diff options
Diffstat (limited to 'gdb/frame.c')
| -rw-r--r-- | gdb/frame.c | 68 |
1 files changed, 52 insertions, 16 deletions
diff --git a/gdb/frame.c b/gdb/frame.c index c4f85fe..55ded7168 100644 --- a/gdb/frame.c +++ b/gdb/frame.c @@ -368,7 +368,33 @@ frame_id_eq (struct frame_id l, struct frame_id r) return eq; } -int +/* Safety net to check whether frame ID L should be inner to + frame ID R, according to their stack addresses. + + This method cannot be used to compare arbitrary frames, as the + ranges of valid stack addresses may be discontiguous (e.g. due + to sigaltstack). + + However, it can be used as safety net to discover invalid frame + IDs in certain circumstances. + + * If frame NEXT is the immediate inner frame to THIS, and NEXT + is a NORMAL frame, then the stack address of NEXT must be + inner-than-or-equal to the stack address of THIS. + + Therefore, if frame_id_inner (THIS, NEXT) holds, some unwind + error has occurred. + + * If frame NEXT is the immediate inner frame to THIS, and NEXT + is a NORMAL frame, and NEXT and THIS have different stack + addresses, no other frame in the frame chain may have a stack + address in between. + + Therefore, if frame_id_inner (TEST, THIS) holds, but + frame_id_inner (TEST, NEXT) does not hold, TEST cannot refer + to a valid frame in the frame chain. */ + +static int frame_id_inner (struct gdbarch *gdbarch, struct frame_id l, struct frame_id r) { int inner; @@ -395,28 +421,34 @@ frame_id_inner (struct gdbarch *gdbarch, struct frame_id l, struct frame_id r) struct frame_info * frame_find_by_id (struct frame_id id) { - struct frame_info *frame; + struct frame_info *frame, *prev_frame; /* ZERO denotes the null frame, let the caller decide what to do about it. Should it instead return get_current_frame()? */ if (!frame_id_p (id)) return NULL; - for (frame = get_current_frame (); - frame != NULL; - frame = get_prev_frame (frame)) + for (frame = get_current_frame (); ; frame = prev_frame) { struct frame_id this = get_frame_id (frame); if (frame_id_eq (id, this)) /* An exact match. */ return frame; - if (frame_id_inner (get_frame_arch (frame), id, this)) - /* Gone to far. */ + + prev_frame = get_prev_frame (frame); + if (!prev_frame) + return NULL; + + /* As a safety net to avoid unnecessary backtracing while trying + to find an invalid ID, we check for a common situation where + we can detect from comparing stack addresses that no other + frame in the current frame chain can have this ID. See the + comment at frame_id_inner for details. */ + if (get_frame_type (frame) == NORMAL_FRAME + && !frame_id_inner (get_frame_arch (frame), id, this) + && frame_id_inner (get_frame_arch (prev_frame), id, + get_frame_id (prev_frame))) return NULL; - /* Either we're not yet gone far enough out along the frame - chain (inner(this,id)), or we're comparing frameless functions - (same .base, different .func, no test available). Struggle - on until we've definitly gone to far. */ } return NULL; } @@ -517,6 +549,11 @@ frame_pop (struct frame_info *this_frame) scratch = frame_save_as_regcache (prev_frame); cleanups = make_cleanup_regcache_xfree (scratch); + /* If we are popping a dummy frame, clean up the associated + data as well. */ + if (get_frame_type (this_frame) == DUMMY_FRAME) + dummy_frame_pop (get_frame_id (this_frame)); + /* FIXME: cagney/2003-03-16: It should be possible to tell the target's register cache that it is about to be hit with a burst register transfer and that the sequence of register writes should @@ -1207,11 +1244,10 @@ get_prev_frame_1 (struct frame_info *this_frame) /* Check that this frame's ID isn't inner to (younger, below, next) the next frame. This happens when a frame unwind goes backwards. - Exclude signal trampolines (due to sigaltstack the frame ID can - go backwards) and sentinel frames (the test is meaningless). */ - if (this_frame->next->level >= 0 - && this_frame->next->unwind->type != SIGTRAMP_FRAME - && frame_id_inner (get_frame_arch (this_frame), this_id, + This check is valid only if the next frame is NORMAL. See the + comment at frame_id_inner for details. */ + if (this_frame->next->unwind->type == NORMAL_FRAME + && frame_id_inner (get_frame_arch (this_frame->next), this_id, get_frame_id (this_frame->next))) { if (frame_debug) |