Messages in this thread | | | Subject | Re: [PATCH v5 01/10] arm64: Provide a command line to disable spectre_v2 mitigation | From | Suzuki K Poulose <> | Date | Thu, 28 Feb 2019 18:14:34 +0000 |
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Hi Jeremy
On 27/02/2019 01:05, Jeremy Linton wrote: > There are various reasons, including bencmarking, to disable spectrev2 > mitigation on a machine. Provide a command-line to do so. > > Signed-off-by: Jeremy Linton <jeremy.linton@arm.com> > Cc: Jonathan Corbet <corbet@lwn.net> > Cc: linux-doc@vger.kernel.org
> diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c > index 9950bb0cbd52..d2b2c69d31bb 100644 > --- a/arch/arm64/kernel/cpu_errata.c > +++ b/arch/arm64/kernel/cpu_errata.c > @@ -220,6 +220,14 @@ static void qcom_link_stack_sanitization(void) > : "=&r" (tmp)); > } > > +static bool __nospectre_v2; > +static int __init parse_nospectre_v2(char *str) > +{ > + __nospectre_v2 = true; > + return 0; > +} > +early_param("nospectre_v2", parse_nospectre_v2); > + > static void > enable_smccc_arch_workaround_1(const struct arm64_cpu_capabilities *entry) > { > @@ -231,6 +239,11 @@ enable_smccc_arch_workaround_1(const struct arm64_cpu_capabilities *entry) > if (!entry->matches(entry, SCOPE_LOCAL_CPU)) > return; > > + if (__nospectre_v2) { > + pr_info_once("spectrev2 mitigation disabled by command line option\n"); > + return; > + } > +
Could we not disable the "cap" altogether instead, rather than disabling the work around ? Or do we need that information ?
Cheers Suzuki
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