Commit c118c730 authored by Christophe Leroy's avatar Christophe Leroy Committed by Michael Ellerman
Browse files

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



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: 02847487 ("powerpc/32: prepare for CONFIG_VMAP_STACK")
Cc: stable@vger.kernel.org
Signed-off-by: default avatarChristophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/a027d447022a006c9c4958ac734128e577a3c5c1.1599486108.git.christophe.leroy@csgroup.eu
parent 7fdf966b

arch/powerpc/kernel/head_32.S

+0 −6
Original line number Diff line number Diff line
@@ -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

arch/powerpc/kernel/head_32.h

+6 −25
Original line number Diff line number Diff line
@@ -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 @@ 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

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