From: Anton Blanchard <anton@samba.org>
Clean up xmon backtrace code, it was doing all manner of scary things.
---
25-akpm/arch/ppc64/xmon/xmon.c | 136 +++++++++++++++++------------------------
1 files changed, 57 insertions(+), 79 deletions(-)
diff -puN arch/ppc64/xmon/xmon.c~ppc64-xmon_backtrace arch/ppc64/xmon/xmon.c
--- 25/arch/ppc64/xmon/xmon.c~ppc64-xmon_backtrace 2004-03-14 15:35:16.662405512 -0800
+++ 25-akpm/arch/ppc64/xmon/xmon.c 2004-03-14 15:35:16.665405056 -0800
@@ -56,9 +56,6 @@ static u_int bus_error_jmp[100];
#define setjmp xmon_setjmp
#define longjmp xmon_longjmp
-/* Max number of stack frames we are willing to produce on a backtrace. */
-#define MAXFRAMECOUNT 50
-
/* Breakpoint stuff */
struct bpt {
unsigned long address;
@@ -85,7 +82,6 @@ static void dump(void);
static void prdump(unsigned long, long);
static int ppc_inst_dump(unsigned long, long);
void print_address(unsigned long);
-static int getsp(void);
static void backtrace(struct pt_regs *);
static void excprint(struct pt_regs *);
static void prregs(struct pt_regs *);
@@ -897,93 +893,75 @@ const char *getvecname(unsigned long vec
return ret;
}
-static void
-backtrace(struct pt_regs *excp)
+/*
+ * Most of our exceptions are in the form:
+ * bl handler
+ * b .ret_from_exception
+ * and this currently fails to catch them.
+ */
+static inline int exception_frame(unsigned long ip)
{
- unsigned long sp;
- unsigned long lr;
- unsigned long stack[3];
+ extern void *ret_from_syscall_1, *ret_from_syscall_2, *ret_from_except;
+
+ if ((ip == (unsigned long)ret_from_syscall_1) ||
+ (ip == (unsigned long)ret_from_syscall_2) ||
+ (ip == (unsigned long)ret_from_except))
+ return 1;
+
+ return 0;
+}
+
+static int xmon_depth_to_print = 64;
+
+static void xmon_show_stack(unsigned long sp)
+{
+ unsigned long ip;
+ unsigned long newsp;
+ int count = 0;
struct pt_regs regs;
- int framecount;
- char *funcname;
- /* declare these as raw ptrs so we don't get func descriptors */
- extern void *ret_from_except, *ret_from_syscall_1;
- if (excp != NULL) {
- lr = excp->link;
- sp = excp->gpr[1];
- } else {
- /* Use care not to call any function before this point
- so the saved lr has a chance of being good. */
- asm volatile ("mflr %0" : "=r" (lr) :);
- sp = getsp();
- }
- scanhex(&sp);
- scannl();
- for (framecount = 0;
- sp != 0 && framecount < MAXFRAMECOUNT;
- sp = stack[0], framecount++) {
- if (mread(sp, stack, sizeof(stack)) != sizeof(stack))
- break;
-#if 0
- if (lr != 0) {
- stack[2] = lr; /* fake out the first saved lr. It may not be saved yet. */
- lr = 0;
+ do {
+ if (sp < PAGE_OFFSET) {
+ printf("SP in userspace\n");
+ break;
}
-#endif
- printf("%.16lx %.16lx", sp, stack[2]);
- /* TAI -- for now only the ones cast to unsigned long will match.
- * Need to test the rest...
- */
- if ((stack[2] == (unsigned long)ret_from_except &&
- (funcname = "ret_from_except"))
- || (stack[2] == (unsigned long)ret_from_syscall_1 &&
- (funcname = "ret_from_syscall_1"))
-#if 0
- || stack[2] == (unsigned) &ret_from_syscall_2
- || stack[2] == (unsigned) &do_signal_ret
-#endif
- ) {
- printf(" %s\n", funcname);
+
+ if (!mread((sp + 16), &ip, sizeof(unsigned long)))
+ break;
+
+ printf("[%016lx] [%016lx] ", sp, ip);
+ xmon_print_symbol("%s\n", ip);
+
+ if (exception_frame(ip)) {
if (mread(sp+112, ®s, sizeof(regs)) != sizeof(regs))
break;
- printf("exception: %lx %s regs %lx\n", regs.trap, getvecname(regs.trap), sp+112);
- printf(" %.16lx", regs.nip);
- if (regs.nip & 0xffffffff00000000UL)
- xmon_print_symbol(" %s", regs.nip);
- printf("\n");
- if (regs.gpr[1] < sp) {
- printf("<Stack drops into userspace %.16lx>\n", regs.gpr[1]);
- break;
- }
- sp = regs.gpr[1];
- if (mread(sp, stack, sizeof(stack)) != sizeof(stack))
- break;
- } else {
- if (stack[2])
- xmon_print_symbol(" %s", stack[2]);
- printf("\n");
- }
- if (stack[0] && stack[0] <= sp) {
- if ((stack[0] & 0xffffffff00000000UL) == 0)
- printf("<Stack drops into 32-bit userspace %.16lx>\n", stack[0]);
- else
- printf("<Corrupt stack. Next backchain is %.16lx>\n", stack[0]);
- break;
+ printf(" exception: %lx %s regs %lx\n", regs.trap,
+ getvecname(regs.trap), sp+112);
}
- }
- if (framecount >= MAXFRAMECOUNT)
- printf("<Punt. Too many stack frames>\n");
+
+ if (!mread(sp, &newsp, sizeof(unsigned long)))
+ break;
+ if (newsp < sp)
+ break;
+
+ sp = newsp;
+ } while (count++ < xmon_depth_to_print);
}
-int
-getsp()
+static void backtrace(struct pt_regs *excp)
{
- int x;
+ unsigned long sp;
+
+ if (excp == NULL)
+ sp = __get_SP();
+ else
+ sp = excp->gpr[1];
+
+ scanhex(&sp);
+ scannl();
- asm("mr %0,1" : "=r" (x) :);
- return x;
+ xmon_show_stack(sp);
}
spinlock_t exception_print_lock = SPIN_LOCK_UNLOCKED;
_