* [PATCH v4 3/5] powerpc/8xx: dont save CR in SCRATCH registers
@ 2015-02-04 14:49 ` Christophe Leroy
0 siblings, 0 replies; 2+ messages in thread
From: Christophe Leroy @ 2015-02-04 14:49 UTC (permalink / raw)
To: Benjamin Herrenschmidt, Paul Mackerras, Michael Ellerman, scottwood
Cc: linux-kernel, linuxppc-dev, Joakim Tjernlund
CR only needs to be preserved when checking if we are handling a kernel address.
So we can preserve CR in a register:
- In ITLBMiss, check is done only when CONFIG_MODULES is defined. Otherwise we
don't need to do anything at all with CR.
- We use r10, then we reload SRR0/MD_EPN into r10 when CR is restored
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
v2: removed the CPU6 specific handling of CR which was saving (only) 1 cycle but
was making the code more difficult to maintain due to too many different cases
v3: no change (but impacted by patch 07)
v4: Respined against scootwood.git next (0dc294f7)
arch/powerpc/kernel/head_8xx.S | 29 +++++++++++++++--------------
1 file changed, 15 insertions(+), 14 deletions(-)
diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index 5a69c5e..150d03f 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -312,10 +312,6 @@ InstructionTLBMiss:
mtspr SPRN_DAR, r3
#endif
EXCEPTION_PROLOG_0
- mfcr r10
- mtspr SPRN_SPRG_SCRATCH2, r10
- mfspr r10, SPRN_SRR0 /* Get effective address of fault */
- INVALIDATE_ADJACENT_PAGES_CPU15(r11, r10)
/* If we are faulting a kernel address, we have to use the
* kernel page tables.
@@ -323,13 +319,20 @@ InstructionTLBMiss:
#ifdef CONFIG_MODULES
/* Only modules will cause ITLB Misses as we always
* pin the first 8MB of kernel memory */
- andis. r11, r10, 0x8000 /* Address >= 0x80000000 */
-#endif
+ mfspr r11, SPRN_SRR0 /* Get effective address of fault */
+ INVALIDATE_ADJACENT_PAGES_CPU15(r10, r11)
+ mfcr r10
+ andis. r11, r11, 0x8000 /* Address >= 0x80000000 */
mfspr r11, SPRN_M_TW /* Get level 1 table */
-#ifdef CONFIG_MODULES
beq 3f
lis r11, (swapper_pg_dir-PAGE_OFFSET)@ha
3:
+ mtcr r10
+ mfspr r10, SPRN_SRR0 /* Get effective address of fault */
+#else
+ mfspr r10, SPRN_SRR0 /* Get effective address of fault */
+ INVALIDATE_ADJACENT_PAGES_CPU15(r11, r10)
+ mfspr r11, SPRN_M_TW /* Get level 1 table base address */
#endif
/* Insert level 1 index */
rlwimi r11, r10, 32 - ((PAGE_SHIFT - 2) << 1), (PAGE_SHIFT - 2) << 1, 29
@@ -362,8 +365,6 @@ InstructionTLBMiss:
mfspr r3, SPRN_DAR
mtspr SPRN_DAR, r11 /* Tag DAR */
#endif
- mfspr r10, SPRN_SPRG_SCRATCH2
- mtcr r10
EXCEPTION_EPILOG_0
rfi
@@ -374,17 +375,19 @@ DataStoreTLBMiss:
#endif
EXCEPTION_PROLOG_0
mfcr r10
- mtspr SPRN_SPRG_SCRATCH2, r10
- mfspr r10, SPRN_MD_EPN
/* If we are faulting a kernel address, we have to use the
* kernel page tables.
*/
- andis. r11, r10, 0x8000
+ mfspr r11, SPRN_MD_EPN
+ andis. r11, r11, 0x8000
mfspr r11, SPRN_M_TW /* Get level 1 table */
beq 3f
lis r11, (swapper_pg_dir-PAGE_OFFSET)@ha
3:
+ mtcr r10
+ mfspr r10, SPRN_MD_EPN
+
/* Insert level 1 index */
rlwimi r11, r10, 32 - ((PAGE_SHIFT - 2) << 1), (PAGE_SHIFT - 2) << 1, 29
lwz r11, (swapper_pg_dir-PAGE_OFFSET)@l(r11) /* Get the level 1 entry */
@@ -438,8 +441,6 @@ DataStoreTLBMiss:
mfspr r3, SPRN_DAR
#endif
mtspr SPRN_DAR, r11 /* Tag DAR */
- mfspr r10, SPRN_SPRG_SCRATCH2
- mtcr r10
EXCEPTION_EPILOG_0
rfi
--
2.1.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* [PATCH v4 3/5] powerpc/8xx: dont save CR in SCRATCH registers
@ 2015-02-04 14:49 ` Christophe Leroy
0 siblings, 0 replies; 2+ messages in thread
From: Christophe Leroy @ 2015-02-04 14:49 UTC (permalink / raw)
To: Benjamin Herrenschmidt, Paul Mackerras, Michael Ellerman, scottwood
Cc: linuxppc-dev, linux-kernel
CR only needs to be preserved when checking if we are handling a kernel address.
So we can preserve CR in a register:
- In ITLBMiss, check is done only when CONFIG_MODULES is defined. Otherwise we
don't need to do anything at all with CR.
- We use r10, then we reload SRR0/MD_EPN into r10 when CR is restored
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
v2: removed the CPU6 specific handling of CR which was saving (only) 1 cycle but
was making the code more difficult to maintain due to too many different cases
v3: no change (but impacted by patch 07)
v4: Respined against scootwood.git next (0dc294f7)
arch/powerpc/kernel/head_8xx.S | 29 +++++++++++++++--------------
1 file changed, 15 insertions(+), 14 deletions(-)
diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
index 5a69c5e..150d03f 100644
--- a/arch/powerpc/kernel/head_8xx.S
+++ b/arch/powerpc/kernel/head_8xx.S
@@ -312,10 +312,6 @@ InstructionTLBMiss:
mtspr SPRN_DAR, r3
#endif
EXCEPTION_PROLOG_0
- mfcr r10
- mtspr SPRN_SPRG_SCRATCH2, r10
- mfspr r10, SPRN_SRR0 /* Get effective address of fault */
- INVALIDATE_ADJACENT_PAGES_CPU15(r11, r10)
/* If we are faulting a kernel address, we have to use the
* kernel page tables.
@@ -323,13 +319,20 @@ InstructionTLBMiss:
#ifdef CONFIG_MODULES
/* Only modules will cause ITLB Misses as we always
* pin the first 8MB of kernel memory */
- andis. r11, r10, 0x8000 /* Address >= 0x80000000 */
-#endif
+ mfspr r11, SPRN_SRR0 /* Get effective address of fault */
+ INVALIDATE_ADJACENT_PAGES_CPU15(r10, r11)
+ mfcr r10
+ andis. r11, r11, 0x8000 /* Address >= 0x80000000 */
mfspr r11, SPRN_M_TW /* Get level 1 table */
-#ifdef CONFIG_MODULES
beq 3f
lis r11, (swapper_pg_dir-PAGE_OFFSET)@ha
3:
+ mtcr r10
+ mfspr r10, SPRN_SRR0 /* Get effective address of fault */
+#else
+ mfspr r10, SPRN_SRR0 /* Get effective address of fault */
+ INVALIDATE_ADJACENT_PAGES_CPU15(r11, r10)
+ mfspr r11, SPRN_M_TW /* Get level 1 table base address */
#endif
/* Insert level 1 index */
rlwimi r11, r10, 32 - ((PAGE_SHIFT - 2) << 1), (PAGE_SHIFT - 2) << 1, 29
@@ -362,8 +365,6 @@ InstructionTLBMiss:
mfspr r3, SPRN_DAR
mtspr SPRN_DAR, r11 /* Tag DAR */
#endif
- mfspr r10, SPRN_SPRG_SCRATCH2
- mtcr r10
EXCEPTION_EPILOG_0
rfi
@@ -374,17 +375,19 @@ DataStoreTLBMiss:
#endif
EXCEPTION_PROLOG_0
mfcr r10
- mtspr SPRN_SPRG_SCRATCH2, r10
- mfspr r10, SPRN_MD_EPN
/* If we are faulting a kernel address, we have to use the
* kernel page tables.
*/
- andis. r11, r10, 0x8000
+ mfspr r11, SPRN_MD_EPN
+ andis. r11, r11, 0x8000
mfspr r11, SPRN_M_TW /* Get level 1 table */
beq 3f
lis r11, (swapper_pg_dir-PAGE_OFFSET)@ha
3:
+ mtcr r10
+ mfspr r10, SPRN_MD_EPN
+
/* Insert level 1 index */
rlwimi r11, r10, 32 - ((PAGE_SHIFT - 2) << 1), (PAGE_SHIFT - 2) << 1, 29
lwz r11, (swapper_pg_dir-PAGE_OFFSET)@l(r11) /* Get the level 1 entry */
@@ -438,8 +441,6 @@ DataStoreTLBMiss:
mfspr r3, SPRN_DAR
#endif
mtspr SPRN_DAR, r11 /* Tag DAR */
- mfspr r10, SPRN_SPRG_SCRATCH2
- mtcr r10
EXCEPTION_EPILOG_0
rfi
--
2.1.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
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2015-02-04 14:49 [PATCH v4 3/5] powerpc/8xx: dont save CR in SCRATCH registers Christophe Leroy
2015-02-04 14:49 ` Christophe Leroy
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