Messages in this thread | | | Date | Fri, 12 Jan 2018 14:57:14 -0800 | From | Andi Kleen <> | Subject | Re: [PATCH 1/4] x86/retpoline: Add new mode RETPOLINE_UNDERFLOW |
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On Fri, Jan 12, 2018 at 11:13:13PM +0100, Dominik Brodowski wrote: > > @@ -209,6 +234,11 @@ static void __init spectre_v2_select_mitigation(void) > > mode = retp_compiler() ? SPECTRE_V2_RETPOLINE_GENERIC : > > SPECTRE_V2_RETPOLINE_MINIMAL; > > setup_force_cpu_cap(X86_FEATURE_RETPOLINE); > > + if (mode == SPECTRE_V2_RETPOLINE_GENERIC && > > + cpu_needs_underflow_protection()) { > > + mode = SPECTRE_V2_RETPOLINE_UNDERFLOW; > > + setup_force_cpu_cap(X86_FEATURE_RETURN_UNDERFLOW); > > + } > > } > > Why does this require a retp-compatible compiler to be enabled?
Without the compiler you have a lot of other problems already, so it's fairly pointless.
-Andi
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