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/* ----------------------------------------------------------------------- *
*
* Copyright 2000 Transmeta Corporation - All Rights Reserved
* Copyright 2004-2008 H. Peter Anvin - All Rights Reserved
*
* 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, Inc., 51 Franklin St, Fifth Floor,
* Boston MA 02110-1301, USA; either version 2 of the License, or
* (at your option) any later version; incorporated herein by reference.
*
* ----------------------------------------------------------------------- */
/*
* wrmsr.c
*
* Utility to write to an MSR.
*/
#include <errno.h>
#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#include <getopt.h>
#include <inttypes.h>
#include <sys/types.h>
#include "version.h"
static const struct option long_options[] = {
{"help", 0, 0, 'h'},
{"version", 0, 0, 'V'},
{"all", 0, 0, 'a'},
{"processor", 1, 0, 'p'},
{"cpu", 1, 0, 'p'},
{0, 0, 0, 0}
};
static const char short_options[] = "hVap:";
static const char *proc_stat = "/proc/stat";
const char *program;
static void usage(void)
{
fprintf(stderr, "Usage: %s [options] regno value...\n"
" --help -h Print this help\n"
" --version -V Print current version\n"
" --all -a all processors\n"
" --processor # -p Select processor number (default 0)\n",
program);
}
static void wrmsr_on_cpu(uint32_t reg, uint64_t data, int cpu)
{
int fd;
char msr_file_name[64];
sprintf(msr_file_name, "/dev/cpu/%d/msr", cpu);
fd = open(msr_file_name, O_WRONLY);
if (fd < 0) {
if (errno == ENXIO) {
fprintf(stderr, "wrmsr: No CPU %d\n", cpu);
exit(2);
} else if (errno == EIO) {
fprintf(stderr, "wrmsr: CPU %d doesn't support MSRs\n",
cpu);
exit(3);
} else {
perror("wrmsr: open");
exit(127);
}
}
if (pwrite(fd, &data, sizeof data, reg) != sizeof data) {
if (errno == EIO) {
fprintf(stderr,
"wrmsr: CPU %d cannot set MSR "
"0x%08"PRIx32" to 0x%016"PRIx64"\n",
cpu, reg, data);
exit(4);
} else {
perror("wrmsr: pwrite");
exit(127);
}
}
close(fd);
}
static void wrmsr_on_all_cpus(uint32_t reg, uint64_t data)
{
FILE *fp;
int retval;
fp = fopen(proc_stat, "r");
if (fp == NULL) {
perror(proc_stat);
exit(-1);
}
retval = fscanf(fp, "cpu %*d %*d %*d %*d %*d %*d %*d %*d %*d %*d\n");
if (retval != 0) {
perror("/proc/stat format");
exit(-1);
}
for (;;) {
int cpu;
retval = fscanf(fp, "cpu%u %*d %*d %*d %*d %*d %*d %*d %*d "
"%*d %*d\n", &cpu);
if (retval != 1)
return;
wrmsr_on_cpu(reg, data, cpu);
}
fclose(fp);
}
int main(int argc, char *argv[])
{
uint32_t reg;
uint64_t data;
int c;
int cpu = 0;
unsigned long arg;
char *endarg;
program = argv[0];
while ((c = getopt_long(argc, argv, short_options,
long_options, NULL)) != -1) {
switch (c) {
case 'h':
usage();
exit(0);
case 'V':
fprintf(stderr, "%s: version %s\n", program,
VERSION_STRING);
exit(0);
case 'a':
cpu = -1;
break;
case 'p':
arg = strtoul(optarg, &endarg, 0);
if (*endarg || arg > 255) {
usage();
exit(127);
}
cpu = (int)arg;
break;
default:
usage();
exit(127);
}
}
if (optind > argc - 2) {
/* Should have at least two arguments */
usage();
exit(127);
}
reg = strtoul(argv[optind++], NULL, 0);
while (optind < argc) {
data = strtoull(argv[optind++], NULL, 0);
if (cpu == -1)
wrmsr_on_all_cpus(reg, data);
else
wrmsr_on_cpu(reg, data, cpu);
}
exit(0);
}
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