x86: Fixup wrong irq frame link in stacktraces

[safe/jmp/linux-2.6] / arch / x86 / kernel / dumpstack_64.c

diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c
index a071e6b..004b8aa 100644 (file)
--- a/arch/x86/kernel/dumpstack_64.c
+++ b/arch/x86/kernel/dumpstack_64.c
@@ -101,6 +101,35 @@ static unsigned long *in_exception_stack(unsigned cpu, unsigned long stack,
        return NULL;
 }
 
+static inline int
+in_irq_stack(unsigned long *stack, unsigned long *irq_stack,
+            unsigned long *irq_stack_end)
+{
+       return (stack >= irq_stack && stack < irq_stack_end);
+}
+
+/*
+ * We are returning from the irq stack and go to the previous one.
+ * If the previous stack is also in the irq stack, then bp in the first
+ * frame of the irq stack points to the previous, interrupted one.
+ * Otherwise we have another level of indirection: We first save
+ * the bp of the previous stack, then we switch the stack to the irq one
+ * and save a new bp that links to the previous one.
+ * (See save_args())
+ */
+static inline unsigned long
+fixup_bp_irq_link(unsigned long bp, unsigned long *stack,
+                 unsigned long *irq_stack, unsigned long *irq_stack_end)
+{
+#ifdef CONFIG_FRAME_POINTER
+       struct stack_frame *frame = (struct stack_frame *)bp;
+
+       if (!in_irq_stack(stack, irq_stack, irq_stack_end))
+               return (unsigned long)frame->next_frame;
+#endif
+       return bp;
+}
+
 /*
  * x86-64 can have up to three kernel stacks:
  * process stack
@@ -173,7 +202,7 @@ void dump_trace(struct task_struct *task, struct pt_regs *regs,
                        irq_stack = irq_stack_end -
                                (IRQ_STACK_SIZE - 64) / sizeof(*irq_stack);
 
-                       if (stack >= irq_stack && stack < irq_stack_end) {
+                       if (in_irq_stack(stack, irq_stack, irq_stack_end)) {
                                if (ops->stack(data, "IRQ") < 0)
                                        break;
                                bp = print_context_stack(tinfo, stack, bp,
@@ -184,6 +213,8 @@ void dump_trace(struct task_struct *task, struct pt_regs *regs,
                                 * pointer (index -1 to end) in the IRQ stack:
                                 */
                                stack = (unsigned long *) (irq_stack_end[-1]);
+                               bp = fixup_bp_irq_link(bp, stack, irq_stack,
+                                                      irq_stack_end);
                                irq_stack_end = NULL;
                                ops->stack(data, "EOI");
                                continue;