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 <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)
> +{
> + 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
