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| author |   Will Deacon <will.deacon@arm.com> | 2017-12-06 10:51:12 +0000 |
|---|---|---|
| committer | Will Deacon <will.deacon@arm.com> | 2017-12-06 18:28:10 +0000 |
| commit | d96cc49bff5a7735576cc6f6f111f875d101cec8 (patch) | |
| tree | 414b9a833517440b52162e784b3c0ddd96ad6915 /arch/arm64 | |
| parent | arm64: SW PAN: Point saved ttbr0 at the zero page when switching to init_mm (diff) | |
| download | linux-dev-d96cc49bff5a7735576cc6f6f111f875d101cec8.tar.xz linux-dev-d96cc49bff5a7735576cc6f6f111f875d101cec8.zip | |
arm64: SW PAN: Update saved ttbr0 value on enter_lazy_tlb
enter_lazy_tlb is called when a kernel thread rides on the back of
another mm, due to a context switch or an explicit call to unuse_mm
where a call to switch_mm is elided.
In these cases, it's important to keep the saved ttbr value up to date
with the active mm, otherwise we can end up with a stale value which
points to a potentially freed page table.
This patch implements enter_lazy_tlb for arm64, so that the saved ttbr0
is kept up-to-date with the active mm for kernel threads.
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Vinayak Menon <vinmenon@codeaurora.org>
Cc: <stable@vger.kernel.org>
Fixes: 39bc88e5e38e9b21 ("arm64: Disable TTBR0_EL1 during normal kernel execution")
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Reported-by: Vinayak Menon <vinmenon@codeaurora.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'arch/arm64')
| -rw-r--r-- | arch/arm64/include/asm/mmu_context.h | 24 |
1 files changed, 10 insertions, 14 deletions
diff --git a/arch/arm64/include/asm/mmu_context.h b/arch/arm64/include/asm/mmu_context.h index f7773f90546e..9d155fa9a507 100644 --- a/arch/arm64/include/asm/mmu_context.h +++ b/arch/arm64/include/asm/mmu_context.h @@ -156,20 +156,6 @@ void check_and_switch_context(struct mm_struct *mm, unsigned int cpu); #define init_new_context(tsk,mm) ({ atomic64_set(&(mm)->context.id, 0); 0; }) -/* - * This is called when "tsk" is about to enter lazy TLB mode. - * - * mm: describes the currently active mm context - * tsk: task which is entering lazy tlb - * cpu: cpu number which is entering lazy tlb - * - * tsk->mm will be NULL - */ -static inline void -enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk) -{ -} - #ifdef CONFIG_ARM64_SW_TTBR0_PAN static inline void update_saved_ttbr0(struct task_struct *tsk, struct mm_struct *mm) @@ -193,6 +179,16 @@ static inline void update_saved_ttbr0(struct task_struct *tsk, } #endif +static inline void +enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk) +{ + /* + * We don't actually care about the ttbr0 mapping, so point it at the + * zero page. + */ + update_saved_ttbr0(tsk, &init_mm); +} + static inline void __switch_mm(struct mm_struct *next) { unsigned int cpu = smp_processor_id(); |