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/* intelmetool
*
* Copyright (C) 2013-2016 Philipp Deppenwiese <zaolin@das-labor.org>,
* Copyright (C) 2013-2016 Alexander Couzens <lynxis@fe80.eu>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of
* the License, or any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include "msr.h"
#ifndef __DARWIN__
static int fd_msr = 0;
static int rdmsr(int addr, uint64_t *msr)
{
if (lseek(fd_msr, (off_t) addr, SEEK_SET) == -1) {
perror("Could not lseek() to MSR");
close(fd_msr);
return -1;
}
if (read(fd_msr, msr, 8) == 8) {
close(fd_msr);
return 0;
}
if (errno == EIO) {
perror("IO error couldn't read MSR.");
close(fd_msr);
/* On older platforms the MSR might not exists */
return -2;
}
perror("Couldn't read() MSR");
close(fd_msr);
return -1;
}
#endif
int msr_bootguard(uint64_t *msr, int debug)
{
#ifndef __DARWIN__
fd_msr = open("/dev/cpu/0/msr", O_RDONLY);
if (fd_msr < 0) {
perror("Error while opening /dev/cpu/0/msr");
printf("Did you run 'modprobe msr'?\n");
return -1;
}
if (rdmsr(MSR_BOOTGUARD, msr) < 0)
return -1;
#endif
if (!debug)
*msr &= ~0xff;
return 0;
}
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