at_pc_with_number
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+ (struct gdbarch *, CORE_ADDR pc, enum bptype type);
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+
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extern struct breakpoint *clone_momentary_breakpoint (struct breakpoint *bpkt);
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extern void set_ignore_count (int, int, int);
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Index: gdb-7.0.90.20100312/gdb/infcall.c
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===================================================================
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--- gdb-7.0.90.20100312.orig/gdb/infcall.c 2010-03-12 14:54:26.000000000 +0100
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+++ gdb-7.0.90.20100312/gdb/infcall.c 2010-03-12 14:55:19.000000000 +0100
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@@ -410,6 +410,18 @@ run_inferior_call (struct thread_info *c
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return e;
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}
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+/* A cleanup function that deletes a breakpoint, if it still exists,
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+ given the breakpoint's number. */
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+
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+static void
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+do_delete_breakpoint_by_number (void *arg)
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+{
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+ int *num = arg;
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+ struct breakpoint *bp = get_breakpoint (*num);
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+ if (bp)
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+ delete_breakpoint (bp);
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+}
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+
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/* All this stuff with a dummy frame may seem unnecessarily complicated
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(why not just save registers in GDB?). The purpose of pushing a dummy
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frame which looks just like a real frame is so that if you call a
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@@ -447,7 +459,8 @@ call_function_by_hand (struct value *fun
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struct cleanup *args_cleanup;
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struct frame_info *frame;
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struct gdbarch *gdbarch;
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- struct breakpoint *terminate_bp = NULL;
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+ int terminate_bp_num = 0;
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+ CORE_ADDR terminate_bp_addr = 0;
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struct minimal_symbol *tm;
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struct cleanup *terminate_bp_cleanup = NULL;
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ptid_t call_thread_ptid;
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@@ -765,8 +778,13 @@ call_function_by_hand (struct value *fun
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struct minimal_symbol *tm = lookup_minimal_symbol ("std::terminate()",
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NULL, NULL);
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if (tm != NULL)
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- terminate_bp = set_momentary_breakpoint_at_pc
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+ {
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+ struct breakpoint *bp;
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+ bp = set_momentary_breakpoint_at_pc_with_number
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(gdbarch, SYMBOL_VALUE_ADDRESS (tm), bp_breakpoint);
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+ terminate_bp_num = bp->number;
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+ terminate_bp_addr = bp->loc->address;
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+ }
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}
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/* Everything's ready, push all the info needed to restore the
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@@ -780,8 +798,9 @@ call_function_by_hand (struct value *fun
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discard_cleanups (inf_status_cleanup);
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/* Register a clean-up for unwind_on_terminating_exception_breakpoint. */
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- if (terminate_bp)
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- terminate_bp_cleanup = make_cleanup_delete_breakpoint (terminate_bp);
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+ if (terminate_bp_num != 0)
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+ terminate_bp_cleanup = make_cleanup (do_delete_breakpoint_by_number,
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+ &terminate_bp_num);
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/* - SNIP - SNIP - SNIP - SNIP - SNIP - SNIP - SNIP - SNIP - SNIP -
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If you're looking to implement asynchronous dummy-frames, then
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@@ -947,9 +966,9 @@ When the function is done executing, GDB
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in an inferior function call. Rewind, and warn the
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user. */
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- if (terminate_bp != NULL
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+ if (terminate_bp_num != 0
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&& (inferior_thread ()->stop_bpstat->breakpoint_at->address
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- == terminate_bp->loc->address))
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+ == terminate_bp_addr))
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{
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/* We must get back to the frame we were before the
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dummy call. */
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@@ -998,7 +1017,7 @@ When the function is done executing, GDB
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/* If we get here and the std::terminate() breakpoint has been set,
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it has to be cleaned manually. */
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- if (terminate_bp)
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+ if (terminate_bp_num != 0)
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do_cleanups (terminate_bp_cleanup);
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/* If we get here the called FUNCTION ran to completion,
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