korg/linux
0
0
Fork 0
mirror of https://mirrors.bfsu.edu.cn/git/linux.git synced 2024-11-26 21:54:11 +08:00
Code Issues Packages Projects Releases Wiki Activity

powerpc/40x: Don't use SPRN_SPRG_SCRATCH0/1 in TLB miss handlers

Browse Source 
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
This commit is contained in:
Christophe Leroy 2021-03-12 12:50:11 +00:00 committed by Michael Ellerman
parent a58cbed683
commit 52ae92cc29
1 changed files with 18 additions and 21 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

39
arch/powerpc/kernel/head_40x.S
View File

@ -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 */