Messages in this thread | | | Date | Wed, 18 Jun 2014 16:44:29 +0200 | From | Borislav Petkov <> | Subject | Re: [PATCH v6 03/10] x86, mpx: add macro cpu_has_mpx |
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On Wed, Jun 18, 2014 at 07:35:17AM -0700, Dave Hansen wrote: > On 06/18/2014 02:57 AM, Borislav Petkov wrote: > >> > @@ -339,6 +339,12 @@ extern const char * const x86_power_flags[32]; > >> > #define cpu_has_eager_fpu boot_cpu_has(X86_FEATURE_EAGER_FPU) > >> > #define cpu_has_topoext boot_cpu_has(X86_FEATURE_TOPOEXT) > >> > > >> > +#ifdef CONFIG_X86_INTEL_MPX > >> > +#define cpu_has_mpx boot_cpu_has(X86_FEATURE_MPX) > > I think we don't want those macros anymore because they're obfuscating > > the code. You should use static_cpu_has instead. > > It looks like static_cpu_has() is the right thing to use instead of > boot_cpu_has(). But, this doesn't just obfuscate things. > > We actually _want_ the compiler to cull code out when the config option > is off. Things like do_bounds() will see code savings with _some_ kind > of #ifdef rather than using static_cpu_has().
Why?
Practically, distros will have it enabled anyway (you have X86_INTEL_MPX depend on CPU_SUP_INTEL).
Are you talking about the miniscule percentage of people building their own kernels?
-- Regards/Gruss, Boris.
Sent from a fat crate under my desk. Formatting is fine. --
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