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| author | Christophe Leroy <christophe.leroy@csgroup.eu> | 2021-03-12 15:50:11 +0300 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2021-03-29 05:22:03 +0300 |
| commit | 52ae92cc290f0506eef9ad5466bb453ce4a9e80e (patch) | |
| tree | 723d57404fc95babb53520190c272455027be352 /arch | |
| parent | a58cbed68315111c663f35603a42547f72acd6f8 (diff) | |
| download | linux-52ae92cc290f0506eef9ad5466bb453ce4a9e80e.tar.xz | |
powerpc/40x: Don't use SPRN_SPRG_SCRATCH0/1 in TLB miss handlers
SPRN_SPRG_SCRATCH5 is used to save SPRN_PID.
SPRN_SPRG_SCRATCH6 is already available.
SPRN_PID is only 8 bits. We have r12 that contains CR.
We only need to preserve CR0, so we have space available in r12
to save PID.
Keep PID in r12 and free up SPRN_SPRG_SCRATCH5.
Then In TLB miss handlers, instead of using SPRN_SPRG_SCRATCH0 and
SPRN_SPRG_SCRATCH1, use SPRN_SPRG_SCRATCH5 and SPRN_SPRG_SCRATCH6
to avoid future conflicts with normal exception prologs.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/4cdaa85d38e14d594ba902424060ec55babf2c42.1615552866.git.christophe.leroy@csgroup.eu
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/powerpc/kernel/head_40x.S | 39 |
1 files changed, 18 insertions, 21 deletions
diff --git a/arch/powerpc/kernel/head_40x.S b/arch/powerpc/kernel/head_40x.S index 24724a7dad49..383238a98f77 100644 --- a/arch/powerpc/kernel/head_40x.S +++ b/arch/powerpc/kernel/head_40x.S @@ -249,13 +249,13 @@ _ENTRY(saved_ksp_limit) * load TLB entries from the page table if they exist. */ START_EXCEPTION(0x1100, DTLBMiss) - mtspr SPRN_SPRG_SCRATCH0, r10 /* Save some working registers */ - mtspr SPRN_SPRG_SCRATCH1, r11 + mtspr SPRN_SPRG_SCRATCH5, r10 /* Save some working registers */ + mtspr SPRN_SPRG_SCRATCH6, r11 mtspr SPRN_SPRG_SCRATCH3, r12 mtspr SPRN_SPRG_SCRATCH4, r9 mfcr r12 mfspr r9, SPRN_PID - mtspr SPRN_SPRG_SCRATCH5, r9 + rlwimi r12, r9, 0, 0xff mfspr r10, SPRN_DEAR /* Get faulting address */ /* If we are faulting a kernel address, we have to use the @@ -316,13 +316,12 @@ _ENTRY(saved_ksp_limit) /* The bailout. Restore registers to pre-exception conditions * and call the heavyweights to help us out. */ - mfspr r9, SPRN_SPRG_SCRATCH5 - mtspr SPRN_PID, r9 - mtcr r12 + mtspr SPRN_PID, r12 + mtcrf 0x80, r12 mfspr r9, SPRN_SPRG_SCRATCH4 mfspr r12, SPRN_SPRG_SCRATCH3 - mfspr r11, SPRN_SPRG_SCRATCH1 - mfspr r10, SPRN_SPRG_SCRATCH0 + mfspr r11, SPRN_SPRG_SCRATCH6 + mfspr r10, SPRN_SPRG_SCRATCH5 b DataStorage /* 0x1200 - Instruction TLB Miss Exception @@ -330,13 +329,13 @@ _ENTRY(saved_ksp_limit) * registers and bailout to a different point. */ START_EXCEPTION(0x1200, ITLBMiss) - mtspr SPRN_SPRG_SCRATCH0, r10 /* Save some working registers */ - mtspr SPRN_SPRG_SCRATCH1, r11 + mtspr SPRN_SPRG_SCRATCH5, r10 /* Save some working registers */ + mtspr SPRN_SPRG_SCRATCH6, r11 mtspr SPRN_SPRG_SCRATCH3, r12 mtspr SPRN_SPRG_SCRATCH4, r9 mfcr r12 mfspr r9, SPRN_PID - mtspr SPRN_SPRG_SCRATCH5, r9 + rlwimi r12, r9, 0, 0xff mfspr r10, SPRN_SRR0 /* Get faulting address */ /* If we are faulting a kernel address, we have to use the @@ -397,13 +396,12 @@ _ENTRY(saved_ksp_limit) /* The bailout. Restore registers to pre-exception conditions * and call the heavyweights to help us out. */ - mfspr r9, SPRN_SPRG_SCRATCH5 - mtspr SPRN_PID, r9 - mtcr r12 + mtspr SPRN_PID, r12 + mtcrf 0x80, r12 mfspr r9, SPRN_SPRG_SCRATCH4 mfspr r12, SPRN_SPRG_SCRATCH3 - mfspr r11, SPRN_SPRG_SCRATCH1 - mfspr r10, SPRN_SPRG_SCRATCH0 + mfspr r11, SPRN_SPRG_SCRATCH6 + mfspr r10, SPRN_SPRG_SCRATCH5 b InstructionAccess EXCEPTION(0x1300, Trap_13, unknown_exception, EXC_XFER_STD) @@ -543,13 +541,12 @@ finish_tlb_load: /* Done...restore registers and get out of here. */ - mfspr r9, SPRN_SPRG_SCRATCH5 - mtspr SPRN_PID, r9 - mtcr r12 + mtspr SPRN_PID, r12 + mtcrf 0x80, r12 mfspr r9, SPRN_SPRG_SCRATCH4 mfspr r12, SPRN_SPRG_SCRATCH3 - mfspr r11, SPRN_SPRG_SCRATCH1 - mfspr r10, SPRN_SPRG_SCRATCH0 + mfspr r11, SPRN_SPRG_SCRATCH6 + mfspr r10, SPRN_SPRG_SCRATCH5 rfi /* Should sync shadow TLBs */ b . /* prevent prefetch past rfi */ |