[PATCH 05/14] arm64: Add 'ssbd' command-line option
From: Randy Dunlap <hidden>
Date: 2018-05-22 15:29:38
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kvmarm, lkml
On 05/22/2018 08:06 AM, Marc Zyngier wrote:
quoted hunk ↗ jump to hunk
On a system where the firmware implements ARCH_WORKAROUND_2, it may be useful to either permanently enable or disable the workaround for cases where the user decides that they'd rather not get a trap overhead, and keep the mitigation permanently on or off instead of switching it on exception entry/exit. In any case, default to the mitigation being enabled. Signed-off-by: Marc Zyngier <redacted> --- Documentation/admin-guide/kernel-parameters.txt | 17 ++++ arch/arm64/include/asm/cpufeature.h | 6 ++ arch/arm64/kernel/cpu_errata.c | 102 ++++++++++++++++++++---- 3 files changed, 109 insertions(+), 16 deletions(-)diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index f2040d46f095..646e112c6f63 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt@@ -4092,6 +4092,23 @@ expediting. Set to zero to disable automatic expediting. + ssbd= [ARM64,HW] + Speculative Store Bypass Disable control + + On CPUs that are vulnerable to the Speculative + Store Bypass vulnerability and offer a + firmware based mitigation, this parameter + indicates how the mitigation should be used: + + force-on: Unconditionnaly enable mitigation for
Unconditionally
+ for both kernel and userspace + force-off: Unconditionnaly disable mitigation for
Unconditionally
+ for both kernel and userspace + kernel: Always enable mitigation in the + kernel, and offer a prctl interface + to allow userspace to register its + interest in being mitigated too. + stack_guard_gap= [MM] override the default stack gap protection. The value is in page units and it defines how many pages prior
-- ~Randy