Messages in this thread | | | Date | Fri, 2 Feb 2018 15:37:31 +0100 | From | Borislav Petkov <> | Subject | Re: [PATCH] x86/perf : Add check for CPUID instruction before using |
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On Fri, Feb 02, 2018 at 09:30:51AM -0500, Matthew Whitehead wrote: > We still officially support the ancient i486 cpu. First generation > versions of this processor do not have the CPUID instruction, though > later versions do. Therefore you must check that the cpu supports > it before using it. At present it fails with an "Illegal Instruction" > signal on the early processors. > > This code was based on similar code in the gcc package. > > Signed-off-by: Matthew Whitehead <tedheadster@gmail.com> > --- > tools/perf/arch/x86/util/header.c | 51 +++++++++++++++++++++++++++++++++++++++ > tools/perf/util/header.h | 2 ++ > 2 files changed, 53 insertions(+) > > diff --git a/tools/perf/arch/x86/util/header.c b/tools/perf/arch/x86/util/header.c > index fb0d71afee8b..d4d12894c64d 100644 > --- a/tools/perf/arch/x86/util/header.c > +++ b/tools/perf/arch/x86/util/header.c > @@ -7,6 +7,54 @@ > > #include "../../util/header.h" > > +/* This code based on gcc cpuid.h __get_cpuid_max() */ > +unsigned int have_cpuid(void)
You could've copied have_cpuid_p() from arch/x86/kernel/cpu/common.c
> +{ > + unsigned int __eax, __ebx; > + > +#ifndef __x86_64__ > +/* See if we can use cpuid. On AMD64 we always can. */ > +#if __GNUC__ >= 3 > + __asm__ ("pushf{l|d}\n\t" > + "pushf{l|d}\n\t" > + "pop{l}\t%0\n\t" > + "mov{l}\t{%0, %1|%1, %0}\n\t" > + "xor{l}\t{%2, %0|%0, %2}\n\t" > + "push{l}\t%0\n\t" > + "popf{l|d}\n\t" > + "pushf{l|d}\n\t" > + "pop{l}\t%0\n\t" > + "popf{l|d}\n\t" > + : "=&r" (__eax), "=&r" (__ebx) > + : "i" (0x00200000)); > +#else > +/* Host GCCs older than 3.0 weren't supporting Intel asm syntax > + * nor alternatives in i386 code.
We don't support gcc < 3
#if GCC_VERSION < 30200 # error Sorry, your compiler is too old - please upgrade it. #endif
There's even talk currently to raise the minimum version to 4.9 or so.
-- Regards/Gruss, Boris.
Good mailing practices for 400: avoid top-posting and trim the reply.
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