[PATCH v2 2/4] powerpc: select ARCH_WANT_IRQS_OFF_ACTIVATE_MM

Nicholas Piggin
2020-09-14T04:52:58Z

powerpc uses IPIs in some situations to switch a kernel thread away
from a lazy tlb mm, which is subject to the TLB flushing race
described in the changelog introducing ARCH_WANT_IRQS_OFF_ACTIVATE_MM.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
arch/powerpc/Kconfig | 1 +
arch/powerpc/include/asm/mmu_context.h | 2 +-
2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 65bed1fdeaad..587ba8352d01 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -149,6 +149,7 @@ config PPC
select ARCH_USE_QUEUED_RWLOCKS if PPC_QUEUED_SPINLOCKS
select ARCH_USE_QUEUED_SPINLOCKS if PPC_QUEUED_SPINLOCKS
select ARCH_WANT_IPC_PARSE_VERSION
+ select ARCH_WANT_IRQS_OFF_ACTIVATE_MM
select ARCH_WEAK_RELEASE_ACQUIRE
select BINFMT_ELF
select BUILDTIME_TABLE_SORT
diff --git a/arch/powerpc/include/asm/mmu_context.h b/arch/powerpc/include/asm/mmu_context.h
index a3a12a8341b2..b42813359f49 100644
--- a/arch/powerpc/include/asm/mmu_context.h
+++ b/arch/powerpc/include/asm/mmu_context.h
@@ -244,7 +244,7 @@ static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
#define activate_mm activate_mm
static inline void activate_mm(struct mm_struct *prev, struct mm_struct *next)
{
- switch_mm(prev, next, current);
+ switch_mm_irqs_off(prev, next, current);
}

/* We don't currently use enter_lazy_tlb() for anything */
--
2.23.0