From 3a64e6a9989e0748ff17b6deeec659cb1a3e1938 Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Fri, 20 Jul 2018 10:56:25 +0100 Subject: arm64: Add 'ssbd' command-line option commit a43ae4dfe56a01f5b98ba0cb2f784b6a43bafcc6 upstream. 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. Reviewed-by: Julien Grall Reviewed-by: Mark Rutland Acked-by: Will Deacon Signed-off-by: Marc Zyngier Signed-off-by: Catalin Marinas Signed-off-by: Marc Zyngier Signed-off-by: Greg Kroah-Hartman --- Documentation/kernel-parameters.txt | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) (limited to 'Documentation') diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 52240a63132e..a16f87e4dd10 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -4023,6 +4023,23 @@ bytes respectively. Such letter suffixes can also be entirely omitted. spia_pedr= spia_peddr= + 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: Unconditionally enable mitigation for + for both kernel and userspace + force-off: Unconditionally disable mitigation for + 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 -- cgit v1.2.3