Commit | Line | Data |
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735bef47 | 1 | /* |
c0c0989a | 2 | * SPDX-License-Identifier: LGPL-2.1-only |
735bef47 MJ |
3 | * |
4 | * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
c0c0989a | 5 | * Copyright (C) 2019 Michael Jeanson <mjeanson@efficios.com> |
735bef47 | 6 | * |
c0c0989a | 7 | * LTTng UST ipc namespace context. |
735bef47 MJ |
8 | */ |
9 | ||
10 | #define _LGPL_SOURCE | |
9af5d97a | 11 | #include <limits.h> |
b4051ad8 | 12 | #include <stddef.h> |
735bef47 MJ |
13 | #include <sys/types.h> |
14 | #include <sys/stat.h> | |
15 | #include <unistd.h> | |
16 | #include <lttng/ust-events.h> | |
17 | #include <lttng/ust-tracer.h> | |
9d315d6d | 18 | #include "common/compat/tid.h" |
735bef47 | 19 | #include <urcu/tls-compat.h> |
0b4b8811 | 20 | #include <lttng/ust-ringbuffer-context.h> |
fc80554e MJ |
21 | |
22 | #include "context-internal.h" | |
735bef47 | 23 | #include "lttng-tracer-core.h" |
c5e8ef85 | 24 | #include "common/ns.h" |
735bef47 | 25 | |
735bef47 MJ |
26 | /* |
27 | * We cache the result to ensure we don't stat(2) the proc filesystem on | |
28 | * each event. | |
29 | */ | |
a251a209 | 30 | static DEFINE_URCU_TLS_INIT(ino_t, cached_ipc_ns, NS_INO_UNINITIALIZED); |
735bef47 MJ |
31 | |
32 | static | |
33 | ino_t get_ipc_ns(void) | |
34 | { | |
35 | struct stat sb; | |
36 | ino_t ipc_ns; | |
37 | ||
38 | ipc_ns = CMM_LOAD_SHARED(URCU_TLS(cached_ipc_ns)); | |
39 | ||
40 | /* | |
41 | * If the cache is populated, do nothing and return the | |
42 | * cached inode number. | |
43 | */ | |
44 | if (caa_likely(ipc_ns != NS_INO_UNINITIALIZED)) | |
45 | return ipc_ns; | |
46 | ||
47 | /* | |
48 | * At this point we have to populate the cache, set the initial | |
49 | * value to NS_INO_UNAVAILABLE (0), if we fail to get the inode | |
50 | * number from the proc filesystem, this is the value we will | |
51 | * cache. | |
52 | */ | |
53 | ipc_ns = NS_INO_UNAVAILABLE; | |
54 | ||
55 | /* | |
56 | * /proc/thread-self was introduced in kernel v3.17 | |
57 | */ | |
58 | if (stat("/proc/thread-self/ns/ipc", &sb) == 0) { | |
59 | ipc_ns = sb.st_ino; | |
60 | } else { | |
61 | char proc_ns_path[LTTNG_PROC_NS_PATH_MAX]; | |
62 | ||
63 | if (snprintf(proc_ns_path, LTTNG_PROC_NS_PATH_MAX, | |
64 | "/proc/self/task/%d/ns/ipc", | |
65 | lttng_gettid()) >= 0) { | |
66 | ||
67 | if (stat(proc_ns_path, &sb) == 0) { | |
68 | ipc_ns = sb.st_ino; | |
69 | } | |
70 | } | |
71 | } | |
72 | ||
73 | /* | |
74 | * And finally, store the inode number in the cache. | |
75 | */ | |
76 | CMM_STORE_SHARED(URCU_TLS(cached_ipc_ns), ipc_ns); | |
77 | ||
78 | return ipc_ns; | |
79 | } | |
80 | ||
81 | /* | |
82 | * The ipc namespace can change for 3 reasons | |
83 | * * clone(2) called with CLONE_NEWIPC | |
84 | * * setns(2) called with the fd of a different ipc ns | |
85 | * * unshare(2) called with CLONE_NEWIPC | |
86 | */ | |
87 | void lttng_context_ipc_ns_reset(void) | |
88 | { | |
89 | CMM_STORE_SHARED(URCU_TLS(cached_ipc_ns), NS_INO_UNINITIALIZED); | |
90 | } | |
91 | ||
92 | static | |
4e48b5d2 | 93 | size_t ipc_ns_get_size(void *priv __attribute__((unused)), |
b2e37d27 | 94 | struct lttng_ust_probe_ctx *probe_ctx __attribute__((unused)), |
2208d8b5 | 95 | size_t offset) |
735bef47 MJ |
96 | { |
97 | size_t size = 0; | |
98 | ||
b5457df5 | 99 | size += lttng_ust_ring_buffer_align(offset, lttng_ust_rb_alignof(ino_t)); |
735bef47 MJ |
100 | size += sizeof(ino_t); |
101 | return size; | |
102 | } | |
103 | ||
104 | static | |
4e48b5d2 | 105 | void ipc_ns_record(void *priv __attribute__((unused)), |
b2e37d27 MD |
106 | struct lttng_ust_probe_ctx *probe_ctx __attribute__((unused)), |
107 | struct lttng_ust_ring_buffer_ctx *ctx, | |
108 | struct lttng_ust_channel_buffer *chan) | |
735bef47 MJ |
109 | { |
110 | ino_t ipc_ns; | |
111 | ||
112 | ipc_ns = get_ipc_ns(); | |
8936b6c0 | 113 | chan->ops->event_write(ctx, &ipc_ns, sizeof(ipc_ns), lttng_ust_rb_alignof(ipc_ns)); |
735bef47 MJ |
114 | } |
115 | ||
116 | static | |
4e48b5d2 | 117 | void ipc_ns_get_value(void *priv __attribute__((unused)), |
b2e37d27 | 118 | struct lttng_ust_probe_ctx *probe_ctx __attribute__((unused)), |
daacdbfc | 119 | struct lttng_ust_ctx_value *value) |
735bef47 | 120 | { |
b2e37d27 | 121 | value->u.u64 = get_ipc_ns(); |
735bef47 MJ |
122 | } |
123 | ||
95fa2ba4 | 124 | static const struct lttng_ust_ctx_field *ctx_field = lttng_ust_static_ctx_field( |
4e48b5d2 MD |
125 | lttng_ust_static_event_field("ipc_ns", |
126 | lttng_ust_static_type_integer(sizeof(ino_t) * CHAR_BIT, | |
127 | lttng_ust_rb_alignof(ino_t) * CHAR_BIT, | |
128 | lttng_ust_is_signed_type(ino_t), | |
baa8acf3 | 129 | LTTNG_UST_BYTE_ORDER, 10), |
4e48b5d2 MD |
130 | false, false), |
131 | ipc_ns_get_size, | |
132 | ipc_ns_record, | |
133 | ipc_ns_get_value, | |
134 | NULL, NULL); | |
135 | ||
daacdbfc | 136 | int lttng_add_ipc_ns_to_ctx(struct lttng_ust_ctx **ctx) |
735bef47 | 137 | { |
a084756d MD |
138 | int ret; |
139 | ||
4e48b5d2 | 140 | if (lttng_find_context(*ctx, ctx_field->event_field->name)) { |
a084756d MD |
141 | ret = -EEXIST; |
142 | goto error_find_context; | |
143 | } | |
4e48b5d2 MD |
144 | ret = lttng_ust_context_append(ctx, ctx_field); |
145 | if (ret) | |
146 | return ret; | |
735bef47 | 147 | return 0; |
a084756d | 148 | |
a084756d | 149 | error_find_context: |
a084756d | 150 | return ret; |
735bef47 MJ |
151 | } |
152 | ||
153 | /* | |
a9fd951a MJ |
154 | * Force a read (imply TLS allocation for dlopen) of TLS variables. |
155 | */ | |
c246521d | 156 | void lttng_ust_ipc_ns_init_thread(int flags) |
735bef47 | 157 | { |
742ac92a | 158 | __asm__ __volatile__ ("" : : "m" (URCU_TLS(cached_ipc_ns))); |
c246521d NL |
159 | if (flags & LTTNG_UST_INIT_THREAD_CONTEXT_CACHE) |
160 | (void)get_ipc_ns(); | |
735bef47 | 161 | } |