powerpc: Use names rather than numbers for SPRGs (v2)

The kernel uses SPRG registers for various purposes, typically in
low level assembly code as scratch registers or to hold per-cpu
global infos such as the PACA or the current thread_info pointer.

We want to be able to easily shuffle the usage of those registers
as some implementations have specific constraints realted to some
of them, for example, some have userspace readable aliases, etc..
and the current choice isn't always the best.

This patch should not change any code generation, and replaces the
usage of SPRN_SPRGn everywhere in the kernel with a named replacement
and adds documentation next to the definition of the names as to
what those are used for on each processor family.

The only parts that still use the original numbers are bits of KVM
or suspend/resume code that just blindly needs to save/restore all
the SPRGs.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

2 files changed, 16 insertions, 16 deletions

diff --git a/arch/powerpc/platforms/iseries/exception.S b/arch/powerpc/platforms/iseries/exception.S
index 2f581521eb9..2b807597923 100644
--- a/arch/powerpc/platforms/iseries/exception.S
+++ b/arch/powerpc/platforms/iseries/exception.S
@@ -47,7 +47,7 @@ system_reset_iSeries:
         LOAD_REG_ADDR(r13, paca)
         mulli   r0,r23,PACA_SIZE
         add     r13,r13,r0
-        mtspr   SPRN_SPRG3,r13          /* Save it away for the future */
+        mtspr   SPRN_SPRG_PACA,r13      /* Save it away for the future */
         mfmsr   r24
         ori     r24,r24,MSR_RI
         mtmsrd  r24                     /* RI on */
@@ -116,7 +116,7 @@ iSeries_secondary_smp_loop:
 #endif /* CONFIG_SMP */
         li      r0,-1                   /* r0=-1 indicates a Hypervisor call */
         sc                              /* Invoke the hypervisor via a system call */
-        mfspr   r13,SPRN_SPRG3          /* Put r13 back ???? */
+        mfspr   r13,SPRN_SPRG_PACA      /* Put r13 back ???? */
         b       2b                      /* If SMP not configured, secondaries
                                          * loop forever */
 
@@ -126,9 +126,9 @@ iSeries_secondary_smp_loop:
 
         .globl data_access_iSeries
 data_access_iSeries:
-        mtspr   SPRN_SPRG1,r13
+        mtspr   SPRN_SPRG_SCRATCH0,r13
 BEGIN_FTR_SECTION
-        mtspr   SPRN_SPRG2,r12
+        mtspr   SPRN_SPRG_SCRATCH1,r12
         mfspr   r13,SPRN_DAR
         mfspr   r12,SPRN_DSISR
         srdi    r13,r13,60
@@ -137,7 +137,7 @@ BEGIN_FTR_SECTION
         cmpwi   r13,0x2c
         beq     .do_stab_bolted_iSeries
         mtcrf   0x80,r12
-        mfspr   r12,SPRN_SPRG2
+        mfspr   r12,SPRN_SPRG_SCRATCH1
 END_FTR_SECTION_IFCLR(CPU_FTR_SLB)
         EXCEPTION_PROLOG_1(PACA_EXGEN)
         EXCEPTION_PROLOG_ISERIES_1
@@ -145,15 +145,15 @@ END_FTR_SECTION_IFCLR(CPU_FTR_SLB)
 
 .do_stab_bolted_iSeries:
         mtcrf   0x80,r12
-        mfspr   r12,SPRN_SPRG2
+        mfspr   r12,SPRN_SPRG_SCRATCH1
         EXCEPTION_PROLOG_1(PACA_EXSLB)
         EXCEPTION_PROLOG_ISERIES_1
         b       .do_stab_bolted
 
         .globl  data_access_slb_iSeries
 data_access_slb_iSeries:
-        mtspr   SPRN_SPRG1,r13          /* save r13 */
-        mfspr   r13,SPRN_SPRG3          /* get paca address into r13 */
+        mtspr   SPRN_SPRG_SCRATCH0,r13  /* save r13 */
+        mfspr   r13,SPRN_SPRG_PACA      /* get paca address into r13 */
         std     r3,PACA_EXSLB+EX_R3(r13)
         mfspr   r3,SPRN_DAR
         std     r9,PACA_EXSLB+EX_R9(r13)
@@ -165,7 +165,7 @@ data_access_slb_iSeries:
         std     r10,PACA_EXSLB+EX_R10(r13)
         std     r11,PACA_EXSLB+EX_R11(r13)
         std     r12,PACA_EXSLB+EX_R12(r13)
-        mfspr   r10,SPRN_SPRG1
+        mfspr   r10,SPRN_SPRG_SCRATCH0
         std     r10,PACA_EXSLB+EX_R13(r13)
         ld      r12,PACALPPACAPTR(r13)
         ld      r12,LPPACASRR1(r12)
@@ -175,8 +175,8 @@ data_access_slb_iSeries:
 
         .globl  instruction_access_slb_iSeries
 instruction_access_slb_iSeries:
-        mtspr   SPRN_SPRG1,r13          /* save r13 */
-        mfspr   r13,SPRN_SPRG3          /* get paca address into r13 */
+        mtspr   SPRN_SPRG_SCRATCH0,r13  /* save r13 */
+        mfspr   r13,SPRN_SPRG_PACA      /* get paca address into r13 */
         std     r3,PACA_EXSLB+EX_R3(r13)
         ld      r3,PACALPPACAPTR(r13)
         ld      r3,LPPACASRR0(r3)       /* get SRR0 value */
@@ -189,7 +189,7 @@ instruction_access_slb_iSeries:
         std     r10,PACA_EXSLB+EX_R10(r13)
         std     r11,PACA_EXSLB+EX_R11(r13)
         std     r12,PACA_EXSLB+EX_R12(r13)
-        mfspr   r10,SPRN_SPRG1
+        mfspr   r10,SPRN_SPRG_SCRATCH0
         std     r10,PACA_EXSLB+EX_R13(r13)
         ld      r12,PACALPPACAPTR(r13)
         ld      r12,LPPACASRR1(r12)
@@ -200,7 +200,7 @@ slb_miss_user_iseries:
         std     r10,PACA_EXGEN+EX_R10(r13)
         std     r11,PACA_EXGEN+EX_R11(r13)
         std     r12,PACA_EXGEN+EX_R12(r13)
-        mfspr   r10,SPRG1
+        mfspr   r10,SPRG_SCRATCH0
         ld      r11,PACA_EXSLB+EX_R9(r13)
         ld      r12,PACA_EXSLB+EX_R3(r13)
         std     r10,PACA_EXGEN+EX_R13(r13)
@@ -221,7 +221,7 @@ slb_miss_user_iseries:
         .globl  system_call_iSeries
 system_call_iSeries:
         mr      r9,r13
-        mfspr   r13,SPRN_SPRG3
+        mfspr   r13,SPRN_SPRG_PACA
         EXCEPTION_PROLOG_ISERIES_1
         b       system_call_common
 
diff --git a/arch/powerpc/platforms/iseries/exception.h b/arch/powerpc/platforms/iseries/exception.h
index e26eb86ac73..bae3fba5ad8 100644
--- a/arch/powerpc/platforms/iseries/exception.h
+++ b/arch/powerpc/platforms/iseries/exception.h
@@ -38,7 +38,7 @@
         .globl label##_iSeries;                                         \
 label##_iSeries:                                                        \
         HMT_MEDIUM;                                                     \
-        mtspr   SPRN_SPRG1,r13;         /* save r13 */                  \
+        mtspr   SPRN_SPRG_SCRATCH0,r13; /* save r13 */                  \
         EXCEPTION_PROLOG_1(area);                                       \
         EXCEPTION_PROLOG_ISERIES_1;                                     \
         b       label##_common
@@ -47,7 +47,7 @@ label##_iSeries:							\
         .globl label##_iSeries;                                         \
 label##_iSeries:                                                        \
         HMT_MEDIUM;                                                     \
-        mtspr   SPRN_SPRG1,r13;         /* save r13 */                  \
+        mtspr   SPRN_SPRG_SCRATCH0,r13; /* save r13 */                  \
         EXCEPTION_PROLOG_1(PACA_EXGEN);                                 \
         lbz     r10,PACASOFTIRQEN(r13);                                 \
         cmpwi   0,r10,0;                                                \