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powerpc/ppc32/tracing: Add stack frame to calls of trace_hardirqs_on/off

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32-bit variant of the previous patch for 64-bit:

<<
    When an interrupt occurs in userspace, we can call trace_hardirqs_on/off()
    With one level stack. But if we have irqsoff tracing enabled,
    it checks both CALLER_ADDR0 and CALLER_ADDR1. The second call
    goes two stack frames up. If this is from user space, then there may
    not exist a second stack....
>>

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Steven Rostedt 2010-12-22 16:42:56 +00:00 committed by Benjamin Herrenschmidt
parent 3cb5f1a3e5
commit 06ca2188ec
1 changed files with 11 additions and 0 deletions
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11
arch/powerpc/kernel/entry_32.S
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@ -880,7 +880,18 @@ END_MMU_FTR_SECTION_IFSET(MMU_FTR_TYPE_47x)
*/
andi. r10,r9,MSR_EE
beq 1f
/*
* Since the ftrace irqsoff latency trace checks CALLER_ADDR1,
* which is the stack frame here, we need to force a stack frame
* in case we came from user space.
*/
stwu r1,-32(r1)
mflr r0
stw r0,4(r1)
stwu r1,-32(r1)
bl trace_hardirqs_on
lwz r1,0(r1)
lwz r1,0(r1)
lwz r9,_MSR(r1)
1:
#endif /* CONFIG_TRACE_IRQFLAGS */