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#include <string.h>
14
15#include "cpupower.h"
16#include "cpupower_intern.h"
17
18int is_valid_path(const char *path)
19{
20 if (access(path, F_OK) == -1)
21 return 0;
22 return 1;
23}
24
25unsigned int cpupower_read_sysfs(const char *path, char *buf, size_t buflen)
26{
27 ssize_t numread;
28 int fd;
29
30 fd = open(path, O_RDONLY);
31 if (fd == -1)
32 return 0;
33
34 numread = read(fd, buf, buflen - 1);
35 if (numread < 1) {
36 close(fd);
37 return 0;
38 }
39
40 buf[numread] = '\0';
41 close(fd);
42
43 return (unsigned int) numread;
44}
45
46unsigned int cpupower_write_sysfs(const char *path, char *buf, size_t buflen)
47{
48 ssize_t numwritten;
49 int fd;
50
51 fd = open(path, O_WRONLY);
52 if (fd == -1)
53 return 0;
54
55 numwritten = write(fd, buf, buflen - 1);
56 if (numwritten < 1) {
57 perror(path);
58 close(fd);
59 return 0;
60 }
61
62 close(fd);
63
64 return (unsigned int) numwritten;
65}
66
67/*
68 * Detect whether a CPU is online
69 *
70 * Returns:
71 * 1 -> if CPU is online
72 * 0 -> if CPU is offline
73 * negative errno values in error case
74 */
75int cpupower_is_cpu_online(unsigned int cpu)
76{
77 char path[SYSFS_PATH_MAX];
78 int fd;
79 ssize_t numread;
80 unsigned long long value;
81 char linebuf[MAX_LINE_LEN];
82 char *endp;
83 struct stat statbuf;
84
85 snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u", cpu);
86
87 if (stat(path, &statbuf) != 0)
88 return 0;
89
90 /*
91 * kernel without CONFIG_HOTPLUG_CPU
92 * -> cpuX directory exists, but not cpuX/online file
93 */
94 snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/online", cpu);
95 if (stat(path, &statbuf) != 0)
96 return 1;
97
98 fd = open(path, O_RDONLY);
99 if (fd == -1)
100 return -errno;
101
102 numread = read(fd, linebuf, MAX_LINE_LEN - 1);
103 if (numread < 1) {
104 close(fd);
105 return -EIO;
106 }
107 linebuf[numread] = '\0';
108 close(fd);
109
110 value = strtoull(linebuf, &endp, 0);
111 if (value > 1)
112 return -EINVAL;
113
114 return value;
115}
116
117/* returns -1 on failure, 0 on success */
118static int sysfs_topology_read_file(unsigned int cpu, const char *fname, int *result)
119{
120 char linebuf[MAX_LINE_LEN];
121 char *endp;
122 char path[SYSFS_PATH_MAX];
123
124 snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/topology/%s",
125 cpu, fname);
126 if (cpupower_read_sysfs(path, linebuf, MAX_LINE_LEN) == 0)
127 return -1;
128 *result = strtol(linebuf, &endp, 0);
129 if (endp == linebuf || errno == ERANGE)
130 return -1;
131 return 0;
132}
133
134static int __compare(const void *t1, const void *t2)
135{
136 struct cpuid_core_info *top1 = (struct cpuid_core_info *)t1;
137 struct cpuid_core_info *top2 = (struct cpuid_core_info *)t2;
138 if (top1->pkg < top2->pkg)
139 return -1;
140 else if (top1->pkg > top2->pkg)
141 return 1;
142 else if (top1->core < top2->core)
143 return -1;
144 else if (top1->core > top2->core)
145 return 1;
146 else if (top1->cpu < top2->cpu)
147 return -1;
148 else if (top1->cpu > top2->cpu)
149 return 1;
150 else
151 return 0;
152}
153
154static int __compare_core_cpu_list(const void *t1, const void *t2)
155{
156 struct cpuid_core_info *top1 = (struct cpuid_core_info *)t1;
157 struct cpuid_core_info *top2 = (struct cpuid_core_info *)t2;
158
159 return strcmp(top1->core_cpu_list, top2->core_cpu_list);
160}
161
162/*
163 * Returns amount of cpus, negative on error, cpu_top must be
164 * passed to cpu_topology_release to free resources
165 *
166 * Array is sorted after ->cpu_smt_list ->pkg, ->core
167 */
168int get_cpu_topology(struct cpupower_topology *cpu_top)
169{
170 int cpu, last_pkg, cpus = sysconf(_SC_NPROCESSORS_CONF);
171 char path[SYSFS_PATH_MAX];
172 char *last_cpu_list;
173
174 cpu_top->core_info = malloc(sizeof(struct cpuid_core_info) * cpus);
175 if (cpu_top->core_info == NULL)
176 return -ENOMEM;
177 cpu_top->pkgs = cpu_top->cores = 0;
178 for (cpu = 0; cpu < cpus; cpu++) {
179 cpu_top->core_info[cpu].cpu = cpu;
180 cpu_top->core_info[cpu].is_online = cpupower_is_cpu_online(cpu);
181 if(sysfs_topology_read_file(
182 cpu,
183 fname: "physical_package_id",
184 result: &(cpu_top->core_info[cpu].pkg)) < 0) {
185 cpu_top->core_info[cpu].pkg = -1;
186 cpu_top->core_info[cpu].core = -1;
187 continue;
188 }
189 if(sysfs_topology_read_file(
190 cpu,
191 fname: "core_id",
192 result: &(cpu_top->core_info[cpu].core)) < 0) {
193 cpu_top->core_info[cpu].pkg = -1;
194 cpu_top->core_info[cpu].core = -1;
195 continue;
196 }
197 if (cpu_top->core_info[cpu].core == -1) {
198 strncpy(cpu_top->core_info[cpu].core_cpu_list, "-1", CPULIST_BUFFER);
199 continue;
200 }
201 snprintf(path, sizeof(path), PATH_TO_CPU "cpu%u/topology/%s",
202 cpu, "core_cpus_list");
203 if (cpupower_read_sysfs(
204 path,
205 cpu_top->core_info[cpu].core_cpu_list,
206 CPULIST_BUFFER) < 1) {
207 printf("Warning CPU%u has a 0 size core_cpus_list string", cpu);
208 }
209 }
210
211 /* Count the number of distinct cpu lists to get the physical core
212 * count.
213 */
214 qsort(cpu_top->core_info, cpus, sizeof(struct cpuid_core_info),
215 __compare_core_cpu_list);
216
217 last_cpu_list = cpu_top->core_info[0].core_cpu_list;
218 cpu_top->cores = 1;
219 for (cpu = 1; cpu < cpus; cpu++) {
220 if (strcmp(cpu_top->core_info[cpu].core_cpu_list, last_cpu_list) != 0 &&
221 cpu_top->core_info[cpu].pkg != -1) {
222 last_cpu_list = cpu_top->core_info[cpu].core_cpu_list;
223 cpu_top->cores++;
224 }
225 }
226
227 qsort(cpu_top->core_info, cpus, sizeof(struct cpuid_core_info),
228 __compare);
229
230 /* Count the number of distinct pkgs values. This works
231 because the primary sort of the core_info struct was just
232 done by pkg value. */
233 last_pkg = cpu_top->core_info[0].pkg;
234 for(cpu = 1; cpu < cpus; cpu++) {
235 if (cpu_top->core_info[cpu].pkg != last_pkg &&
236 cpu_top->core_info[cpu].pkg != -1) {
237
238 last_pkg = cpu_top->core_info[cpu].pkg;
239 cpu_top->pkgs++;
240 }
241 }
242 if (!(cpu_top->core_info[0].pkg == -1))
243 cpu_top->pkgs++;
244
245 return cpus;
246}
247
248void cpu_topology_release(struct cpupower_topology cpu_top)
249{
250 free(cpu_top.core_info);
251}
252

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