powerpc/book3s: Split the common exception prolog logic into two section.

This patch splits the common exception prolog logic into three parts to
facilitate reuse of existing code in the next patch. This patch also
re-arranges few instructions in such a way that the second part now deals
with saving register values from paca save area to stack frame, and
the third part deals with saving current register values to stack frame.

The second and third part will be reused in the machine check exception
routine in the subsequent patch.

Please note that this patch does not introduce or change existing code
logic. Instead it is just a code movement and instruction re-ordering.

Patch Acked-by Paul. But made some minor modification (explained above) to
address Paul's comment in the later patch(3).

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

1 files changed, 14 insertions, 7 deletions

diff --git a/arch/powerpc/include/asm/exception-64s.h b/arch/powerpc/include/asm/exception-64s.h
index 894662a5d4d5..ff4e2e80856d 100644
--- a/arch/powerpc/include/asm/exception-64s.h
+++ b/arch/powerpc/include/asm/exception-64s.h
@@ -301,9 +301,12 @@ do_kvm_##n:								\
         beq     4f;                     /* if from kernel mode          */ \
         ACCOUNT_CPU_USER_ENTRY(r9, r10);                                   \
         SAVE_PPR(area, r9, r10);                                           \
-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    */ \
+4:      EXCEPTION_PROLOG_COMMON_2(area)                                    \
+        EXCEPTION_PROLOG_COMMON_3(n)                                       \
+        ACCOUNT_STOLEN_TIME
+
+/* Save original regs values from save area to stack frame. */
+#define EXCEPTION_PROLOG_COMMON_2(area)                                    \
         ld      r9,area+EX_R9(r13);     /* move r9, r10 to stackframe   */ \
         ld      r10,area+EX_R10(r13);                                      \
         std     r9,GPR9(r1);                                               \
@@ -318,11 +321,16 @@ do_kvm_##n:								\
         ld      r10,area+EX_CFAR(r13);                                     \
         std     r10,ORIG_GPR3(r1);                                         \
         END_FTR_SECTION_NESTED(CPU_FTR_CFAR, CPU_FTR_CFAR, 66);            \
+        GET_CTR(r10, area);                                                \
+        std     r10,_CTR(r1);
+
+#define EXCEPTION_PROLOG_COMMON_3(n)                                       \
+        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    */ \
         mflr    r9;                     /* Get LR, later save to stack  */ \
         ld      r2,PACATOC(r13);        /* get kernel TOC into r2       */ \
         std     r9,_LINK(r1);                                              \
-        GET_CTR(r10, area);                                                \
-        std     r10,_CTR(r1);                                              \
         lbz     r10,PACASOFTIRQEN(r13);                            \
         mfspr   r11,SPRN_XER;           /* save XER in stackframe       */ \
         std     r10,SOFTE(r1);                                             \
@@ -332,8 +340,7 @@ do_kvm_##n:								\
         li      r10,0;                                                     \
         ld      r11,exception_marker@toc(r2);                              \
         std     r10,RESULT(r1);         /* clear regs->result           */ \
-        std     r11,STACK_FRAME_OVERHEAD-16(r1); /* mark the frame      */ \
-        ACCOUNT_STOLEN_TIME
+        std     r11,STACK_FRAME_OVERHEAD-16(r1); /* mark the frame      */
 
 /*
  * Exception vectors.