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 
is_valid_path(const char * path)18 int is_valid_path(const char *path)
19 {
20 	if (access(path, F_OK) == -1)
21 		return 0;
22 	return 1;
23 }
24 
cpupower_read_sysfs(const char * path,char * buf,size_t buflen)25 unsigned 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 
cpupower_write_sysfs(const char * path,char * buf,size_t buflen)46 unsigned 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 -1;
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  */
cpupower_is_cpu_online(unsigned int cpu)75 int 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 */
sysfs_topology_read_file(unsigned int cpu,const char * fname,int * result)118 static 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 
__compare(const void * t1,const void * t2)134 static 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 
__compare_core_cpu_list(const void * t1,const void * t2)154 static 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  */
get_cpu_topology(struct cpupower_topology * cpu_top)168 int 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 			"physical_package_id",
184 			&(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 			"core_id",
192 			&(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 
cpu_topology_release(struct cpupower_topology cpu_top)248 void cpu_topology_release(struct cpupower_topology cpu_top)
249 {
250 	free(cpu_top.core_info);
251 }
252