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Subject[PATCH v6 09/20] 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 beginning 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 | 58 ++++++++++++++++++++----------------------
1 file changed, 28 insertions(+), 30 deletions(-)

diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index 3b67b9533c82..c203defe49a4 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.
@@ -384,17 +401,16 @@ InstructionTLBMiss:

#ifdef CONFIG_PERF_EVENTS
patch_site 0f, patch__itlbmiss_perf
-0: 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
+0: 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
#if defined(ITLB_MISS_KERNEL) || defined(CONFIG_HUGETLB_PAGE)
mfspr r12, SPRN_SPRG_SCRATCH2
#endif
rfi
+#endif

#ifdef CONFIG_HUGETLB_PAGE
10: /* 8M pages */
@@ -509,15 +525,14 @@ DataStoreTLBMiss:

#ifdef CONFIG_PERF_EVENTS
patch_site 0f, patch__dtlbmiss_perf
-0: 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
+0: 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
mfspr r12, SPRN_SPRG_SCRATCH2
rfi
+#endif

#ifdef CONFIG_HUGETLB_PAGE
10: /* 8M pages */
@@ -625,16 +640,13 @@ 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)
@@ -1065,17 +1077,3 @@ 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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