From 990118c84b3e90b2b5354b6e2acd961044d7fa12 Mon Sep 17 00:00:00 2001
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: Fri, 2 Mar 2012 11:01:31 +1100
Subject: [PATCH] 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>
---
 arch/powerpc/include/asm/ppc_asm.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/powerpc/include/asm/ppc_asm.h b/arch/powerpc/include/asm/ppc_asm.h
index 368f72f798087b..50f73aa2ba219a 100644
--- a/arch/powerpc/include/asm/ppc_asm.h
+++ b/arch/powerpc/include/asm/ppc_asm.h
@@ -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)
 
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