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/*
* 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");
}
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