| 1 | /* |
| 2 | * SPDX-License-Identifier: LGPL-2.1-only |
| 3 | * |
| 4 | * Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
| 5 | * |
| 6 | * LTTng UST trace/channel/event context management. |
| 7 | */ |
| 8 | |
| 9 | #define _LGPL_SOURCE |
| 10 | #include <lttng/ust-events.h> |
| 11 | #include <lttng/ust-tracer.h> |
| 12 | #include <common/ust-context-provider.h> |
| 13 | #include <lttng/urcu/pointer.h> |
| 14 | #include <lttng/urcu/urcu-ust.h> |
| 15 | #include "common/logging.h" |
| 16 | #include "common/macros.h" |
| 17 | #include <stddef.h> |
| 18 | #include <string.h> |
| 19 | #include <assert.h> |
| 20 | #include <limits.h> |
| 21 | #include "common/tracepoint.h" |
| 22 | |
| 23 | #include "context-internal.h" |
| 24 | |
| 25 | /* |
| 26 | * The filter implementation requires that two consecutive "get" for the |
| 27 | * same context performed by the same thread return the same result. |
| 28 | */ |
| 29 | |
| 30 | int lttng_find_context(struct lttng_ust_ctx *ctx, const char *name) |
| 31 | { |
| 32 | unsigned int i; |
| 33 | const char *subname; |
| 34 | |
| 35 | if (!ctx) |
| 36 | return 0; |
| 37 | if (strncmp(name, "$ctx.", strlen("$ctx.")) == 0) { |
| 38 | subname = name + strlen("$ctx."); |
| 39 | } else { |
| 40 | subname = name; |
| 41 | } |
| 42 | for (i = 0; i < ctx->nr_fields; i++) { |
| 43 | /* Skip allocated (but non-initialized) contexts */ |
| 44 | if (!ctx->fields[i].event_field->name) |
| 45 | continue; |
| 46 | if (!strcmp(ctx->fields[i].event_field->name, subname)) |
| 47 | return 1; |
| 48 | } |
| 49 | return 0; |
| 50 | } |
| 51 | |
| 52 | int lttng_get_context_index(struct lttng_ust_ctx *ctx, const char *name) |
| 53 | { |
| 54 | unsigned int i; |
| 55 | const char *subname; |
| 56 | |
| 57 | if (!ctx) |
| 58 | return -1; |
| 59 | if (strncmp(name, "$ctx.", strlen("$ctx.")) == 0) { |
| 60 | subname = name + strlen("$ctx."); |
| 61 | } else { |
| 62 | subname = name; |
| 63 | } |
| 64 | for (i = 0; i < ctx->nr_fields; i++) { |
| 65 | /* Skip allocated (but non-initialized) contexts */ |
| 66 | if (!ctx->fields[i].event_field->name) |
| 67 | continue; |
| 68 | if (!strcmp(ctx->fields[i].event_field->name, subname)) |
| 69 | return i; |
| 70 | } |
| 71 | return -1; |
| 72 | } |
| 73 | |
| 74 | static int lttng_find_context_provider(struct lttng_ust_ctx *ctx, const char *name) |
| 75 | { |
| 76 | unsigned int i; |
| 77 | |
| 78 | for (i = 0; i < ctx->nr_fields; i++) { |
| 79 | /* Skip allocated (but non-initialized) contexts */ |
| 80 | if (!ctx->fields[i].event_field->name) |
| 81 | continue; |
| 82 | if (!strncmp(ctx->fields[i].event_field->name, name, |
| 83 | strlen(name))) |
| 84 | return 1; |
| 85 | } |
| 86 | return 0; |
| 87 | } |
| 88 | |
| 89 | /* |
| 90 | * Note: as we append context information, the pointer location may change. |
| 91 | * lttng_ust_context_add_field leaves the new last context initialized to NULL. |
| 92 | */ |
| 93 | static |
| 94 | int lttng_ust_context_add_field(struct lttng_ust_ctx **ctx_p) |
| 95 | { |
| 96 | struct lttng_ust_ctx *ctx; |
| 97 | |
| 98 | if (!*ctx_p) { |
| 99 | *ctx_p = zmalloc(sizeof(struct lttng_ust_ctx)); |
| 100 | if (!*ctx_p) |
| 101 | return -ENOMEM; |
| 102 | (*ctx_p)->largest_align = 1; |
| 103 | } |
| 104 | ctx = *ctx_p; |
| 105 | if (ctx->nr_fields + 1 > ctx->allocated_fields) { |
| 106 | struct lttng_ust_ctx_field *new_fields; |
| 107 | |
| 108 | ctx->allocated_fields = max_t(size_t, 1, 2 * ctx->allocated_fields); |
| 109 | new_fields = zmalloc(ctx->allocated_fields * sizeof(*new_fields)); |
| 110 | if (!new_fields) |
| 111 | return -ENOMEM; |
| 112 | /* Copy elements */ |
| 113 | if (ctx->fields) |
| 114 | memcpy(new_fields, ctx->fields, sizeof(*ctx->fields) * ctx->nr_fields); |
| 115 | free(ctx->fields); |
| 116 | ctx->fields = new_fields; |
| 117 | } |
| 118 | ctx->nr_fields++; |
| 119 | return 0; |
| 120 | } |
| 121 | |
| 122 | static size_t get_type_max_align(const struct lttng_ust_type_common *type) |
| 123 | { |
| 124 | switch (type->type) { |
| 125 | case lttng_ust_type_integer: |
| 126 | return lttng_ust_get_type_integer(type)->alignment; |
| 127 | case lttng_ust_type_string: |
| 128 | return CHAR_BIT; |
| 129 | case lttng_ust_type_dynamic: |
| 130 | return 0; |
| 131 | case lttng_ust_type_enum: |
| 132 | return get_type_max_align(lttng_ust_get_type_enum(type)->container_type); |
| 133 | case lttng_ust_type_array: |
| 134 | return max_t(size_t, get_type_max_align(lttng_ust_get_type_array(type)->elem_type), |
| 135 | lttng_ust_get_type_array(type)->alignment); |
| 136 | case lttng_ust_type_sequence: |
| 137 | return max_t(size_t, get_type_max_align(lttng_ust_get_type_sequence(type)->elem_type), |
| 138 | lttng_ust_get_type_sequence(type)->alignment); |
| 139 | case lttng_ust_type_struct: |
| 140 | { |
| 141 | unsigned int i; |
| 142 | size_t field_align = 0; |
| 143 | const struct lttng_ust_type_struct *struct_type = lttng_ust_get_type_struct(type); |
| 144 | |
| 145 | for (i = 0; i < struct_type->nr_fields; i++) { |
| 146 | field_align = max_t(size_t, |
| 147 | get_type_max_align(struct_type->fields[i]->type), |
| 148 | field_align); |
| 149 | } |
| 150 | return field_align; |
| 151 | } |
| 152 | default: |
| 153 | WARN_ON_ONCE(1); |
| 154 | return 0; |
| 155 | } |
| 156 | } |
| 157 | |
| 158 | /* |
| 159 | * lttng_context_update() should be called at least once between context |
| 160 | * modification and trace start. |
| 161 | */ |
| 162 | static |
| 163 | void lttng_context_update(struct lttng_ust_ctx *ctx) |
| 164 | { |
| 165 | int i; |
| 166 | size_t largest_align = 8; /* in bits */ |
| 167 | |
| 168 | for (i = 0; i < ctx->nr_fields; i++) { |
| 169 | size_t field_align = 8; |
| 170 | |
| 171 | field_align = get_type_max_align(ctx->fields[i].event_field->type); |
| 172 | largest_align = max_t(size_t, largest_align, field_align); |
| 173 | } |
| 174 | ctx->largest_align = largest_align >> 3; /* bits to bytes */ |
| 175 | } |
| 176 | |
| 177 | int lttng_ust_context_append_rcu(struct lttng_ust_ctx **ctx_p, |
| 178 | const struct lttng_ust_ctx_field *f) |
| 179 | { |
| 180 | struct lttng_ust_ctx *old_ctx = *ctx_p, *new_ctx = NULL; |
| 181 | struct lttng_ust_ctx_field *new_fields = NULL; |
| 182 | int ret; |
| 183 | |
| 184 | if (old_ctx) { |
| 185 | new_ctx = zmalloc(sizeof(struct lttng_ust_ctx)); |
| 186 | if (!new_ctx) |
| 187 | return -ENOMEM; |
| 188 | *new_ctx = *old_ctx; |
| 189 | new_fields = zmalloc(new_ctx->allocated_fields * sizeof(*new_fields)); |
| 190 | if (!new_fields) { |
| 191 | free(new_ctx); |
| 192 | return -ENOMEM; |
| 193 | } |
| 194 | /* Copy elements */ |
| 195 | memcpy(new_fields, old_ctx->fields, |
| 196 | sizeof(*old_ctx->fields) * old_ctx->nr_fields); |
| 197 | new_ctx->fields = new_fields; |
| 198 | } |
| 199 | ret = lttng_ust_context_add_field(&new_ctx); |
| 200 | if (ret) { |
| 201 | free(new_fields); |
| 202 | free(new_ctx); |
| 203 | return ret; |
| 204 | } |
| 205 | new_ctx->fields[new_ctx->nr_fields - 1] = *f; |
| 206 | lttng_context_update(new_ctx); |
| 207 | lttng_ust_rcu_assign_pointer(*ctx_p, new_ctx); |
| 208 | lttng_ust_urcu_synchronize_rcu(); |
| 209 | if (old_ctx) { |
| 210 | free(old_ctx->fields); |
| 211 | free(old_ctx); |
| 212 | } |
| 213 | return 0; |
| 214 | } |
| 215 | |
| 216 | int lttng_ust_context_append(struct lttng_ust_ctx **ctx_p, |
| 217 | const struct lttng_ust_ctx_field *f) |
| 218 | { |
| 219 | int ret; |
| 220 | |
| 221 | ret = lttng_ust_context_add_field(ctx_p); |
| 222 | if (ret) |
| 223 | return ret; |
| 224 | (*ctx_p)->fields[(*ctx_p)->nr_fields - 1] = *f; |
| 225 | lttng_context_update(*ctx_p); |
| 226 | return 0; |
| 227 | } |
| 228 | |
| 229 | void lttng_destroy_context(struct lttng_ust_ctx *ctx) |
| 230 | { |
| 231 | int i; |
| 232 | |
| 233 | if (!ctx) |
| 234 | return; |
| 235 | for (i = 0; i < ctx->nr_fields; i++) { |
| 236 | if (ctx->fields[i].destroy) |
| 237 | ctx->fields[i].destroy(ctx->fields[i].priv); |
| 238 | } |
| 239 | free(ctx->fields); |
| 240 | free(ctx); |
| 241 | } |
| 242 | |
| 243 | /* |
| 244 | * Can be safely performed concurrently with tracing using the struct |
| 245 | * lttng_ctx. Using RCU update. Needs to match RCU read-side handling of |
| 246 | * contexts. |
| 247 | * |
| 248 | * This does not allow adding, removing, or changing typing of the |
| 249 | * contexts, since this needs to stay invariant for metadata. However, |
| 250 | * it allows updating the handlers associated with all contexts matching |
| 251 | * a provider (by name) while tracing is using it, in a way that ensures |
| 252 | * a single RCU read-side critical section see either all old, or all |
| 253 | * new handlers. |
| 254 | */ |
| 255 | int lttng_ust_context_set_provider_rcu(struct lttng_ust_ctx **_ctx, |
| 256 | const char *name, |
| 257 | size_t (*get_size)(void *priv, struct lttng_ust_probe_ctx *probe_ctx, |
| 258 | size_t offset), |
| 259 | void (*record)(void *priv, struct lttng_ust_probe_ctx *probe_ctx, |
| 260 | struct lttng_ust_ring_buffer_ctx *ctx, |
| 261 | struct lttng_ust_channel_buffer *chan), |
| 262 | void (*get_value)(void *priv, struct lttng_ust_probe_ctx *probe_ctx, |
| 263 | struct lttng_ust_ctx_value *value)) |
| 264 | { |
| 265 | int i, ret; |
| 266 | struct lttng_ust_ctx *ctx = *_ctx, *new_ctx; |
| 267 | struct lttng_ust_ctx_field *new_fields; |
| 268 | |
| 269 | if (!ctx || !lttng_find_context_provider(ctx, name)) |
| 270 | return 0; |
| 271 | /* |
| 272 | * We have at least one instance of context for the provider. |
| 273 | */ |
| 274 | new_ctx = zmalloc(sizeof(*new_ctx)); |
| 275 | if (!new_ctx) |
| 276 | return -ENOMEM; |
| 277 | *new_ctx = *ctx; |
| 278 | new_fields = zmalloc(sizeof(*new_fields) * ctx->allocated_fields); |
| 279 | if (!new_fields) { |
| 280 | ret = -ENOMEM; |
| 281 | goto field_error; |
| 282 | } |
| 283 | /* Copy elements */ |
| 284 | memcpy(new_fields, ctx->fields, |
| 285 | sizeof(*new_fields) * ctx->allocated_fields); |
| 286 | for (i = 0; i < ctx->nr_fields; i++) { |
| 287 | if (strncmp(new_fields[i].event_field->name, |
| 288 | name, strlen(name)) != 0) |
| 289 | continue; |
| 290 | new_fields[i].get_size = get_size; |
| 291 | new_fields[i].record = record; |
| 292 | new_fields[i].get_value = get_value; |
| 293 | } |
| 294 | new_ctx->fields = new_fields; |
| 295 | lttng_ust_rcu_assign_pointer(*_ctx, new_ctx); |
| 296 | lttng_ust_urcu_synchronize_rcu(); |
| 297 | free(ctx->fields); |
| 298 | free(ctx); |
| 299 | return 0; |
| 300 | |
| 301 | field_error: |
| 302 | free(new_ctx); |
| 303 | return ret; |
| 304 | } |
| 305 | |
| 306 | int lttng_context_init_all(struct lttng_ust_ctx **ctx) |
| 307 | { |
| 308 | int ret; |
| 309 | |
| 310 | ret = lttng_add_pthread_id_to_ctx(ctx); |
| 311 | if (ret) { |
| 312 | WARN("Cannot add context lttng_add_pthread_id_to_ctx"); |
| 313 | goto error; |
| 314 | } |
| 315 | ret = lttng_add_vtid_to_ctx(ctx); |
| 316 | if (ret) { |
| 317 | WARN("Cannot add context lttng_add_vtid_to_ctx"); |
| 318 | goto error; |
| 319 | } |
| 320 | ret = lttng_add_vpid_to_ctx(ctx); |
| 321 | if (ret) { |
| 322 | WARN("Cannot add context lttng_add_vpid_to_ctx"); |
| 323 | goto error; |
| 324 | } |
| 325 | ret = lttng_add_procname_to_ctx(ctx); |
| 326 | if (ret) { |
| 327 | WARN("Cannot add context lttng_add_procname_to_ctx"); |
| 328 | goto error; |
| 329 | } |
| 330 | ret = lttng_add_cpu_id_to_ctx(ctx); |
| 331 | if (ret) { |
| 332 | WARN("Cannot add context lttng_add_cpu_id_to_ctx"); |
| 333 | goto error; |
| 334 | } |
| 335 | ret = lttng_add_cgroup_ns_to_ctx(ctx); |
| 336 | if (ret) { |
| 337 | WARN("Cannot add context lttng_add_cgroup_ns_to_ctx"); |
| 338 | goto error; |
| 339 | } |
| 340 | ret = lttng_add_ipc_ns_to_ctx(ctx); |
| 341 | if (ret) { |
| 342 | WARN("Cannot add context lttng_add_ipc_ns_to_ctx"); |
| 343 | goto error; |
| 344 | } |
| 345 | ret = lttng_add_mnt_ns_to_ctx(ctx); |
| 346 | if (ret) { |
| 347 | WARN("Cannot add context lttng_add_mnt_ns_to_ctx"); |
| 348 | goto error; |
| 349 | } |
| 350 | ret = lttng_add_net_ns_to_ctx(ctx); |
| 351 | if (ret) { |
| 352 | WARN("Cannot add context lttng_add_net_ns_to_ctx"); |
| 353 | goto error; |
| 354 | } |
| 355 | ret = lttng_add_pid_ns_to_ctx(ctx); |
| 356 | if (ret) { |
| 357 | WARN("Cannot add context lttng_add_pid_ns_to_ctx"); |
| 358 | goto error; |
| 359 | } |
| 360 | ret = lttng_add_time_ns_to_ctx(ctx); |
| 361 | if (ret) { |
| 362 | WARN("Cannot add context lttng_add_time_ns_to_ctx"); |
| 363 | goto error; |
| 364 | } |
| 365 | ret = lttng_add_user_ns_to_ctx(ctx); |
| 366 | if (ret) { |
| 367 | WARN("Cannot add context lttng_add_user_ns_to_ctx"); |
| 368 | goto error; |
| 369 | } |
| 370 | ret = lttng_add_uts_ns_to_ctx(ctx); |
| 371 | if (ret) { |
| 372 | WARN("Cannot add context lttng_add_uts_ns_to_ctx"); |
| 373 | goto error; |
| 374 | } |
| 375 | ret = lttng_add_vuid_to_ctx(ctx); |
| 376 | if (ret) { |
| 377 | WARN("Cannot add context lttng_add_vuid_to_ctx"); |
| 378 | goto error; |
| 379 | } |
| 380 | ret = lttng_add_veuid_to_ctx(ctx); |
| 381 | if (ret) { |
| 382 | WARN("Cannot add context lttng_add_veuid_to_ctx"); |
| 383 | goto error; |
| 384 | } |
| 385 | ret = lttng_add_vsuid_to_ctx(ctx); |
| 386 | if (ret) { |
| 387 | WARN("Cannot add context lttng_add_vsuid_to_ctx"); |
| 388 | goto error; |
| 389 | } |
| 390 | ret = lttng_add_vgid_to_ctx(ctx); |
| 391 | if (ret) { |
| 392 | WARN("Cannot add context lttng_add_vgid_to_ctx"); |
| 393 | goto error; |
| 394 | } |
| 395 | ret = lttng_add_vegid_to_ctx(ctx); |
| 396 | if (ret) { |
| 397 | WARN("Cannot add context lttng_add_vegid_to_ctx"); |
| 398 | goto error; |
| 399 | } |
| 400 | ret = lttng_add_vsgid_to_ctx(ctx); |
| 401 | if (ret) { |
| 402 | WARN("Cannot add context lttng_add_vsgid_to_ctx"); |
| 403 | goto error; |
| 404 | } |
| 405 | lttng_context_update(*ctx); |
| 406 | return 0; |
| 407 | |
| 408 | error: |
| 409 | lttng_destroy_context(*ctx); |
| 410 | return ret; |
| 411 | } |