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powerpc/40x: Avoid using r12 in TLB miss handlers 

Let's reduce the number of registers used in TLB miss handlers.

We have both r9 and r12 available for any temporary use.

r9 is enough, avoid using r12.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/7f330e971952abb2645fb9ca4310c0f527e84dcb.1590079969.git.christophe.leroy@csgroup.eu
This commit is contained in:
Christophe Leroy 2020-05-21 16:56:03 +00:00 committed by Michael Ellerman
parent 455531e9d8
commit 797f4016f6
1 changed files with 33 additions and 37 deletions
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70
arch/powerpc/kernel/head_40x.S
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@ -255,9 +255,9 @@ _ENTRY(saved_ksp_limit)
mtspr SPRN_SPRG_SCRATCH3, r12 mtspr SPRN_SPRG_SCRATCH3, r12
mtspr SPRN_SPRG_SCRATCH4, r9 mtspr SPRN_SPRG_SCRATCH4, r9
mfcr r11 mfcr r11
mfspr r12, SPRN_PID mfspr r9, SPRN_PID
mtspr SPRN_SPRG_SCRATCH6, r11 mtspr SPRN_SPRG_SCRATCH6, r11
mtspr SPRN_SPRG_SCRATCH5, r12 mtspr SPRN_SPRG_SCRATCH5, r9
mfspr r10, SPRN_DEAR /* Get faulting address */ mfspr r10, SPRN_DEAR /* Get faulting address */
/* If we are faulting a kernel address, we have to use the /* If we are faulting a kernel address, we have to use the
@ -280,12 +280,12 @@ _ENTRY(saved_ksp_limit)
4: 4:
tophys(r11, r11) tophys(r11, r11)
rlwimi r11, r10, 12, 20, 29 /* Create L1 (pgdir/pmd) address */ rlwimi r11, r10, 12, 20, 29 /* Create L1 (pgdir/pmd) address */
lwz r12, 0(r11) /* Get L1 entry */ lwz r11, 0(r11) /* Get L1 entry */
andi. r9, r12, _PMD_PRESENT /* Check if it points to a PTE page */ andi. r9, r11, _PMD_PRESENT /* Check if it points to a PTE page */
beq 2f /* Bail if no table */ beq 2f /* Bail if no table */
rlwimi r12, r10, 22, 20, 29 /* Compute PTE address */ rlwimi r11, r10, 22, 20, 29 /* Compute PTE address */
lwz r11, 0(r12) /* Get Linux PTE */ lwz r11, 0(r11) /* Get Linux PTE */
#ifdef CONFIG_SWAP #ifdef CONFIG_SWAP
li r9, _PAGE_PRESENT | _PAGE_ACCESSED li r9, _PAGE_PRESENT | _PAGE_ACCESSED
#else #else
@ -301,13 +301,13 @@ _ENTRY(saved_ksp_limit)
/* Create TLB tag. This is the faulting address plus a static /* Create TLB tag. This is the faulting address plus a static
* set of bits. These are size, valid, E, U0. * set of bits. These are size, valid, E, U0.
*/ */
li r12, 0x00c0 li r9, 0x00c0
rlwimi r10, r12, 0, 20, 31 rlwimi r10, r9, 0, 20, 31
b finish_tlb_load b finish_tlb_load
2: /* Check for possible large-page pmd entry */ 2: /* Check for possible large-page pmd entry */
rlwinm. r9, r12, 2, 22, 24 rlwinm. r9, r11, 2, 22, 24
beq 5f beq 5f
/* Create TLB tag. This is the faulting address, plus a static /* Create TLB tag. This is the faulting address, plus a static
@ -315,7 +315,6 @@ _ENTRY(saved_ksp_limit)
*/ */
ori r9, r9, 0x40 ori r9, r9, 0x40
rlwimi r10, r9, 0, 20, 31 rlwimi r10, r9, 0, 20, 31
mr r11, r12
b finish_tlb_load b finish_tlb_load
@ -323,9 +322,9 @@ _ENTRY(saved_ksp_limit)
/* The bailout. Restore registers to pre-exception conditions /* The bailout. Restore registers to pre-exception conditions
* and call the heavyweights to help us out. * and call the heavyweights to help us out.
*/ */
mfspr r12, SPRN_SPRG_SCRATCH5 mfspr r9, SPRN_SPRG_SCRATCH5
mfspr r11, SPRN_SPRG_SCRATCH6 mfspr r11, SPRN_SPRG_SCRATCH6
mtspr SPRN_PID, r12 mtspr SPRN_PID, r9
mtcr r11 mtcr r11
mfspr r9, SPRN_SPRG_SCRATCH4 mfspr r9, SPRN_SPRG_SCRATCH4
mfspr r12, SPRN_SPRG_SCRATCH3 mfspr r12, SPRN_SPRG_SCRATCH3
@ -343,9 +342,9 @@ _ENTRY(saved_ksp_limit)
mtspr SPRN_SPRG_SCRATCH3, r12 mtspr SPRN_SPRG_SCRATCH3, r12
mtspr SPRN_SPRG_SCRATCH4, r9 mtspr SPRN_SPRG_SCRATCH4, r9
mfcr r11 mfcr r11
mfspr r12, SPRN_PID mfspr r9, SPRN_PID
mtspr SPRN_SPRG_SCRATCH6, r11 mtspr SPRN_SPRG_SCRATCH6, r11
mtspr SPRN_SPRG_SCRATCH5, r12 mtspr SPRN_SPRG_SCRATCH5, r9
mfspr r10, SPRN_SRR0 /* Get faulting address */ mfspr r10, SPRN_SRR0 /* Get faulting address */
/* If we are faulting a kernel address, we have to use the /* If we are faulting a kernel address, we have to use the
@ -368,12 +367,12 @@ _ENTRY(saved_ksp_limit)
4: 4:
tophys(r11, r11) tophys(r11, r11)
rlwimi r11, r10, 12, 20, 29 /* Create L1 (pgdir/pmd) address */ rlwimi r11, r10, 12, 20, 29 /* Create L1 (pgdir/pmd) address */
lwz r12, 0(r11) /* Get L1 entry */ lwz r11, 0(r11) /* Get L1 entry */
andi. r9, r12, _PMD_PRESENT /* Check if it points to a PTE page */ andi. r9, r11, _PMD_PRESENT /* Check if it points to a PTE page */
beq 2f /* Bail if no table */ beq 2f /* Bail if no table */
rlwimi r12, r10, 22, 20, 29 /* Compute PTE address */ rlwimi r11, r10, 22, 20, 29 /* Compute PTE address */
lwz r11, 0(r12) /* Get Linux PTE */ lwz r11, 0(r11) /* Get Linux PTE */
#ifdef CONFIG_SWAP #ifdef CONFIG_SWAP
li r9, _PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_EXEC li r9, _PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_EXEC
#else #else
@ -389,13 +388,13 @@ _ENTRY(saved_ksp_limit)
/* Create TLB tag. This is the faulting address plus a static /* Create TLB tag. This is the faulting address plus a static
* set of bits. These are size, valid, E, U0. * set of bits. These are size, valid, E, U0.
*/ */
li r12, 0x00c0 li r9, 0x00c0
rlwimi r10, r12, 0, 20, 31 rlwimi r10, r9, 0, 20, 31
b finish_tlb_load b finish_tlb_load
2: /* Check for possible large-page pmd entry */ 2: /* Check for possible large-page pmd entry */
rlwinm. r9, r12, 2, 22, 24 rlwinm. r9, r11, 2, 22, 24
beq 5f beq 5f
/* Create TLB tag. This is the faulting address, plus a static /* Create TLB tag. This is the faulting address, plus a static
@ -403,7 +402,6 @@ _ENTRY(saved_ksp_limit)
*/ */
ori r9, r9, 0x40 ori r9, r9, 0x40
rlwimi r10, r9, 0, 20, 31 rlwimi r10, r9, 0, 20, 31
mr r11, r12
b finish_tlb_load b finish_tlb_load
@ -411,9 +409,9 @@ _ENTRY(saved_ksp_limit)
/* The bailout. Restore registers to pre-exception conditions /* The bailout. Restore registers to pre-exception conditions
* and call the heavyweights to help us out. * and call the heavyweights to help us out.
*/ */
mfspr r12, SPRN_SPRG_SCRATCH5 mfspr r9, SPRN_SPRG_SCRATCH5
mfspr r11, SPRN_SPRG_SCRATCH6 mfspr r11, SPRN_SPRG_SCRATCH6
mtspr SPRN_PID, r12 mtspr SPRN_PID, r9
mtcr r11 mtcr r11
mfspr r9, SPRN_SPRG_SCRATCH4 mfspr r9, SPRN_SPRG_SCRATCH4
mfspr r12, SPRN_SPRG_SCRATCH3 mfspr r12, SPRN_SPRG_SCRATCH3
@ -529,7 +527,7 @@ WDTException:
* miss get to this point to load the TLB. * miss get to this point to load the TLB.
* r10 - TLB_TAG value * r10 - TLB_TAG value
* r11 - Linux PTE * r11 - Linux PTE
* r12, r9 - available to use * r9 - available to use
* PID - loaded with proper value when we get here * PID - loaded with proper value when we get here
* Upon exit, we reload everything and RFI. * Upon exit, we reload everything and RFI.
* Actually, it will fit now, but oh well.....a common place * Actually, it will fit now, but oh well.....a common place
@ -538,30 +536,28 @@ WDTException:
tlb_4xx_index: tlb_4xx_index:
.long 0 .long 0
finish_tlb_load: finish_tlb_load:
/* load the next available TLB index.
*/
lwz r9, tlb_4xx_index@l(0)
addi r9, r9, 1
andi. r9, r9, (PPC40X_TLB_SIZE-1)
stw r9, tlb_4xx_index@l(0)
6:
/* /*
* Clear out the software-only bits in the PTE to generate the * Clear out the software-only bits in the PTE to generate the
* TLB_DATA value. These are the bottom 2 bits of the RPM, the * TLB_DATA value. These are the bottom 2 bits of the RPM, the
* top 3 bits of the zone field, and M. * top 3 bits of the zone field, and M.
*/ */
li r12, 0x0ce2 li r9, 0x0ce2
andc r11, r11, r12 andc r11, r11, r9
/* load the next available TLB index. */
lwz r9, tlb_4xx_index@l(0)
addi r9, r9, 1
andi. r9, r9, PPC40X_TLB_SIZE - 1
stw r9, tlb_4xx_index@l(0)
tlbwe r11, r9, TLB_DATA /* Load TLB LO */ tlbwe r11, r9, TLB_DATA /* Load TLB LO */
tlbwe r10, r9, TLB_TAG /* Load TLB HI */ tlbwe r10, r9, TLB_TAG /* Load TLB HI */
/* Done...restore registers and get out of here. /* Done...restore registers and get out of here.
*/ */
mfspr r12, SPRN_SPRG_SCRATCH5 mfspr r9, SPRN_SPRG_SCRATCH5
mfspr r11, SPRN_SPRG_SCRATCH6 mfspr r11, SPRN_SPRG_SCRATCH6
mtspr SPRN_PID, r12 mtspr SPRN_PID, r9
mtcr r11 mtcr r11
mfspr r9, SPRN_SPRG_SCRATCH4 mfspr r9, SPRN_SPRG_SCRATCH4
mfspr r12, SPRN_SPRG_SCRATCH3 mfspr r12, SPRN_SPRG_SCRATCH3