| /* intelmetool */ |
| /* SPDX-License-Identifier: GPL-2.0-or-later */ |
| |
| #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; |
| } |