diff options
| author | Marc Zyngier <marc.zyngier@arm.com> | 2019-04-15 13:03:51 +0100 |
|---|---|---|
| committer | Will Deacon <will.deacon@arm.com> | 2019-04-30 14:45:53 +0100 |
| commit | 0f80cad3124f986d0e46c14d46b8da06d87a2bf4 (patch) | |
| tree | 23b6c711f1bf624708c45a7dc54d464b8687400e /arch/arm64/kernel | |
| parent | 79a3aaa7b82e3106be97842dedfd8429248896e6 (diff) | |
arm64: Restrict ARM64_ERRATUM_1188873 mitigation to AArch32
We currently deal with ARM64_ERRATUM_1188873 by always trapping EL0
accesses for both instruction sets. Although nothing wrong comes out
of that, people trying to squeeze the last drop of performance from
buggy HW find this over the top. Oh well.
Let's change the mitigation by flipping the counter enable bit
on return to userspace. Non-broken HW gets an extra branch on
the fast path, which is hopefully not the end of the world.
The arch timer workaround is also removed.
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'arch/arm64/kernel')
| -rw-r--r-- | arch/arm64/kernel/entry.S | 19 |
1 files changed, 17 insertions, 2 deletions
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index c50a7a75f2e0..1a7811b7e3c4 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -336,6 +336,21 @@ alternative_if ARM64_WORKAROUND_845719 alternative_else_nop_endif #endif 3: +#ifdef CONFIG_ARM64_ERRATUM_1188873 +alternative_if_not ARM64_WORKAROUND_1188873 + b 4f +alternative_else_nop_endif + /* + * if (x22.mode32 == cntkctl_el1.el0vcten) + * cntkctl_el1.el0vcten = ~cntkctl_el1.el0vcten + */ + mrs x1, cntkctl_el1 + eon x0, x1, x22, lsr #3 + tbz x0, #1, 4f + eor x1, x1, #2 // ARCH_TIMER_USR_VCT_ACCESS_EN + msr cntkctl_el1, x1 +4: +#endif apply_ssbd 0, x0, x1 .endif @@ -362,11 +377,11 @@ alternative_else_nop_endif .if \el == 0 alternative_insn eret, nop, ARM64_UNMAP_KERNEL_AT_EL0 #ifdef CONFIG_UNMAP_KERNEL_AT_EL0 - bne 4f + bne 5f msr far_el1, x30 tramp_alias x30, tramp_exit_native br x30 -4: +5: tramp_alias x30, tramp_exit_compat br x30 #endif |