/*      $OpenBSD: f00f.c,v 1.2 2018/05/21 23:34:20 bluhm Exp $  */
/*
 * Copyright (c) 2018 Alexander Bluhm <bluhm@genua.de>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

/* Test the Pentium f00f bug workaround by executing 0xF0,0x0F,0xC7,0xC8. */

#include <err.h>
#include <signal.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

void
handler(int sig, siginfo_t *sip, void *ctx)
{
        printf("signo %d, code %d, errno %d\n",
            sip->si_signo, sip->si_code, sip->si_errno);
        if (sig != SIGILL)
                errx(1, "expected SIGILL: %d", sig);
        printf("addr %p, trapno %d\n", sip->si_addr, sip->si_trapno);
        printf("instruction %.2x %.2x %.2x %.2x\n",
            ((uint8_t *)sip->si_addr)[0],
            ((uint8_t *)sip->si_addr)[1],
            ((uint8_t *)sip->si_addr)[2],
            ((uint8_t *)sip->si_addr)[3]);
        if (*((uint32_t *)sip->si_addr) != 0xc8c70ff0)
                errx(1, "expected instrcution f0 0f c7 c8");

        exit(0);
}

int
main(int argc, char *argv[])
{
        struct sigaction sa;
        uint64_t mem;
        uint32_t eax, ebx, ecx, edx;

        mem = 0x0123456789abcdefLL;
        eax = 0x11111111;
        ebx = 0x22222222;
        ecx = 0x33333333;
        edx = 0x44444444;

        /* First check that the cmpxchg8b instruction works as expected. */
        printf("mem %.16llx, edx:eax %.8x%8x, ecx:ebx %.8x%.8x\n",
            mem, edx, eax, ecx, ebx);
        printf("cmpxchg8b mem, mem != edx:eax\n");
        asm volatile (
                "lock   cmpxchg8b %0"
                : "+m" (mem), "+a" (eax), "+b" (ebx), "+c" (ecx), "+d" (edx));
        printf("mem %.16llx, edx:eax %.8x%8x, ecx:ebx %.8x%.8x\n",
            mem, edx, eax, ecx, ebx);

        if (mem != 0x0123456789abcdefLL)
                errx(1, "expected mem 0x0123456789abcdef");
        if (edx != 0x01234567 || eax != 0x89abcdef)
                errx(1, "expected edx:eax 0x0123456789abcdef");
        if (ecx != 0x33333333 || ebx != 0x22222222)
                errx(1, "expected ecx:ebx 0x3333333322222222");

        printf("cmpxchg8b mem, mem == edx:eax\n");
        asm volatile (
                "lock cmpxchg8b %0"
                : "+m" (mem), "+a" (eax), "+b" (ebx), "+c" (ecx), "+d" (edx));
        printf("mem %.16llx, edx:eax %.8x%8x, ecx:ebx %.8x%.8x\n",
            mem, edx, eax, ecx, ebx);

        if (mem != 0x3333333322222222LL)
                errx(1, "expected mem 0x3333333322222222");
        if (edx != 0x01234567 || eax != 0x89abcdef)
                errx(1, "expected edx:eax 0x0123456789abcdef");
        if (ecx != 0x33333333 || ebx != 0x22222222)
                errx(1, "expected ecx:ebx 0x3333333322222222");

        /* An illegal instruction must be signalled to user land. */
        memset(&sa, 0 ,sizeof(sa));
        sa.sa_sigaction = handler;
        sa.sa_flags = SA_SIGINFO;
        if (sigaction(SIGILL, &sa, NULL) == -1)
                err(2, "sigaction");

        /* Execute the cmpxchg8b instruction with invalid addressing mode. */
        printf("cmpxchg8b eax\n");
        asm volatile (
                ".byte 0xF0,0x0F,0xC7,0xC8"
                : : : "%eax", "%ebx", "%ecx", "%edx");
        printf("mem %.16llx, edx:eax %.8x%8x, ecx:ebx %.8x%.8x\n",
            mem, edx, eax, ecx, ebx);

        /* Not reached, the processor hangs or the signal handler exits. */
        errx(1, "expected signal");
}