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Subject[PATCH v2 14/14] powerpc/8xx: Move SW perf counters in first 32kb of memory
Date
In order to simplify time critical exceptions handling 8xx
specific SW perf counters, this patch moves the counters into
the begining of memory. This is possible because .text is readable
and the counters are never modified outside of the handlers.

By doing this, we avoid having to set a second register with
the upper part of the address of the counters.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
arch/powerpc/kernel/head_8xx.S | 75 +++++++++++++++++++-----------------------
1 file changed, 34 insertions(+), 41 deletions(-)

diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index f65bd6fd1572..765fc4970c9c 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -106,6 +106,23 @@ turn_on_mmu:
mtspr SPRN_SRR0,r0
rfi /* enables MMU */

+
+#ifdef CONFIG_PERF_EVENTS
+ .align 4
+
+ .globl itlb_miss_counter
+itlb_miss_counter:
+ .space 4
+
+ .globl dtlb_miss_counter
+dtlb_miss_counter:
+ .space 4
+
+ .globl instruction_counter
+instruction_counter:
+ .space 4
+#endif
+
/*
* Exception entry code. This code runs with address translation
* turned off, i.e. using physical addresses.
@@ -368,25 +385,20 @@ _ENTRY(ITLBMiss_cmp)
mtspr SPRN_MI_RPN, r10 /* Update TLB entry */

/* Restore registers */
-_ENTRY(itlb_miss_exit_1)
- mfspr r10, SPRN_SPRG_SCRATCH0
#if defined(ITLB_MISS_KERNEL) || defined(CONFIG_SWAP)
mfspr r11, SPRN_SPRG_SCRATCH1
#endif
+_ENTRY(itlb_miss_exit_1)
+ mfspr r10, SPRN_SPRG_SCRATCH0
rfi
#ifdef CONFIG_PERF_EVENTS
_ENTRY(itlb_miss_perf)
-#if !defined(ITLB_MISS_KERNEL) && !defined(CONFIG_SWAP)
- mtspr SPRN_SPRG_SCRATCH1, r11
-#endif
- lis r10, (itlb_miss_counter - PAGE_OFFSET)@ha
- lwz r11, (itlb_miss_counter - PAGE_OFFSET)@l(r10)
- addi r11, r11, 1
- stw r11, (itlb_miss_counter - PAGE_OFFSET)@l(r10)
-#endif
+ lwz r10, (itlb_miss_counter - PAGE_OFFSET)@l(0)
+ addi r10, r10, 1
+ stw r10, (itlb_miss_counter - PAGE_OFFSET)@l(0)
mfspr r10, SPRN_SPRG_SCRATCH0
- mfspr r11, SPRN_SPRG_SCRATCH1
rfi
+#endif

#ifndef CONFIG_PIN_TLB_TEXT
ITLBMissLinear:
@@ -399,9 +411,9 @@ ITLBMissLinear:
_PAGE_PRESENT
mtspr SPRN_MI_RPN, r10 /* Update TLB entry */

+ mfspr r11, SPRN_SPRG_SCRATCH1
_ENTRY(itlb_miss_exit_2)
mfspr r10, SPRN_SPRG_SCRATCH0
- mfspr r11, SPRN_SPRG_SCRATCH1
rfi
#endif

@@ -465,20 +477,18 @@ _ENTRY(DTLBMiss_jmp)

/* Restore registers */
mtspr SPRN_DAR, r11 /* Tag DAR */
+ mfspr r11, SPRN_SPRG_SCRATCH1
_ENTRY(dtlb_miss_exit_1)
mfspr r10, SPRN_SPRG_SCRATCH0
- mfspr r11, SPRN_SPRG_SCRATCH1
rfi
#ifdef CONFIG_PERF_EVENTS
_ENTRY(dtlb_miss_perf)
- lis r10, (dtlb_miss_counter - PAGE_OFFSET)@ha
- lwz r11, (dtlb_miss_counter - PAGE_OFFSET)@l(r10)
- addi r11, r11, 1
- stw r11, (dtlb_miss_counter - PAGE_OFFSET)@l(r10)
-#endif
+ lwz r10, (dtlb_miss_counter - PAGE_OFFSET)@l(0)
+ addi r10, r10, 1
+ stw r10, (dtlb_miss_counter - PAGE_OFFSET)@l(0)
mfspr r10, SPRN_SPRG_SCRATCH0
- mfspr r11, SPRN_SPRG_SCRATCH1
rfi
+#endif

DTLBMissIMMR:
mtcr r11
@@ -493,9 +503,9 @@ DTLBMissIMMR:

li r11, RPN_PATTERN
mtspr SPRN_DAR, r11 /* Tag DAR */
+ mfspr r11, SPRN_SPRG_SCRATCH1
_ENTRY(dtlb_miss_exit_2)
mfspr r10, SPRN_SPRG_SCRATCH0
- mfspr r11, SPRN_SPRG_SCRATCH1
rfi

DTLBMissLinear:
@@ -510,9 +520,9 @@ DTLBMissLinear:

li r11, RPN_PATTERN
mtspr SPRN_DAR, r11 /* Tag DAR */
+ mfspr r11, SPRN_SPRG_SCRATCH1
_ENTRY(dtlb_miss_exit_3)
mfspr r10, SPRN_SPRG_SCRATCH0
- mfspr r11, SPRN_SPRG_SCRATCH1
rfi

/* This is an instruction TLB error on the MPC8xx. This could be due
@@ -598,16 +608,13 @@ DataBreakpoint:
. = 0x1d00
InstructionBreakpoint:
mtspr SPRN_SPRG_SCRATCH0, r10
- mtspr SPRN_SPRG_SCRATCH1, r11
- lis r10, (instruction_counter - PAGE_OFFSET)@ha
- lwz r11, (instruction_counter - PAGE_OFFSET)@l(r10)
- addi r11, r11, -1
- stw r11, (instruction_counter - PAGE_OFFSET)@l(r10)
+ lwz r10, (instruction_counter - PAGE_OFFSET)@l(0)
+ addi r10, r10, -1
+ stw r10, (instruction_counter - PAGE_OFFSET)@l(0)
lis r10, 0xffff
ori r10, r10, 0x01
mtspr SPRN_COUNTA, r10
mfspr r10, SPRN_SPRG_SCRATCH0
- mfspr r11, SPRN_SPRG_SCRATCH1
rfi
#else
EXCEPTION(0x1d00, Trap_1d, unknown_exception, EXC_XFER_EE)
@@ -966,17 +973,3 @@ swapper_pg_dir:
*/
abatron_pteptrs:
.space 8
-
-#ifdef CONFIG_PERF_EVENTS
- .globl itlb_miss_counter
-itlb_miss_counter:
- .space 4
-
- .globl dtlb_miss_counter
-dtlb_miss_counter:
- .space 4
-
- .globl instruction_counter
-instruction_counter:
- .space 4
-#endif
--
2.13.3
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