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powerpc/32: Fix vmap stack - Do not activate MMU before reading task struct

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We need r1 to be properly set before activating MMU, so
reading task_struct->stack must be done with MMU off.

This means we need an additional register to play with MSR
bits while r11 now points to the stack. For that, move r10
back to CR (As is already done for hash MMU) and use r10.

We still don't have r1 correct yet when we activate MMU.
It is done in following patch.

Fixes: 028474876f ("powerpc/32: prepare for CONFIG_VMAP_STACK")
Cc: stable@vger.kernel.org
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/a027d447022a006c9c4958ac734128e577a3c5c1.1599486108.git.christophe.leroy@csgroup.eu
This commit is contained in:
Christophe Leroy 2020-09-07 13:42:09 +00:00 committed by Michael Ellerman
parent 7fdf966bed
commit c118c7303a
2 changed files with 6 additions and 31 deletions
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6
arch/powerpc/kernel/head_32.S
View File

@ -274,14 +274,8 @@ __secondary_hold_acknowledge:
DO_KVM 0x200
MachineCheck:
EXCEPTION_PROLOG_0
#ifdef CONFIG_VMAP_STACK
li r11, MSR_KERNEL & ~(MSR_IR | MSR_RI) /* can take DTLB miss */
mtmsr r11
isync
#endif
#ifdef CONFIG_PPC_CHRP
mfspr r11, SPRN_SPRG_THREAD
tovirt_vmstack r11, r11
lwz r11, RTAS_SP(r11)
cmpwi cr1, r11, 0
bne cr1, 7f

31
arch/powerpc/kernel/head_32.h
View File

@ -39,24 +39,13 @@
.endm
.macro EXCEPTION_PROLOG_1 for_rtas=0
#ifdef CONFIG_VMAP_STACK
.ifeq \for_rtas
li r11, MSR_KERNEL & ~(MSR_IR | MSR_RI) /* can take DTLB miss */
mtmsr r11
isync
.endif
subi r11, r1, INT_FRAME_SIZE /* use r1 if kernel */
#else
tophys(r11,r1) /* use tophys(r1) if kernel */
subi r11, r11, INT_FRAME_SIZE /* alloc exc. frame */
#endif
beq 1f
mfspr r11,SPRN_SPRG_THREAD
tovirt_vmstack r11, r11
lwz r11,TASK_STACK-THREAD(r11)
addi r11, r11, THREAD_SIZE - INT_FRAME_SIZE
tophys_novmstack r11, r11
1:
tophys_novmstack r11, r11
#ifdef CONFIG_VMAP_STACK
mtcrf 0x7f, r11
bt 32 - THREAD_ALIGN_SHIFT, stack_overflow
@ -64,12 +53,11 @@
.endm
.macro EXCEPTION_PROLOG_2 handle_dar_dsisr=0
#if defined(CONFIG_VMAP_STACK) && defined(CONFIG_PPC_BOOK3S)
BEGIN_MMU_FTR_SECTION
#ifdef CONFIG_VMAP_STACK
mtcr r10
FTR_SECTION_ELSE
stw r10, _CCR(r11)
ALT_MMU_FTR_SECTION_END_IFSET(MMU_FTR_HPTE_TABLE)
li r10, MSR_KERNEL & ~(MSR_IR | MSR_RI) /* can take DTLB miss */
mtmsr r10
isync
#else
stw r10,_CCR(r11) /* save registers */
#endif
@ -77,11 +65,9 @@ ALT_MMU_FTR_SECTION_END_IFSET(MMU_FTR_HPTE_TABLE)
stw r12,GPR12(r11)
stw r9,GPR9(r11)
stw r10,GPR10(r11)
#if defined(CONFIG_VMAP_STACK) && defined(CONFIG_PPC_BOOK3S)
BEGIN_MMU_FTR_SECTION
#ifdef CONFIG_VMAP_STACK
mfcr r10
stw r10, _CCR(r11)
END_MMU_FTR_SECTION_IFSET(MMU_FTR_HPTE_TABLE)
#endif
mfspr r12,SPRN_SPRG_SCRATCH1
stw r12,GPR11(r11)
@ -97,11 +83,7 @@ END_MMU_FTR_SECTION_IFSET(MMU_FTR_HPTE_TABLE)
stw r10, _DSISR(r11)
.endif
lwz r9, SRR1(r12)
#if defined(CONFIG_VMAP_STACK) && defined(CONFIG_PPC_BOOK3S)
BEGIN_MMU_FTR_SECTION
andi. r10, r9, MSR_PR
END_MMU_FTR_SECTION_IFSET(MMU_FTR_HPTE_TABLE)
#endif
lwz r12, SRR0(r12)
#else
mfspr r12,SPRN_SRR0
@ -328,7 +310,6 @@ END_MMU_FTR_SECTION_IFSET(MMU_FTR_HPTE_TABLE)
#ifdef CONFIG_VMAP_STACK
#ifdef CONFIG_SMP
mfspr r11, SPRN_SPRG_THREAD
tovirt(r11, r11)
lwz r11, TASK_CPU - THREAD(r11)
slwi r11, r11, 3
addis r11, r11, emergency_ctx@ha