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powerpc: Fix register clobbering when accumulating stolen time 

When running under a hypervisor that supports stolen time accounting,
we may call C code from the macro EXCEPTION_PROLOG_COMMON in the
exception entry path, which clobbers CR0.

However, the FPU and vector traps rely on CR0 indicating whether we
are coming from userspace or kernel to decide what to do.

So we need to restore that value after the C call

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Benjamin Herrenschmidt 2012-03-02 11:01:31 +11:00
parent 7ac21cd465
commit 990118c84b
1 changed files with 2 additions and 0 deletions
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2
arch/powerpc/include/asm/ppc_asm.h
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@ -60,6 +60,8 @@ BEGIN_FW_FTR_SECTION; \
cmpd cr1,r11,r10; \
beq+ cr1,33f; \
bl .accumulate_stolen_time; \
ld r12,_MSR(r1); \
andi. r10,r12,MSR_PR; /* Restore cr0 (coming from user) */ \
33: \
END_FW_FTR_SECTION_IFSET(FW_FEATURE_SPLPAR)