I've got some code that determines CPU capabilities for x86 processors. I'm interested in RDRAND and AESNI, and I use three functions to determine the capabilities: HasIntel(), HasAESNI() and HasRDRAND().
Debug configurations compiled with GCC and Clang work fine. Release configuration compiled with GCC and Clang work fine. However, I get *one* incorrect result when running under Valgrind. The incorrect result is from HasRDRAND(). Under Valgrind, the result is 0, which means RDRAND is not available. I think its related to "Valgrind shows different results for ubuntu and debian x86 cpuid implementations", http://sourceforge.net/mailarchive/message.php?msg_id=31873412. Can anyone confirm this is related to VEX virtual machine? I want to ensure I'm not seeing success in Debug and Release by dumb-luck (and possibly have an unforeseen problem to fix). Thanks in advance. ********** # Debian 7.3, x64, fully patched $ uname -a Linux debian-q500 3.2.0-4-amd64 #1 SMP Debian 3.2.51-1 x86_64 GNU/Linux # Built from sources a couple of weeks ago $ valgrind --version valgrind-3.9.0 ********** static void get_cpuid_info(CPUIDinfo *info, const unsigned int func, const unsigned int subfunc) { LogDebug("get_cpuid_info"); UNUSED(info); UNUSED(func); UNUSED(subfunc); __asm__ __volatile__ ( "cpuid" : "=a"(info->EAX), "=b"(info->EBX), "=c"(info->ECX), "=d"(info->EDX) : "a"(func), "c"(subfunc) ); } int HasIntel() { static int intel_cpu = 0; static once_flag flag; call_once(flag, []() { CPUIDinfo info; get_cpuid_info(&info,0,0); if(memcmp((char *)(&info.EBX), "Genu", 4) == 0 && memcmp((char *)(&info.EDX), "ineI", 4) == 0 && memcmp((char *)(&info.ECX), "ntel", 4) == 0) { intel_cpu = 1; } }); return intel_cpu; } int HasRDRAND() { static volatile int has_rdrand = 0; static once_flag flag; call_once(flag, []() { if(HasIntel()) { CPUIDinfo info; static const unsigned int RDRAND_CAP_BIT = (1 << 30); AC_ASSERT(0x40000000 == RDRAND_CAP_BIT); get_cpuid_info(&info,1,0); if ((info.ECX & RDRAND_CAP_BIT)==RDRAND_CAP_BIT) has_rdrand = 1; } }); return has_rdrand; } int HasAESNI() { static volatile int has_aesni = 0; static once_flag flag; call_once(flag, []() { if(HasIntel()) { CPUIDinfo info; static const unsigned int AESNI_CAP_BIT = (1 << 25); AC_ASSERT(0x2000000 == AESNI_CAP_BIT); get_cpuid_info(&info,1,0); if ((info.ECX & AESNI_CAP_BIT)==AESNI_CAP_BIT) has_aesni = 1; } }); return has_aesni; } ------------------------------------------------------------------------------ Android apps run on BlackBerry 10 Introducing the new BlackBerry 10.2.1 Runtime for Android apps. Now with support for Jelly Bean, Bluetooth, Mapview and more. Get your Android app in front of a whole new audience. Start now. http://pubads.g.doubleclick.net/gampad/clk?id=124407151&iu=/4140/ostg.clktrk _______________________________________________ Valgrind-users mailing list Valgrind-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/valgrind-users
