powerpc: Move branch instruction from ACCOUNT_CPU_USER_ENTRY to caller

[PATCH 1/6] powerpc: Move branch instruction from ACCOUNT_CPU_USER_ENTRY to caller

The first instruction in ACCOUNT_CPU_USER_ENTRY is 'beq' which checks for
exceptions coming from kernel mode. PPR value will be saved immediately after
ACCOUNT_CPU_USER_ENTRY and is also for user level exceptions. So moved this
branch instruction in the caller code.

Signed-off-by: Haren Myneni <haren@us.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/include/asm/exception-64s.h

@@ -224,8 +224,9 @@ do_kvm_##n:								\
 	std	r10,0(r1);		/* make stack chain pointer	*/ \
 	std	r0,GPR0(r1);		/* save r0 in stackframe	*/ \
 	std	r10,GPR1(r1);		/* save r1 in stackframe	*/ \
+	beq	4f;			/* if from kernel mode		*/ \
 	ACCOUNT_CPU_USER_ENTRY(r9, r10);				   \
-	std	r2,GPR2(r1);		/* save r2 in stackframe	*/ \
+4:	std	r2,GPR2(r1);		/* save r2 in stackframe	*/ \
 	SAVE_4GPRS(3, r1);		/* save r3 - r6 in stackframe	*/ \
 	SAVE_2GPRS(7, r1);		/* save r7, r8 in stackframe	*/ \
 	ld	r9,area+EX_R9(r13);	/* move r9, r10 to stackframe	*/ \

arch/powerpc/include/asm/ppc_asm.h

@@ -30,7 +30,6 @@
 #define ACCOUNT_STOLEN_TIME
 #else
 #define ACCOUNT_CPU_USER_ENTRY(ra, rb)					\
-	beq	2f;			/* if from kernel mode */	\
 	MFTB(ra);			/* get timebase */		\
 	ld	rb,PACA_STARTTIME_USER(r13);				\
 	std	ra,PACA_STARTTIME(r13);					\
@@ -38,7 +37,6 @@
 	ld	ra,PACA_USER_TIME(r13);					\
 	add	ra,ra,rb;		/* add on to user time */	\
 	std	ra,PACA_USER_TIME(r13);					\
-2:
 
 #define ACCOUNT_CPU_USER_EXIT(ra, rb)					\
 	MFTB(ra);			/* get timebase */		\

arch/powerpc/kernel/entry_64.S

@@ -62,8 +62,9 @@ system_call_common:
 	std	r12,_MSR(r1)
 	std	r0,GPR0(r1)
 	std	r10,GPR1(r1)
+	beq	2f			/* if from kernel mode */
 	ACCOUNT_CPU_USER_ENTRY(r10, r11)
-	std	r2,GPR2(r1)
+2:	std	r2,GPR2(r1)
 	std	r3,GPR3(r1)
 	mfcr	r2
 	std	r4,GPR4(r1)

arch/powerpc/kernel/exceptions-64e.S

@@ -159,8 +159,9 @@ exc_##n##_common:							    \
 	std	r9,GPR9(r1);		/* save r9 in stackframe */	    \
 	std	r10,_NIP(r1);		/* save SRR0 to stackframe */	    \
 	std	r11,_MSR(r1);		/* save SRR1 to stackframe */	    \
+	beq	2f;			/* if from kernel mode */	    \
 	ACCOUNT_CPU_USER_ENTRY(r10,r11);/* accounting (uses cr0+eq) */	    \
-	ld	r3,excf+EX_R10(r13);	/* get back r10 */		    \
+2:	ld	r3,excf+EX_R10(r13);	/* get back r10 */		    \
 	ld	r4,excf+EX_R11(r13);	/* get back r11 */		    \
 	mfspr	r5,SPRN_SPRG_GEN_SCRATCH;/* get back r13 */		    \
 	std	r12,GPR12(r1);		/* save r12 in stackframe */	    \