lttng-context.c

   1 /* SPDX-License-Identifier: (GPL-2.0 or LGPL-2.1)
   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-tracer.h>
  17
  18 /*
  19  * The filter implementation requires that two consecutive "get" for the
  20  * same context performed by the same thread return the same result.
  21  */
  22
  23 /*
  24  * Static array of contexts, for $ctx filters.
  25  */
  26 struct lttng_ctx *lttng_static_ctx;
  27
  28 int lttng_find_context(struct lttng_ctx *ctx, const char *name)
  29 {
  30         unsigned int i;
  31
  32         for (i = 0; i < ctx->nr_fields; i++) {
  33                 /* Skip allocated (but non-initialized) contexts */
  34                 if (!ctx->fields[i].event_field.name)
  35                         continue;
  36                 if (!strcmp(ctx->fields[i].event_field.name, name))
  37                         return 1;
  38         }
  39         return 0;
  40 }
  41 EXPORT_SYMBOL_GPL(lttng_find_context);
  42
  43 int lttng_get_context_index(struct lttng_ctx *ctx, const char *name)
  44 {
  45         unsigned int i;
  46         const char *subname;
  47
  48         if (!ctx)
  49                 return -1;
  50         if (strncmp(name, "$ctx.", strlen("$ctx.")) == 0) {
  51                 subname = name + strlen("$ctx.");
  52         } else {
  53                 subname = name;
  54         }
  55         for (i = 0; i < ctx->nr_fields; i++) {
  56                 /* Skip allocated (but non-initialized) contexts */
  57                 if (!ctx->fields[i].event_field.name)
  58                         continue;
  59                 if (!strcmp(ctx->fields[i].event_field.name, subname))
  60                         return i;
  61         }
  62         return -1;
  63 }
  64 EXPORT_SYMBOL_GPL(lttng_get_context_index);
  65
  66 /*
  67  * Note: as we append context information, the pointer location may change.
  68  */
  69 struct lttng_ctx_field *lttng_append_context(struct lttng_ctx **ctx_p)
  70 {
  71         struct lttng_ctx_field *field;
  72         struct lttng_ctx *ctx;
  73
  74         if (!*ctx_p) {
  75                 *ctx_p = kzalloc(sizeof(struct lttng_ctx), GFP_KERNEL);
  76                 if (!*ctx_p)
  77                         return NULL;
  78                 (*ctx_p)->largest_align = 1;
  79         }
  80         ctx = *ctx_p;
  81         if (ctx->nr_fields + 1 > ctx->allocated_fields) {
  82                 struct lttng_ctx_field *new_fields;
  83
  84                 ctx->allocated_fields = max_t(size_t, 1, 2 * ctx->allocated_fields);
  85                 new_fields = lttng_kvzalloc(ctx->allocated_fields * sizeof(struct lttng_ctx_field), GFP_KERNEL);
  86                 if (!new_fields)
  87                         return NULL;
  88                 if (ctx->fields)
  89                         memcpy(new_fields, ctx->fields, sizeof(*ctx->fields) * ctx->nr_fields);
  90                 lttng_kvfree(ctx->fields);
  91                 ctx->fields = new_fields;
  92         }
  93         field = &ctx->fields[ctx->nr_fields];
  94         ctx->nr_fields++;
  95         return field;
  96 }
  97 EXPORT_SYMBOL_GPL(lttng_append_context);
  98
  99 /*
 100  * lttng_context_update() should be called at least once between context
 101  * modification and trace start.
 102  */
 103 void lttng_context_update(struct lttng_ctx *ctx)
 104 {
 105         int i;
 106         size_t largest_align = 8;       /* in bits */
 107
 108         for (i = 0; i < ctx->nr_fields; i++) {
 109                 struct lttng_type *type;
 110                 size_t field_align = 8;
 111
 112                 type = &ctx->fields[i].event_field.type;
 113                 switch (type->atype) {
 114                 case atype_integer:
 115                         field_align = type->u.basic.integer.alignment;
 116                         break;
 117                 case atype_array:
 118                 case atype_array_bitfield:
 119                 {
 120                         struct lttng_basic_type *btype;
 121
 122                         btype = &type->u.array.elem_type;
 123                         switch (btype->atype) {
 124                         case atype_integer:
 125                                 field_align = btype->u.basic.integer.alignment;
 126                                 break;
 127                         case atype_string:
 128                                 break;
 129
 130                         case atype_array:
 131                         case atype_sequence:
 132                         case atype_array_bitfield:
 133                         case atype_sequence_bitfield:
 134                         case atype_struct:
 135                         case atype_array_compound:
 136                         case atype_sequence_compound:
 137                         case atype_variant:
 138                         default:
 139                                 WARN_ON_ONCE(1);
 140                                 break;
 141                         }
 142                         break;
 143                 }
 144                 case atype_sequence:
 145                 case atype_sequence_bitfield:
 146                 {
 147                         struct lttng_basic_type *btype;
 148
 149                         btype = &type->u.sequence.length_type;
 150                         switch (btype->atype) {
 151                         case atype_integer:
 152                                 field_align = btype->u.basic.integer.alignment;
 153                                 break;
 154
 155                         case atype_string:
 156                         case atype_array:
 157                         case atype_sequence:
 158                         case atype_array_bitfield:
 159                         case atype_sequence_bitfield:
 160                         case atype_struct:
 161                         case atype_array_compound:
 162                         case atype_sequence_compound:
 163                         case atype_variant:
 164                         default:
 165                                 WARN_ON_ONCE(1);
 166                                 break;
 167                         }
 168
 169                         btype = &type->u.sequence.elem_type;
 170                         switch (btype->atype) {
 171                         case atype_integer:
 172                                 field_align = max_t(size_t,
 173                                         field_align,
 174                                         btype->u.basic.integer.alignment);
 175                                 break;
 176
 177                         case atype_string:
 178                                 break;
 179
 180                         case atype_array:
 181                         case atype_sequence:
 182                         case atype_array_bitfield:
 183                         case atype_sequence_bitfield:
 184                         case atype_struct:
 185                         case atype_array_compound:
 186                         case atype_sequence_compound:
 187                         case atype_variant:
 188                         default:
 189                                 WARN_ON_ONCE(1);
 190                                 break;
 191                         }
 192                         break;
 193                 }
 194                 case atype_string:
 195                         break;
 196
 197                 case atype_struct:
 198                 case atype_array_compound:
 199                 case atype_sequence_compound:
 200                 case atype_variant:
 201                         break;
 202
 203                 case atype_enum:
 204                 default:
 205                         WARN_ON_ONCE(1);
 206                         break;
 207                 }
 208                 largest_align = max_t(size_t, largest_align, field_align);
 209         }
 210         ctx->largest_align = largest_align >> 3;        /* bits to bytes */
 211 }
 212
 213 /*
 214  * Remove last context field.
 215  */
 216 void lttng_remove_context_field(struct lttng_ctx **ctx_p,
 217                                 struct lttng_ctx_field *field)
 218 {
 219         struct lttng_ctx *ctx;
 220
 221         ctx = *ctx_p;
 222         ctx->nr_fields--;
 223         WARN_ON_ONCE(&ctx->fields[ctx->nr_fields] != field);
 224         memset(&ctx->fields[ctx->nr_fields], 0, sizeof(struct lttng_ctx_field));
 225 }
 226 EXPORT_SYMBOL_GPL(lttng_remove_context_field);
 227
 228 void lttng_destroy_context(struct lttng_ctx *ctx)
 229 {
 230         int i;
 231
 232         if (!ctx)
 233                 return;
 234         for (i = 0; i < ctx->nr_fields; i++) {
 235                 if (ctx->fields[i].destroy)
 236                         ctx->fields[i].destroy(&ctx->fields[i]);
 237         }
 238         lttng_kvfree(ctx->fields);
 239         kfree(ctx);
 240 }
 241
 242 int lttng_context_init(void)
 243 {
 244         int ret;
 245
 246         ret = lttng_add_hostname_to_ctx(&lttng_static_ctx);
 247         if (ret) {
 248                 printk(KERN_WARNING "Cannot add context lttng_add_hostname_to_ctx");
 249         }
 250         ret = lttng_add_nice_to_ctx(&lttng_static_ctx);
 251         if (ret) {
 252                 printk(KERN_WARNING "Cannot add context lttng_add_nice_to_ctx");
 253         }
 254         ret = lttng_add_pid_to_ctx(&lttng_static_ctx);
 255         if (ret) {
 256                 printk(KERN_WARNING "Cannot add context lttng_add_pid_to_ctx");
 257         }
 258         ret = lttng_add_ppid_to_ctx(&lttng_static_ctx);
 259         if (ret) {
 260                 printk(KERN_WARNING "Cannot add context lttng_add_ppid_to_ctx");
 261         }
 262         ret = lttng_add_prio_to_ctx(&lttng_static_ctx);
 263         if (ret) {
 264                 printk(KERN_WARNING "Cannot add context lttng_add_prio_to_ctx");
 265         }
 266         ret = lttng_add_procname_to_ctx(&lttng_static_ctx);
 267         if (ret) {
 268                 printk(KERN_WARNING "Cannot add context lttng_add_procname_to_ctx");
 269         }
 270         ret = lttng_add_tid_to_ctx(&lttng_static_ctx);
 271         if (ret) {
 272                 printk(KERN_WARNING "Cannot add context lttng_add_tid_to_ctx");
 273         }
 274         ret = lttng_add_vppid_to_ctx(&lttng_static_ctx);
 275         if (ret) {
 276                 printk(KERN_WARNING "Cannot add context lttng_add_vppid_to_ctx");
 277         }
 278         ret = lttng_add_vtid_to_ctx(&lttng_static_ctx);
 279         if (ret) {
 280                 printk(KERN_WARNING "Cannot add context lttng_add_vtid_to_ctx");
 281         }
 282         ret = lttng_add_vpid_to_ctx(&lttng_static_ctx);
 283         if (ret) {
 284                 printk(KERN_WARNING "Cannot add context lttng_add_vpid_to_ctx");
 285         }
 286         ret = lttng_add_cpu_id_to_ctx(&lttng_static_ctx);
 287         if (ret) {
 288                 printk(KERN_WARNING "Cannot add context lttng_add_cpu_id_to_ctx");
 289         }
 290         ret = lttng_add_interruptible_to_ctx(&lttng_static_ctx);
 291         if (ret) {
 292                 printk(KERN_WARNING "Cannot add context lttng_add_interruptible_to_ctx");
 293         }
 294         ret = lttng_add_need_reschedule_to_ctx(&lttng_static_ctx);
 295         if (ret) {
 296                 printk(KERN_WARNING "Cannot add context lttng_add_need_reschedule_to_ctx");
 297         }
 298         ret = lttng_add_preemptible_to_ctx(&lttng_static_ctx);
 299         if (ret && ret != -ENOSYS) {
 300                 printk(KERN_WARNING "Cannot add context lttng_add_preemptible_to_ctx");
 301         }
 302         ret = lttng_add_migratable_to_ctx(&lttng_static_ctx);
 303         if (ret && ret != -ENOSYS) {
 304                 printk(KERN_WARNING "Cannot add context lttng_add_migratable_to_ctx");
 305         }
 306         /* TODO: perf counters for filtering */
 307         return 0;
 308 }
 309
 310 void lttng_context_exit(void)
 311 {
 312         lttng_destroy_context(lttng_static_ctx);
 313         lttng_static_ctx = NULL;
 314 }