src/lttng-context.c

   1 /* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
   2  *
   3  * lttng-context.c
   4  *
   5  * LTTng trace/channel/event context management.
   6  *
   7  * Copyright (C) 2011-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   8  */
   9
  10 #include <linux/module.h>
  11 #include <linux/list.h>
  12 #include <linux/mutex.h>
  13 #include <linux/slab.h>
  14 #include <wrapper/vmalloc.h>    /* for wrapper_vmalloc_sync_mappings() */
  15 #include <lttng/events.h>
  16 #include <lttng/events-internal.h>
  17 #include <lttng/tracer.h>
  18
  19 /*
  20  * The filter implementation requires that two consecutive "get" for the
  21  * same context performed by the same thread return the same result.
  22  */
  23
  24 /*
  25  * Static array of contexts, for $ctx filters.
  26  */
  27 struct lttng_kernel_ctx *lttng_static_ctx;
  28
  29 int lttng_kernel_find_context(struct lttng_kernel_ctx *ctx, const char *name)
  30 {
  31         unsigned int i;
  32         const char *subname;
  33
  34         if (!ctx)
  35                 return 0;
  36         if (strncmp(name, "$ctx.", strlen("$ctx.")) == 0) {
  37                 subname = name + strlen("$ctx.");
  38         } else {
  39                 subname = name;
  40         }
  41         for (i = 0; i < ctx->nr_fields; i++) {
  42                 /* Skip allocated (but non-initialized) contexts */
  43                 if (!ctx->fields[i].event_field->name)
  44                         continue;
  45                 if (!strcmp(ctx->fields[i].event_field->name, subname))
  46                         return 1;
  47         }
  48         return 0;
  49 }
  50 EXPORT_SYMBOL_GPL(lttng_kernel_find_context);
  51
  52 int lttng_kernel_get_context_index(struct lttng_kernel_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 EXPORT_SYMBOL_GPL(lttng_kernel_get_context_index);
  74
  75 struct lttng_kernel_ctx_field *lttng_kernel_get_context_field_from_index(struct lttng_kernel_ctx *ctx,
  76                 size_t index)
  77 {
  78         if (index >= ctx->nr_fields)
  79                 return NULL;
  80         return &ctx->fields[index];
  81 }
  82 EXPORT_SYMBOL_GPL(lttng_kernel_get_context_field_from_index);
  83
  84 /*
  85  * Note: as we append context information, the pointer location may change.
  86  * lttng_kernel_context_add_field leaves the new last context initialized to NULL.
  87  */
  88 static
  89 int lttng_kernel_context_add_field(struct lttng_kernel_ctx **ctx_p)
  90 {
  91         struct lttng_kernel_ctx *ctx;
  92
  93         if (!*ctx_p) {
  94                 *ctx_p = kzalloc(sizeof(struct lttng_kernel_ctx), GFP_KERNEL);
  95                 if (!*ctx_p)
  96                         return -ENOMEM;
  97                 (*ctx_p)->largest_align = 1;
  98         }
  99         ctx = *ctx_p;
 100         if (ctx->nr_fields + 1 > ctx->allocated_fields) {
 101                 struct lttng_kernel_ctx_field *new_fields;
 102
 103                 ctx->allocated_fields = max_t(size_t, 1, 2 * ctx->allocated_fields);
 104                 new_fields = lttng_kvzalloc(ctx->allocated_fields * sizeof(*new_fields), GFP_KERNEL);
 105                 if (!new_fields)
 106                         return -ENOMEM;
 107                 if (ctx->fields)
 108                         memcpy(new_fields, ctx->fields, sizeof(*ctx->fields) * ctx->nr_fields);
 109                 lttng_kvfree(ctx->fields);
 110                 ctx->fields = new_fields;
 111         }
 112         ctx->nr_fields++;
 113         return 0;
 114 }
 115
 116 static size_t get_type_max_align(const struct lttng_kernel_type_common *type)
 117 {
 118         switch (type->type) {
 119         case lttng_kernel_type_integer:
 120                 return lttng_kernel_get_type_integer(type)->alignment;
 121         case lttng_kernel_type_string:
 122                 return CHAR_BIT;
 123         case lttng_kernel_type_enum:
 124                 return get_type_max_align(lttng_kernel_get_type_enum(type)->container_type);
 125         case lttng_kernel_type_array:
 126                 return max_t(size_t, get_type_max_align(lttng_kernel_get_type_array(type)->elem_type),
 127                                 lttng_kernel_get_type_array(type)->alignment);
 128         case lttng_kernel_type_sequence:
 129                 return max_t(size_t, get_type_max_align(lttng_kernel_get_type_sequence(type)->elem_type),
 130                                 lttng_kernel_get_type_sequence(type)->alignment);
 131         case lttng_kernel_type_struct:
 132         {
 133                 unsigned int i;
 134                 size_t field_align = 0;
 135                 const struct lttng_kernel_type_struct *struct_type = lttng_kernel_get_type_struct(type);
 136
 137                 for (i = 0; i < struct_type->nr_fields; i++) {
 138                         field_align = max_t(size_t,
 139                                 get_type_max_align(struct_type->fields[i]->type),
 140                                 field_align);
 141                 }
 142                 return field_align;
 143         }
 144         case lttng_kernel_type_variant:
 145                 /* Variants are not accounted in the overall alignment of the type they are embedded in. */
 146                 return 0;
 147         default:
 148                 WARN_ON_ONCE(1);
 149                 return 0;
 150         }
 151 }
 152
 153 /*
 154  * lttng_context_update() should be called at least once between context
 155  * modification and trace start.
 156  */
 157 static
 158 void lttng_context_update(struct lttng_kernel_ctx *ctx)
 159 {
 160         int i;
 161         size_t largest_align = 8;       /* in bits */
 162
 163         for (i = 0; i < ctx->nr_fields; i++) {
 164                 size_t field_align = 8;
 165
 166                 field_align = get_type_max_align(ctx->fields[i].event_field->type);
 167                 largest_align = max_t(size_t, largest_align, field_align);
 168         }
 169         ctx->largest_align = largest_align >> 3;        /* bits to bytes */
 170 }
 171
 172 int lttng_kernel_context_append(struct lttng_kernel_ctx **ctx_p,
 173                 const struct lttng_kernel_ctx_field *f)
 174 {
 175         int ret;
 176
 177         ret = lttng_kernel_context_add_field(ctx_p);
 178         if (ret)
 179                 return ret;
 180         (*ctx_p)->fields[(*ctx_p)->nr_fields - 1] = *f;
 181         lttng_context_update(*ctx_p);
 182         return 0;
 183 }
 184
 185 void lttng_kernel_context_remove_last(struct lttng_kernel_ctx **ctx_p)
 186 {
 187         struct lttng_kernel_ctx *ctx = *ctx_p;
 188
 189         if (!ctx->nr_fields)
 190                 return;
 191         memset(&ctx->fields[ctx->nr_fields - 1], 0, sizeof(struct lttng_kernel_ctx_field));
 192         ctx->nr_fields--;
 193         lttng_context_update(ctx);
 194 }
 195
 196 void lttng_kernel_destroy_context(struct lttng_kernel_ctx *ctx)
 197 {
 198         int i;
 199
 200         if (!ctx)
 201                 return;
 202         for (i = 0; i < ctx->nr_fields; i++) {
 203                 if (ctx->fields[i].destroy)
 204                         ctx->fields[i].destroy(&ctx->fields[i]);
 205         }
 206         lttng_kvfree(ctx->fields);
 207         kfree(ctx);
 208 }
 209
 210 int lttng_context_init(void)
 211 {
 212         int ret;
 213
 214         ret = lttng_add_hostname_to_ctx(&lttng_static_ctx);
 215         if (ret) {
 216                 printk(KERN_WARNING "LTTng: Cannot add context lttng_add_hostname_to_ctx");
 217         }
 218         ret = lttng_add_nice_to_ctx(&lttng_static_ctx);
 219         if (ret) {
 220                 printk(KERN_WARNING "LTTng: Cannot add context lttng_add_nice_to_ctx");
 221         }
 222         ret = lttng_add_pid_to_ctx(&lttng_static_ctx);
 223         if (ret) {
 224                 printk(KERN_WARNING "LTTng: Cannot add context lttng_add_pid_to_ctx");
 225         }
 226         ret = lttng_add_ppid_to_ctx(&lttng_static_ctx);
 227         if (ret) {
 228                 printk(KERN_WARNING "LTTng: Cannot add context lttng_add_ppid_to_ctx");
 229         }
 230         ret = lttng_add_prio_to_ctx(&lttng_static_ctx);
 231         if (ret) {
 232                 printk(KERN_WARNING "LTTng: Cannot add context lttng_add_prio_to_ctx");
 233         }
 234         ret = lttng_add_procname_to_ctx(&lttng_static_ctx);
 235         if (ret) {
 236                 printk(KERN_WARNING "LTTng: Cannot add context lttng_add_procname_to_ctx");
 237         }
 238         ret = lttng_add_tid_to_ctx(&lttng_static_ctx);
 239         if (ret) {
 240                 printk(KERN_WARNING "LTTng: Cannot add context lttng_add_tid_to_ctx");
 241         }
 242         ret = lttng_add_vppid_to_ctx(&lttng_static_ctx);
 243         if (ret) {
 244                 printk(KERN_WARNING "LTTng: Cannot add context lttng_add_vppid_to_ctx");
 245         }
 246         ret = lttng_add_vtid_to_ctx(&lttng_static_ctx);
 247         if (ret) {
 248                 printk(KERN_WARNING "LTTng: Cannot add context lttng_add_vtid_to_ctx");
 249         }
 250         ret = lttng_add_vpid_to_ctx(&lttng_static_ctx);
 251         if (ret) {
 252                 printk(KERN_WARNING "LTTng: Cannot add context lttng_add_vpid_to_ctx");
 253         }
 254         ret = lttng_add_cpu_id_to_ctx(&lttng_static_ctx);
 255         if (ret) {
 256                 printk(KERN_WARNING "LTTng: Cannot add context lttng_add_cpu_id_to_ctx");
 257         }
 258         ret = lttng_add_interruptible_to_ctx(&lttng_static_ctx);
 259         if (ret) {
 260                 printk(KERN_WARNING "LTTng: Cannot add context lttng_add_interruptible_to_ctx");
 261         }
 262         ret = lttng_add_need_reschedule_to_ctx(&lttng_static_ctx);
 263         if (ret) {
 264                 printk(KERN_WARNING "LTTng: Cannot add context lttng_add_need_reschedule_to_ctx");
 265         }
 266         ret = lttng_add_preemptible_to_ctx(&lttng_static_ctx);
 267         if (ret && ret != -ENOSYS) {
 268                 printk(KERN_WARNING "LTTng: Cannot add context lttng_add_preemptible_to_ctx");
 269         }
 270         ret = lttng_add_migratable_to_ctx(&lttng_static_ctx);
 271         if (ret && ret != -ENOSYS) {
 272                 printk(KERN_WARNING "LTTng: Cannot add context lttng_add_migratable_to_ctx");
 273         }
 274         ret = lttng_add_cgroup_ns_to_ctx(&lttng_static_ctx);
 275         if (ret && ret != -ENOSYS) {
 276                 printk(KERN_WARNING "LTTng: Cannot add context lttng_add_cgroup_ns_to_ctx");
 277         }
 278         ret = lttng_add_ipc_ns_to_ctx(&lttng_static_ctx);
 279         if (ret && ret != -ENOSYS) {
 280                 printk(KERN_WARNING "LTTng: Cannot add context lttng_add_ipc_ns_to_ctx");
 281         }
 282         ret = lttng_add_mnt_ns_to_ctx(&lttng_static_ctx);
 283         if (ret && ret != -ENOSYS) {
 284                 printk(KERN_WARNING "LTTng: Cannot add context lttng_add_mnt_ns_to_ctx");
 285         }
 286         ret = lttng_add_net_ns_to_ctx(&lttng_static_ctx);
 287         if (ret && ret != -ENOSYS) {
 288                 printk(KERN_WARNING "LTTng: Cannot add context lttng_add_net_ns_to_ctx");
 289         }
 290         ret = lttng_add_pid_ns_to_ctx(&lttng_static_ctx);
 291         if (ret && ret != -ENOSYS) {
 292                 printk(KERN_WARNING "LTTng: Cannot add context lttng_add_pid_ns_to_ctx");
 293         }
 294         ret = lttng_add_user_ns_to_ctx(&lttng_static_ctx);
 295         if (ret && ret != -ENOSYS) {
 296                 printk(KERN_WARNING "LTTng: Cannot add context lttng_add_user_ns_to_ctx");
 297         }
 298         ret = lttng_add_uts_ns_to_ctx(&lttng_static_ctx);
 299         if (ret && ret != -ENOSYS) {
 300                 printk(KERN_WARNING "LTTng: Cannot add context lttng_add_uts_ns_to_ctx");
 301         }
 302         ret = lttng_add_time_ns_to_ctx(&lttng_static_ctx);
 303         if (ret && ret != -ENOSYS) {
 304                 printk(KERN_WARNING "LTTng: Cannot add context lttng_add_time_ns_to_ctx");
 305         }
 306         /* TODO: perf counters for filtering */
 307         return 0;
 308 }
 309
 310 void lttng_context_exit(void)
 311 {
 312         lttng_kernel_destroy_context(lttng_static_ctx);
 313         lttng_static_ctx = NULL;
 314 }