tools/perf/util/bpf-loader.c

   1 /*
   2  * bpf-loader.c
   3  *
   4  * Copyright (C) 2015 Wang Nan <wangnan0@huawei.com>
   5  * Copyright (C) 2015 Huawei Inc.
   6  */
   7
   8 #include <bpf/libbpf.h>
   9 #include <linux/err.h>
  10 #include "perf.h"
  11 #include "debug.h"
  12 #include "bpf-loader.h"
  13 #include "probe-event.h"
  14 #include "probe-finder.h" // for MAX_PROBES
  15 #include "llvm-utils.h"
  16
  17 #define DEFINE_PRINT_FN(name, level) \
  18 static int libbpf_##name(const char *fmt, ...)  \
  19 {                                               \
  20         va_list args;                           \
  21         int ret;                                \
  22                                                 \
  23         va_start(args, fmt);                    \
  24         ret = veprintf(level, verbose, pr_fmt(fmt), args);\
  25         va_end(args);                           \
  26         return ret;                             \
  27 }
  28
  29 DEFINE_PRINT_FN(warning, 0)
  30 DEFINE_PRINT_FN(info, 0)
  31 DEFINE_PRINT_FN(debug, 1)
  32
  33 struct bpf_prog_priv {
  34         struct perf_probe_event pev;
  35 };
  36
  37 struct bpf_object *bpf__prepare_load(const char *filename, bool source)
  38 {
  39         struct bpf_object *obj;
  40         static bool libbpf_initialized;
  41
  42         if (!libbpf_initialized) {
  43                 libbpf_set_print(libbpf_warning,
  44                                  libbpf_info,
  45                                  libbpf_debug);
  46                 libbpf_initialized = true;
  47         }
  48
  49         if (source) {
  50                 int err;
  51                 void *obj_buf;
  52                 size_t obj_buf_sz;
  53
  54                 err = llvm__compile_bpf(filename, &obj_buf, &obj_buf_sz);
  55                 if (err)
  56                         return ERR_PTR(err);
  57                 obj = bpf_object__open_buffer(obj_buf, obj_buf_sz, filename);
  58                 free(obj_buf);
  59         } else
  60                 obj = bpf_object__open(filename);
  61
  62         if (!obj) {
  63                 pr_debug("bpf: failed to load %s\n", filename);
  64                 return ERR_PTR(-EINVAL);
  65         }
  66
  67         return obj;
  68 }
  69
  70 void bpf__clear(void)
  71 {
  72         struct bpf_object *obj, *tmp;
  73
  74         bpf_object__for_each_safe(obj, tmp) {
  75                 bpf__unprobe(obj);
  76                 bpf_object__close(obj);
  77         }
  78 }
  79
  80 static void
  81 bpf_prog_priv__clear(struct bpf_program *prog __maybe_unused,
  82                      void *_priv)
  83 {
  84         struct bpf_prog_priv *priv = _priv;
  85
  86         cleanup_perf_probe_events(&priv->pev, 1);
  87         free(priv);
  88 }
  89
  90 static int
  91 config_bpf_program(struct bpf_program *prog)
  92 {
  93         struct perf_probe_event *pev = NULL;
  94         struct bpf_prog_priv *priv = NULL;
  95         const char *config_str;
  96         int err;
  97
  98         config_str = bpf_program__title(prog, false);
  99         if (!config_str) {
 100                 pr_debug("bpf: unable to get title for program\n");
 101                 return -EINVAL;
 102         }
 103
 104         priv = calloc(sizeof(*priv), 1);
 105         if (!priv) {
 106                 pr_debug("bpf: failed to alloc priv\n");
 107                 return -ENOMEM;
 108         }
 109         pev = &priv->pev;
 110
 111         pr_debug("bpf: config program '%s'\n", config_str);
 112         err = parse_perf_probe_command(config_str, pev);
 113         if (err < 0) {
 114                 pr_debug("bpf: '%s' is not a valid config string\n",
 115                          config_str);
 116                 err = -EINVAL;
 117                 goto errout;
 118         }
 119
 120         if (pev->group && strcmp(pev->group, PERF_BPF_PROBE_GROUP)) {
 121                 pr_debug("bpf: '%s': group for event is set and not '%s'.\n",
 122                          config_str, PERF_BPF_PROBE_GROUP);
 123                 err = -EINVAL;
 124                 goto errout;
 125         } else if (!pev->group)
 126                 pev->group = strdup(PERF_BPF_PROBE_GROUP);
 127
 128         if (!pev->group) {
 129                 pr_debug("bpf: strdup failed\n");
 130                 err = -ENOMEM;
 131                 goto errout;
 132         }
 133
 134         if (!pev->event) {
 135                 pr_debug("bpf: '%s': event name is missing\n",
 136                          config_str);
 137                 err = -EINVAL;
 138                 goto errout;
 139         }
 140         pr_debug("bpf: config '%s' is ok\n", config_str);
 141
 142         err = bpf_program__set_private(prog, priv, bpf_prog_priv__clear);
 143         if (err) {
 144                 pr_debug("Failed to set priv for program '%s'\n", config_str);
 145                 goto errout;
 146         }
 147
 148         return 0;
 149
 150 errout:
 151         if (pev)
 152                 clear_perf_probe_event(pev);
 153         free(priv);
 154         return err;
 155 }
 156
 157 static int bpf__prepare_probe(void)
 158 {
 159         static int err = 0;
 160         static bool initialized = false;
 161
 162         /*
 163          * Make err static, so if init failed the first, bpf__prepare_probe()
 164          * fails each time without calling init_probe_symbol_maps multiple
 165          * times.
 166          */
 167         if (initialized)
 168                 return err;
 169
 170         initialized = true;
 171         err = init_probe_symbol_maps(false);
 172         if (err < 0)
 173                 pr_debug("Failed to init_probe_symbol_maps\n");
 174         probe_conf.max_probes = MAX_PROBES;
 175         return err;
 176 }
 177
 178 int bpf__probe(struct bpf_object *obj)
 179 {
 180         int err = 0;
 181         struct bpf_program *prog;
 182         struct bpf_prog_priv *priv;
 183         struct perf_probe_event *pev;
 184
 185         err = bpf__prepare_probe();
 186         if (err) {
 187                 pr_debug("bpf__prepare_probe failed\n");
 188                 return err;
 189         }
 190
 191         bpf_object__for_each_program(prog, obj) {
 192                 err = config_bpf_program(prog);
 193                 if (err)
 194                         goto out;
 195
 196                 err = bpf_program__get_private(prog, (void **)&priv);
 197                 if (err || !priv)
 198                         goto out;
 199                 pev = &priv->pev;
 200
 201                 err = convert_perf_probe_events(pev, 1);
 202                 if (err < 0) {
 203                         pr_debug("bpf_probe: failed to convert perf probe events");
 204                         goto out;
 205                 }
 206
 207                 err = apply_perf_probe_events(pev, 1);
 208                 if (err < 0) {
 209                         pr_debug("bpf_probe: failed to apply perf probe events");
 210                         goto out;
 211                 }
 212         }
 213 out:
 214         return err < 0 ? err : 0;
 215 }
 216
 217 #define EVENTS_WRITE_BUFSIZE  4096
 218 int bpf__unprobe(struct bpf_object *obj)
 219 {
 220         int err, ret = 0;
 221         struct bpf_program *prog;
 222         struct bpf_prog_priv *priv;
 223
 224         bpf_object__for_each_program(prog, obj) {
 225                 int i;
 226
 227                 err = bpf_program__get_private(prog, (void **)&priv);
 228                 if (err || !priv)
 229                         continue;
 230
 231                 for (i = 0; i < priv->pev.ntevs; i++) {
 232                         struct probe_trace_event *tev = &priv->pev.tevs[i];
 233                         char name_buf[EVENTS_WRITE_BUFSIZE];
 234                         struct strfilter *delfilter;
 235
 236                         snprintf(name_buf, EVENTS_WRITE_BUFSIZE,
 237                                  "%s:%s", tev->group, tev->event);
 238                         name_buf[EVENTS_WRITE_BUFSIZE - 1] = '\0';
 239
 240                         delfilter = strfilter__new(name_buf, NULL);
 241                         if (!delfilter) {
 242                                 pr_debug("Failed to create filter for unprobing\n");
 243                                 ret = -ENOMEM;
 244                                 continue;
 245                         }
 246
 247                         err = del_perf_probe_events(delfilter);
 248                         strfilter__delete(delfilter);
 249                         if (err) {
 250                                 pr_debug("Failed to delete %s\n", name_buf);
 251                                 ret = err;
 252                                 continue;
 253                         }
 254                 }
 255         }
 256         return ret;
 257 }
 258
 259 int bpf__load(struct bpf_object *obj)
 260 {
 261         int err;
 262
 263         err = bpf_object__load(obj);
 264         if (err) {
 265                 pr_debug("bpf: load objects failed\n");
 266                 return err;
 267         }
 268         return 0;
 269 }
 270
 271 int bpf__foreach_tev(struct bpf_object *obj,
 272                      bpf_prog_iter_callback_t func,
 273                      void *arg)
 274 {
 275         struct bpf_program *prog;
 276         int err;
 277
 278         bpf_object__for_each_program(prog, obj) {
 279                 struct probe_trace_event *tev;
 280                 struct perf_probe_event *pev;
 281                 struct bpf_prog_priv *priv;
 282                 int i, fd;
 283
 284                 err = bpf_program__get_private(prog,
 285                                 (void **)&priv);
 286                 if (err || !priv) {
 287                         pr_debug("bpf: failed to get private field\n");
 288                         return -EINVAL;
 289                 }
 290
 291                 pev = &priv->pev;
 292                 for (i = 0; i < pev->ntevs; i++) {
 293                         tev = &pev->tevs[i];
 294
 295                         fd = bpf_program__fd(prog);
 296                         if (fd < 0) {
 297                                 pr_debug("bpf: failed to get file descriptor\n");
 298                                 return fd;
 299                         }
 300
 301                         err = (*func)(tev, fd, arg);
 302                         if (err) {
 303                                 pr_debug("bpf: call back failed, stop iterate\n");
 304                                 return err;
 305                         }
 306                 }
 307         }
 308         return 0;
 309 }
 310
 311 #define bpf__strerror_head(err, buf, size) \
 312         char sbuf[STRERR_BUFSIZE], *emsg;\
 313         if (!size)\
 314                 return 0;\
 315         if (err < 0)\
 316                 err = -err;\
 317         emsg = strerror_r(err, sbuf, sizeof(sbuf));\
 318         switch (err) {\
 319         default:\
 320                 scnprintf(buf, size, "%s", emsg);\
 321                 break;
 322
 323 #define bpf__strerror_entry(val, fmt...)\
 324         case val: {\
 325                 scnprintf(buf, size, fmt);\
 326                 break;\
 327         }
 328
 329 #define bpf__strerror_end(buf, size)\
 330         }\
 331         buf[size - 1] = '\0';
 332
 333 int bpf__strerror_probe(struct bpf_object *obj __maybe_unused,
 334                         int err, char *buf, size_t size)
 335 {
 336         bpf__strerror_head(err, buf, size);
 337         bpf__strerror_entry(EEXIST, "Probe point exist. Try use 'perf probe -d \"*\"'");
 338         bpf__strerror_entry(EPERM, "You need to be root, and /proc/sys/kernel/kptr_restrict should be 0\n");
 339         bpf__strerror_entry(ENOENT, "You need to check probing points in BPF file\n");
 340         bpf__strerror_end(buf, size);
 341         return 0;
 342 }
 343
 344 int bpf__strerror_load(struct bpf_object *obj __maybe_unused,
 345                        int err, char *buf, size_t size)
 346 {
 347         bpf__strerror_head(err, buf, size);
 348         bpf__strerror_entry(EINVAL, "%s: Are you root and runing a CONFIG_BPF_SYSCALL kernel?",
 349                             emsg)
 350         bpf__strerror_end(buf, size);
 351         return 0;
 352 }