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4ddbd0b7 PP |
1 | lttng-ust-dl(3) |
2 | =============== | |
3 | :object-type: library | |
4 | ||
5 | ||
6 | NAME | |
7 | ---- | |
8 | lttng-ust-dl - Dynamic linker tracing (LTTng-UST helper) | |
9 | ||
10 | ||
11 | SYNOPSIS | |
12 | -------- | |
13 | Launch your application by preloading `liblttng-ust-dl.so`: | |
14 | ||
15 | [role="term"] | |
16 | [verse] | |
0be120c8 | 17 | $ *LD_PRELOAD=liblttng-ust-dl.so* my-app |
4ddbd0b7 PP |
18 | |
19 | ||
20 | DESCRIPTION | |
21 | ----------- | |
22 | When the `liblttng-ust-dl.so` library is preloaded before a given | |
23 | application starts, it causes all calls to man:dlopen(3) and | |
24 | man:dlclose(3) in said application to be traced with LTTng-UST (see | |
25 | man:lttng-ust(3)). | |
26 | ||
27 | See man:lttng(1) to learn more about how to control LTTng tracing | |
28 | sessions. | |
29 | ||
9082c886 PP |
30 | IMPORTANT: This LTTng-UST helper can also emit _shared library |
31 | load/unload_ events (see _Shared library load/unload tracking_ in | |
32 | man:lttng-ust(3)). You should :not: use the event records generated by | |
33 | this LTTng-UST helper (prefixed with `lttng_ust_dl:`) to track the | |
34 | loading and unloading of shared libraries, especially in situations | |
35 | where a dynamically loaded library loads its own dependencies. Instead, | |
36 | do preload `liblttng-ust-dl.so`, but use the shared library load/unload | |
37 | event records, which are more reliable, for your tracking analysis. | |
38 | ||
39 | The following LTTng-UST events are available when using this library. | |
40 | ||
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41 | |
42 | `lttng_ust_dl:dlopen`:: | |
43 | Emitted when man:dlopen(3) is called. | |
44 | + | |
45 | Fields: | |
46 | + | |
47 | [options="header"] | |
ca98b1d7 PP |
48 | |=== |
49 | |Field name |Description | |
50 | ||
51 | |`baddr` | |
610a9e5a | 52 | |Base address of loaded library. |
ca98b1d7 PP |
53 | |
54 | |`memsz` | |
610a9e5a | 55 | |Size of loaded library in memory. |
ca98b1d7 | 56 | |
d91d83e4 PP |
57 | |`flags` |
58 | |Flags passed to man:dlopen(3). | |
59 | ||
60 | |`path` | |
61 | |Path to loaded library file. | |
62 | ||
63 | |`has_build_id` | |
64 | |Whether or not the loaded library has a build ID. If this field is 1, | |
65 | you can expect that an `lttng_ust_dl:build_id` event record | |
66 | follows this one (not necessarily immediately after). | |
67 | ||
68 | |`has_debug_link` | |
69 | |Whether or not the loaded library has debug link information. If this | |
70 | field is 1, you can expect that an `lttng_ust_dl:debug_link` event | |
71 | record follows this one (not necessarily immediately after). | |
72 | |=== | |
73 | ||
74 | `lttng_ust_dl:dlmopen`:: | |
75 | Emitted when man:dlmopen(3) is called. | |
76 | + | |
77 | Fields: | |
78 | + | |
79 | [options="header"] | |
80 | |=== | |
81 | |Field name |Description | |
82 | ||
83 | |`baddr` | |
84 | |Base address of loaded library. | |
85 | ||
86 | |`memsz` | |
87 | |Size of loaded library in memory. | |
88 | ||
89 | |`nsid` | |
90 | |ID of the namespace in which the library is loaded (as passed | |
91 | to man:dlmopen(3)). | |
92 | ||
93 | |`flags` | |
94 | |Flags passed to man:dlmopen(3). | |
95 | ||
ca98b1d7 | 96 | |`path` |
610a9e5a | 97 | |Path to loaded library file. |
d91d83e4 PP |
98 | |
99 | |`has_build_id` | |
100 | |Whether or not the loaded library has a build ID. If this field is 1, | |
101 | you can expect that an `lttng_ust_dl:build_id` event record | |
102 | follows this one (not necessarily immediately after). | |
103 | ||
104 | |`has_debug_link` | |
105 | |Whether or not the loaded library has debug link information. If this | |
106 | field is 1, you can expect that an `lttng_ust_dl:debug_link` event | |
107 | record follows this one (not necessarily immediately after). | |
ca98b1d7 | 108 | |=== |
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109 | |
110 | `lttng_ust_dl:dlclose`:: | |
111 | Emitted when man:dlclose(3) is called. | |
112 | + | |
113 | Fields: | |
114 | + | |
115 | [options="header"] | |
ca98b1d7 PP |
116 | |=== |
117 | |Field name |Description | |
118 | ||
119 | |`baddr` | |
610a9e5a | 120 | |Base address of loaded library. |
ca98b1d7 | 121 | |=== |
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122 | |
123 | `lttng_ust_dl:debug_link`:: | |
124 | Emitted when debug link information is found when loading a library | |
125 | with man:dlopen(3). See | |
126 | https://sourceware.org/gdb/onlinedocs/gdb/Separate-Debug-Files.html[Debugging Information in Separate Files] | |
127 | for more information about debug links. | |
128 | + | |
129 | Fields: | |
130 | + | |
131 | [options="header"] | |
ca98b1d7 PP |
132 | |=== |
133 | |Field name |Description | |
134 | ||
135 | |`baddr` | |
610a9e5a | 136 | |Base address of loaded library. |
ca98b1d7 PP |
137 | |
138 | |`filename` | |
610a9e5a | 139 | |Debug link file name. |
ca98b1d7 PP |
140 | |
141 | |`crc` | |
610a9e5a | 142 | |Debug link file's CRC. |
ca98b1d7 | 143 | |=== |
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144 | |
145 | `lttng_ust_dl:build_id`:: | |
146 | Emitted when a build ID is found when loading a library | |
147 | with man:dlopen(3). See | |
148 | https://sourceware.org/gdb/onlinedocs/gdb/Separate-Debug-Files.html[Debugging Information in Separate Files] | |
149 | for more information about build IDs. | |
150 | + | |
151 | Fields: | |
152 | + | |
153 | [options="header"] | |
ca98b1d7 PP |
154 | |=== |
155 | |Field name |Description | |
156 | ||
157 | |`baddr` | |
610a9e5a | 158 | |Base address of loaded library. |
ca98b1d7 PP |
159 | |
160 | |`build_id` | |
610a9e5a | 161 | |Build ID. |
ca98b1d7 | 162 | |=== |
4ddbd0b7 PP |
163 | |
164 | ||
165 | include::common-footer.txt[] | |
166 | ||
167 | include::common-copyrights.txt[] | |
168 | ||
169 | include::common-authors.txt[] | |
170 | ||
171 | ||
172 | SEE ALSO | |
173 | -------- | |
174 | man:lttng-ust(3), | |
175 | man:dlopen(3), | |
176 | man:lttng(1) |