[PATCH] powerpc/32: Add missing context synchronisation with CONFIG_VMAP_STACK

[Christophe Leroy]

After reactivation of data translation by modifying MSR[DR], a isync
is required to ensure the translation is effective.

Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxx>
---
Rebased on powerpc/merge-test

@mpe: If not too late:
- change to head_32.h should be squashed into "powerpc/32: prepare for CONFIG_VMAP_STACK"
- change to head_32.S should be squashed into "powerpc/32s: Enable CONFIG_VMAP_STACK"

Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxx>
---
 arch/powerpc/kernel/head_32.S | 1 +
 arch/powerpc/kernel/head_32.h | 2 ++
 2 files changed, 3 insertions(+)

diff --git a/arch/powerpc/kernel/head_32.S b/arch/powerpc/kernel/head_32.S
index cb7864091641..0493fcac6409 100644
--- a/arch/powerpc/kernel/head_32.S
+++ b/arch/powerpc/kernel/head_32.S
@@ -277,6 +277,7 @@ MachineCheck:
 #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
diff --git a/arch/powerpc/kernel/head_32.h b/arch/powerpc/kernel/head_32.h
index 73a035b40dbf..a6a5fbbf8504 100644
--- a/arch/powerpc/kernel/head_32.h
+++ b/arch/powerpc/kernel/head_32.h
@@ -43,6 +43,7 @@
 	.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
@@ -123,6 +124,7 @@
 #ifdef CONFIG_VMAP_STACK
 	li	r9, MSR_KERNEL & ~(MSR_IR | MSR_RI) /* can take DTLB miss */
 	mtmsr	r9
+	isync
 #endif
 	tovirt_vmstack r12, r12
 	tophys_novmstack r11, r11
-- 
2.25.0