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[PATCH] x86_64: Fix backtracing for interrupt stacks

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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 swapgs
1: incl %gs:pda_irqcount # RED-PEN should check preempt count 1: incl %gs:pda_irqcount # RED-PEN should check preempt count
cmoveq %gs:pda_irqstackptr,%rsp cmoveq %gs:pda_irqstackptr,%rsp
push %rbp # backlink for old unwinder
/* /*
* We entered an interrupt context - irqs are off: * We entered an interrupt context - irqs are off:
*/ */
@ -1139,18 +1140,21 @@ ENTRY(machine_check)
END(machine_check) END(machine_check)
#endif #endif
/* Call softirq on interrupt stack. Interrupts are off. */
ENTRY(call_softirq) ENTRY(call_softirq)
CFI_STARTPROC CFI_STARTPROC
movq %gs:pda_irqstackptr,%rax push %rbp
movq %rsp,%rdx CFI_ADJUST_CFA_OFFSET 8
CFI_DEF_CFA_REGISTER rdx CFI_REL_OFFSET rbp,0
mov %rsp,%rbp
CFI_DEF_CFA_REGISTER rbp
incl %gs:pda_irqcount incl %gs:pda_irqcount
cmove %rax,%rsp cmove %gs:pda_irqstackptr,%rsp
pushq %rdx push %rbp # backlink for old unwinder
/*todo CFI_DEF_CFA_EXPRESSION ...*/
call __do_softirq call __do_softirq
popq %rsp leaveq
CFI_DEF_CFA_REGISTER rsp CFI_DEF_CFA_REGISTER rsp
CFI_ADJUST_CFA_OFFSET -8
decl %gs:pda_irqcount decl %gs:pda_irqcount
ret ret
CFI_ENDPROC CFI_ENDPROC