[CRIU] [PATCH] zdtm/x86: Don't override %ebx in fpu00

[Andrei Vagin]

Applied, thanks!

On Wed, Oct 31, 2018 at 12:16:14AM +0000, Dmitry Safonov wrote:
> %ebx, %ecx, %eax aren't specified as clobbers in chk_proc_fpu(),
> while asm cpuid overwrites them.
> 
> In the turn, %ebx is used as a code position by gcc now:
>     1661:       e8 9a 00 00 00          call   1700 <__x86.get_pc_thunk.bx>
>     1666:       81 c3 46 68 00 00       add    $0x6846,%ebx
> 
> Which results in dereferencing some ugly garbage (result of cpuid).
> 
> Let's use zdtm/lib cpuid() function instead.
> 
> Signed-off-by: Dmitry Safonov <dima at arista.com>
> ---
>  test/zdtm/static/fpu00.c | 16 +++++++++-------
>  1 file changed, 9 insertions(+), 7 deletions(-)
> 
> diff --git a/test/zdtm/static/fpu00.c b/test/zdtm/static/fpu00.c
> index 3e168a2f..04aa738f 100644
> --- a/test/zdtm/static/fpu00.c
> +++ b/test/zdtm/static/fpu00.c
> @@ -7,6 +7,9 @@ const char *test_doc	= "Start a calculation, leaving FPU in a certain state,\n"
>  const char *test_author	= "Pavel Emelianov <xemul at parallels.com>";
>  
>  #if defined(__i386__) || defined(__x86_64__)
> +
> +#include "cpuid.h"
> +
>  void start(float a, float b, float c, float d)
>  {
>  	__asm__ volatile (
> @@ -31,16 +34,15 @@ float finish(void)
>  	return res;
>  }
>  
> +#define CPUID_FEAT_EDX_FPU (1 << 0)
> +
>  int chk_proc_fpu(void)
>  {
> -	unsigned long fi;
> +	uint32_t eax, ebx, ecx, edx;
>  
> -	__asm__ volatile (
> -			"mov $1, %%eax\n"
> -			"cpuid\n"
> -			: "=d" (fi) : : "eax"
> -		);
> -	return fi & (1 << 0);
> +	cpuid(1, &eax, &ebx, &ecx, &edx);
> +
> +	return edx & CPUID_FEAT_EDX_FPU;
>  }
>  #endif
>  
> -- 
> 2.19.1
> 
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