Em Fri, Feb 02, 2018 at 03:37:31PM +0100, Borislav Petkov escreveu: > 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 <tedheads...@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.
But this is for the kernel build process, right? If we don't have a strict reason to forbid archeology... 8-) - Arnaldo