2 * lttng-context-procname.c
4 * LTTng UST procname context.
6 * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
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.
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.
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
23 #include <lttng/ust-events.h>
24 #include <lttng/ust-tracer.h>
25 #include <lttng/ringbuffer-config.h>
30 * We cache the result to ensure we don't trigger a system call for
32 * Upon exec, procname changes, but exec takes care of throwing away
33 * this cached version.
34 * The procname can also change by calling prctl(). The procname should
35 * be set for a thread before the first event is logged within this
38 static __thread
char cached_procname
[17];
41 char *wrapper_getprocname(void)
43 if (caa_unlikely(!cached_procname
[0])) {
44 lttng_ust_getprocname(cached_procname
);
45 cached_procname
[LTTNG_UST_PROCNAME_LEN
- 1] = '\0';
47 return cached_procname
;
50 void lttng_context_procname_reset(void)
52 cached_procname
[0] = '\0';
56 size_t procname_get_size(size_t offset
)
60 size
+= LTTNG_UST_PROCNAME_LEN
;
65 void procname_record(struct lttng_ctx_field
*field
,
66 struct lttng_ust_lib_ring_buffer_ctx
*ctx
,
67 struct lttng_channel
*chan
)
71 procname
= wrapper_getprocname();
72 chan
->ops
->event_write(ctx
, procname
, LTTNG_UST_PROCNAME_LEN
);
75 int lttng_add_procname_to_ctx(struct lttng_ctx
**ctx
)
77 struct lttng_ctx_field
*field
;
79 field
= lttng_append_context(ctx
);
82 if (lttng_find_context(*ctx
, "procname")) {
83 lttng_remove_context_field(ctx
, field
);
86 field
->event_field
.name
= "procname";
87 field
->event_field
.type
.atype
= atype_array
;
88 field
->event_field
.type
.u
.array
.elem_type
.atype
= atype_integer
;
89 field
->event_field
.type
.u
.array
.elem_type
.u
.basic
.integer
.size
= sizeof(char) * CHAR_BIT
;
90 field
->event_field
.type
.u
.array
.elem_type
.u
.basic
.integer
.alignment
= lttng_alignof(char) * CHAR_BIT
;
91 field
->event_field
.type
.u
.array
.elem_type
.u
.basic
.integer
.signedness
= lttng_is_signed_type(char);
92 field
->event_field
.type
.u
.array
.elem_type
.u
.basic
.integer
.reverse_byte_order
= 0;
93 field
->event_field
.type
.u
.array
.elem_type
.u
.basic
.integer
.base
= 10;
94 field
->event_field
.type
.u
.array
.elem_type
.u
.basic
.integer
.encoding
= lttng_encode_UTF8
;
95 field
->event_field
.type
.u
.array
.length
= LTTNG_UST_PROCNAME_LEN
;
96 field
->get_size
= procname_get_size
;
97 field
->record
= procname_record
;
102 * Force a read (imply TLS fixup for dlopen) of TLS variables.
104 void lttng_fixup_procname_tls(void)
106 asm volatile ("" : : "m" (cached_procname
[0]));