Re: [PING] Re: [PATCH] Fix MPX tests on systems with MPX disabled

[Ilya Enkovich <enkovich dot gnu at gmail dot com>]

2016-07-04 22:58 GMT+03:00 Andi Kleen <andi@firstfloor.org>:
> Andi Kleen <andi@firstfloor.org> writes:
>
> PING!
>
>> From: Andi Kleen <ak@linux.intel.com>
>>
>> I have a Skylake system with MPX in the CPU, but MPX is disabled
>> in the kernel configuration.
>>
>> This makes all the MPX tests fail because they assume if MPX
>> is in CPUID it works
>>
>> Check the output of XGETBV too to detect non MPX kernels.

The patch is OK for trunk and GCC 6 branch

Thanks,
Ilya

>>
>> gcc/testsuite/:
>>
>> 2016-06-25  Andi Kleen  <ak@linux.intel.com>
>>
>>       * gcc.target/i386/mpx/mpx-check.h: Check XGETBV output
>>       if kernel supports MPX.
>> ---
>>  gcc/testsuite/gcc.target/i386/mpx/mpx-check.h | 12 +++++++++++-
>>  1 file changed, 11 insertions(+), 1 deletion(-)
>>
>> diff --git a/gcc/testsuite/gcc.target/i386/mpx/mpx-check.h b/gcc/testsuite/gcc.target/i386/mpx/mpx-check.h
>> index 3afa460..73aa01f 100644
>> --- a/gcc/testsuite/gcc.target/i386/mpx/mpx-check.h
>> +++ b/gcc/testsuite/gcc.target/i386/mpx/mpx-check.h
>> @@ -16,6 +16,16 @@ mpx_test (int, const char **);
>>
>>  #define DEBUG
>>
>> +#define XSTATE_BNDREGS (1 << 3)
>> +
>> +/* This should be an intrinsic, but isn't.  */
>> +static int xgetbv (unsigned x)
>> +{
>> +   unsigned eax, edx;
>> +   asm ("xgetbv" : "=a" (eax), "=d" (edx) : "c" (x));
>> +   return eax;
>> +}
>> +
>>  int
>>  main (int argc, const char **argv)
>>  {
>> @@ -27,7 +37,7 @@ main (int argc, const char **argv)
>>    __cpuid_count (7, 0, eax, ebx, ecx, edx);
>>
>>    /* Run MPX test only if host has MPX support.  */
>> -  if (ebx & bit_MPX)
>> +  if ((ebx & bit_MPX) && (xgetbv (0) & XSTATE_BNDREGS))
>>      mpx_test (argc, argv);
>>    else
>>      {
>
> --
> ak@linux.intel.com -- Speaking for myself only