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authorCatalin Marinas <catalin.marinas@arm.com>2015-03-23 15:06:50 +0000
committerSasha Levin <sasha.levin@oracle.com>2015-04-16 20:13:17 -0400
commit20ecb85c6e0c815de560b6b56409e9e89183d5c6 (patch)
tree8365e9de479a6dc4d724b13b87edc12900a42b33
parent3d8fc13835497f122ba638f96d72c71063586f4f (diff)
arm64: Use the reserved TTBR0 if context switching to the init_mm
[ Upstream commit e53f21bce4d35a93b23d8fa1a840860f6c74f59e ] The idle_task_exit() function may call switch_mm() with next == &init_mm. On arm64, init_mm.pgd cannot be used for user mappings, so this patch simply sets the reserved TTBR0. Cc: <stable@vger.kernel.org> Reported-by: Jon Medhurst (Tixy) <tixy@linaro.org> Tested-by: Jon Medhurst (Tixy) <tixy@linaro.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
-rw-r--r--arch/arm64/include/asm/mmu_context.h9
1 files changed, 9 insertions, 0 deletions
diff --git a/arch/arm64/include/asm/mmu_context.h b/arch/arm64/include/asm/mmu_context.h
index a9eee33dfa62..101a42bde728 100644
--- a/arch/arm64/include/asm/mmu_context.h
+++ b/arch/arm64/include/asm/mmu_context.h
@@ -151,6 +151,15 @@ switch_mm(struct mm_struct *prev, struct mm_struct *next,
{
unsigned int cpu = smp_processor_id();
+ /*
+ * init_mm.pgd does not contain any user mappings and it is always
+ * active for kernel addresses in TTBR1. Just set the reserved TTBR0.
+ */
+ if (next == &init_mm) {
+ cpu_set_reserved_ttbr0();
+ return;
+ }
+
if (!cpumask_test_and_set_cpu(cpu, mm_cpumask(next)) || prev != next)
check_and_switch_context(next, tsk);
}