diff mbox series

[1/2] powerpc/32: Fix vmap stack - Do not activate MMU before reading task struct

Message ID a027d447022a006c9c4958ac734128e577a3c5c1.1599486108.git.christophe.leroy@csgroup.eu (mailing list archive)
State Accepted
Commit c118c7303ad528be8ff2aea8cd1ee15452c763f0
Headers show
Series [1/2] powerpc/32: Fix vmap stack - Do not activate MMU before reading task struct | expand

Checks

Context Check Description
snowpatch_ozlabs/apply_patch success Successfully applied on branch powerpc/merge (35f066fda170dde0a31f1447547a5d30b83c3920)
snowpatch_ozlabs/checkpatch success total: 0 errors, 0 warnings, 0 checks, 85 lines checked
snowpatch_ozlabs/needsstable success Patch is tagged for stable

Commit Message

Christophe Leroy Sept. 7, 2020, 1:42 p.m. UTC 
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@vger.kernel.org
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 arch/powerpc/kernel/head_32.S |  6 ------
 arch/powerpc/kernel/head_32.h | 31 ++++++-------------------------
 2 files changed, 6 insertions(+), 31 deletions(-)

Comments

Michael Ellerman Sept. 17, 2020, 11:27 a.m. UTC | #1 
On Mon, 7 Sep 2020 13:42:09 +0000 (UTC), Christophe Leroy wrote:
> 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.
> 
> [...]

Applied to powerpc/next.

[1/2] powerpc/32: Fix vmap stack - Do not activate MMU before reading task struct
      https://git.kernel.org/powerpc/c/c118c7303ad528be8ff2aea8cd1ee15452c763f0
[2/2] powerpc/32: Fix vmap stack - Properly set r1 before activating MMU
      https://git.kernel.org/powerpc/c/da7bb43ab9da39bcfed0d146ce94e1f0cbae4ca0

cheers
diff mbox series

Patch

diff --git a/arch/powerpc/kernel/head_32.S b/arch/powerpc/kernel/head_32.S
index f3ab94d73936..d967266d62e8 100644
--- 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
diff --git a/arch/powerpc/kernel/head_32.h b/arch/powerpc/kernel/head_32.h
index 9abec6cd099c..21effebb9277 100644
--- 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_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