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247c2ecd MJ |
1 | /* |
2 | * SPDX-License-Identifier: LGPL-2.1-only | |
3 | * | |
4 | * Copyright (C) 2014 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
5 | */ | |
6 | ||
7 | #define _LGPL_SOURCE | |
8 | #include <error.h> | |
9 | #include <dlfcn.h> | |
10 | #include <stdlib.h> | |
11 | #include "common/logging.h" | |
12 | #include <urcu/system.h> | |
13 | #include <urcu/arch.h> | |
14 | ||
910dcd72 | 15 | #include "common/getenv.h" |
247c2ecd MJ |
16 | #include "lib/lttng-ust/getcpu.h" |
17 | ||
18 | /* Function pointer to the current getcpu callback. */ | |
19 | int (*lttng_ust_get_cpu_sym)(void); | |
20 | ||
21 | static | |
22 | void *getcpu_plugin_handle; | |
23 | ||
24 | /* | |
25 | * Override the user provided getcpu implementation. | |
26 | */ | |
27 | int lttng_ust_getcpu_override(int (*getcpu)(void)) | |
28 | { | |
29 | CMM_STORE_SHARED(lttng_ust_get_cpu_sym, getcpu); | |
30 | return 0; | |
31 | } | |
32 | ||
33 | /* | |
34 | * Initialize the getcpu plugin if it's present. | |
35 | */ | |
36 | void lttng_ust_getcpu_plugin_init(void) | |
37 | { | |
38 | const char *libname; | |
39 | void (*getcpu_plugin_init)(void); | |
40 | ||
41 | /* If a plugin is already loaded, do nothing. */ | |
42 | if (getcpu_plugin_handle) | |
43 | return; | |
44 | ||
45 | /* | |
46 | * If the LTTNG_UST_GETCPU_PLUGIN environment variable is undefined, do | |
47 | * nothing. | |
48 | */ | |
49 | libname = lttng_ust_getenv("LTTNG_UST_GETCPU_PLUGIN"); | |
50 | if (!libname) | |
51 | return; | |
52 | ||
53 | /* | |
54 | * Thy to dlopen the getcpu plugin shared object specified in | |
55 | * LTTNG_UST_GETCPU_PLUGIN. | |
56 | */ | |
57 | getcpu_plugin_handle = dlopen(libname, RTLD_NOW); | |
58 | if (!getcpu_plugin_handle) { | |
59 | PERROR("Cannot load LTTng UST getcpu override library %s", | |
60 | libname); | |
61 | return; | |
62 | } | |
63 | dlerror(); | |
64 | ||
65 | /* Locate the getcpu plugin init function in the shared object. */ | |
66 | getcpu_plugin_init = (void (*)(void)) dlsym(getcpu_plugin_handle, | |
67 | "lttng_ust_getcpu_plugin_init"); | |
68 | if (!getcpu_plugin_init) { | |
69 | PERROR("Cannot find LTTng UST getcpu override library %s initialization function lttng_ust_getcpu_plugin_init()", | |
70 | libname); | |
71 | return; | |
72 | } | |
73 | ||
74 | /* Run the user provided getcpu plugin init function. */ | |
75 | getcpu_plugin_init(); | |
76 | } |