+extern int __tracepoint_probe_register(const char *name, void (*func)(void),
+ void *data, const char *signature);
+extern int __tracepoint_probe_unregister(const char *name, void (*func)(void),
+ void *data);
+
+/*
+ * tracepoint dynamic linkage handling (callbacks). Hidden visibility:
+ * shared across objects in a module/main executable.
+ */
+struct lttng_ust_tracepoint_dlopen {
+ void *liblttngust_handle;
+
+ int (*tracepoint_register_lib)(struct lttng_ust_tracepoint * const *tracepoints_start,
+ int tracepoints_count);
+ int (*tracepoint_unregister_lib)(struct lttng_ust_tracepoint * const *tracepoints_start);
+ void (*rcu_read_lock_sym)(void);
+ void (*rcu_read_unlock_sym)(void);
+ void *(*rcu_dereference_sym)(void *p);
+};
+
+extern struct lttng_ust_tracepoint_dlopen tracepoint_dlopen;
+extern struct lttng_ust_tracepoint_dlopen *tracepoint_dlopen_ptr;
+
+/*
+ * These weak symbols, the constructor, and destructor take care of
+ * registering only _one_ instance of the tracepoints per shared-ojbect
+ * (or for the whole main program).
+ */
+int __tracepoint_registered
+ __attribute__((weak, visibility("hidden")));
+int __tracepoint_ptrs_registered
+ __attribute__((weak, visibility("hidden")));
+struct lttng_ust_tracepoint_dlopen tracepoint_dlopen
+ __attribute__((weak, visibility("hidden")));
+/*
+ * Deal with gcc O1 optimisation issues with weak hidden symbols. gcc
+ * 4.8 and prior does not have the same behavior for symbol scoping on
+ * 32-bit powerpc depending on the object size: symbols for objects of 8
+ * bytes or less have the same address throughout a module, whereas they
+ * have different addresses between compile units for objects larger
+ * than 8 bytes. Add this pointer indirection to ensure that the symbol
+ * scoping match that of the other weak hidden symbols found in this
+ * header.
+ */
+struct lttng_ust_tracepoint_dlopen *tracepoint_dlopen_ptr
+ __attribute__((weak, visibility("hidden")));
+
+/*
+ * Tracepoint dynamic linkage handling (callbacks). Hidden visibility: shared
+ * across objects in a module/main executable. The callbacks are used to
+ * control and check if the destructors should be executed.
+ */
+struct lttng_ust_tracepoint_destructors_syms {
+ void (*tracepoint_disable_destructors)(void);
+ int (*tracepoint_get_destructors_state)(void);
+};
+
+extern struct lttng_ust_tracepoint_destructors_syms tracepoint_destructors_syms;
+extern struct lttng_ust_tracepoint_destructors_syms *tracepoint_destructors_syms_ptr;
+
+struct lttng_ust_tracepoint_destructors_syms tracepoint_destructors_syms
+ __attribute__((weak, visibility("hidden")));
+struct lttng_ust_tracepoint_destructors_syms *tracepoint_destructors_syms_ptr
+ __attribute__((weak, visibility("hidden")));
+
+static inline void tracepoint_disable_destructors(void)
+{
+ if (!tracepoint_dlopen_ptr)
+ tracepoint_dlopen_ptr = &tracepoint_dlopen;
+ if (!tracepoint_destructors_syms_ptr)
+ tracepoint_destructors_syms_ptr = &tracepoint_destructors_syms;
+ if (tracepoint_dlopen_ptr->liblttngust_handle
+ && tracepoint_destructors_syms_ptr->tracepoint_disable_destructors)
+ tracepoint_destructors_syms_ptr->tracepoint_disable_destructors();
+}
+
+#ifndef _LGPL_SOURCE
+static inline void lttng_ust_notrace
+__tracepoint__init_urcu_sym(void);
+static inline void
+__tracepoint__init_urcu_sym(void)
+{
+ if (!tracepoint_dlopen_ptr)
+ tracepoint_dlopen_ptr = &tracepoint_dlopen;
+ /*
+ * Symbols below are needed by tracepoint call sites and probe
+ * providers.
+ */
+ if (!tracepoint_dlopen_ptr->rcu_read_lock_sym)
+ tracepoint_dlopen_ptr->rcu_read_lock_sym =
+ URCU_FORCE_CAST(void (*)(void),
+ dlsym(tracepoint_dlopen_ptr->liblttngust_handle,
+ "tp_rcu_read_lock"));
+ if (!tracepoint_dlopen_ptr->rcu_read_unlock_sym)
+ tracepoint_dlopen_ptr->rcu_read_unlock_sym =
+ URCU_FORCE_CAST(void (*)(void),
+ dlsym(tracepoint_dlopen_ptr->liblttngust_handle,
+ "tp_rcu_read_unlock"));
+ if (!tracepoint_dlopen_ptr->rcu_dereference_sym)
+ tracepoint_dlopen_ptr->rcu_dereference_sym =
+ URCU_FORCE_CAST(void *(*)(void *p),
+ dlsym(tracepoint_dlopen_ptr->liblttngust_handle,
+ "tp_rcu_dereference_sym"));
+}
+#else
+static inline void lttng_ust_notrace
+__tracepoint__init_urcu_sym(void);
+static inline void
+__tracepoint__init_urcu_sym(void)
+{
+}
+#endif
+
+static void lttng_ust_notrace __attribute__((constructor))
+__tracepoints__init(void);
+static void
+__tracepoints__init(void)
+{
+ if (__tracepoint_registered++) {
+ if (!tracepoint_dlopen_ptr->liblttngust_handle)
+ return;
+ __tracepoint__init_urcu_sym();
+ return;
+ }
+
+ if (!tracepoint_dlopen_ptr)
+ tracepoint_dlopen_ptr = &tracepoint_dlopen;
+ if (!tracepoint_dlopen_ptr->liblttngust_handle)
+ tracepoint_dlopen_ptr->liblttngust_handle =
+ dlopen("liblttng-ust-tracepoint.so.1", RTLD_NOW | RTLD_GLOBAL);
+ if (!tracepoint_dlopen_ptr->liblttngust_handle)
+ return;
+ __tracepoint__init_urcu_sym();
+}
+
+static void lttng_ust_notrace __attribute__((destructor))
+__tracepoints__destroy(void);
+static void
+__tracepoints__destroy(void)
+{
+ int ret;
+
+ if (--__tracepoint_registered)
+ return;
+ if (!tracepoint_dlopen_ptr)
+ tracepoint_dlopen_ptr = &tracepoint_dlopen;
+ if (!tracepoint_destructors_syms_ptr)
+ tracepoint_destructors_syms_ptr = &tracepoint_destructors_syms;
+ if (!tracepoint_dlopen_ptr->liblttngust_handle)
+ return;
+ if (__tracepoint_ptrs_registered)
+ return;
+ /*
+ * Lookup if destructors must be executed using the new method.
+ */
+ if (tracepoint_destructors_syms_ptr->tracepoint_get_destructors_state
+ && !tracepoint_destructors_syms_ptr->tracepoint_get_destructors_state()) {
+ /*
+ * The tracepoint_get_destructors_state symbol was found with
+ * dlsym but its returned value is 0 meaning that destructors
+ * must not be executed.
+ */
+ return;
+ }
+ ret = dlclose(tracepoint_dlopen_ptr->liblttngust_handle);
+ if (ret) {
+ fprintf(stderr, "Error (%d) in dlclose\n", ret);
+ abort();
+ }
+ memset(tracepoint_dlopen_ptr, 0, sizeof(*tracepoint_dlopen_ptr));
+}