powerpc/64e: Clarify register saves and clears with {SAVE,ZEROIZE}_GPRS

The common interrupt handler prologue macro and the bad_stack
trampolines include consecutive sequences of register saves, and some
register clears. Neaten such instances by expanding use of the SAVE_GPRS
macro and employing the ZEROIZE_GPR macro when appropriate.

Also simplify an invocation of SAVE_GPRS targetting all non-volatile
registers to SAVE_NVGPRS.

Signed-off-by: Rohan McLure <rmclure@linux.ibm.com>
Reported-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220921065605.1051927-7-rmclure@linux.ibm.com

diff --git a/arch/powerpc/kernel/exceptions-64e.S b/arch/powerpc/kernel/exceptions-64e.S
index 3afba070a5d81ec464db55017dbf12c2abd19ccb..d6b7aa0229beb28c57de4a08c4d7d5808e8a16b1 100644 (file)
--- a/arch/powerpc/kernel/exceptions-64e.S
+++ b/arch/powerpc/kernel/exceptions-64e.S
@@ -216,17 +216,15 @@ END_FTR_SECTION_IFSET(CPU_FTR_EMB_HV)
        mtlr    r10
        mtcr    r11
 
-       ld      r10,GPR10(r1)
-       ld      r11,GPR11(r1)
-       ld      r12,GPR12(r1)
+       REST_GPRS(10, 12, r1)
        mtspr   \scratch,r0
 
        std     r10,\paca_ex+EX_R10(r13);
        std     r11,\paca_ex+EX_R11(r13);
        ld      r10,_NIP(r1)
        ld      r11,_MSR(r1)
-       ld      r0,GPR0(r1)
-       ld      r1,GPR1(r1)
+       REST_GPR(0, r1)
+       REST_GPR(1, r1)
        mtspr   \srr0,r10
        mtspr   \srr1,r11
        ld      r10,\paca_ex+EX_R10(r13)
@@ -364,16 +362,15 @@ ret_from_mc_except:
 /* Core exception code for all exceptions except TLB misses. */
 #define EXCEPTION_COMMON_LVL(n, scratch, excf)                             \
 exc_##n##_common:                                                          \
-       std     r0,GPR0(r1);            /* save r0 in stackframe */         \
-       std     r2,GPR2(r1);            /* save r2 in stackframe */         \
-       SAVE_GPRS(3, 9, r1);            /* save r3 - r9 in stackframe */    \
+       SAVE_GPR(0, r1);                /* save r0 in stackframe */         \
+       SAVE_GPRS(2, 9, r1);            /* save r2 - 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 */           \
 2:     ld      r3,excf+EX_R10(r13);    /* get back r10 */                  \
        ld      r4,excf+EX_R11(r13);    /* get back r11 */                  \
        mfspr   r5,scratch;             /* get back r13 */                  \
-       std     r12,GPR12(r1);          /* save r12 in stackframe */        \
+       SAVE_GPR(12, r1);               /* save r12 in stackframe */        \
        ld      r2,PACATOC(r13);        /* get kernel TOC into r2 */        \
        mflr    r6;                     /* save LR in stackframe */         \
        mfctr   r7;                     /* save CTR in stackframe */        \
@@ -382,7 +379,7 @@ exc_##n##_common:                                                       \
        lwz     r10,excf+EX_CR(r13);    /* load orig CR back from PACA  */  \
        lbz     r11,PACAIRQSOFTMASK(r13); /* get current IRQ softe */       \
        ld      r12,exception_marker@toc(r2);                               \
-       li      r0,0;                                                       \
+       ZEROIZE_GPR(0);                                                     \
        std     r3,GPR10(r1);           /* save r10 to stackframe */        \
        std     r4,GPR11(r1);           /* save r11 to stackframe */        \
        std     r5,GPR13(r1);           /* save it to stackframe */         \
@@ -1048,15 +1045,14 @@ bad_stack_book3e:
        mfspr   r11,SPRN_ESR
        std     r10,_DEAR(r1)
        std     r11,_ESR(r1)
-       std     r0,GPR0(r1);            /* save r0 in stackframe */         \
-       std     r2,GPR2(r1);            /* save r2 in stackframe */         \
-       SAVE_GPRS(3, 9, r1);            /* save r3 - r9 in stackframe */    \
+       SAVE_GPR(0, r1);                /* save r0 in stackframe */         \
+       SAVE_GPRS(2, 9, r1);            /* save r2 - r9 in stackframe */    \
        ld      r3,PACA_EXGEN+EX_R10(r13);/* get back r10 */                \
        ld      r4,PACA_EXGEN+EX_R11(r13);/* get back r11 */                \
        mfspr   r5,SPRN_SPRG_GEN_SCRATCH;/* get back r13 XXX can be wrong */ \
        std     r3,GPR10(r1);           /* save r10 to stackframe */        \
        std     r4,GPR11(r1);           /* save r11 to stackframe */        \
-       std     r12,GPR12(r1);          /* save r12 in stackframe */        \
+       SAVE_GPR(12, r1);               /* save r12 in stackframe */        \
        std     r5,GPR13(r1);           /* save it to stackframe */         \
        mflr    r10
        mfctr   r11
@@ -1064,12 +1060,12 @@ bad_stack_book3e:
        std     r10,_LINK(r1)
        std     r11,_CTR(r1)
        std     r12,_XER(r1)
-       SAVE_GPRS(14, 31, r1)
+       SAVE_NVGPRS(r1)
        lhz     r12,PACA_TRAP_SAVE(r13)
        std     r12,_TRAP(r1)
        addi    r11,r1,INT_FRAME_SIZE
        std     r11,0(r1)
-       li      r12,0
+       ZEROIZE_GPR(12)
        std     r12,0(r11)
        ld      r2,PACATOC(r13)
 1:     addi    r3,r1,STACK_FRAME_OVERHEAD