From: Jan Beulich <jbeulich@novell.com>
Date: Wed, 11 Jan 2006 21:43:21 +0000 (+0100)
Subject: [PATCH] x86_64: fix page fault from show_trace()
X-Git-Tag: v2.6.16-rc1~361
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=bd9cb64df1d99c07ea9672661ede6ca3ba5c6579;p=linux-2.6

[PATCH] x86_64: fix page fault from show_trace()

The introduction of call_softirq switching to the interrupt stack several
releases earlier resulted in a problem with the code in show_trace, which
assumes that it can pick the previous stack pointer from the end of the
interrupt stack.

Cc: Andi Kleen <ak@muc.de>
Cc: Arjan van de Ven <arjanv@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---

diff --git a/arch/x86_64/kernel/entry.S b/arch/x86_64/kernel/entry.S
index 28b3c8e6b0..45e0ab8a1f 100644
--- a/arch/x86_64/kernel/entry.S
+++ b/arch/x86_64/kernel/entry.S
@@ -1045,17 +1045,15 @@ ENTRY(call_debug)
 ENTRY(call_softirq)
 	CFI_STARTPROC
 	movq %gs:pda_irqstackptr,%rax
-	pushq %r15
-	CFI_ADJUST_CFA_OFFSET 8
-	movq %rsp,%r15
-	CFI_DEF_CFA_REGISTER	r15
+	movq %rsp,%rdx
+	CFI_DEF_CFA_REGISTER	rdx
 	incl %gs:pda_irqcount
 	cmove %rax,%rsp
+	pushq %rdx
+	/*todo CFI_DEF_CFA_EXPRESSION ...*/
 	call __do_softirq
-	movq %r15,%rsp
+	popq %rsp
 	CFI_DEF_CFA_REGISTER	rsp
 	decl %gs:pda_irqcount
-	popq %r15
-	CFI_ADJUST_CFA_OFFSET -8
 	ret
 	CFI_ENDPROC