1 // SPDX-License-Identifier: GPL-2.0 2 #include "util.h" 3 #include "../perf.h" 4 #include <subcmd/parse-options.h> 5 #include "evsel.h" 6 #include "cgroup.h" 7 #include "evlist.h" 8 #include <linux/stringify.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(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 snprintf(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 int add_cgroup(struct perf_evlist *evlist, char *str) 94 { 95 struct perf_evsel *counter; 96 struct cgroup_sel *cgrp = NULL; 97 int n; 98 /* 99 * check if cgrp is already defined, if so we reuse it 100 */ 101 evlist__for_each_entry(evlist, counter) { 102 cgrp = counter->cgrp; 103 if (!cgrp) 104 continue; 105 if (!strcmp(cgrp->name, str)) { 106 refcount_inc(&cgrp->refcnt); 107 break; 108 } 109 110 cgrp = NULL; 111 } 112 113 if (!cgrp) { 114 cgrp = zalloc(sizeof(*cgrp)); 115 if (!cgrp) 116 return -1; 117 118 cgrp->name = str; 119 refcount_set(&cgrp->refcnt, 1); 120 121 cgrp->fd = open_cgroup(str); 122 if (cgrp->fd == -1) { 123 free(cgrp); 124 return -1; 125 } 126 } 127 128 /* 129 * find corresponding event 130 * if add cgroup N, then need to find event N 131 */ 132 n = 0; 133 evlist__for_each_entry(evlist, counter) { 134 if (n == nr_cgroups) 135 goto found; 136 n++; 137 } 138 if (refcount_dec_and_test(&cgrp->refcnt)) 139 free(cgrp); 140 141 return -1; 142 found: 143 counter->cgrp = cgrp; 144 return 0; 145 } 146 147 void close_cgroup(struct cgroup_sel *cgrp) 148 { 149 if (cgrp && refcount_dec_and_test(&cgrp->refcnt)) { 150 close(cgrp->fd); 151 zfree(&cgrp->name); 152 free(cgrp); 153 } 154 } 155 156 int parse_cgroups(const struct option *opt __maybe_unused, const char *str, 157 int unset __maybe_unused) 158 { 159 struct perf_evlist *evlist = *(struct perf_evlist **)opt->value; 160 const char *p, *e, *eos = str + strlen(str); 161 char *s; 162 int ret; 163 164 if (list_empty(&evlist->entries)) { 165 fprintf(stderr, "must define events before cgroups\n"); 166 return -1; 167 } 168 169 for (;;) { 170 p = strchr(str, ','); 171 e = p ? p : eos; 172 173 /* allow empty cgroups, i.e., skip */ 174 if (e - str) { 175 /* termination added */ 176 s = strndup(str, e - str); 177 if (!s) 178 return -1; 179 ret = add_cgroup(evlist, s); 180 if (ret) { 181 free(s); 182 return -1; 183 } 184 } 185 /* nr_cgroups is increased een for empty cgroups */ 186 nr_cgroups++; 187 if (!p) 188 break; 189 str = p+1; 190 } 191 return 0; 192 } 193