powerpc/book3s: Fix CFAR clobbering issue in machine check handler.

While checking powersaving mode in machine check handler at 0x200, we
clobber CFAR register. Fix it by saving and restoring it during beq/bgt.

Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

diff --git a/arch/powerpc/include/asm/exception-64s.h b/arch/powerpc/include/asm/exception-64s.h
index 66830618cc19b2f4b12a5b6cefa8d1663425187e..aeaa56cd9b5465100b00025c7a1da36b3d58e1c5 100644 (file)
--- a/arch/powerpc/include/asm/exception-64s.h
+++ b/arch/powerpc/include/asm/exception-64s.h
@@ -146,6 +146,14 @@ BEGIN_FTR_SECTION_NESTED(943)                                              \
        mfspr   ra,spr;                                                 \
 END_FTR_SECTION_NESTED(ftr,ftr,943)
 
+/*
+ * Set an SPR from a register if the CPU has the given feature
+ */
+#define OPT_SET_SPR(ra, spr, ftr)                                      \
+BEGIN_FTR_SECTION_NESTED(943)                                          \
+       mtspr   spr,ra;                                                 \
+END_FTR_SECTION_NESTED(ftr,ftr,943)
+
 /*
  * Save a register to the PACA if the CPU has the given feature
  */

diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index 38d507306a111dc40f06028c90d5014e2fedd817..4c34c3c827ad5be65a4f59381c9f485086662fe9 100644 (file)
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -164,13 +164,18 @@ BEGIN_FTR_SECTION
         */
        mfspr   r13,SPRN_SRR1
        rlwinm. r13,r13,47-31,30,31
+       OPT_GET_SPR(r13, SPRN_CFAR, CPU_FTR_CFAR)
        beq     9f
 
+       mfspr   r13,SPRN_SRR1
+       rlwinm. r13,r13,47-31,30,31
        /* waking up from powersave (nap) state */
        cmpwi   cr1,r13,2
        /* Total loss of HV state is fatal. let's just stay stuck here */
+       OPT_GET_SPR(r13, SPRN_CFAR, CPU_FTR_CFAR)
        bgt     cr1,.
 9:
+       OPT_SET_SPR(r13, SPRN_CFAR, CPU_FTR_CFAR)
 END_FTR_SECTION_IFSET(CPU_FTR_HVMODE | CPU_FTR_ARCH_206)
 #endif /* CONFIG_PPC_P7_NAP */
        EXCEPTION_PROLOG_0(PACA_EXMC)