powerpc: select ARCH_WANT_IRQS_OFF_ACTIVATE_MM

[ Upstream commit 66acd46 ] 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> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200914045219.3736466-3-npiggin@gmail.com Signed-off-by: Sasha Levin <sashal@kernel.org>
xanmod · Nov 5, 2020 · e3783eb · e3783eb
1 parent 5311d47
commit e3783eb
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diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
@@ -148,6 +148,7 @@ 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
@@ -244,7 +244,7 @@ static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
  */
 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 */