1 // SPDX-License-Identifier: GPL-2.0 2 #include "../perf.h" 3 #include <subcmd/parse-options.h> 4 #include "evsel.h" 5 #include "cgroup.h" 6 #include "evlist.h" 7 #include <linux/stringify.h> 8 #include <linux/zalloc.h> 9 #include <sys/types.h> 10 #include <sys/stat.h> 11 #include <fcntl.h> 12 13 int nr_cgroups; 14 15 static int 16 cgroupfs_find_mountpoint(char *buf, size_t maxlen) 17 { 18 FILE *fp; 19 char mountpoint[PATH_MAX + 1], tokens[PATH_MAX + 1], type[PATH_MAX + 1]; 20 char path_v1[PATH_MAX + 1], path_v2[PATH_MAX + 2], *path; 21 char *token, *saved_ptr = NULL; 22 23 fp = fopen("/proc/mounts", "r"); 24 if (!fp) 25 return -1; 26 27 /* 28 * in order to handle split hierarchy, we need to scan /proc/mounts 29 * and inspect every cgroupfs mount point to find one that has 30 * perf_event subsystem 31 */ 32 path_v1[0] = '\0'; 33 path_v2[0] = '\0'; 34 35 while (fscanf(fp, "%*s %"__stringify(PATH_MAX)"s %"__stringify(PATH_MAX)"s %" 36 __stringify(PATH_MAX)"s %*d %*d\n", 37 mountpoint, type, tokens) == 3) { 38 39 if (!path_v1[0] && !strcmp(type, "cgroup")) { 40 41 token = strtok_r(tokens, ",", &saved_ptr); 42 43 while (token != NULL) { 44 if (!strcmp(token, "perf_event")) { 45 strcpy(path_v1, mountpoint); 46 break; 47 } 48 token = strtok_r(NULL, ",", &saved_ptr); 49 } 50 } 51 52 if (!path_v2[0] && !strcmp(type, "cgroup2")) 53 strcpy(path_v2, mountpoint); 54 55 if (path_v1[0] && path_v2[0]) 56 break; 57 } 58 fclose(fp); 59 60 if (path_v1[0]) 61 path = path_v1; 62 else if (path_v2[0]) 63 path = path_v2; 64 else 65 return -1; 66 67 if (strlen(path) < maxlen) { 68 strcpy(buf, path); 69 return 0; 70 } 71 return -1; 72 } 73 74 static int open_cgroup(const char *name) 75 { 76 char path[PATH_MAX + 1]; 77 char mnt[PATH_MAX + 1]; 78 int fd; 79 80 81 if (cgroupfs_find_mountpoint(mnt, PATH_MAX + 1)) 82 return -1; 83 84 scnprintf(path, PATH_MAX, "%s/%s", mnt, name); 85 86 fd = open(path, O_RDONLY); 87 if (fd == -1) 88 fprintf(stderr, "no access to cgroup %s\n", path); 89 90 return fd; 91 } 92 93 static struct cgroup *evlist__find_cgroup(struct perf_evlist *evlist, const char *str) 94 { 95 struct perf_evsel *counter; 96 /* 97 * check if cgrp is already defined, if so we reuse it 98 */ 99 evlist__for_each_entry(evlist, counter) { 100 if (!counter->cgrp) 101 continue; 102 if (!strcmp(counter->cgrp->name, str)) 103 return cgroup__get(counter->cgrp); 104 } 105 106 return NULL; 107 } 108 109 static struct cgroup *cgroup__new(const char *name) 110 { 111 struct cgroup *cgroup = zalloc(sizeof(*cgroup)); 112 113 if (cgroup != NULL) { 114 refcount_set(&cgroup->refcnt, 1); 115 116 cgroup->name = strdup(name); 117 if (!cgroup->name) 118 goto out_err; 119 cgroup->fd = open_cgroup(name); 120 if (cgroup->fd == -1) 121 goto out_free_name; 122 } 123 124 return cgroup; 125 126 out_free_name: 127 zfree(&cgroup->name); 128 out_err: 129 free(cgroup); 130 return NULL; 131 } 132 133 struct cgroup *evlist__findnew_cgroup(struct perf_evlist *evlist, const char *name) 134 { 135 struct cgroup *cgroup = evlist__find_cgroup(evlist, name); 136 137 return cgroup ?: cgroup__new(name); 138 } 139 140 static int add_cgroup(struct perf_evlist *evlist, const char *str) 141 { 142 struct perf_evsel *counter; 143 struct cgroup *cgrp = evlist__findnew_cgroup(evlist, str); 144 int n; 145 146 if (!cgrp) 147 return -1; 148 /* 149 * find corresponding event 150 * if add cgroup N, then need to find event N 151 */ 152 n = 0; 153 evlist__for_each_entry(evlist, counter) { 154 if (n == nr_cgroups) 155 goto found; 156 n++; 157 } 158 159 cgroup__put(cgrp); 160 return -1; 161 found: 162 counter->cgrp = cgrp; 163 return 0; 164 } 165 166 static void cgroup__delete(struct cgroup *cgroup) 167 { 168 close(cgroup->fd); 169 zfree(&cgroup->name); 170 free(cgroup); 171 } 172 173 void cgroup__put(struct cgroup *cgrp) 174 { 175 if (cgrp && refcount_dec_and_test(&cgrp->refcnt)) { 176 cgroup__delete(cgrp); 177 } 178 } 179 180 struct cgroup *cgroup__get(struct cgroup *cgroup) 181 { 182 if (cgroup) 183 refcount_inc(&cgroup->refcnt); 184 return cgroup; 185 } 186 187 static void evsel__set_default_cgroup(struct perf_evsel *evsel, struct cgroup *cgroup) 188 { 189 if (evsel->cgrp == NULL) 190 evsel->cgrp = cgroup__get(cgroup); 191 } 192 193 void evlist__set_default_cgroup(struct perf_evlist *evlist, struct cgroup *cgroup) 194 { 195 struct perf_evsel *evsel; 196 197 evlist__for_each_entry(evlist, evsel) 198 evsel__set_default_cgroup(evsel, cgroup); 199 } 200 201 int parse_cgroups(const struct option *opt, const char *str, 202 int unset __maybe_unused) 203 { 204 struct perf_evlist *evlist = *(struct perf_evlist **)opt->value; 205 struct perf_evsel *counter; 206 struct cgroup *cgrp = NULL; 207 const char *p, *e, *eos = str + strlen(str); 208 char *s; 209 int ret, i; 210 211 if (list_empty(&evlist->entries)) { 212 fprintf(stderr, "must define events before cgroups\n"); 213 return -1; 214 } 215 216 for (;;) { 217 p = strchr(str, ','); 218 e = p ? p : eos; 219 220 /* allow empty cgroups, i.e., skip */ 221 if (e - str) { 222 /* termination added */ 223 s = strndup(str, e - str); 224 if (!s) 225 return -1; 226 ret = add_cgroup(evlist, s); 227 free(s); 228 if (ret) 229 return -1; 230 } 231 /* nr_cgroups is increased een for empty cgroups */ 232 nr_cgroups++; 233 if (!p) 234 break; 235 str = p+1; 236 } 237 /* for the case one cgroup combine to multiple events */ 238 i = 0; 239 if (nr_cgroups == 1) { 240 evlist__for_each_entry(evlist, counter) { 241 if (i == 0) 242 cgrp = counter->cgrp; 243 else { 244 counter->cgrp = cgrp; 245 refcount_inc(&cgrp->refcnt); 246 } 247 i++; 248 } 249 } 250 return 0; 251 } 252