1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * (C) 2004-2009 Dominik Brodowski <linux@dominikbrodowski.de>
4 */
5
6#include <sys/types.h>
7#include <sys/stat.h>
8#include <fcntl.h>
9#include <unistd.h>
10#include <stdio.h>
11#include <errno.h>
12#include <stdlib.h>
13
14#include "cpupower.h"
15#include "cpupower_intern.h"
16
17int is_valid_path(const char *path)
18{
19 if (access(path, F_OK) == -1)
20 return 0;
21 return 1;
22}
23
24unsigned int cpupower_read_sysfs(const char *path, char *buf, size_t buflen)
25{
26 ssize_t numread;
27 int fd;
28
29 fd = open(path, O_RDONLY);
30 if (fd == -1)
31 return 0;
32
33 numread = read(fd, buf, buflen - 1);
34 if (numread < 1) {
35 close(fd);
36 return 0;
37 }
38
39 buf[numread] = '\0';
40 close(fd);
41
42 return (unsigned int) numread;
43}
44
45unsigned int cpupower_write_sysfs(const char *path, char *buf, size_t buflen)
46{
47 ssize_t numwritten;
48 int fd;
49
50 fd = open(path, O_WRONLY);
51 if (fd == -1)
52 return 0;
53
54 numwritten = write(fd, buf, buflen - 1);
55 if (numwritten < 1) {
56 perror(path);
57 close(fd);
58 return -1;
59 }
60
61 close(fd);
62
63 return (unsigned int) numwritten;
64}
65
66/*
67 * Detect whether a CPU is online
68 *
69 * Returns:
70 * 1 -> if CPU is online
71 * 0 -> if CPU is offline
72 * negative errno values in error case
73 */
74int cpupower_is_cpu_online(unsigned int cpu)
75{
76 char path[SYSFS_PATH_MAX];
77 int fd;
78 ssize_t numread;
79 unsigned long long value;
80 char linebuf[MAX_LINE_LEN];
81 char *endp;
82 struct stat statbuf;
83
84 snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u", cpu);
85
86 if (stat(path, &statbuf) != 0)
87 return 0;
88
89 /*
90 * kernel without CONFIG_HOTPLUG_CPU
91 * -> cpuX directory exists, but not cpuX/online file
92 */
93 snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/online", cpu);
94 if (stat(path, &statbuf) != 0)
95 return 1;
96
97 fd = open(path, O_RDONLY);
98 if (fd == -1)
99 return -errno;
100
101 numread = read(fd, linebuf, MAX_LINE_LEN - 1);
102 if (numread < 1) {
103 close(fd);
104 return -EIO;
105 }
106 linebuf[numread] = '\0';
107 close(fd);
108
109 value = strtoull(linebuf, &endp, 0);
110 if (value > 1)
111 return -EINVAL;
112
113 return value;
114}
115
116/* returns -1 on failure, 0 on success */
117static int sysfs_topology_read_file(unsigned int cpu, const char *fname, int *result)
118{
119 char linebuf[MAX_LINE_LEN];
120 char *endp;
121 char path[SYSFS_PATH_MAX];
122
123 snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/topology/%s",
124 cpu, fname);
125 if (cpupower_read_sysfs(path, linebuf, MAX_LINE_LEN) == 0)
126 return -1;
127 *result = strtol(linebuf, &endp, 0);
128 if (endp == linebuf || errno == ERANGE)
129 return -1;
130 return 0;
131}
132
133static int __compare(const void *t1, const void *t2)
134{
135 struct cpuid_core_info *top1 = (struct cpuid_core_info *)t1;
136 struct cpuid_core_info *top2 = (struct cpuid_core_info *)t2;
137 if (top1->pkg < top2->pkg)
138 return -1;
139 else if (top1->pkg > top2->pkg)
140 return 1;
141 else if (top1->core < top2->core)
142 return -1;
143 else if (top1->core > top2->core)
144 return 1;
145 else if (top1->cpu < top2->cpu)
146 return -1;
147 else if (top1->cpu > top2->cpu)
148 return 1;
149 else
150 return 0;
151}
152
153/*
154 * Returns amount of cpus, negative on error, cpu_top must be
155 * passed to cpu_topology_release to free resources
156 *
157 * Array is sorted after ->pkg, ->core, then ->cpu
158 */
159int get_cpu_topology(struct cpupower_topology *cpu_top)
160{
161 int cpu, last_pkg, cpus = sysconf(_SC_NPROCESSORS_CONF);
162
163 cpu_top->core_info = malloc(sizeof(struct cpuid_core_info) * cpus);
164 if (cpu_top->core_info == NULL)
165 return -ENOMEM;
166 cpu_top->pkgs = cpu_top->cores = 0;
167 for (cpu = 0; cpu < cpus; cpu++) {
168 cpu_top->core_info[cpu].cpu = cpu;
169 cpu_top->core_info[cpu].is_online = cpupower_is_cpu_online(cpu);
170 if(sysfs_topology_read_file(
171 cpu,
172 fname: "physical_package_id",
173 result: &(cpu_top->core_info[cpu].pkg)) < 0) {
174 cpu_top->core_info[cpu].pkg = -1;
175 cpu_top->core_info[cpu].core = -1;
176 continue;
177 }
178 if(sysfs_topology_read_file(
179 cpu,
180 fname: "core_id",
181 result: &(cpu_top->core_info[cpu].core)) < 0) {
182 cpu_top->core_info[cpu].pkg = -1;
183 cpu_top->core_info[cpu].core = -1;
184 continue;
185 }
186 }
187
188 qsort(cpu_top->core_info, cpus, sizeof(struct cpuid_core_info),
189 __compare);
190
191 /* Count the number of distinct pkgs values. This works
192 because the primary sort of the core_info struct was just
193 done by pkg value. */
194 last_pkg = cpu_top->core_info[0].pkg;
195 for(cpu = 1; cpu < cpus; cpu++) {
196 if (cpu_top->core_info[cpu].pkg != last_pkg &&
197 cpu_top->core_info[cpu].pkg != -1) {
198
199 last_pkg = cpu_top->core_info[cpu].pkg;
200 cpu_top->pkgs++;
201 }
202 }
203 if (!(cpu_top->core_info[0].pkg == -1))
204 cpu_top->pkgs++;
205
206 /* Intel's cores count is not consecutively numbered, there may
207 * be a core_id of 3, but none of 2. Assume there always is 0
208 * Get amount of cores by counting duplicates in a package
209 for (cpu = 0; cpu_top->core_info[cpu].pkg = 0 && cpu < cpus; cpu++) {
210 if (cpu_top->core_info[cpu].core == 0)
211 cpu_top->cores++;
212 */
213 return cpus;
214}
215
216void cpu_topology_release(struct cpupower_topology cpu_top)
217{
218 free(cpu_top.core_info);
219}
220

source code of linux/tools/power/cpupower/lib/cpupower.c