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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 | |
247c2ecd MJ |
8 | #include <dlfcn.h> |
9 | #include <stdlib.h> | |
247c2ecd MJ |
10 | #include <urcu/system.h> |
11 | #include <urcu/arch.h> | |
12 | ||
f73bcf5e | 13 | #include "common/getcpu.h" |
910dcd72 | 14 | #include "common/getenv.h" |
f73bcf5e MJ |
15 | #include "common/logging.h" |
16 | ||
17 | #include "lib/lttng-ust-common/getcpu.h" | |
247c2ecd MJ |
18 | |
19 | /* Function pointer to the current getcpu callback. */ | |
20 | int (*lttng_ust_get_cpu_sym)(void); | |
21 | ||
22 | static | |
23 | void *getcpu_plugin_handle; | |
24 | ||
25 | /* | |
26 | * Override the user provided getcpu implementation. | |
27 | */ | |
28 | int lttng_ust_getcpu_override(int (*getcpu)(void)) | |
29 | { | |
30 | CMM_STORE_SHARED(lttng_ust_get_cpu_sym, getcpu); | |
31 | return 0; | |
32 | } | |
33 | ||
34 | /* | |
35 | * Initialize the getcpu plugin if it's present. | |
36 | */ | |
37 | void lttng_ust_getcpu_plugin_init(void) | |
38 | { | |
39 | const char *libname; | |
40 | void (*getcpu_plugin_init)(void); | |
41 | ||
42 | /* If a plugin is already loaded, do nothing. */ | |
43 | if (getcpu_plugin_handle) | |
44 | return; | |
45 | ||
46 | /* | |
47 | * If the LTTNG_UST_GETCPU_PLUGIN environment variable is undefined, do | |
48 | * nothing. | |
49 | */ | |
50 | libname = lttng_ust_getenv("LTTNG_UST_GETCPU_PLUGIN"); | |
51 | if (!libname) | |
52 | return; | |
53 | ||
54 | /* | |
55 | * Thy to dlopen the getcpu plugin shared object specified in | |
56 | * LTTNG_UST_GETCPU_PLUGIN. | |
57 | */ | |
58 | getcpu_plugin_handle = dlopen(libname, RTLD_NOW); | |
59 | if (!getcpu_plugin_handle) { | |
60 | PERROR("Cannot load LTTng UST getcpu override library %s", | |
61 | libname); | |
62 | return; | |
63 | } | |
64 | dlerror(); | |
65 | ||
66 | /* Locate the getcpu plugin init function in the shared object. */ | |
67 | getcpu_plugin_init = (void (*)(void)) dlsym(getcpu_plugin_handle, | |
68 | "lttng_ust_getcpu_plugin_init"); | |
69 | if (!getcpu_plugin_init) { | |
70 | PERROR("Cannot find LTTng UST getcpu override library %s initialization function lttng_ust_getcpu_plugin_init()", | |
71 | libname); | |
72 | return; | |
73 | } | |
74 | ||
75 | /* Run the user provided getcpu plugin init function. */ | |
76 | getcpu_plugin_init(); | |
77 | } |