cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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centrino-decode.c (2028B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 *  (C) 2003 - 2004  Dominik Brodowski <linux@dominikbrodowski.de>
      4 *
      5 * Based on code found in
      6 * linux/arch/i386/kernel/cpu/cpufreq/speedstep-centrino.c
      7 * and originally developed by Jeremy Fitzhardinge.
      8 *
      9 * USAGE: simply run it to decode the current settings on CPU 0,
     10 *	  or pass the CPU number as argument, or pass the MSR content
     11 *	  as argument.
     12 */
     13
     14#include <stdio.h>
     15#include <stdlib.h>
     16#include <stdint.h>
     17#include <unistd.h>
     18#include <errno.h>
     19#include <fcntl.h>
     20
     21#include <sys/types.h>
     22#include <sys/stat.h>
     23
     24#define MCPU	32
     25
     26#define MSR_IA32_PERF_STATUS	0x198
     27
     28static int rdmsr(unsigned int cpu, unsigned int msr,
     29		 unsigned int *lo, unsigned int *hi)
     30{
     31	int fd;
     32	char file[20];
     33	unsigned long long val;
     34	int retval = -1;
     35
     36	*lo = *hi = 0;
     37
     38	if (cpu > MCPU)
     39		goto err1;
     40
     41	sprintf(file, "/dev/cpu/%d/msr", cpu);
     42	fd = open(file, O_RDONLY);
     43
     44	if (fd < 0)
     45		goto err1;
     46
     47	if (lseek(fd, msr, SEEK_CUR) == -1)
     48		goto err2;
     49
     50	if (read(fd, &val, 8) != 8)
     51		goto err2;
     52
     53	*lo = (uint32_t )(val & 0xffffffffull);
     54	*hi = (uint32_t )(val>>32 & 0xffffffffull);
     55
     56	retval = 0;
     57err2:
     58	close(fd);
     59err1:
     60	return retval;
     61}
     62
     63static void decode (unsigned int msr)
     64{
     65	unsigned int multiplier;
     66	unsigned int mv;
     67
     68	multiplier = ((msr >> 8) & 0xFF);
     69
     70	mv = (((msr & 0xFF) * 16) + 700);
     71
     72	printf("0x%x means multiplier %d @ %d mV\n", msr, multiplier, mv);
     73}
     74
     75static int decode_live(unsigned int cpu)
     76{
     77	unsigned int lo, hi;
     78	int err;
     79
     80	err = rdmsr(cpu, MSR_IA32_PERF_STATUS, &lo, &hi);
     81
     82	if (err) {
     83		printf("can't get MSR_IA32_PERF_STATUS for cpu %d\n", cpu);
     84		printf("Possible trouble: you don't run an Enhanced SpeedStep capable cpu\n");
     85		printf("or you are not root, or the msr driver is not present\n");
     86		return 1;
     87	}
     88
     89	decode(lo);
     90
     91	return 0;
     92}
     93
     94int main (int argc, char **argv)
     95{
     96	unsigned int cpu, mode = 0;
     97
     98	if (argc < 2)
     99		cpu = 0;
    100	else {
    101		cpu = strtoul(argv[1], NULL, 0);
    102		if (cpu >= MCPU)
    103			mode = 1;
    104	}
    105
    106	if (mode)
    107		decode(cpu);
    108	else
    109		decode_live(cpu);
    110
    111	return 0;
    112}