Messages in this thread Patch in this message | | | From | Alex Shi <> | Subject | [PATCH 24/52] arm64: Move BP hardening to check_and_switch_context | Date | Mon, 26 Feb 2018 16:19:58 +0800 |
| |
From: Marc Zyngier <marc.zyngier@arm.com>
commit a8e4c0a919ae upstream.
We call arm64_apply_bp_hardening() from post_ttbr_update_workaround, which has the unexpected consequence of being triggered on every exception return to userspace when ARM64_SW_TTBR0_PAN is selected, even if no context switch actually occured.
This is a bit suboptimal, and it would be more logical to only invalidate the branch predictor when we actually switch to a different mm.
In order to solve this, move the call to arm64_apply_bp_hardening() into check_and_switch_context(), where we're guaranteed to pick a different mm context.
Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Alex Shi <alex.shi@linaro.org>
Conflicts: no sw pan in arch/arm64/mm/context.c --- arch/arm64/mm/context.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/arch/arm64/mm/context.c b/arch/arm64/mm/context.c index afc9266..36416e4 100644 --- a/arch/arm64/mm/context.c +++ b/arch/arm64/mm/context.c @@ -221,6 +221,7 @@ void check_and_switch_context(struct mm_struct *mm, unsigned int cpu) raw_spin_unlock_irqrestore(&cpu_asid_lock, flags); switch_mm_fastpath: + arm64_apply_bp_hardening(); cpu_switch_mm(mm->pgd, mm); } @@ -231,8 +232,6 @@ asmlinkage void post_ttbr_update_workaround(void) "ic iallu; dsb nsh; isb", ARM64_WORKAROUND_CAVIUM_27456, CONFIG_CAVIUM_ERRATUM_27456)); - - arm64_apply_bp_hardening(); } static int asids_init(void) -- 2.7.4
| |