x86: Keep current stack in NMI breakpoints

[linux-2.6-block.git] / arch / x86 / kernel / nmi.c

diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c
index e88f37b58dddeeaecfb8951649db799986b7e247..de8d4b333f405ab875462ea49c9b2b2cf7d2400e 100644 (file)
--- a/arch/x86/kernel/nmi.c
+++ b/arch/x86/kernel/nmi.c
@@ -408,6 +408,18 @@ static notrace __kprobes void default_do_nmi(struct pt_regs *regs)
 dotraplinkage notrace __kprobes void
 do_nmi(struct pt_regs *regs, long error_code)
 {
+       int update_debug_stack = 0;
+
+       /*
+        * If we interrupted a breakpoint, it is possible that
+        * the nmi handler will have breakpoints too. We need to
+        * change the IDT such that breakpoints that happen here
+        * continue to use the NMI stack.
+        */
+       if (unlikely(is_debug_stack(regs->sp))) {
+               debug_stack_set_zero();
+               update_debug_stack = 1;
+       }
        nmi_enter();
 
        inc_irq_stat(__nmi_count);
@@ -416,6 +428,9 @@ do_nmi(struct pt_regs *regs, long error_code)
                default_do_nmi(regs);
 
        nmi_exit();
+
+       if (unlikely(update_debug_stack))
+               debug_stack_reset();
 }
 
 void stop_nmi(void)