text: /* 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;
  }
  