Don't use __builtin_return_address for stack traces

1c3d2bb6 · Silas Boyd-Wickizer · 553de92d · 1c3d2bb6 · 1c3d2bb6
--- a/amd64.h
+++ b/amd64.h
@@ -191,6 +191,14 @@ rrsp(void)
  return val;
 }

+static inline u64
+rrbp(void)
+{
+  u64 val;
+  __asm volatile("movq %%rbp,%0" : "=r" (val));
+  return val;
+}
+
 static inline void
 lcr4(u64 val)
 {

--- a/console.c
+++ b/console.c
@@ -135,26 +135,13 @@ puts(const char *s)
 }

 static inline void
-stacktrace(void)
+printtrace(u64 rbp)
 {
-#define PRINT_RET(i)                                       \
-  do {                                                     \
-    uptr addr = (uptr) __builtin_return_address(i);        \
-    if ((addr & KBASE) == KBASE)                           \
-      __cprintf("  %lx\n", addr);                          \
-    else                                                   \
-      return;                                              \
-} while (0)
-
-  PRINT_RET(0);
-  PRINT_RET(1);
-  PRINT_RET(2);
-  PRINT_RET(3);
-  PRINT_RET(4);
-  PRINT_RET(5);
-  PRINT_RET(6);
-
-#undef PRINT_RET
+  uptr pc[10];
+
+  getcallerpcs((void*)rbp, pc, NELEM(pc));
+  for (int i = 0; i < NELEM(pc) && pc[i] != 0; i++)
+    __cprintf("  %p\n", pc[i]);
 }

 void __noret__
@@ -164,8 +151,6 @@ kerneltrap(struct trapframe *tf)
  const char *name = "(no name)";
  void *kstack = NULL;
  int pid = 0;
-  uptr pc[10];
-  int i;

  cli();
  acquire(&cons.lock);
@@ -182,9 +167,7 @@ kerneltrap(struct trapframe *tf)
          tf->trapno, mycpu()->id, 
          tf->rip, tf->rsp, rcr2(),
          name, pid, kstack);
-  getcallerpcs((void*)tf->rbp, pc, NELEM(pc));
-  for (i = 0; i < NELEM(pc) && pc[i] != 0; i++)
-    __cprintf("  %p\n", pc[i]);
+  printtrace(tf->rbp);

  panicked = 1;
  sys_halt();
@@ -206,7 +189,7 @@ panic(const char *fmt, ...)
  vprintfmt(writecons, 0, fmt, ap);
  va_end(ap);
  __cprintf("\n");
-  stacktrace();
+  printtrace(rrbp());

  panicked = 1;
  sys_halt();