diff options
| author | Mark Rutland <mark.rutland@arm.com> | 2018-04-12 12:11:14 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-04-20 08:20:44 +0200 |
| commit | bfacceccc8fd9fd30f70563569d7bd1d1453a841 (patch) | |
| tree | 7c9c93cb3c43133b3d5de4686b571edda47d7865 | |
| parent | 4732001f7721d89d3dc921d5f4c8208405cb88c1 (diff) | |
arm64: Move BP hardening to check_and_switch_context
From: Marc Zyngier <marc.zyngier@arm.com>
commit a8e4c0a919ae310944ed2c9ace11cf3ccd8a609b 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: Mark Rutland <mark.rutland@arm.com> [v4.9 backport]
Tested-by: Greg Hackmann <ghackmann@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | arch/arm64/mm/context.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/arch/arm64/mm/context.c b/arch/arm64/mm/context.c index accf7ead3945..62d976e843fc 100644 --- a/arch/arm64/mm/context.c +++ b/arch/arm64/mm/context.c @@ -230,6 +230,9 @@ 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); } @@ -240,8 +243,6 @@ 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) |