SCRATCH0 and SCRATCH1 are only used in Exceptions prologs where no other
exception can happen. There is therefore no need to preserve them accross
TLB handlers, we can use them there as in other exceptions. One of the
advantages is that they do not suffer CPU6 errata unlike M_TW register.
Signed-off-by: Christophe Leroy <christophe.le...@c-s.fr>
---
Changes in v2:
- None
Changes in v3:
- None
arch/powerpc/kernel/head_8xx.S | 104 ++++++++++++----------------------
1 files changed, 36 insertions(+), 68 deletions(-)
diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index 1329c5a..3af6db1 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -104,12 +104,15 @@ turn_on_mmu:
* task's thread_struct.
*/
#define EXCEPTION_PROLOG \
- mtspr SPRN_SPRG_SCRATCH0,r10; \
- mtspr SPRN_SPRG_SCRATCH1,r11; \
- mfcr r10; \
+ EXCEPTION_PROLOG_0; \
EXCEPTION_PROLOG_1; \
EXCEPTION_PROLOG_2
+#define EXCEPTION_PROLOG_0 \
+ mtspr SPRN_SPRG_SCRATCH0,r10; \
+ mtspr SPRN_SPRG_SCRATCH1,r11; \
+ mfcr r10
+
#define EXCEPTION_PROLOG_1 \
mfspr r11,SPRN_SRR1; /* check whether user or kernel */ \
andi. r11,r11,MSR_PR; \
@@ -145,6 +148,14 @@ turn_on_mmu:
SAVE_2GPRS(7, r11)
/*
+ * Exception exit code.
+ */
+#define EXCEPTION_EPILOG_0 \
+ mtcr r10; \
+ mfspr r10,SPRN_SPRG_SCRATCH0; \
+ mfspr r11,SPRN_SPRG_SCRATCH1
+
+/*
* Note: code which follows this uses cr0.eq (set if from kernel),
* r11, r12 (SRR0), and r9 (SRR1).
*
@@ -293,16 +304,8 @@ InstructionTLBMiss:
#ifdef CONFIG_8xx_CPU6
stw r3, 8(r0)
#endif
- DO_8xx_CPU6(0x3f80, r3)
- mtspr SPRN_M_TW, r10 /* Save a couple of working registers */
- mfcr r10
-#ifdef CONFIG_8xx_CPU6
- stw r10, 0(r0)
- stw r11, 4(r0)
-#else
- mtspr SPRN_DAR, r10
- mtspr SPRN_SPRG_SCRATCH2, r11
-#endif
+ EXCEPTION_PROLOG_0
+ mtspr SPRN_SPRG_SCRATCH2, r10
mfspr r10, SPRN_SRR0 /* Get effective address of fault */
#ifdef CONFIG_8xx_CPU15
addi r11, r10, 0x1000
@@ -359,18 +362,11 @@ InstructionTLBMiss:
mtspr SPRN_MI_RPN, r10 /* Update TLB entry */
/* Restore registers */
-#ifndef CONFIG_8xx_CPU6
- mfspr r10, SPRN_DAR
- mtcr r10
- mtspr SPRN_DAR, r11 /* Tag DAR */
- mfspr r11, SPRN_SPRG_SCRATCH2
-#else
- lwz r11, 0(r0)
- mtcr r11
- lwz r11, 4(r0)
+#ifdef CONFIG_8xx_CPU6
lwz r3, 8(r0)
#endif
- mfspr r10, SPRN_M_TW
+ mfspr r10, SPRN_SPRG_SCRATCH2
+ EXCEPTION_EPILOG_0
rfi
2:
mfspr r11, SPRN_SRR1
@@ -381,19 +377,11 @@ InstructionTLBMiss:
mtspr SPRN_SRR1, r11
/* Restore registers */
-#ifndef CONFIG_8xx_CPU6
- mfspr r10, SPRN_DAR
- mtcr r10
- li r11, 0x00f0
- mtspr SPRN_DAR, r11 /* Tag DAR */
- mfspr r11, SPRN_SPRG_SCRATCH2
-#else
- lwz r11, 0(r0)
- mtcr r11
- lwz r11, 4(r0)
+#ifdef CONFIG_8xx_CPU6
lwz r3, 8(r0)
#endif
- mfspr r10, SPRN_M_TW
+ mfspr r10, SPRN_SPRG_SCRATCH2
+ EXCEPTION_EPILOG_0
b InstructionAccess
. = 0x1200
@@ -401,16 +389,8 @@ DataStoreTLBMiss:
#ifdef CONFIG_8xx_CPU6
stw r3, 8(r0)
#endif
- DO_8xx_CPU6(0x3f80, r3)
- mtspr SPRN_M_TW, r10 /* Save a couple of working registers */
- mfcr r10
-#ifdef CONFIG_8xx_CPU6
- stw r10, 0(r0)
- stw r11, 4(r0)
-#else
- mtspr SPRN_DAR, r10
- mtspr SPRN_SPRG_SCRATCH2, r11
-#endif
+ EXCEPTION_PROLOG_0
+ mtspr SPRN_SPRG_SCRATCH2, r10
mfspr r10, SPRN_M_TWB /* Get level 1 table entry address */
/* If we are faulting a kernel address, we have to use the
@@ -483,19 +463,12 @@ DataStoreTLBMiss:
mtspr SPRN_MD_RPN, r10 /* Update TLB entry */
/* Restore registers */
-#ifndef CONFIG_8xx_CPU6
- mfspr r10, SPRN_DAR
- mtcr r10
- mtspr SPRN_DAR, r11 /* Tag DAR */
- mfspr r11, SPRN_SPRG_SCRATCH2
-#else
- mtspr SPRN_DAR, r11 /* Tag DAR */
- lwz r11, 0(r0)
- mtcr r11
- lwz r11, 4(r0)
+#ifdef CONFIG_8xx_CPU6
lwz r3, 8(r0)
#endif
- mfspr r10, SPRN_M_TW
+ mtspr SPRN_DAR, r11 /* Tag DAR */
+ mfspr r10, SPRN_SPRG_SCRATCH2
+ EXCEPTION_EPILOG_0
rfi
/* This is an instruction TLB error on the MPC8xx. This could be due
@@ -519,23 +492,18 @@ DataTLBError:
#ifdef CONFIG_8xx_CPU6
stw r3, 8(r0)
#endif
- DO_8xx_CPU6(0x3f80, r3)
- mtspr SPRN_M_TW, r10 /* Save a couple of working registers */
- mfcr r10
- stw r10, 0(r0)
- stw r11, 4(r0)
+ EXCEPTION_PROLOG_0
+ mtspr SPRN_SPRG_SCRATCH2, r10
mfspr r10, SPRN_DAR
cmpwi cr0, r10, 0x00f0
beq- FixupDAR /* must be a buggy dcbX, icbi insn. */
DARFixed:/* Return from dcbx instruction bug workaround, r10 holds value of
DAR */
- mfspr r10, SPRN_M_TW /* Restore registers */
- lwz r11, 0(r0)
- mtcr r11
- lwz r11, 4(r0)
#ifdef CONFIG_8xx_CPU6
lwz r3, 8(r0)
#endif
+ mfspr r10,SPRN_SPRG_SCRATCH2
+ EXCEPTION_EPILOG_0
b DataAccess
EXCEPTION(0x1500, Trap_15, unknown_exception, EXC_XFER_EE)
@@ -619,8 +587,8 @@ FixupDAR:/* Entry point for dcbx workaround. */
stw r11,0(r10) /* store add/and instruction */
dcbf 0,r10 /* flush new instr. to memory. */
icbi 0,r10 /* invalidate instr. cache line */
- lwz r11, 4(r0) /* restore r11 from memory */
- mfspr r10, SPRN_M_TW /* restore r10 from M_TW */
+ mfspr r11, SPRN_SPRG_SCRATCH1 /* restore r11 */
+ mfspr r10, SPRN_SPRG_SCRATCH0 /* restore r10 */
isync /* Wait until new instr is loaded from memory */
modified_instr:
.space 4 /* this is where the add instr. is stored */
@@ -683,9 +651,9 @@ modified_instr:
b DARFixed /* Go back to normal TLB handling */
/* special handling for r10,r11 since these are modified already */
-153: lwz r11, 4(r0) /* load r11 from memory */
+153: mfspr r11, SPRN_SPRG_SCRATCH1 /* load r11 from SPRN_SPRG_SCRATCH1 */
b 155f
-154: mfspr r11, SPRN_M_TW /* load r10 from M_TW */
+154: mfspr r11, SPRN_SPRG_SCRATCH0 /* load r10 from SPRN_SPRG_SCRATCH0 */
155: add r10, r10, r11 /* add it */
mfctr r11 /* restore r11 */
b 151b
--
1.7.1
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