Messages in this thread | | | Date | Fri, 2 Feb 2018 11:54:48 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [PATCH] x86/perf : Add check for CPUID instruction before using |
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Em Fri, Feb 02, 2018 at 09:30:51AM -0500, Matthew Whitehead escreveu: > 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.
Can you provide an URL for the code used as a reference, please?
- Arnaldo
> 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) > +{ > + 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. > + */ > + __asm__ ("pushfl\n\t" > + "pushfl\n\t" > + "popl\t%0\n\t" > + "movl\t%0, %1\n\t" > + "xorl\t%2, %0\n\t" > + "pushl\t%0\n\t" > + "popfl\n\t" > + "pushfl\n\t" > + "popl\t%0\n\t" > + "popfl\n\t" > + : "=&r" (__eax), "=&r" (__ebx) > + : "i" (0x00200000)); > +#endif > + > + if (!((__eax ^ __ebx) & 0x00200000)) > + return 0; > + else > + return 1; > +#endif > + > +/* All x86_64 support cpuid */ > + return 1; > +} > + > static inline void > cpuid(unsigned int op, unsigned int *a, unsigned int *b, unsigned int *c, > unsigned int *d) > @@ -28,6 +76,9 @@ __get_cpuid(char *buffer, size_t sz, const char *fmt) > int nb; > char vendor[16]; > > + if (!have_cpuid()) > + return -1; > + > cpuid(0, &lvl, &b, &c, &d); > strncpy(&vendor[0], (char *)(&b), 4); > strncpy(&vendor[4], (char *)(&d), 4); > diff --git a/tools/perf/util/header.h b/tools/perf/util/header.h > index f28aaaa3a440..ce31fca36077 100644 > --- a/tools/perf/util/header.h > +++ b/tools/perf/util/header.h > @@ -171,6 +171,8 @@ int write_padded(struct feat_fd *fd, const void *bf, > /* > * arch specific callback > */ > +unsigned int have_cpuid(void); > + > int get_cpuid(char *buffer, size_t sz); > > char *get_cpuid_str(struct perf_pmu *pmu __maybe_unused); > -- > 2.13.6
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