rdmsr.c

/* ----------------------------------------------------------------------- *
 *
 *   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.
 *
 * ----------------------------------------------------------------------- */

/*
 * rdmsr.c
 *
 * Utility to read 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'},
	{"hexadecimal",		0, 0, 'x'},
	{"capital-hexadecimal",	0, 0, 'X'},
	{"decimal",		0, 0, 'd'},
	{"signed-decimal",	0, 0, 'd'},
	{"unsigned-decimal",	0, 0, 'u'},
	{"octal",		0, 0, 'o'},
	{"c-language",		0, 0, 'c'},
	{"zero-fill",		0, 0, '0'},
	{"zero-pad",		0, 0, '0'},
	{"raw",			0, 0, 'r'},
	{"all",			0, 0, 'a'},
	{"processor",		1, 0, 'p'},
	{"cpu",			1, 0, 'p'},
	{"bitfield",		1, 0, 'f'},
	{0, 0, 0, 0}
};
static const char short_options[] = "hVxXdoruc0ap:f:";

static const char *proc_stat = "/proc/stat";

/* Number of decimal digits for a certain number of bits */
/* (int) ceil(log(2^n)/log(10)) */
static const int decdigits[] = {
	1, 1, 1, 1, 2, 2, 2, 3, 3, 3, 4, 4, 4, 4, 5, 5,
	5, 6, 6, 6, 7, 7, 7, 7, 8, 8, 8, 9, 9, 9, 10, 10,
	10, 10, 11, 11, 11, 12, 12, 12, 13, 13, 13, 13, 14, 14, 14, 15,
	15, 15, 16, 16, 16, 16, 17, 17, 17, 18, 18, 18, 19, 19, 19, 19,
	20
};

#define mo_hex  0x01
#define mo_dec  0x02
#define mo_oct  0x03
#define mo_raw  0x04
#define mo_uns  0x05
#define mo_chx  0x06
#define mo_mask 0x0f
#define mo_fill 0x40
#define mo_c    0x80

const char *program;

static void usage(void)
{
	fprintf(stderr,
		"Usage: %s [options] regno\n"
		"  --help         -h  Print this help\n"
		"  --version      -V  Print current version\n"
		"  --hexadecimal  -x  Hexadecimal output (lower case)\n"
		"  --capital-hex  -X  Hexadecimal output (upper case)\n"
		"  --decimal      -d  Signed decimal output\n"
		"  --unsigned     -u  Unsigned decimal output\n"
		"  --octal        -o  Octal output\n"
		"  --c-language   -c  Format output as a C language constant\n"
		"  --zero-pad     -0  Output leading zeroes\n"
		"  --raw          -r  Raw binary output\n"
		"  --all          -a  all processors\n"
		"  --processor #  -p  Select processor number (default 0)\n"
		"  --bitfield h:l -f  Output bits [h:l] only\n", program);
}

struct format {
	unsigned int mode;
	unsigned int highbit;
	unsigned int lowbit;
};

static void rdmsr_on_cpu(const struct format *fmt, uint32_t reg, int cpu)
{
	uint64_t data;
	int fd;
	char *pat;
	int width;
	char msr_file_name[64];
	unsigned int bits;

	sprintf(msr_file_name, "/dev/cpu/%d/msr", cpu);
	fd = open(msr_file_name, O_RDONLY);
	if (fd < 0) {
		if (errno == ENXIO) {
			fprintf(stderr, "rdmsr: No CPU %d\n", cpu);
			exit(2);
		} else if (errno == EIO) {
			fprintf(stderr, "rdmsr: CPU %d doesn't support MSRs\n",
				cpu);
			exit(3);
		} else {
			perror("rdmsr: open");
			exit(127);
		}
	}

	if (pread(fd, &data, sizeof data, reg) != sizeof data) {
		if (errno == EIO) {
			fprintf(stderr, "rdmsr: CPU %d cannot read "
				"MSR 0x%08"PRIx32"\n",
				cpu, reg);
			exit(4);
		} else {
			perror("rdmsr: pread");
			exit(127);
		}
	}

	close(fd);

	bits = fmt->highbit - fmt->lowbit + 1;
	if (bits < 64) {
		/* Show only part of register */
		data >>= fmt->lowbit;
		data &= (1ULL << bits) - 1;
	}

	pat = NULL;

	width = 1;		/* Default */
	switch (fmt->mode) {
	case mo_hex:
		pat = "%*llx\n";
		break;
	case mo_chx:
		pat = "%*llX\n";
		break;
	case mo_dec:
	case mo_dec | mo_c:
	case mo_dec | mo_fill | mo_c:
		/* Make sure we get sign correct */
		if (data & (1ULL << (bits - 1))) {
			data &= ~(1ULL << (bits - 1));
			data = -data;
		}
		pat = "%*lld\n";
		break;
	case mo_uns:
		pat = "%*llu\n";
		break;
	case mo_oct:
		pat = "%*llo\n";
		break;
	case mo_hex | mo_c:
		pat = "0x%*llx\n";
		break;
	case mo_chx | mo_c:
		pat = "0x%*llX\n";
		break;
	case mo_oct | mo_c:
		pat = "0%*llo\n";
		break;
	case mo_uns | mo_c:
	case mo_uns | mo_fill | mo_c:
		pat = "%*lluU\n";
		break;
	case mo_hex | mo_fill:
		pat = "%0*llx\n";
		width = (bits + 3) / 4;
		break;
	case mo_chx | mo_fill:
		pat = "%0*llX\n";
		width = (bits + 3) / 4;
		break;
	case mo_dec | mo_fill:
		/* Make sure we get sign correct */
		if (data & (1ULL << (bits - 1))) {
			data &= ~(1ULL << (bits - 1));
			data = -data;
		}
		pat = "%0*lld\n";
		width = decdigits[bits - 1] + 1;
		break;
	case mo_uns | mo_fill:
		pat = "%0*llu\n";
		width = decdigits[bits];
		break;
	case mo_oct | mo_fill:
		pat = "%0*llo\n";
		width = (bits + 2) / 3;
		break;
	case mo_hex | mo_fill | mo_c:
		pat = "0x%0*llx\n";
		width = (bits + 3) / 4;
		break;
	case mo_chx | mo_fill | mo_c:
		pat = "0x%0*llX\n";
		width = (bits + 3) / 4;
		break;
	case mo_oct | mo_fill | mo_c:
		pat = "0%0*llo\n";
		width = (bits + 2) / 3;
		break;
	case mo_raw:
	case mo_raw | mo_fill:
		fwrite(&data, sizeof data, 1, stdout);
		break;
	case mo_raw | mo_c:
	case mo_raw | mo_fill | mo_c:
		{
			unsigned char *p = (unsigned char *)&data;
			int i;
			for (i = 0; i < sizeof data; i++) {
				printf("%s0x%02x", i ? "," : "{",
				       (unsigned int)(*p++));
			}
			printf("}\n");
		}
		break;
	default:
		fprintf(stderr, "%s: Impossible case, line %d\n", program,
			__LINE__);
		exit(127);
	}

	if (width < 1)
		width = 1;

	if (pat)
		printf(pat, width, data);
	return;
}

static void rdmsr_on_all_cpus(const struct format *fmt, uint32_t reg)
{
	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;

		rdmsr_on_cpu(fmt, reg, cpu);
	}
	fclose(fp);
}

int main(int argc, char *argv[])
{
	uint32_t reg;
	int c;
	int cpu = 0;
	unsigned long arg;
	char *endarg;
	struct format fmt;

	fmt.mode    = mo_hex;
	fmt.highbit = 63;
	fmt.lowbit  = 0;

	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 'x':
			fmt.mode = (fmt.mode & ~mo_mask) | mo_hex;
			break;
		case 'X':
			fmt.mode = (fmt.mode & ~mo_mask) | mo_chx;
			break;
		case 'o':
			fmt.mode = (fmt.mode & ~mo_mask) | mo_oct;
			break;
		case 'd':
			fmt.mode = (fmt.mode & ~mo_mask) | mo_dec;
			break;
		case 'r':
			fmt.mode = (fmt.mode & ~mo_mask) | mo_raw;
			break;
		case 'u':
			fmt.mode = (fmt.mode & ~mo_mask) | mo_uns;
			break;
		case 'c':
			fmt.mode |= mo_c;
			break;
		case '0':
			fmt.mode |= mo_fill;
			break;
		case 'a':
			cpu = -1;
			break;
		case 'p':
			arg = strtoul(optarg, &endarg, 0);
			if (*endarg || arg > 255) {
				usage();
				exit(127);
			}
			cpu = (int)arg;
			break;
		case 'f':
			if (sscanf(optarg, "%u:%u", &fmt.highbit, &fmt.lowbit)
			    != 2 ||
			    fmt.highbit > 63 ||
			    fmt.lowbit > fmt.highbit) {
				usage();
				exit(127);
			}
			break;
		default:
			usage();
			exit(127);
		}
	}

	if (optind != argc - 1) {
		/* Should have exactly one argument */
		usage();
		exit(127);
	}

	reg = strtoul(argv[optind], NULL, 0);

	if (cpu == -1)
		rdmsr_on_all_cpus(&fmt, reg);
	else
		rdmsr_on_cpu(&fmt, reg, cpu);
	exit(0);
}