11th Gen Core CPU PKRU

pkru.c

#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <sys/mman.h>

static uint32_t rdpkru(void)
{
        uint32_t ecx = 0;
        uint32_t edx, pkru;
        asm volatile(".byte 0x0f,0x01,0xee\n\t"
                        : "=a" (pkru), "=d" (edx)
                        : "c" (ecx));
        return pkru;
}

int main(void) {
        int pkey = pkey_alloc(0,0);
        assert(pkey >= 0);
        uint32_t original_pkru = rdpkru();
        for (int iterations = 0; true ; iterations++) {
                uint32_t pkru = rdpkru();
                if (pkru != original_pkru) {
                        fprintf(stderr, "unexpected value on iteration %d value:0x%08x expected:0x%08x\n",
                                        iterations, pkru, original_pkru);
                        exit(1);
                }
        }
        return 0;
}