From: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
commit c118c7303ad528be8ff2aea8cd1ee15452c763f0 upstream.
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: 028474876f47 ("powerpc/32: prepare for CONFIG_VMAP_STACK")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/a027d447022a006c9c4958ac734128e577a3c5c1.1599486108.git.christophe.leroy@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/powerpc/kernel/head_32.S | 6 ------
arch/powerpc/kernel/head_32.h | 31 ++++++-------------------------
2 files changed, 6 insertions(+), 31 deletions(-)
--- a/arch/powerpc/kernel/head_32.S
+++ b/arch/powerpc/kernel/head_32.S
@@ -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
--- a/arch/powerpc/kernel/head_32.h
+++ b/arch/powerpc/kernel/head_32.h
@@ -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_HP
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_T
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 @@ label:
#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
