1 /* SPDX-License-Identifier: GPL-2.0 */ 2 3 #include "perf-sys.h" 4 #include "util/cloexec.h" 5 #include "util/evlist.h" 6 #include "util/evsel.h" 7 #include "util/parse-events.h" 8 #include "util/perf_api_probe.h" 9 #include <perf/cpumap.h> 10 #include <errno.h> 11 12 typedef void (*setup_probe_fn_t)(struct evsel *evsel); 13 14 static int perf_do_probe_api(setup_probe_fn_t fn, struct perf_cpu cpu, const char *str) 15 { 16 struct evlist *evlist; 17 struct evsel *evsel; 18 unsigned long flags = perf_event_open_cloexec_flag(); 19 int err = -EAGAIN, fd; 20 static pid_t pid = -1; 21 22 evlist = evlist__new(); 23 if (!evlist) 24 return -ENOMEM; 25 26 if (parse_event(evlist, str)) 27 goto out_delete; 28 29 evsel = evlist__first(evlist); 30 31 while (1) { 32 fd = sys_perf_event_open(&evsel->core.attr, pid, cpu.cpu, -1, flags); 33 if (fd < 0) { 34 if (pid == -1 && errno == EACCES) { 35 pid = 0; 36 continue; 37 } 38 goto out_delete; 39 } 40 break; 41 } 42 close(fd); 43 44 fn(evsel); 45 46 fd = sys_perf_event_open(&evsel->core.attr, pid, cpu.cpu, -1, flags); 47 if (fd < 0) { 48 if (errno == EINVAL) 49 err = -EINVAL; 50 goto out_delete; 51 } 52 close(fd); 53 err = 0; 54 55 out_delete: 56 evlist__delete(evlist); 57 return err; 58 } 59 60 static bool perf_probe_api(setup_probe_fn_t fn) 61 { 62 const char *try[] = {"cycles:u", "instructions:u", "cpu-clock:u", NULL}; 63 struct perf_cpu_map *cpus; 64 struct perf_cpu cpu; 65 int ret, i = 0; 66 67 cpus = perf_cpu_map__new_online_cpus(); 68 if (!cpus) 69 return false; 70 cpu = perf_cpu_map__cpu(cpus, 0); 71 perf_cpu_map__put(cpus); 72 73 do { 74 ret = perf_do_probe_api(fn, cpu, try[i++]); 75 if (!ret) 76 return true; 77 } while (ret == -EAGAIN && try[i]); 78 79 return false; 80 } 81 82 static void perf_probe_sample_identifier(struct evsel *evsel) 83 { 84 evsel->core.attr.sample_type |= PERF_SAMPLE_IDENTIFIER; 85 } 86 87 static void perf_probe_comm_exec(struct evsel *evsel) 88 { 89 evsel->core.attr.comm_exec = 1; 90 } 91 92 static void perf_probe_context_switch(struct evsel *evsel) 93 { 94 evsel->core.attr.context_switch = 1; 95 } 96 97 static void perf_probe_text_poke(struct evsel *evsel) 98 { 99 evsel->core.attr.text_poke = 1; 100 } 101 102 static void perf_probe_build_id(struct evsel *evsel) 103 { 104 evsel->core.attr.build_id = 1; 105 } 106 107 static void perf_probe_cgroup(struct evsel *evsel) 108 { 109 evsel->core.attr.cgroup = 1; 110 } 111 112 bool perf_can_sample_identifier(void) 113 { 114 return perf_probe_api(perf_probe_sample_identifier); 115 } 116 117 bool perf_can_comm_exec(void) 118 { 119 return perf_probe_api(perf_probe_comm_exec); 120 } 121 122 bool perf_can_record_switch_events(void) 123 { 124 return perf_probe_api(perf_probe_context_switch); 125 } 126 127 bool perf_can_record_text_poke_events(void) 128 { 129 return perf_probe_api(perf_probe_text_poke); 130 } 131 132 bool perf_can_record_cpu_wide(void) 133 { 134 struct perf_event_attr attr = { 135 .type = PERF_TYPE_SOFTWARE, 136 .config = PERF_COUNT_SW_CPU_CLOCK, 137 .exclude_kernel = 1, 138 }; 139 struct perf_cpu_map *cpus; 140 struct perf_cpu cpu; 141 int fd; 142 143 cpus = perf_cpu_map__new_online_cpus(); 144 if (!cpus) 145 return false; 146 147 cpu = perf_cpu_map__cpu(cpus, 0); 148 perf_cpu_map__put(cpus); 149 150 fd = sys_perf_event_open(&attr, -1, cpu.cpu, -1, 0); 151 if (fd < 0) 152 return false; 153 close(fd); 154 155 return true; 156 } 157 158 /* 159 * Architectures are expected to know if AUX area sampling is supported by the 160 * hardware. Here we check for kernel support. 161 */ 162 bool perf_can_aux_sample(void) 163 { 164 struct perf_event_attr attr = { 165 .size = sizeof(struct perf_event_attr), 166 .exclude_kernel = 1, 167 /* 168 * Non-zero value causes the kernel to calculate the effective 169 * attribute size up to that byte. 170 */ 171 .aux_sample_size = 1, 172 }; 173 int fd; 174 175 fd = sys_perf_event_open(&attr, -1, 0, -1, 0); 176 /* 177 * If the kernel attribute is big enough to contain aux_sample_size 178 * then we assume that it is supported. We are relying on the kernel to 179 * validate the attribute size before anything else that could be wrong. 180 */ 181 if (fd < 0 && errno == E2BIG) 182 return false; 183 if (fd >= 0) 184 close(fd); 185 186 return true; 187 } 188 189 bool perf_can_record_build_id(void) 190 { 191 return perf_probe_api(perf_probe_build_id); 192 } 193 194 bool perf_can_record_cgroup(void) 195 { 196 return perf_probe_api(perf_probe_cgroup); 197 } 198