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| author | Catalin Marinas <catalin.marinas@arm.com> | 2015-03-23 15:06:50 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2015-04-13 14:03:03 +0200 |
| commit | 7edf68cf19a58342ef270621438a5e8c1045c34b (patch) | |
| tree | 66d07178630cc1183161c189eb2b5f8e9495fd4b | |
| parent | 31e970605408a0656d90cca2f2a727ae8eb3c3fe (diff) | |
| download | lwn-7edf68cf19a58342ef270621438a5e8c1045c34b.tar.gz lwn-7edf68cf19a58342ef270621438a5e8c1045c34b.zip | |
arm64: Use the reserved TTBR0 if context switching to the init_mm
commit e53f21bce4d35a93b23d8fa1a840860f6c74f59e upstream.
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.
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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | arch/arm64/include/asm/mmu_context.h | 9 |
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); } |