---

yaml
---
r: 19640
b: refs/heads/master
c: 23332c2
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 8145916996b91d42b8bb4b0fcd508af295222c7c
+refs/heads/master: 23332c2e9da16b717f18fd95bc90211a663aa6ee

trunk/arch/i386/oprofile/backtrace.c

@@ -49,21 +49,36 @@ dump_backtrace(struct frame_head * head)
  * |    stack    |
  * --------------- saved regs->ebp value if valid (frame_head address)
  * .             .
- * --------------- struct pt_regs stored on stack (struct pt_regs *)
+ * --------------- saved regs->rsp value if x86_64
+ * |             |
+ * --------------- struct pt_regs * stored on stack if 32-bit
  * |             |
  * .             .
  * |             |
  * --------------- %esp
  * |             |
  * |             | \/ Lower addresses
  *
- * Thus, &pt_regs <-> stack base restricts the valid(ish) ebp values
+ * Thus, regs (or regs->rsp for x86_64) <-> stack base restricts the
+ * valid(ish) ebp values. Note: (1) for x86_64, NMI and several other
+ * exceptions use special stacks, maintained by the interrupt stack table
+ * (IST). These stacks are set up in trap_init() in
+ * arch/x86_64/kernel/traps.c. Thus, for x86_64, regs now does not point
+ * to the kernel stack; instead, it points to some location on the NMI
+ * stack. On the other hand, regs->rsp is the stack pointer saved when the
+ * NMI occurred. (2) For 32-bit, regs->esp is not valid because the
+ * processor does not save %esp on the kernel stack when interrupts occur
+ * in the kernel mode.
  */
 #ifdef CONFIG_FRAME_POINTER
 static int valid_kernel_stack(struct frame_head * head, struct pt_regs * regs)
 {
 	unsigned long headaddr = (unsigned long)head;
+#ifdef CONFIG_X86_64
+	unsigned long stack = (unsigned long)regs->rsp;
+#else
 	unsigned long stack = (unsigned long)regs;
+#endif
 	unsigned long stack_base = (stack & ~(THREAD_SIZE - 1)) + THREAD_SIZE;
 
 	return headaddr > stack && headaddr < stack_base;