liblttng-ust/lttng-context.c

   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 <ust-context-provider.h>
  13 #include <lttng/urcu/pointer.h>
  14 #include <lttng/urcu/urcu-ust.h>
  15 #include <usterr-signal-safe.h>
  16 #include <ust-helper.h>
  17 #include <stddef.h>
  18 #include <string.h>
  19 #include <assert.h>
  20 #include "tracepoint-internal.h"
  21
  22 #include "context-internal.h"
  23
  24 /*
  25  * The filter implementation requires that two consecutive "get" for the
  26  * same context performed by the same thread return the same result.
  27  */
  28
  29 int lttng_find_context(struct lttng_ust_ctx *ctx, const char *name)
  30 {
  31         unsigned int i;
  32         const char *subname;
  33
  34         if (strncmp(name, "$ctx.", strlen("$ctx.")) == 0) {
  35                 subname = name + strlen("$ctx.");
  36         } else {
  37                 subname = name;
  38         }
  39         for (i = 0; i < ctx->nr_fields; i++) {
  40                 /* Skip allocated (but non-initialized) contexts */
  41                 if (!ctx->fields[i]->event_field->name)
  42                         continue;
  43                 if (!strcmp(ctx->fields[i]->event_field->name, subname))
  44                         return 1;
  45         }
  46         return 0;
  47 }
  48
  49 int lttng_get_context_index(struct lttng_ust_ctx *ctx, const char *name)
  50 {
  51         unsigned int i;
  52         const char *subname;
  53
  54         if (!ctx)
  55                 return -1;
  56         if (strncmp(name, "$ctx.", strlen("$ctx.")) == 0) {
  57                 subname = name + strlen("$ctx.");
  58         } else {
  59                 subname = name;
  60         }
  61         for (i = 0; i < ctx->nr_fields; i++) {
  62                 /* Skip allocated (but non-initialized) contexts */
  63                 if (!ctx->fields[i]->event_field->name)
  64                         continue;
  65                 if (!strcmp(ctx->fields[i]->event_field->name, subname))
  66                         return i;
  67         }
  68         return -1;
  69 }
  70
  71 static int lttng_find_context_provider(struct lttng_ust_ctx *ctx, const char *name)
  72 {
  73         unsigned int i;
  74
  75         for (i = 0; i < ctx->nr_fields; i++) {
  76                 /* Skip allocated (but non-initialized) contexts */
  77                 if (!ctx->fields[i]->event_field->name)
  78                         continue;
  79                 if (!strncmp(ctx->fields[i]->event_field->name, name,
  80                                 strlen(name)))
  81                         return 1;
  82         }
  83         return 0;
  84 }
  85
  86 /*
  87  * Note: as we append context information, the pointer location may change.
  88  * lttng_add_context leaves the new last context initialized to NULL.
  89  */
  90 static
  91 int lttng_add_context(struct lttng_ust_ctx **ctx_p)
  92 {
  93         struct lttng_ust_ctx *ctx;
  94
  95         if (!*ctx_p) {
  96                 *ctx_p = zmalloc(sizeof(struct lttng_ust_ctx));
  97                 if (!*ctx_p)
  98                         return -ENOMEM;
  99                 (*ctx_p)->struct_size = sizeof(struct lttng_ust_ctx);
 100                 (*ctx_p)->largest_align = 1;
 101         }
 102         ctx = *ctx_p;
 103         if (ctx->nr_fields + 1 > ctx->allocated_fields) {
 104                 struct lttng_ust_ctx_field **new_fields;
 105
 106                 ctx->allocated_fields = max_t(size_t, 1, 2 * ctx->allocated_fields);
 107                 new_fields = zmalloc(ctx->allocated_fields * sizeof(*new_fields));
 108                 if (!new_fields)
 109                         return -ENOMEM;
 110                 /* Copy pointers */
 111                 if (ctx->fields)
 112                         memcpy(new_fields, ctx->fields, sizeof(*ctx->fields) * ctx->nr_fields);
 113                 free(ctx->fields);
 114                 ctx->fields = new_fields;
 115         }
 116         ctx->nr_fields++;
 117         return 0;
 118 }
 119
 120 struct lttng_ust_ctx_field *lttng_append_context(struct lttng_ust_ctx **ctx_p)
 121 {
 122         struct lttng_ust_ctx_field *field;
 123         int ret;
 124
 125         field = zmalloc(sizeof(struct lttng_ust_ctx_field));
 126         if (!field)
 127                 goto error_alloc_field;
 128         field->struct_size = sizeof(struct lttng_ust_ctx_field);
 129         field->event_field = zmalloc(sizeof(struct lttng_ust_event_field));
 130         if (!field->event_field)
 131                 goto error_alloc_event_field;
 132         field->event_field->struct_size = sizeof(struct lttng_ust_event_field);
 133
 134         ret = lttng_add_context(ctx_p);
 135         if (ret)
 136                 goto error_add_context;
 137         (*ctx_p)->fields[(*ctx_p)->nr_fields - 1] = field;
 138         return field;
 139
 140 error_add_context:
 141         free(field->event_field);
 142 error_alloc_event_field:
 143         free(field);
 144 error_alloc_field:
 145         return NULL;
 146 }
 147
 148 /*
 149  * Takes ownership of @f on success.
 150  */
 151 int lttng_context_add_rcu(struct lttng_ust_ctx **ctx_p,
 152                 struct lttng_ust_ctx_field *f)
 153 {
 154         struct lttng_ust_ctx *old_ctx = *ctx_p, *new_ctx = NULL;
 155         struct lttng_ust_ctx_field **new_fields = NULL;
 156         int ret;
 157
 158         if (old_ctx) {
 159                 new_ctx = zmalloc(sizeof(struct lttng_ust_ctx));
 160                 if (!new_ctx)
 161                         return -ENOMEM;
 162                 new_ctx->struct_size = sizeof(struct lttng_ust_ctx);
 163                 *new_ctx = *old_ctx;
 164                 new_fields = zmalloc(new_ctx->allocated_fields * sizeof(*new_fields));
 165                 if (!new_fields) {
 166                         free(new_ctx);
 167                         return -ENOMEM;
 168                 }
 169                 /* Copy pointers */
 170                 memcpy(new_fields, old_ctx->fields,
 171                                 sizeof(*old_ctx->fields) * old_ctx->nr_fields);
 172                 new_ctx->fields = new_fields;
 173         }
 174         ret = lttng_add_context(&new_ctx);
 175         if (ret) {
 176                 free(new_fields);
 177                 free(new_ctx);
 178                 return ret;
 179         }
 180         /* Taking ownership of f. */
 181         (*ctx_p)->fields[(*ctx_p)->nr_fields - 1] = f;
 182         lttng_context_update(new_ctx);
 183         lttng_ust_rcu_assign_pointer(*ctx_p, new_ctx);
 184         lttng_ust_urcu_synchronize_rcu();
 185         if (old_ctx) {
 186                 free(old_ctx->fields);
 187                 free(old_ctx);
 188         }
 189         return 0;
 190 }
 191
 192 static size_t get_type_max_align(struct lttng_ust_type_common *type)
 193 {
 194         switch (type->type) {
 195         case lttng_ust_type_integer:
 196                 return lttng_ust_get_type_integer(type)->alignment;
 197         case lttng_ust_type_string:
 198                 return CHAR_BIT;
 199         case lttng_ust_type_dynamic:
 200                 return 0;
 201         case lttng_ust_type_enum:
 202                 return get_type_max_align(lttng_ust_get_type_enum(type)->container_type);
 203         case lttng_ust_type_array:
 204                 return max_t(size_t, get_type_max_align(lttng_ust_get_type_array(type)->elem_type),
 205                                 lttng_ust_get_type_array(type)->alignment);
 206         case lttng_ust_type_sequence:
 207                 return max_t(size_t, get_type_max_align(lttng_ust_get_type_sequence(type)->elem_type),
 208                                 lttng_ust_get_type_sequence(type)->alignment);
 209         case lttng_ust_type_struct:
 210         {
 211                 unsigned int i;
 212                 size_t field_align = 0;
 213                 struct lttng_ust_type_struct *struct_type = lttng_ust_get_type_struct(type);
 214
 215                 for (i = 0; i < struct_type->nr_fields; i++) {
 216                         field_align = max_t(size_t,
 217                                 get_type_max_align(struct_type->fields[i]->type),
 218                                 field_align);
 219                 }
 220                 return field_align;
 221         }
 222         default:
 223                 WARN_ON_ONCE(1);
 224                 return 0;
 225         }
 226 }
 227
 228 /*
 229  * lttng_context_update() should be called at least once between context
 230  * modification and trace start.
 231  */
 232 void lttng_context_update(struct lttng_ust_ctx *ctx)
 233 {
 234         int i;
 235         size_t largest_align = 8;       /* in bits */
 236
 237         for (i = 0; i < ctx->nr_fields; i++) {
 238                 size_t field_align = 8;
 239
 240                 field_align = get_type_max_align(ctx->fields[i]->event_field->type);
 241                 largest_align = max_t(size_t, largest_align, field_align);
 242         }
 243         ctx->largest_align = largest_align >> 3;        /* bits to bytes */
 244 }
 245
 246 /*
 247  * Remove last context field.
 248  */
 249 void lttng_remove_context_field(struct lttng_ust_ctx **ctx_p,
 250                                 struct lttng_ust_ctx_field *field)
 251 {
 252         struct lttng_ust_ctx *ctx;
 253
 254         ctx = *ctx_p;
 255         ctx->nr_fields--;
 256         assert(ctx->fields[ctx->nr_fields] == field);
 257         lttng_ust_destroy_type(field->event_field->type);
 258         free((char *) field->event_field->name);
 259         free(field->event_field);
 260         free(field);
 261         ctx->fields[ctx->nr_fields] = NULL;
 262 }
 263
 264 void lttng_destroy_context(struct lttng_ust_ctx *ctx)
 265 {
 266         int i;
 267
 268         if (!ctx)
 269                 return;
 270         for (i = 0; i < ctx->nr_fields; i++) {
 271                 if (ctx->fields[i]->destroy)
 272                         ctx->fields[i]->destroy(ctx->fields[i]);
 273                 lttng_ust_destroy_type(ctx->fields[i]->event_field->type);
 274                 free((char *) ctx->fields[i]->event_field->name);
 275                 free(ctx->fields[i]->event_field);
 276                 free(ctx->fields[i]);
 277         }
 278         free(ctx->fields);
 279         free(ctx);
 280 }
 281
 282 /*
 283  * Can be safely performed concurrently with tracing using the struct
 284  * lttng_ctx. Using RCU update. Needs to match RCU read-side handling of
 285  * contexts.
 286  *
 287  * This does not allow adding, removing, or changing typing of the
 288  * contexts, since this needs to stay invariant for metadata. However,
 289  * it allows updating the handlers associated with all contexts matching
 290  * a provider (by name) while tracing is using it, in a way that ensures
 291  * a single RCU read-side critical section see either all old, or all
 292  * new handlers.
 293  */
 294 int lttng_ust_context_set_provider_rcu(struct lttng_ust_ctx **_ctx,
 295                 const char *name,
 296                 size_t (*get_size)(struct lttng_ust_ctx_field *field, size_t offset),
 297                 void (*record)(struct lttng_ust_ctx_field *field,
 298                         struct lttng_ust_lib_ring_buffer_ctx *ctx,
 299                         struct lttng_channel *chan),
 300                 void (*get_value)(struct lttng_ust_ctx_field *field,
 301                         struct lttng_ust_ctx_value *value))
 302 {
 303         int i, ret;
 304         struct lttng_ust_ctx *ctx = *_ctx, *new_ctx;
 305         struct lttng_ust_ctx_field **new_fields;
 306
 307         if (!ctx || !lttng_find_context_provider(ctx, name))
 308                 return 0;
 309         /*
 310          * We have at least one instance of context for the provider.
 311          */
 312         new_ctx = zmalloc(sizeof(*new_ctx));
 313         if (!new_ctx)
 314                 return -ENOMEM;
 315         new_ctx->struct_size = sizeof(*new_ctx);
 316         *new_ctx = *ctx;
 317         new_fields = zmalloc(sizeof(*new_fields) * ctx->allocated_fields);
 318         if (!new_fields) {
 319                 ret = -ENOMEM;
 320                 goto field_error;
 321         }
 322         /* Copy pointers */
 323         memcpy(new_fields, ctx->fields,
 324                 sizeof(*new_fields) * ctx->allocated_fields);
 325         for (i = 0; i < ctx->nr_fields; i++) {
 326                 if (strncmp(new_fields[i]->event_field->name,
 327                                 name, strlen(name)) != 0)
 328                         continue;
 329                 new_fields[i]->get_size = get_size;
 330                 new_fields[i]->record = record;
 331                 new_fields[i]->get_value = get_value;
 332         }
 333         new_ctx->fields = new_fields;
 334         lttng_ust_rcu_assign_pointer(*_ctx, new_ctx);
 335         lttng_ust_urcu_synchronize_rcu();
 336         free(ctx->fields);
 337         free(ctx);
 338         return 0;
 339
 340 field_error:
 341         free(new_ctx);
 342         return ret;
 343 }
 344
 345 int lttng_context_init_all(struct lttng_ust_ctx **ctx)
 346 {
 347         int ret;
 348
 349         ret = lttng_add_pthread_id_to_ctx(ctx);
 350         if (ret) {
 351                 WARN("Cannot add context lttng_add_pthread_id_to_ctx");
 352                 goto error;
 353         }
 354         ret = lttng_add_vtid_to_ctx(ctx);
 355         if (ret) {
 356                 WARN("Cannot add context lttng_add_vtid_to_ctx");
 357                 goto error;
 358         }
 359         ret = lttng_add_vpid_to_ctx(ctx);
 360         if (ret) {
 361                 WARN("Cannot add context lttng_add_vpid_to_ctx");
 362                 goto error;
 363         }
 364         ret = lttng_add_procname_to_ctx(ctx);
 365         if (ret) {
 366                 WARN("Cannot add context lttng_add_procname_to_ctx");
 367                 goto error;
 368         }
 369         ret = lttng_add_cpu_id_to_ctx(ctx);
 370         if (ret) {
 371                 WARN("Cannot add context lttng_add_cpu_id_to_ctx");
 372                 goto error;
 373         }
 374         ret = lttng_add_cgroup_ns_to_ctx(ctx);
 375         if (ret) {
 376                 WARN("Cannot add context lttng_add_cgroup_ns_to_ctx");
 377                 goto error;
 378         }
 379         ret = lttng_add_ipc_ns_to_ctx(ctx);
 380         if (ret) {
 381                 WARN("Cannot add context lttng_add_ipc_ns_to_ctx");
 382                 goto error;
 383         }
 384         ret = lttng_add_mnt_ns_to_ctx(ctx);
 385         if (ret) {
 386                 WARN("Cannot add context lttng_add_mnt_ns_to_ctx");
 387                 goto error;
 388         }
 389         ret = lttng_add_net_ns_to_ctx(ctx);
 390         if (ret) {
 391                 WARN("Cannot add context lttng_add_net_ns_to_ctx");
 392                 goto error;
 393         }
 394         ret = lttng_add_pid_ns_to_ctx(ctx);
 395         if (ret) {
 396                 WARN("Cannot add context lttng_add_pid_ns_to_ctx");
 397                 goto error;
 398         }
 399         ret = lttng_add_time_ns_to_ctx(ctx);
 400         if (ret) {
 401                 WARN("Cannot add context lttng_add_time_ns_to_ctx");
 402                 goto error;
 403         }
 404         ret = lttng_add_user_ns_to_ctx(ctx);
 405         if (ret) {
 406                 WARN("Cannot add context lttng_add_user_ns_to_ctx");
 407                 goto error;
 408         }
 409         ret = lttng_add_uts_ns_to_ctx(ctx);
 410         if (ret) {
 411                 WARN("Cannot add context lttng_add_uts_ns_to_ctx");
 412                 goto error;
 413         }
 414         ret = lttng_add_vuid_to_ctx(ctx);
 415         if (ret) {
 416                 WARN("Cannot add context lttng_add_vuid_to_ctx");
 417                 goto error;
 418         }
 419         ret = lttng_add_veuid_to_ctx(ctx);
 420         if (ret) {
 421                 WARN("Cannot add context lttng_add_veuid_to_ctx");
 422                 goto error;
 423         }
 424         ret = lttng_add_vsuid_to_ctx(ctx);
 425         if (ret) {
 426                 WARN("Cannot add context lttng_add_vsuid_to_ctx");
 427                 goto error;
 428         }
 429         ret = lttng_add_vgid_to_ctx(ctx);
 430         if (ret) {
 431                 WARN("Cannot add context lttng_add_vgid_to_ctx");
 432                 goto error;
 433         }
 434         ret = lttng_add_vegid_to_ctx(ctx);
 435         if (ret) {
 436                 WARN("Cannot add context lttng_add_vegid_to_ctx");
 437                 goto error;
 438         }
 439         ret = lttng_add_vsgid_to_ctx(ctx);
 440         if (ret) {
 441                 WARN("Cannot add context lttng_add_vsgid_to_ctx");
 442                 goto error;
 443         }
 444         lttng_context_update(*ctx);
 445         return 0;
 446
 447 error:
 448         lttng_destroy_context(*ctx);
 449         return ret;
 450 }