Author: avg
Date: Thu May 3 07:47:03 2018
New Revision: 333204
URL: https://svnweb.freebsd.org/changeset/base/333204
Log:
MFC r332752: set kdb_why to "trap" when calling kdb_trap from trap_fatal
This will allow to hook a ddb script to "kdb.enter.trap" event.
Previously there was no specific name for this event, so it could only
be handled by either "kdb.enter.unknown" or "kdb.enter.default" hooks.
Both are very unspecific.
Having a specific event is useful because the fatal trap condition is
very similar to panic but it has an additional property that the current
stack frame is the frame where the trap occurred. So, both a register
dump and a stack bottom dump have additional information that can help
analyze the problem.
I have added the event only on architectures that have trap_fatal()
function defined. I haven't looked at other architectures. Their
maintainers can add support for the event later.
Sample script:
kdb.enter.trap=bt; show reg; x/aS $rsp,20; x/agx $rsp,20
Sponsored by: Panzura
Modified:
stable/11/sys/amd64/amd64/trap.c
stable/11/sys/i386/i386/trap.c
stable/11/sys/powerpc/powerpc/trap.c
stable/11/sys/sys/kdb.h
Directory Properties:
stable/11/ (props changed)
Modified: stable/11/sys/amd64/amd64/trap.c
==============================================================================
--- stable/11/sys/amd64/amd64/trap.c Thu May 3 07:38:45 2018
(r333203)
+++ stable/11/sys/amd64/amd64/trap.c Thu May 3 07:47:03 2018
(r333204)
@@ -758,6 +758,9 @@ trap_fatal(frame, eva)
u_int type;
struct soft_segment_descriptor softseg;
char *msg;
+#ifdef KDB
+ bool handled;
+#endif
code = frame->tf_err;
type = frame->tf_trapno;
@@ -808,9 +811,13 @@ trap_fatal(frame, eva)
curproc->p_pid, curthread->td_name);
#ifdef KDB
- if (debugger_on_panic)
- if (kdb_trap(type, 0, frame))
+ if (debugger_on_panic) {
+ kdb_why = KDB_WHY_TRAP;
+ handled = kdb_trap(type, 0, frame);
+ kdb_why = KDB_WHY_UNSET;
+ if (handled)
return;
+ }
#endif
printf("trap number = %d\n", type);
if (type <= MAX_TRAP_MSG)
Modified: stable/11/sys/i386/i386/trap.c
==============================================================================
--- stable/11/sys/i386/i386/trap.c Thu May 3 07:38:45 2018
(r333203)
+++ stable/11/sys/i386/i386/trap.c Thu May 3 07:47:03 2018
(r333204)
@@ -880,6 +880,9 @@ trap_fatal(frame, eva)
u_int type;
struct soft_segment_descriptor softseg;
char *msg;
+#ifdef KDB
+ bool handled;
+#endif
code = frame->tf_err;
type = frame->tf_trapno;
@@ -945,12 +948,13 @@ trap_fatal(frame, eva)
#ifdef KDB
if (debugger_on_panic) {
+ kdb_why = KDB_WHY_TRAP;
frame->tf_err = eva; /* smuggle fault address to ddb */
- if (kdb_trap(type, 0, frame)) {
- frame->tf_err = code; /* restore error code */
+ handled = kdb_trap(type, 0, frame);
+ frame->tf_err = code; /* restore error code */
+ kdb_why = KDB_WHY_UNSET;
+ if (handled)
return;
- }
- frame->tf_err = code; /* restore error code */
}
#endif
printf("trap number = %d\n", type);
Modified: stable/11/sys/powerpc/powerpc/trap.c
==============================================================================
--- stable/11/sys/powerpc/powerpc/trap.c Thu May 3 07:38:45 2018
(r333203)
+++ stable/11/sys/powerpc/powerpc/trap.c Thu May 3 07:47:03 2018
(r333204)
@@ -389,11 +389,19 @@ trap(struct trapframe *frame)
static void
trap_fatal(struct trapframe *frame)
{
+#ifdef KDB
+ bool handled;
+#endif
printtrap(frame->exc, frame, 1, (frame->srr1 & PSL_PR));
#ifdef KDB
- if (debugger_on_panic && kdb_trap(frame->exc, 0, frame))
- return;
+ if (debugger_on_panic) {
+ kdb_why = KDB_WHY_TRAP;
+ handled = kdb_trap(frame->exc, 0, frame);
+ kdb_why = KDB_WHY_UNSET;
+ if (handled)
+ return;
+ }
#endif
panic("%s trap", trapname(frame->exc));
}
Modified: stable/11/sys/sys/kdb.h
==============================================================================
--- stable/11/sys/sys/kdb.h Thu May 3 07:38:45 2018 (r333203)
+++ stable/11/sys/sys/kdb.h Thu May 3 07:47:03 2018 (r333204)
@@ -98,6 +98,7 @@ extern const char * volatile kdb_why;
#define KDB_WHY_UNSET NULL /* No reason set. */
#define KDB_WHY_PANIC "panic" /* panic() was called.
*/
#define KDB_WHY_KASSERT "kassert" /* kassert failed. */
+#define KDB_WHY_TRAP "trap" /* Fatal trap. */
#define KDB_WHY_SYSCTL "sysctl" /* Sysctl entered
debugger. */
#define KDB_WHY_BOOTFLAGS "bootflags" /* Boot flags were set.
*/
#define KDB_WHY_WITNESS "witness" /* Witness entered
debugger. */
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