Valgrind正在更改CPUID opcode instruction返回的值。简单地说，如何让Valgrind遵守实际的CPUID指令？
作为参考，这是我在一台旧电脑上检测aes-ni支持时发现的奇怪错误，我知道这台电脑没有aes-ni指令集。然而，这种行为显然改变了多个值。
使用以下C代码，可以在valgrind-3.10.1中观察到这种行为：

#include <stdio.h>

int main() {
        unsigned eax, ebx, ecx, edx;
        eax = 1;
        __asm__ volatile("cpuid"
                : "=a" (eax), "=b" (ebx), "=c" (ecx), "=d" (edx)
                :  "0" (eax),  "2" (ecx)
        );
        if(ecx & (1<<25)) {
                printf("aes-ni enabled (ecx=%08x)n", ecx);
        } else {
                printf("no aes-ni support (ecx=%08x)\n", ecx);
        }
        return 1;
}

它的编译和运行方式如下：

$ gcc -o test test.c
$ ./test
no aes-ni support (ecx=0098e3fd)
$ valgrind ./test
==25361== Memcheck, a memory error detector
==25361== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al.
==25361== Using Valgrind-3.10.1 and LibVEX; rerun with -h for copyright info
==25361== Command: ./test
==25361==
aes-ni enabled (ecx=0298e3ff)
==25361==
==25361== HEAP SUMMARY:
==25361==     in use at exit: 0 bytes in 0 blocks
==25361==   total heap usage: 0 allocs, 0 frees, 0 bytes allocated
==25361==
==25361== All heap blocks were freed -- no leaks are possible
==25361==
==25361== For counts of detected and suppressed errors, rerun with: -v
==25361== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)

请注意，同样的二进制文件在正常情况下返回0098 e3 fd，但在valgrind下返回0298 e3 ff，这是错误的！