lttng-context-vtid.c

   1 /* SPDX-License-Identifier: (GPL-2.0 or LGPL-2.1)
   2  *
   3  * lttng-context-vtid.c
   4  *
   5  * LTTng vTID context.
   6  *
   7  * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   8  */
   9
  10 #include <linux/module.h>
  11 #include <linux/slab.h>
  12 #include <linux/sched.h>
  13 #include <lttng-events.h>
  14 #include <wrapper/ringbuffer/frontend_types.h>
  15 #include <wrapper/vmalloc.h>
  16 #include <lttng-tracer.h>
  17
  18 static
  19 size_t vtid_get_size(size_t offset)
  20 {
  21         size_t size = 0;
  22
  23         size += lib_ring_buffer_align(offset, lttng_alignof(pid_t));
  24         size += sizeof(pid_t);
  25         return size;
  26 }
  27
  28 static
  29 void vtid_record(struct lttng_ctx_field *field,
  30                  struct lib_ring_buffer_ctx *ctx,
  31                  struct lttng_channel *chan)
  32 {
  33         pid_t vtid;
  34
  35         /*
  36          * nsproxy can be NULL when scheduled out of exit.
  37          */
  38         if (!current->nsproxy)
  39                 vtid = 0;
  40         else
  41                 vtid = task_pid_vnr(current);
  42         lib_ring_buffer_align_ctx(ctx, lttng_alignof(vtid));
  43         chan->ops->event_write(ctx, &vtid, sizeof(vtid));
  44 }
  45
  46 static
  47 void vtid_get_value(struct lttng_ctx_field *field,
  48                 struct lttng_probe_ctx *lttng_probe_ctx,
  49                 union lttng_ctx_value *value)
  50 {
  51         pid_t vtid;
  52
  53         /*
  54          * nsproxy can be NULL when scheduled out of exit.
  55          */
  56         if (!current->nsproxy)
  57                 vtid = 0;
  58         else
  59                 vtid = task_pid_vnr(current);
  60         value->s64 = vtid;
  61 }
  62
  63 int lttng_add_vtid_to_ctx(struct lttng_ctx **ctx)
  64 {
  65         struct lttng_ctx_field *field;
  66
  67         field = lttng_append_context(ctx);
  68         if (!field)
  69                 return -ENOMEM;
  70         if (lttng_find_context(*ctx, "vtid")) {
  71                 lttng_remove_context_field(ctx, field);
  72                 return -EEXIST;
  73         }
  74         field->event_field.name = "vtid";
  75         field->event_field.type.atype = atype_integer;
  76         field->event_field.type.u.basic.integer.size = sizeof(pid_t) * CHAR_BIT;
  77         field->event_field.type.u.basic.integer.alignment = lttng_alignof(pid_t) * CHAR_BIT;
  78         field->event_field.type.u.basic.integer.signedness = lttng_is_signed_type(pid_t);
  79         field->event_field.type.u.basic.integer.reverse_byte_order = 0;
  80         field->event_field.type.u.basic.integer.base = 10;
  81         field->event_field.type.u.basic.integer.encoding = lttng_encode_none;
  82         field->get_size = vtid_get_size;
  83         field->record = vtid_record;
  84         field->get_value = vtid_get_value;
  85         lttng_context_update(*ctx);
  86         wrapper_vmalloc_sync_mappings();
  87         return 0;
  88 }
  89 EXPORT_SYMBOL_GPL(lttng_add_vtid_to_ctx);