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RFA: Fix check for no-saved-pc
- From: Michael Snyder <msnyder at specifix dot com>
- To: gdb-patches at sourceware dot org
- Date: Fri, 30 Nov 2007 14:40:31 -0800
- Subject: RFA: Fix check for no-saved-pc
There's a check in get_prev_frame to see if the next saved pc
is zero. I think it has an off-by-one error, and is checking
for the pc of the wrong frame.
To test this, I took the corefile that's generated by the
testsuite (gdb.base/corefile.exp), edited it with khexedit,
and nulled out one of the saved return addresses on the stack.
This is the gdb output before my change:
Core was generated by `gdb/testsuite/gdb.base/coremaker'.
Program terminated with signal 6, Aborted.
#0 0x40000402 in __kernel_vsyscall ()
(gdb) bt
#0 0x40000402 in __kernel_vsyscall ()
#1 0x00a7bfa0 in raise () from /lib/libc.so.6
#2 0x00a7d8b1 in abort () from /lib/libc.so.6
#3 0x080486ce in func2 () at gdb/testsuite/gdb.base/coremaker.c:127
#4 0x080486d9 in func1 () at gdb/testsuite/gdb.base/coremaker.c:133
#5 0x00000000 in ?? ()
(gdb)
And this is the output with the attached patch:
(gdb) bt
#0 0x40000402 in __kernel_vsyscall ()
#1 0x00a7bfa0 in raise () from /lib/libc.so.6
#2 0x00a7d8b1 in abort () from /lib/libc.so.6
#3 0x080486ce in func2 () at gdb/testsuite/gdb.base/coremaker.c:127
#4 0x080486d9 in func1 () at gdb/testsuite/gdb.base/coremaker.c:133
Backtrace stopped: frame did not save the PC
(gdb)
No other test suite changes, tests run on native i386 linux.
2007-11-30 Michael Snyder <msnyder@specifix.com>
* frame.c (get_prev_frame): Remove unused local variable.
(get_prev_frame): Check for null saved pc in the following
("prev") frame, not the current (already valid) frame.
Set up stop_reason conditions for printing stop reason.
Index: frame.c
===================================================================
RCS file: /cvs/src/src/gdb/frame.c,v
retrieving revision 1.235
diff -u -p -r1.235 frame.c
--- frame.c 2 Nov 2007 14:47:27 -0000 1.235
+++ frame.c 30 Nov 2007 22:48:47 -0000
@@ -1355,8 +1355,6 @@ inside_entry_func (struct frame_info *th
struct frame_info *
get_prev_frame (struct frame_info *this_frame)
{
- struct frame_info *prev_frame;
-
/* Return the inner-most frame, when the caller passes in NULL. */
/* NOTE: cagney/2002-11-09: Not sure how this would happen. The
caller should have previously obtained a valid frame using
@@ -1469,9 +1467,12 @@ get_prev_frame (struct frame_info *this_
if (this_frame->level > 0
&& get_frame_type (this_frame) == NORMAL_FRAME
&& get_frame_type (get_next_frame (this_frame)) == NORMAL_FRAME
- && get_frame_pc (this_frame) == 0)
+ && frame_pc_unwind (this_frame) == 0)
{
frame_debug_got_null_frame (gdb_stdlog, this_frame, "zero PC");
+ this_frame->stop_reason = UNWIND_NO_SAVED_PC;
+ this_frame->prev_p = 1;
+ this_frame->prev = NULL;
return NULL;
}