lttng-context.c

   1 /*
   2  * lttng-context.c
   3  *
   4  * LTTng trace/channel/event context management.
   5  *
   6  * Copyright (C) 2011-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   7  *
   8  * This library is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; only
  11  * version 2.1 of the License.
  12  *
  13  * This library is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with this library; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  */
  22
  23 #include <linux/module.h>
  24 #include <linux/list.h>
  25 #include <linux/mutex.h>
  26 #include <linux/slab.h>
  27 #include <wrapper/vmalloc.h>    /* for wrapper_vmalloc_sync_all() */
  28 #include <lttng-events.h>
  29 #include <lttng-tracer.h>
  30
  31 /*
  32  * The filter implementation requires that two consecutive "get" for the
  33  * same context performed by the same thread return the same result.
  34  */
  35
  36 /*
  37  * Static array of contexts, for $ctx filters.
  38  */
  39 struct lttng_ctx *lttng_static_ctx;
  40
  41 int lttng_find_context(struct lttng_ctx *ctx, const char *name)
  42 {
  43         unsigned int i;
  44
  45         for (i = 0; i < ctx->nr_fields; i++) {
  46                 /* Skip allocated (but non-initialized) contexts */
  47                 if (!ctx->fields[i].event_field.name)
  48                         continue;
  49                 if (!strcmp(ctx->fields[i].event_field.name, name))
  50                         return 1;
  51         }
  52         return 0;
  53 }
  54 EXPORT_SYMBOL_GPL(lttng_find_context);
  55
  56 int lttng_get_context_index(struct lttng_ctx *ctx, const char *name)
  57 {
  58         unsigned int i;
  59         const char *subname;
  60
  61         if (!ctx)
  62                 return -1;
  63         if (strncmp(name, "$ctx.", strlen("$ctx.")) == 0) {
  64                 subname = name + strlen("$ctx.");
  65         } else {
  66                 subname = name;
  67         }
  68         for (i = 0; i < ctx->nr_fields; i++) {
  69                 /* Skip allocated (but non-initialized) contexts */
  70                 if (!ctx->fields[i].event_field.name)
  71                         continue;
  72                 if (!strcmp(ctx->fields[i].event_field.name, subname))
  73                         return i;
  74         }
  75         return -1;
  76 }
  77 EXPORT_SYMBOL_GPL(lttng_get_context_index);
  78
  79 /*
  80  * Note: as we append context information, the pointer location may change.
  81  */
  82 struct lttng_ctx_field *lttng_append_context(struct lttng_ctx **ctx_p)
  83 {
  84         struct lttng_ctx_field *field;
  85         struct lttng_ctx *ctx;
  86
  87         if (!*ctx_p) {
  88                 *ctx_p = kzalloc(sizeof(struct lttng_ctx), GFP_KERNEL);
  89                 if (!*ctx_p)
  90                         return NULL;
  91                 (*ctx_p)->largest_align = 1;
  92         }
  93         ctx = *ctx_p;
  94         if (ctx->nr_fields + 1 > ctx->allocated_fields) {
  95                 struct lttng_ctx_field *new_fields;
  96
  97                 ctx->allocated_fields = max_t(size_t, 1, 2 * ctx->allocated_fields);
  98                 new_fields = kzalloc(ctx->allocated_fields * sizeof(struct lttng_ctx_field), GFP_KERNEL);
  99                 if (!new_fields)
 100                         return NULL;
 101                 if (ctx->fields)
 102                         memcpy(new_fields, ctx->fields, sizeof(*ctx->fields) * ctx->nr_fields);
 103                 kfree(ctx->fields);
 104                 ctx->fields = new_fields;
 105         }
 106         field = &ctx->fields[ctx->nr_fields];
 107         ctx->nr_fields++;
 108         return field;
 109 }
 110 EXPORT_SYMBOL_GPL(lttng_append_context);
 111
 112 /*
 113  * lttng_context_update() should be called at least once between context
 114  * modification and trace start.
 115  */
 116 void lttng_context_update(struct lttng_ctx *ctx)
 117 {
 118         int i;
 119         size_t largest_align = 8;       /* in bits */
 120
 121         for (i = 0; i < ctx->nr_fields; i++) {
 122                 struct lttng_type *type;
 123                 size_t field_align = 8;
 124
 125                 type = &ctx->fields[i].event_field.type;
 126                 switch (type->atype) {
 127                 case atype_integer:
 128                         field_align = type->u.basic.integer.alignment;
 129                         break;
 130                 case atype_array:
 131                 {
 132                         struct lttng_basic_type *btype;
 133
 134                         btype = &type->u.array.elem_type;
 135                         switch (btype->atype) {
 136                         case atype_integer:
 137                                 field_align = btype->u.basic.integer.alignment;
 138                                 break;
 139                         case atype_string:
 140                                 break;
 141
 142                         case atype_array:
 143                         case atype_sequence:
 144                         case atype_struct:
 145                         case atype_array_compound:
 146                         case atype_sequence_compound:
 147                         case atype_variant:
 148                         default:
 149                                 WARN_ON_ONCE(1);
 150                                 break;
 151                         }
 152                         break;
 153                 }
 154                 case atype_sequence:
 155                 {
 156                         struct lttng_basic_type *btype;
 157
 158                         btype = &type->u.sequence.length_type;
 159                         switch (btype->atype) {
 160                         case atype_integer:
 161                                 field_align = btype->u.basic.integer.alignment;
 162                                 break;
 163
 164                         case atype_string:
 165                         case atype_array:
 166                         case atype_sequence:
 167                         case atype_struct:
 168                         case atype_array_compound:
 169                         case atype_sequence_compound:
 170                         case atype_variant:
 171                         default:
 172                                 WARN_ON_ONCE(1);
 173                                 break;
 174                         }
 175
 176                         btype = &type->u.sequence.elem_type;
 177                         switch (btype->atype) {
 178                         case atype_integer:
 179                                 field_align = max_t(size_t,
 180                                         field_align,
 181                                         btype->u.basic.integer.alignment);
 182                                 break;
 183
 184                         case atype_string:
 185                                 break;
 186
 187                         case atype_array:
 188                         case atype_sequence:
 189                         case atype_struct:
 190                         case atype_array_compound:
 191                         case atype_sequence_compound:
 192                         case atype_variant:
 193                         default:
 194                                 WARN_ON_ONCE(1);
 195                                 break;
 196                         }
 197                         break;
 198                 }
 199                 case atype_string:
 200                         break;
 201
 202                 case atype_struct:
 203                 case atype_array_compound:
 204                 case atype_sequence_compound:
 205                 case atype_variant:
 206                         break;
 207
 208                 case atype_enum:
 209                 default:
 210                         WARN_ON_ONCE(1);
 211                         break;
 212                 }
 213                 largest_align = max_t(size_t, largest_align, field_align);
 214         }
 215         ctx->largest_align = largest_align >> 3;        /* bits to bytes */
 216 }
 217
 218 /*
 219  * Remove last context field.
 220  */
 221 void lttng_remove_context_field(struct lttng_ctx **ctx_p,
 222                                 struct lttng_ctx_field *field)
 223 {
 224         struct lttng_ctx *ctx;
 225
 226         ctx = *ctx_p;
 227         ctx->nr_fields--;
 228         WARN_ON_ONCE(&ctx->fields[ctx->nr_fields] != field);
 229         memset(&ctx->fields[ctx->nr_fields], 0, sizeof(struct lttng_ctx_field));
 230 }
 231 EXPORT_SYMBOL_GPL(lttng_remove_context_field);
 232
 233 void lttng_destroy_context(struct lttng_ctx *ctx)
 234 {
 235         int i;
 236
 237         if (!ctx)
 238                 return;
 239         for (i = 0; i < ctx->nr_fields; i++) {
 240                 if (ctx->fields[i].destroy)
 241                         ctx->fields[i].destroy(&ctx->fields[i]);
 242         }
 243         kfree(ctx->fields);
 244         kfree(ctx);
 245 }
 246
 247 int lttng_context_init(void)
 248 {
 249         int ret;
 250
 251         ret = lttng_add_hostname_to_ctx(&lttng_static_ctx);
 252         if (ret) {
 253                 printk(KERN_WARNING "Cannot add context lttng_add_hostname_to_ctx");
 254         }
 255         ret = lttng_add_nice_to_ctx(&lttng_static_ctx);
 256         if (ret) {
 257                 printk(KERN_WARNING "Cannot add context lttng_add_nice_to_ctx");
 258         }
 259         ret = lttng_add_pid_to_ctx(&lttng_static_ctx);
 260         if (ret) {
 261                 printk(KERN_WARNING "Cannot add context lttng_add_pid_to_ctx");
 262         }
 263         ret = lttng_add_ppid_to_ctx(&lttng_static_ctx);
 264         if (ret) {
 265                 printk(KERN_WARNING "Cannot add context lttng_add_ppid_to_ctx");
 266         }
 267         ret = lttng_add_prio_to_ctx(&lttng_static_ctx);
 268         if (ret) {
 269                 printk(KERN_WARNING "Cannot add context lttng_add_prio_to_ctx");
 270         }
 271         ret = lttng_add_procname_to_ctx(&lttng_static_ctx);
 272         if (ret) {
 273                 printk(KERN_WARNING "Cannot add context lttng_add_procname_to_ctx");
 274         }
 275         ret = lttng_add_tid_to_ctx(&lttng_static_ctx);
 276         if (ret) {
 277                 printk(KERN_WARNING "Cannot add context lttng_add_tid_to_ctx");
 278         }
 279         ret = lttng_add_vppid_to_ctx(&lttng_static_ctx);
 280         if (ret) {
 281                 printk(KERN_WARNING "Cannot add context lttng_add_vppid_to_ctx");
 282         }
 283         ret = lttng_add_vtid_to_ctx(&lttng_static_ctx);
 284         if (ret) {
 285                 printk(KERN_WARNING "Cannot add context lttng_add_vtid_to_ctx");
 286         }
 287         ret = lttng_add_vpid_to_ctx(&lttng_static_ctx);
 288         if (ret) {
 289                 printk(KERN_WARNING "Cannot add context lttng_add_vpid_to_ctx");
 290         }
 291         ret = lttng_add_cpu_id_to_ctx(&lttng_static_ctx);
 292         if (ret) {
 293                 printk(KERN_WARNING "Cannot add context lttng_add_cpu_id_to_ctx");
 294         }
 295         ret = lttng_add_interruptible_to_ctx(&lttng_static_ctx);
 296         if (ret) {
 297                 printk(KERN_WARNING "Cannot add context lttng_add_interruptible_to_ctx");
 298         }
 299         ret = lttng_add_need_reschedule_to_ctx(&lttng_static_ctx);
 300         if (ret) {
 301                 printk(KERN_WARNING "Cannot add context lttng_add_need_reschedule_to_ctx");
 302         }
 303 #if defined(CONFIG_PREEMPT_RT_FULL) || defined(CONFIG_PREEMPT)
 304         ret = lttng_add_preemptible_to_ctx(&lttng_static_ctx);
 305         if (ret != -ENOSYS) {
 306                 printk(KERN_WARNING "Cannot add context lttng_add_preemptible_to_ctx");
 307         }
 308 #endif
 309 #ifdef CONFIG_PREEMPT_RT_FULL
 310         ret = lttng_add_migratable_to_ctx(&lttng_static_ctx);
 311         if (ret != -ENOSYS) {
 312                 printk(KERN_WARNING "Cannot add context lttng_add_migratable_to_ctx");
 313         }
 314 #endif
 315         /* TODO: perf counters for filtering */
 316         return 0;
 317 }
 318
 319 void lttng_context_exit(void)
 320 {
 321         lttng_destroy_context(lttng_static_ctx);
 322         lttng_static_ctx = NULL;
 323 }