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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acpi_cppc.c (1405B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2
      3#include <stdio.h>
      4#include <errno.h>
      5#include <stdlib.h>
      6#include <string.h>
      7#include <sys/types.h>
      8#include <sys/stat.h>
      9#include <fcntl.h>
     10#include <unistd.h>
     11
     12#include "cpupower_intern.h"
     13#include "acpi_cppc.h"
     14
     15/* ACPI CPPC sysfs access ***********************************************/
     16
     17static int acpi_cppc_read_file(unsigned int cpu, const char *fname,
     18			       char *buf, size_t buflen)
     19{
     20	char path[SYSFS_PATH_MAX];
     21
     22	snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/acpi_cppc/%s",
     23		 cpu, fname);
     24	return cpupower_read_sysfs(path, buf, buflen);
     25}
     26
     27static const char * const acpi_cppc_value_files[] = {
     28	[HIGHEST_PERF] = "highest_perf",
     29	[LOWEST_PERF] = "lowest_perf",
     30	[NOMINAL_PERF] = "nominal_perf",
     31	[LOWEST_NONLINEAR_PERF] = "lowest_nonlinear_perf",
     32	[LOWEST_FREQ] = "lowest_freq",
     33	[NOMINAL_FREQ] = "nominal_freq",
     34	[REFERENCE_PERF] = "reference_perf",
     35	[WRAPAROUND_TIME] = "wraparound_time"
     36};
     37
     38unsigned long acpi_cppc_get_data(unsigned int cpu, enum acpi_cppc_value which)
     39{
     40	unsigned long long value;
     41	unsigned int len;
     42	char linebuf[MAX_LINE_LEN];
     43	char *endp;
     44
     45	if (which >= MAX_CPPC_VALUE_FILES)
     46		return 0;
     47
     48	len = acpi_cppc_read_file(cpu, acpi_cppc_value_files[which],
     49				  linebuf, sizeof(linebuf));
     50	if (len == 0)
     51		return 0;
     52
     53	value = strtoull(linebuf, &endp, 0);
     54
     55	if (endp == linebuf || errno == ERANGE)
     56		return 0;
     57
     58	return value;
     59}