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 <limits.h>
  21 #include "tracepoint-internal.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 (strncmp(name, "$ctx.", strlen("$ctx.")) == 0) {
  36                 subname = name + strlen("$ctx.");
  37         } else {
  38                 subname = name;
  39         }
  40         for (i = 0; i < ctx->nr_fields; i++) {
  41                 /* Skip allocated (but non-initialized) contexts */
  42                 if (!ctx->fields[i]->event_field->name)
  43                         continue;
  44                 if (!strcmp(ctx->fields[i]->event_field->name, subname))
  45                         return 1;
  46         }
  47         return 0;
  48 }
  49
  50 int lttng_get_context_index(struct lttng_ust_ctx *ctx, const char *name)
  51 {
  52         unsigned int i;
  53         const char *subname;
  54
  55         if (!ctx)
  56                 return -1;
  57         if (strncmp(name, "$ctx.", strlen("$ctx.")) == 0) {
  58                 subname = name + strlen("$ctx.");
  59         } else {
  60                 subname = name;
  61         }
  62         for (i = 0; i < ctx->nr_fields; i++) {
  63                 /* Skip allocated (but non-initialized) contexts */
  64                 if (!ctx->fields[i]->event_field->name)
  65                         continue;
  66                 if (!strcmp(ctx->fields[i]->event_field->name, subname))
  67                         return i;
  68         }
  69         return -1;
  70 }
  71
  72 static int lttng_find_context_provider(struct lttng_ust_ctx *ctx, const char *name)
  73 {
  74         unsigned int i;
  75
  76         for (i = 0; i < ctx->nr_fields; i++) {
  77                 /* Skip allocated (but non-initialized) contexts */
  78                 if (!ctx->fields[i]->event_field->name)
  79                         continue;
  80                 if (!strncmp(ctx->fields[i]->event_field->name, name,
  81                                 strlen(name)))
  82                         return 1;
  83         }
  84         return 0;
  85 }
  86
  87 /*
  88  * Note: as we append context information, the pointer location may change.
  89  * lttng_add_context leaves the new last context initialized to NULL.
  90  */
  91 static
  92 int lttng_add_context(struct lttng_ust_ctx **ctx_p)
  93 {
  94         struct lttng_ust_ctx *ctx;
  95
  96         if (!*ctx_p) {
  97                 *ctx_p = zmalloc(sizeof(struct lttng_ust_ctx));
  98                 if (!*ctx_p)
  99                         return -ENOMEM;
 100                 (*ctx_p)->struct_size = sizeof(struct lttng_ust_ctx);
 101                 (*ctx_p)->largest_align = 1;
 102         }
 103         ctx = *ctx_p;
 104         if (ctx->nr_fields + 1 > ctx->allocated_fields) {
 105                 struct lttng_ust_ctx_field **new_fields;
 106
 107                 ctx->allocated_fields = max_t(size_t, 1, 2 * ctx->allocated_fields);
 108                 new_fields = zmalloc(ctx->allocated_fields * sizeof(*new_fields));
 109                 if (!new_fields)
 110                         return -ENOMEM;
 111                 /* Copy pointers */
 112                 if (ctx->fields)
 113                         memcpy(new_fields, ctx->fields, sizeof(*ctx->fields) * ctx->nr_fields);
 114                 free(ctx->fields);
 115                 ctx->fields = new_fields;
 116         }
 117         ctx->nr_fields++;
 118         return 0;
 119 }
 120
 121 struct lttng_ust_ctx_field *lttng_append_context(struct lttng_ust_ctx **ctx_p)
 122 {
 123         struct lttng_ust_ctx_field *field;
 124         int ret;
 125
 126         field = zmalloc(sizeof(struct lttng_ust_ctx_field));
 127         if (!field)
 128                 goto error_alloc_field;
 129         field->struct_size = sizeof(struct lttng_ust_ctx_field);
 130         field->event_field = zmalloc(sizeof(struct lttng_ust_event_field));
 131         if (!field->event_field)
 132                 goto error_alloc_event_field;
 133         field->event_field->struct_size = sizeof(struct lttng_ust_event_field);
 134
 135         ret = lttng_add_context(ctx_p);
 136         if (ret)
 137                 goto error_add_context;
 138         (*ctx_p)->fields[(*ctx_p)->nr_fields - 1] = field;
 139         return field;
 140
 141 error_add_context:
 142         free(field->event_field);
 143 error_alloc_event_field:
 144         free(field);
 145 error_alloc_field:
 146         return NULL;
 147 }
 148
 149 /*
 150  * Takes ownership of @f on success.
 151  */
 152 int lttng_context_add_rcu(struct lttng_ust_ctx **ctx_p,
 153                 struct lttng_ust_ctx_field *f)
 154 {
 155         struct lttng_ust_ctx *old_ctx = *ctx_p, *new_ctx = NULL;
 156         struct lttng_ust_ctx_field **new_fields = NULL;
 157         int ret;
 158
 159         if (old_ctx) {
 160                 new_ctx = zmalloc(sizeof(struct lttng_ust_ctx));
 161                 if (!new_ctx)
 162                         return -ENOMEM;
 163                 new_ctx->struct_size = sizeof(struct lttng_ust_ctx);
 164                 *new_ctx = *old_ctx;
 165                 new_fields = zmalloc(new_ctx->allocated_fields * sizeof(*new_fields));
 166                 if (!new_fields) {
 167                         free(new_ctx);
 168                         return -ENOMEM;
 169                 }
 170                 /* Copy pointers */
 171                 memcpy(new_fields, old_ctx->fields,
 172                                 sizeof(*old_ctx->fields) * old_ctx->nr_fields);
 173                 new_ctx->fields = new_fields;
 174         }
 175         ret = lttng_add_context(&new_ctx);
 176         if (ret) {
 177                 free(new_fields);
 178                 free(new_ctx);
 179                 return ret;
 180         }
 181         /* Taking ownership of f. */
 182         (*ctx_p)->fields[(*ctx_p)->nr_fields - 1] = f;
 183         lttng_context_update(new_ctx);
 184         lttng_ust_rcu_assign_pointer(*ctx_p, new_ctx);
 185         lttng_ust_urcu_synchronize_rcu();
 186         if (old_ctx) {
 187                 free(old_ctx->fields);
 188                 free(old_ctx);
 189         }
 190         return 0;
 191 }
 192
 193 static size_t get_type_max_align(struct lttng_ust_type_common *type)
 194 {
 195         switch (type->type) {
 196         case lttng_ust_type_integer:
 197                 return lttng_ust_get_type_integer(type)->alignment;
 198         case lttng_ust_type_string:
 199                 return CHAR_BIT;
 200         case lttng_ust_type_dynamic:
 201                 return 0;
 202         case lttng_ust_type_enum:
 203                 return get_type_max_align(lttng_ust_get_type_enum(type)->container_type);
 204         case lttng_ust_type_array:
 205                 return max_t(size_t, get_type_max_align(lttng_ust_get_type_array(type)->elem_type),
 206                                 lttng_ust_get_type_array(type)->alignment);
 207         case lttng_ust_type_sequence:
 208                 return max_t(size_t, get_type_max_align(lttng_ust_get_type_sequence(type)->elem_type),
 209                                 lttng_ust_get_type_sequence(type)->alignment);
 210         case lttng_ust_type_struct:
 211         {
 212                 unsigned int i;
 213                 size_t field_align = 0;
 214                 struct lttng_ust_type_struct *struct_type = lttng_ust_get_type_struct(type);
 215
 216                 for (i = 0; i < struct_type->nr_fields; i++) {
 217                         field_align = max_t(size_t,
 218                                 get_type_max_align(struct_type->fields[i]->type),
 219                                 field_align);
 220                 }
 221                 return field_align;
 222         }
 223         default:
 224                 WARN_ON_ONCE(1);
 225                 return 0;
 226         }
 227 }
 228
 229 /*
 230  * lttng_context_update() should be called at least once between context
 231  * modification and trace start.
 232  */
 233 void lttng_context_update(struct lttng_ust_ctx *ctx)
 234 {
 235         int i;
 236         size_t largest_align = 8;       /* in bits */
 237
 238         for (i = 0; i < ctx->nr_fields; i++) {
 239                 size_t field_align = 8;
 240
 241                 field_align = get_type_max_align(ctx->fields[i]->event_field->type);
 242                 largest_align = max_t(size_t, largest_align, field_align);
 243         }
 244         ctx->largest_align = largest_align >> 3;        /* bits to bytes */
 245 }
 246
 247 /*
 248  * Remove last context field.
 249  */
 250 void lttng_remove_context_field(struct lttng_ust_ctx **ctx_p,
 251                                 struct lttng_ust_ctx_field *field)
 252 {
 253         struct lttng_ust_ctx *ctx;
 254
 255         ctx = *ctx_p;
 256         ctx->nr_fields--;
 257         assert(ctx->fields[ctx->nr_fields] == field);
 258         lttng_ust_destroy_type(field->event_field->type);
 259         free((char *) field->event_field->name);
 260         free(field->event_field);
 261         free(field);
 262         ctx->fields[ctx->nr_fields] = NULL;
 263 }
 264
 265 void lttng_destroy_context(struct lttng_ust_ctx *ctx)
 266 {
 267         int i;
 268
 269         if (!ctx)
 270                 return;
 271         for (i = 0; i < ctx->nr_fields; i++) {
 272                 if (ctx->fields[i]->destroy)
 273                         ctx->fields[i]->destroy(ctx->fields[i]);
 274                 lttng_ust_destroy_type(ctx->fields[i]->event_field->type);
 275                 free((char *) ctx->fields[i]->event_field->name);
 276                 free(ctx->fields[i]->event_field);
 277                 free(ctx->fields[i]);
 278         }
 279         free(ctx->fields);
 280         free(ctx);
 281 }
 282
 283 /*
 284  * Can be safely performed concurrently with tracing using the struct
 285  * lttng_ctx. Using RCU update. Needs to match RCU read-side handling of
 286  * contexts.
 287  *
 288  * This does not allow adding, removing, or changing typing of the
 289  * contexts, since this needs to stay invariant for metadata. However,
 290  * it allows updating the handlers associated with all contexts matching
 291  * a provider (by name) while tracing is using it, in a way that ensures
 292  * a single RCU read-side critical section see either all old, or all
 293  * new handlers.
 294  */
 295 int lttng_ust_context_set_provider_rcu(struct lttng_ust_ctx **_ctx,
 296                 const char *name,
 297                 size_t (*get_size)(struct lttng_ust_ctx_field *field, size_t offset),
 298                 void (*record)(struct lttng_ust_ctx_field *field,
 299                         struct lttng_ust_lib_ring_buffer_ctx *ctx,
 300                         struct lttng_ust_channel_buffer *chan),
 301                 void (*get_value)(struct lttng_ust_ctx_field *field,
 302                         struct lttng_ust_ctx_value *value))
 303 {
 304         int i, ret;
 305         struct lttng_ust_ctx *ctx = *_ctx, *new_ctx;
 306         struct lttng_ust_ctx_field **new_fields;
 307
 308         if (!ctx || !lttng_find_context_provider(ctx, name))
 309                 return 0;
 310         /*
 311          * We have at least one instance of context for the provider.
 312          */
 313         new_ctx = zmalloc(sizeof(*new_ctx));
 314         if (!new_ctx)
 315                 return -ENOMEM;
 316         new_ctx->struct_size = sizeof(*new_ctx);
 317         *new_ctx = *ctx;
 318         new_fields = zmalloc(sizeof(*new_fields) * ctx->allocated_fields);
 319         if (!new_fields) {
 320                 ret = -ENOMEM;
 321                 goto field_error;
 322         }
 323         /* Copy pointers */
 324         memcpy(new_fields, ctx->fields,
 325                 sizeof(*new_fields) * ctx->allocated_fields);
 326         for (i = 0; i < ctx->nr_fields; i++) {
 327                 if (strncmp(new_fields[i]->event_field->name,
 328                                 name, strlen(name)) != 0)
 329                         continue;
 330                 new_fields[i]->get_size = get_size;
 331                 new_fields[i]->record = record;
 332                 new_fields[i]->get_value = get_value;
 333         }
 334         new_ctx->fields = new_fields;
 335         lttng_ust_rcu_assign_pointer(*_ctx, new_ctx);
 336         lttng_ust_urcu_synchronize_rcu();
 337         free(ctx->fields);
 338         free(ctx);
 339         return 0;
 340
 341 field_error:
 342         free(new_ctx);
 343         return ret;
 344 }
 345
 346 int lttng_context_init_all(struct lttng_ust_ctx **ctx)
 347 {
 348         int ret;
 349
 350         ret = lttng_add_pthread_id_to_ctx(ctx);
 351         if (ret) {
 352                 WARN("Cannot add context lttng_add_pthread_id_to_ctx");
 353                 goto error;
 354         }
 355         ret = lttng_add_vtid_to_ctx(ctx);
 356         if (ret) {
 357                 WARN("Cannot add context lttng_add_vtid_to_ctx");
 358                 goto error;
 359         }
 360         ret = lttng_add_vpid_to_ctx(ctx);
 361         if (ret) {
 362                 WARN("Cannot add context lttng_add_vpid_to_ctx");
 363                 goto error;
 364         }
 365         ret = lttng_add_procname_to_ctx(ctx);
 366         if (ret) {
 367                 WARN("Cannot add context lttng_add_procname_to_ctx");
 368                 goto error;
 369         }
 370         ret = lttng_add_cpu_id_to_ctx(ctx);
 371         if (ret) {
 372                 WARN("Cannot add context lttng_add_cpu_id_to_ctx");
 373                 goto error;
 374         }
 375         ret = lttng_add_cgroup_ns_to_ctx(ctx);
 376         if (ret) {
 377                 WARN("Cannot add context lttng_add_cgroup_ns_to_ctx");
 378                 goto error;
 379         }
 380         ret = lttng_add_ipc_ns_to_ctx(ctx);
 381         if (ret) {
 382                 WARN("Cannot add context lttng_add_ipc_ns_to_ctx");
 383                 goto error;
 384         }
 385         ret = lttng_add_mnt_ns_to_ctx(ctx);
 386         if (ret) {
 387                 WARN("Cannot add context lttng_add_mnt_ns_to_ctx");
 388                 goto error;
 389         }
 390         ret = lttng_add_net_ns_to_ctx(ctx);
 391         if (ret) {
 392                 WARN("Cannot add context lttng_add_net_ns_to_ctx");
 393                 goto error;
 394         }
 395         ret = lttng_add_pid_ns_to_ctx(ctx);
 396         if (ret) {
 397                 WARN("Cannot add context lttng_add_pid_ns_to_ctx");
 398                 goto error;
 399         }
 400         ret = lttng_add_time_ns_to_ctx(ctx);
 401         if (ret) {
 402                 WARN("Cannot add context lttng_add_time_ns_to_ctx");
 403                 goto error;
 404         }
 405         ret = lttng_add_user_ns_to_ctx(ctx);
 406         if (ret) {
 407                 WARN("Cannot add context lttng_add_user_ns_to_ctx");
 408                 goto error;
 409         }
 410         ret = lttng_add_uts_ns_to_ctx(ctx);
 411         if (ret) {
 412                 WARN("Cannot add context lttng_add_uts_ns_to_ctx");
 413                 goto error;
 414         }
 415         ret = lttng_add_vuid_to_ctx(ctx);
 416         if (ret) {
 417                 WARN("Cannot add context lttng_add_vuid_to_ctx");
 418                 goto error;
 419         }
 420         ret = lttng_add_veuid_to_ctx(ctx);
 421         if (ret) {
 422                 WARN("Cannot add context lttng_add_veuid_to_ctx");
 423                 goto error;
 424         }
 425         ret = lttng_add_vsuid_to_ctx(ctx);
 426         if (ret) {
 427                 WARN("Cannot add context lttng_add_vsuid_to_ctx");
 428                 goto error;
 429         }
 430         ret = lttng_add_vgid_to_ctx(ctx);
 431         if (ret) {
 432                 WARN("Cannot add context lttng_add_vgid_to_ctx");
 433                 goto error;
 434         }
 435         ret = lttng_add_vegid_to_ctx(ctx);
 436         if (ret) {
 437                 WARN("Cannot add context lttng_add_vegid_to_ctx");
 438                 goto error;
 439         }
 440         ret = lttng_add_vsgid_to_ctx(ctx);
 441         if (ret) {
 442                 WARN("Cannot add context lttng_add_vsgid_to_ctx");
 443                 goto error;
 444         }
 445         lttng_context_update(*ctx);
 446         return 0;
 447
 448 error:
 449         lttng_destroy_context(*ctx);
 450         return ret;
 451 }