KDB_TRACE and no backend

[Andriy Gapon]

Here's a small patch that adds support for printing stack trace in form of frame
addresses when KDB_TRACE is enabled, but there is no debugger backend configured.
The patch is styled after "cheap" variant of stack_ktr.

What do you think (useful/useless, correct, etc) ?

--- a/sys/kern/subr_kdb.c
+++ b/sys/kern/subr_kdb.c
@@ -37,6 +37,7 @@
 #include <sys/pcpu.h>
 #include <sys/proc.h>
 #include <sys/smp.h>
+#include <sys/stack.h>
 #include <sys/sysctl.h>

 #include <machine/kdb.h>
@@ -295,10 +296,16 @@
 void
 kdb_backtrace(void)
 {
+	struct stack st;
+	int i;

-	if (kdb_dbbe != NULL && kdb_dbbe->dbbe_trace != NULL) {
-		printf("KDB: stack backtrace:\n");
+	printf("KDB: stack backtrace:\n");
+	if (kdb_dbbe != NULL && kdb_dbbe->dbbe_trace != NULL)
 		kdb_dbbe->dbbe_trace();
+	else {
+		stack_save(&st);
+		for (i = 0; i < st.depth; i++)
+			printf("#%d %p\n", i, (void*)(uintptr_t)st.pcs[i]);
 	}
 }




-- 
Andriy Gapon