Date: Sun, 18 May 2003 22:27:22 +0100 From: Ian Dowse <iedowse@maths.tcd.ie> To: obrien@freebsd.org, mp@freebsd.org Cc: current@freebsd.org Subject: kgdb missing stack frames Message-ID: <200305182227.aa40061@salmon.maths.tcd.ie>
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Support for decoding i386 trap frames in kgdb appears to have been
lost by revision 1.3 of contrib/gdb/gdb/config/i386/tm-fbsd.h, since
FRAME_SAVED_PC() is defined there in terms of i386bsd_frame_saved_pc(),
so fbsd_kern_frame_saved_pc() in gnu/usr.bin/binutils/gdb/kvm-fbsd.c
never gets called. A simple way to see this is to run
gdb -k kernel.debug /dev/mem
and get a backtrace from the idle process:
(kgdb) proc 11
(kgdb) bt
#0 mi_switch () at ../../../kern/kern_synch.c:530
#1 0xc01edb92 in ithread_schedule (ithread=0xc1898280, do_switch=1)
at ../../../kern/kern_intr.c:402
#2 0xc034ad43 in sched_ithd (cookie=0xc1894d80)
at ../../../i386/isa/ithread.c:77
#3 0xc03380cc in Xintr14 () at {standard input}:382
#4 0xc01ed16c in idle_proc (dummy=0x0) at ../../../kern/kern_idle.c:114
#5 0xc01ecea0 in fork_exit (callout=0xc01ed130 <idle_proc>, arg=0x0,
frame=0x0) at ../../../kern/kern_fork.c:792
This is what it should look like:
(kgdb) proc 11
(kgdb) bt
#0 mi_switch () at ../../../kern/kern_synch.c:530
#1 0xc01edb92 in ithread_schedule (ithread=0xc1898280, do_switch=1)
at ../../../kern/kern_intr.c:402
#2 0xc034ad43 in sched_ithd (cookie=0xc1898280)
at ../../../i386/isa/ithread.c:77
#3 0xc033e242 in cpu_idle () at ../../../i386/i386/machdep.c:1074
#4 0xc01ed16c in idle_proc (dummy=0x0) at ../../../kern/kern_idle.c:114
#5 0xc01ecea0 in fork_exit (callout=0xc01ed130 <idle_proc>, arg=0x0,
frame=0x0) at ../../../kern/kern_fork.c:792
i.e, the cpu_idle() frame now appears instead of Xintr14().
The following patch appears to fix this on the i386 (I haven't
looked at whether the problem affects other architectures). I also
haven't looked in detail to see what else could be stripped from
fbsd-kgdb-i386.h.
Ian
Index: contrib/gdb/gdb/config/i386/tm-fbsd.h
===================================================================
RCS file: /dump/FreeBSD-CVS/src/contrib/gdb/gdb/config/i386/tm-fbsd.h,v
retrieving revision 1.4
diff -u -r1.4 tm-fbsd.h
--- contrib/gdb/gdb/config/i386/tm-fbsd.h 12 Oct 2002 17:56:56 -0000 1.4
+++ contrib/gdb/gdb/config/i386/tm-fbsd.h 18 May 2003 21:12:05 -0000
@@ -77,7 +77,11 @@
/* Override FRAME_SAVED_PC to enable the recognition of signal handlers. */
#undef FRAME_SAVED_PC
-#define FRAME_SAVED_PC(frame) i386bsd_frame_saved_pc (frame)
+#define FRAME_SAVED_PC(frame) \
+ (kernel_debugging ? fbsd_kern_frame_saved_pc (frame) : \
+ i386bsd_frame_saved_pc (frame))
+
+extern CORE_ADDR fbsd_kern_frame_saved_pc(struct frame_info *fr);
extern CORE_ADDR i386bsd_frame_saved_pc (struct frame_info *frame);
Index: gnu/usr.bin/binutils/gdb/fbsd-kgdb-i386.h
===================================================================
RCS file: /dump/FreeBSD-CVS/src/gnu/usr.bin/binutils/gdb/fbsd-kgdb-i386.h,v
retrieving revision 1.3
diff -u -r1.3 fbsd-kgdb-i386.h
--- gnu/usr.bin/binutils/gdb/fbsd-kgdb-i386.h 18 Sep 2002 16:20:49 -0000 1.3
+++ gnu/usr.bin/binutils/gdb/fbsd-kgdb-i386.h 18 May 2003 21:05:35 -0000
@@ -12,19 +12,6 @@
#undef SIGTRAMP_END
#define SIGTRAMP_END(pc) 0xbfbfdff0
-
-/* Override FRAME_SAVED_PC to enable the recognition of signal handlers. */
-
-extern CORE_ADDR fbsd_kern_frame_saved_pc(struct frame_info *fr);
-
-#undef FRAME_SAVED_PC
-#define FRAME_SAVED_PC(FRAME) \
- (kernel_debugging \
- ? fbsd_kern_frame_saved_pc (FRAME) : \
- (FRAME)->signal_handler_caller \
- ? sigtramp_saved_pc (FRAME) \
- : read_memory_integer ((FRAME)->frame + 4, 4))
-
/* Offset to saved PC in sigcontext, from <sys/signal.h>. */
#define SIGCONTEXT_PC_OFFSET 20
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