[PATCH] ppc64: set SMT thread priority to medium for all exceptions

We need to set the thread priority to medium when entering all exceptions. 
We may have been executing in low priority (eg the idle loop), but
definitely do not want to remain in that priority for the duration of the
exception (eg a device interrupt).
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/ppc64/kernel/head.S

@@ -303,12 +303,14 @@ exception_marker:
 	. = n;						\
 	.globl label##_Pseries;				\
 label##_Pseries:					\
+	HMT_MEDIUM;					\
 	mtspr	SPRG1,r13;		/* save r13 */	\
 	EXCEPTION_PROLOG_PSERIES(PACA_EXGEN, label##_common)
 
 #define STD_EXCEPTION_ISERIES(n, label, area)		\
 	.globl label##_Iseries;				\
 label##_Iseries:					\
+	HMT_MEDIUM;					\
 	mtspr	SPRG1,r13;		/* save r13 */	\
 	EXCEPTION_PROLOG_ISERIES_1(area);		\
 	EXCEPTION_PROLOG_ISERIES_2;			\
@@ -317,6 +319,7 @@ label##_Iseries:					\
 #define MASKABLE_EXCEPTION_ISERIES(n, label)				\
 	.globl label##_Iseries;						\
 label##_Iseries:							\
+	HMT_MEDIUM;							\
 	mtspr	SPRG1,r13;		/* save r13 */			\
 	EXCEPTION_PROLOG_ISERIES_1(PACA_EXGEN);				\
 	lbz	r10,PACAPROFENABLED(r13);				\
@@ -410,12 +413,14 @@ __start_interrupts:
 
 	. = 0x200
 _MachineCheckPseries:
+	HMT_MEDIUM
 	mtspr	SPRG1,r13		/* save r13 */
 	EXCEPTION_PROLOG_PSERIES(PACA_EXMC, MachineCheck_common)
 
 	. = 0x300
 	.globl DataAccess_Pseries
 DataAccess_Pseries:
+	HMT_MEDIUM
 	mtspr	SPRG1,r13
 BEGIN_FTR_SECTION
 	mtspr	SPRG2,r12
@@ -434,6 +439,7 @@ END_FTR_SECTION_IFCLR(CPU_FTR_SLB)
 	. = 0x380
 	.globl DataAccessSLB_Pseries
 DataAccessSLB_Pseries:
+	HMT_MEDIUM
 	mtspr	SPRG1,r13
 	mfspr	r13,SPRG3		/* get paca address into r13 */
 	std	r9,PACA_EXSLB+EX_R9(r13)	/* save r9 - r12 */
@@ -461,6 +467,7 @@ DataAccessSLB_Pseries:
 	. = 0x480
 	.globl InstructionAccessSLB_Pseries
 InstructionAccessSLB_Pseries:
+	HMT_MEDIUM
 	mtspr	SPRG1,r13
 	mfspr	r13,SPRG3		/* get paca address into r13 */
 	std	r9,PACA_EXSLB+EX_R9(r13)	/* save r9 - r12 */
@@ -494,6 +501,7 @@ InstructionAccessSLB_Pseries:
 	. = 0xc00
 	.globl	SystemCall_Pseries
 SystemCall_Pseries:
+	HMT_MEDIUM
 	mr	r9,r13
 	mfmsr	r10
 	mfspr	r13,SPRG3
@@ -747,10 +755,12 @@ fwnmi_data_area:
 	. = 0x8000
 	.globl SystemReset_FWNMI
 SystemReset_FWNMI:
+	HMT_MEDIUM
 	mtspr	SPRG1,r13		/* save r13 */
 	EXCEPTION_PROLOG_PSERIES(PACA_EXGEN, SystemReset_common)
 	.globl MachineCheck_FWNMI
 MachineCheck_FWNMI:
+	HMT_MEDIUM
 	mtspr	SPRG1,r13		/* save r13 */
 	EXCEPTION_PROLOG_PSERIES(PACA_EXMC, MachineCheck_common)