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                         default:
 145                                 WARN_ON_ONCE(1);
 146                                 break;
 147                         }
 148                         break;
 149                 }
 150                 case atype_sequence:
 151                 {
 152                         struct lttng_basic_type *btype;
 153
 154                         btype = &type->u.sequence.length_type;
 155                         switch (btype->atype) {
 156                         case atype_integer:
 157                                 field_align = btype->u.basic.integer.alignment;
 158                                 break;
 159
 160                         case atype_string:
 161                         case atype_array:
 162                         case atype_sequence:
 163                         default:
 164                                 WARN_ON_ONCE(1);
 165                                 break;
 166                         }
 167
 168                         btype = &type->u.sequence.elem_type;
 169                         switch (btype->atype) {
 170                         case atype_integer:
 171                                 field_align = max_t(size_t,
 172                                         field_align,
 173                                         btype->u.basic.integer.alignment);
 174                                 break;
 175
 176                         case atype_string:
 177                                 break;
 178
 179                         case atype_array:
 180                         case atype_sequence:
 181                         default:
 182                                 WARN_ON_ONCE(1);
 183                                 break;
 184                         }
 185                         break;
 186                 }
 187                 case atype_string:
 188                         break;
 189
 190                 case atype_enum:
 191                 default:
 192                         WARN_ON_ONCE(1);
 193                         break;
 194                 }
 195                 largest_align = max_t(size_t, largest_align, field_align);
 196         }
 197         ctx->largest_align = largest_align >> 3;        /* bits to bytes */
 198 }
 199
 200 /*
 201  * Remove last context field.
 202  */
 203 void lttng_remove_context_field(struct lttng_ctx **ctx_p,
 204                                 struct lttng_ctx_field *field)
 205 {
 206         struct lttng_ctx *ctx;
 207
 208         ctx = *ctx_p;
 209         ctx->nr_fields--;
 210         WARN_ON_ONCE(&ctx->fields[ctx->nr_fields] != field);
 211         memset(&ctx->fields[ctx->nr_fields], 0, sizeof(struct lttng_ctx_field));
 212 }
 213 EXPORT_SYMBOL_GPL(lttng_remove_context_field);
 214
 215 void lttng_destroy_context(struct lttng_ctx *ctx)
 216 {
 217         int i;
 218
 219         if (!ctx)
 220                 return;
 221         for (i = 0; i < ctx->nr_fields; i++) {
 222                 if (ctx->fields[i].destroy)
 223                         ctx->fields[i].destroy(&ctx->fields[i]);
 224         }
 225         kfree(ctx->fields);
 226         kfree(ctx);
 227 }
 228
 229 int lttng_context_init(void)
 230 {
 231         int ret;
 232
 233         ret = lttng_add_hostname_to_ctx(&lttng_static_ctx);
 234         if (ret) {
 235                 printk(KERN_WARNING "Cannot add context lttng_add_hostname_to_ctx");
 236         }
 237         ret = lttng_add_nice_to_ctx(&lttng_static_ctx);
 238         if (ret) {
 239                 printk(KERN_WARNING "Cannot add context lttng_add_nice_to_ctx");
 240         }
 241         ret = lttng_add_pid_to_ctx(&lttng_static_ctx);
 242         if (ret) {
 243                 printk(KERN_WARNING "Cannot add context lttng_add_pid_to_ctx");
 244         }
 245         ret = lttng_add_ppid_to_ctx(&lttng_static_ctx);
 246         if (ret) {
 247                 printk(KERN_WARNING "Cannot add context lttng_add_ppid_to_ctx");
 248         }
 249         ret = lttng_add_prio_to_ctx(&lttng_static_ctx);
 250         if (ret) {
 251                 printk(KERN_WARNING "Cannot add context lttng_add_prio_to_ctx");
 252         }
 253         ret = lttng_add_procname_to_ctx(&lttng_static_ctx);
 254         if (ret) {
 255                 printk(KERN_WARNING "Cannot add context lttng_add_procname_to_ctx");
 256         }
 257         ret = lttng_add_tid_to_ctx(&lttng_static_ctx);
 258         if (ret) {
 259                 printk(KERN_WARNING "Cannot add context lttng_add_tid_to_ctx");
 260         }
 261         ret = lttng_add_vppid_to_ctx(&lttng_static_ctx);
 262         if (ret) {
 263                 printk(KERN_WARNING "Cannot add context lttng_add_vppid_to_ctx");
 264         }
 265         ret = lttng_add_vtid_to_ctx(&lttng_static_ctx);
 266         if (ret) {
 267                 printk(KERN_WARNING "Cannot add context lttng_add_vtid_to_ctx");
 268         }
 269         ret = lttng_add_vpid_to_ctx(&lttng_static_ctx);
 270         if (ret) {
 271                 printk(KERN_WARNING "Cannot add context lttng_add_vpid_to_ctx");
 272         }
 273         ret = lttng_add_cpu_id_to_ctx(&lttng_static_ctx);
 274         if (ret) {
 275                 printk(KERN_WARNING "Cannot add context lttng_add_cpu_id_to_ctx");
 276         }
 277         ret = lttng_add_interruptible_to_ctx(&lttng_static_ctx);
 278         if (ret) {
 279                 printk(KERN_WARNING "Cannot add context lttng_add_interruptible_to_ctx");
 280         }
 281         ret = lttng_add_need_reschedule_to_ctx(&lttng_static_ctx);
 282         if (ret) {
 283                 printk(KERN_WARNING "Cannot add context lttng_add_need_reschedule_to_ctx");
 284         }
 285 #if defined(CONFIG_PREEMPT_RT_FULL) || defined(CONFIG_PREEMPT)
 286         ret = lttng_add_preemptible_to_ctx(&lttng_static_ctx);
 287         if (ret != -ENOSYS) {
 288                 printk(KERN_WARNING "Cannot add context lttng_add_preemptible_to_ctx");
 289         }
 290 #endif
 291 #ifdef CONFIG_PREEMPT_RT_FULL
 292         ret = lttng_add_migratable_to_ctx(&lttng_static_ctx);
 293         if (ret != -ENOSYS) {
 294                 printk(KERN_WARNING "Cannot add context lttng_add_migratable_to_ctx");
 295         }
 296 #endif
 297         /* TODO: perf counters for filtering */
 298         return 0;
 299 }
 300
 301 void lttng_context_exit(void)
 302 {
 303         lttng_destroy_context(lttng_static_ctx);
 304         lttng_static_ctx = NULL;
 305 }