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[PATCH] x86_64: Fix backtracing for interrupt stacks 

Re-add backlink for old style unwinder to stack switching.  Add proper
stack frame and CFI annotations to call_softirq

This prevents a oops when backtracing with fallback through the
interrupt stack top.

Suggested by Jan Beulich and Herbert Xu wanted it in 2.6.18.

Cc: jbeulich@novell.com
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Andi Kleen 2006-08-02 22:37:28 +02:00 committed by Linus Torvalds
parent ae74c3b69a
commit 2699500b31
1 changed files with 11 additions and 7 deletions
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18
arch/x86_64/kernel/entry.S
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@ -513,6 +513,7 @@ END(stub_rt_sigreturn)
swapgs
1: incl %gs:pda_irqcount # RED-PEN should check preempt count
cmoveq %gs:pda_irqstackptr,%rsp
push %rbp # backlink for old unwinder
/*
* We entered an interrupt context - irqs are off:
*/
@ -1139,18 +1140,21 @@ ENTRY(machine_check)
END(machine_check)
#endif
/* Call softirq on interrupt stack. Interrupts are off. */
ENTRY(call_softirq)
CFI_STARTPROC
movq %gs:pda_irqstackptr,%rax
movq %rsp,%rdx
CFI_DEF_CFA_REGISTER rdx
push %rbp
CFI_ADJUST_CFA_OFFSET 8
CFI_REL_OFFSET rbp,0
mov %rsp,%rbp
CFI_DEF_CFA_REGISTER rbp
incl %gs:pda_irqcount
cmove %rax,%rsp
pushq %rdx
/*todo CFI_DEF_CFA_EXPRESSION ...*/
cmove %gs:pda_irqstackptr,%rsp
push %rbp # backlink for old unwinder
call __do_softirq
popq %rsp
leaveq
CFI_DEF_CFA_REGISTER rsp
CFI_ADJUST_CFA_OFFSET -8
decl %gs:pda_irqcount
ret
CFI_ENDPROC