X-Git-Url: http://git.lttng.org/?a=blobdiff_plain;f=include%2Flttng%2Ftracepoint.h;h=a91faa42c475bc0c34a16fcc5f65eb22bb401f7b;hb=a60af3a5ee5d990c867ef190acfa81c180301ea2;hp=ed20594497ab65bab366b594bb965e740d3e9b29;hpb=664ccf245fcb343e1ea10e145bab3749423e9d0f;p=lttng-ust.git diff --git a/include/lttng/tracepoint.h b/include/lttng/tracepoint.h index ed205944..a91faa42 100644 --- a/include/lttng/tracepoint.h +++ b/include/lttng/tracepoint.h @@ -218,31 +218,13 @@ struct lttng_ust_tracepoint_dlopen { 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); -#ifndef _LGPL_SOURCE void (*rcu_read_lock_sym_bp)(void); void (*rcu_read_unlock_sym_bp)(void); void *(*rcu_dereference_sym_bp)(void *p); -#endif }; extern struct lttng_ust_tracepoint_dlopen tracepoint_dlopen; - -/* Disable tracepoint destructors. */ -int __tracepoints__disable_destructors __attribute__((weak)); - -/* - * Programs that have threads that survive after they exit, and - * therefore call library destructors, should disable the tracepoint - * destructors by calling tracepoint_disable_destructors(). This will - * leak the tracepoint instrumentation library shared object, leaving - * its teardown to the operating system process teardown. - */ -static inline void tracepoint_disable_destructors(void) -{ - __tracepoints__disable_destructors = 1; -} - -#if defined(TRACEPOINT_DEFINE) || defined(TRACEPOINT_CREATE_PROBES) +extern struct lttng_ust_tracepoint_dlopen *tracepoint_dlopen_ptr; /* * These weak symbols, the constructor, and destructor take care of @@ -255,6 +237,49 @@ 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 { + int *old_tracepoint_disable_destructors; + 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(); + *tracepoint_destructors_syms_ptr->old_tracepoint_disable_destructors = 1; +} #ifndef _LGPL_SOURCE static inline void lttng_ust_notrace @@ -262,24 +287,26 @@ __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.rcu_read_lock_sym_bp) - tracepoint_dlopen.rcu_read_lock_sym_bp = + if (!tracepoint_dlopen_ptr->rcu_read_lock_sym_bp) + tracepoint_dlopen_ptr->rcu_read_lock_sym_bp = URCU_FORCE_CAST(void (*)(void), - dlsym(tracepoint_dlopen.liblttngust_handle, + dlsym(tracepoint_dlopen_ptr->liblttngust_handle, "tp_rcu_read_lock_bp")); - if (!tracepoint_dlopen.rcu_read_unlock_sym_bp) - tracepoint_dlopen.rcu_read_unlock_sym_bp = + if (!tracepoint_dlopen_ptr->rcu_read_unlock_sym_bp) + tracepoint_dlopen_ptr->rcu_read_unlock_sym_bp = URCU_FORCE_CAST(void (*)(void), - dlsym(tracepoint_dlopen.liblttngust_handle, + dlsym(tracepoint_dlopen_ptr->liblttngust_handle, "tp_rcu_read_unlock_bp")); - if (!tracepoint_dlopen.rcu_dereference_sym_bp) - tracepoint_dlopen.rcu_dereference_sym_bp = + if (!tracepoint_dlopen_ptr->rcu_dereference_sym_bp) + tracepoint_dlopen_ptr->rcu_dereference_sym_bp = URCU_FORCE_CAST(void *(*)(void *p), - dlsym(tracepoint_dlopen.liblttngust_handle, + dlsym(tracepoint_dlopen_ptr->liblttngust_handle, "tp_rcu_dereference_sym_bp")); } #else @@ -296,13 +323,19 @@ __tracepoints__init(void); static void __tracepoints__init(void) { - if (__tracepoint_registered++) + if (__tracepoint_registered++) { + if (!tracepoint_dlopen_ptr->liblttngust_handle) + return; + __tracepoint__init_urcu_sym(); return; + } - if (!tracepoint_dlopen.liblttngust_handle) - tracepoint_dlopen.liblttngust_handle = + 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.0", RTLD_NOW | RTLD_GLOBAL); - if (!tracepoint_dlopen.liblttngust_handle) + if (!tracepoint_dlopen_ptr->liblttngust_handle) return; __tracepoint__init_urcu_sym(); } @@ -316,19 +349,46 @@ __tracepoints__destroy(void) if (--__tracepoint_registered) return; - if (!__tracepoints__disable_destructors - && tracepoint_dlopen.liblttngust_handle - && !__tracepoint_ptrs_registered) { - ret = dlclose(tracepoint_dlopen.liblttngust_handle); - if (ret) { - fprintf(stderr, "Error (%d) in dlclose\n", ret); - abort(); - } - memset(&tracepoint_dlopen, 0, sizeof(tracepoint_dlopen)); + 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; + } + /* + * Lookup if destructors must be executed using the old method. + */ + if (tracepoint_destructors_syms_ptr->old_tracepoint_disable_destructors + && *tracepoint_destructors_syms_ptr->old_tracepoint_disable_destructors) { + /* + * The old_tracepoint_disable_destructors symbol was found with + * dlsym but its value is 1 meaning that destructors must not + * be executed. + */ + return; } -} -#endif + 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)); +} #ifdef TRACEPOINT_DEFINE @@ -391,22 +451,38 @@ __tracepoints__ptrs_init(void) { if (__tracepoint_ptrs_registered++) return; - if (!tracepoint_dlopen.liblttngust_handle) - tracepoint_dlopen.liblttngust_handle = + 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.0", RTLD_NOW | RTLD_GLOBAL); - if (!tracepoint_dlopen.liblttngust_handle) + if (!tracepoint_dlopen_ptr->liblttngust_handle) return; - tracepoint_dlopen.tracepoint_register_lib = + if (!tracepoint_destructors_syms_ptr) + tracepoint_destructors_syms_ptr = &tracepoint_destructors_syms; + tracepoint_dlopen_ptr->tracepoint_register_lib = URCU_FORCE_CAST(int (*)(struct lttng_ust_tracepoint * const *, int), - dlsym(tracepoint_dlopen.liblttngust_handle, + dlsym(tracepoint_dlopen_ptr->liblttngust_handle, "tracepoint_register_lib")); - tracepoint_dlopen.tracepoint_unregister_lib = + tracepoint_dlopen_ptr->tracepoint_unregister_lib = URCU_FORCE_CAST(int (*)(struct lttng_ust_tracepoint * const *), - dlsym(tracepoint_dlopen.liblttngust_handle, + dlsym(tracepoint_dlopen_ptr->liblttngust_handle, "tracepoint_unregister_lib")); + tracepoint_destructors_syms_ptr->old_tracepoint_disable_destructors = + URCU_FORCE_CAST(int *, + dlsym(tracepoint_dlopen_ptr->liblttngust_handle, + "__tracepoints__disable_destructors")); + tracepoint_destructors_syms_ptr->tracepoint_disable_destructors = + URCU_FORCE_CAST(void (*)(void), + dlsym(tracepoint_dlopen_ptr->liblttngust_handle, + "tp_disable_destructors")); + tracepoint_destructors_syms_ptr->tracepoint_get_destructors_state = + URCU_FORCE_CAST(int (*)(void), + dlsym(tracepoint_dlopen_ptr->liblttngust_handle, + "tp_get_destructors_state")); __tracepoint__init_urcu_sym(); - if (tracepoint_dlopen.tracepoint_register_lib) { - tracepoint_dlopen.tracepoint_register_lib(__start___tracepoints_ptrs, + if (tracepoint_dlopen_ptr->tracepoint_register_lib) { + tracepoint_dlopen_ptr->tracepoint_register_lib(__start___tracepoints_ptrs, __stop___tracepoints_ptrs - __start___tracepoints_ptrs); } @@ -421,17 +497,22 @@ __tracepoints__ptrs_destroy(void) if (--__tracepoint_ptrs_registered) return; - if (tracepoint_dlopen.tracepoint_unregister_lib) - tracepoint_dlopen.tracepoint_unregister_lib(__start___tracepoints_ptrs); - if (!__tracepoints__disable_destructors - && tracepoint_dlopen.liblttngust_handle + 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->tracepoint_unregister_lib) + tracepoint_dlopen_ptr->tracepoint_unregister_lib(__start___tracepoints_ptrs); + if (tracepoint_dlopen_ptr->liblttngust_handle + && tracepoint_destructors_syms_ptr->tracepoint_get_destructors_state + && tracepoint_destructors_syms_ptr->tracepoint_get_destructors_state() && !__tracepoint_ptrs_registered) { - ret = dlclose(tracepoint_dlopen.liblttngust_handle); + ret = dlclose(tracepoint_dlopen_ptr->liblttngust_handle); if (ret) { fprintf(stderr, "Error (%d) in dlclose\n", ret); abort(); } - memset(&tracepoint_dlopen, 0, sizeof(tracepoint_dlopen)); + memset(tracepoint_dlopen_ptr, 0, sizeof(*tracepoint_dlopen_ptr)); } } @@ -499,7 +580,7 @@ __tracepoints__ptrs_destroy(void) * How to use the TRACEPOINT_EVENT macro: * * An example: - * + * * TRACEPOINT_EVENT(someproject_component, event_name, * * * TP_ARGS takes from 0 to 10 "type, field_name" pairs * @@ -510,23 +591,23 @@ __tracepoints__ptrs_destroy(void) * * TP_FIELDS describes the event payload layout in the trace * * * TP_FIELDS( - * * Integer, printed in base 10 * + * * Integer, printed in base 10 * * ctf_integer(int, field_a, arg0) * - * * Integer, printed with 0x base 16 * + * * Integer, printed with 0x base 16 * * ctf_integer_hex(unsigned long, field_d, arg1) * * * Enumeration * * ctf_enum(someproject_component, enum_name, int, field_e, arg0) * - * * Array Sequence, printed as UTF8-encoded array of bytes * + * * Array Sequence, printed as UTF8-encoded array of bytes * * ctf_array_text(char, field_b, string, FIXED_LEN) * ctf_sequence_text(char, field_c, string, size_t, strlen) * - * * String, printed as UTF8-encoded string * + * * String, printed as UTF8-encoded string * * ctf_string(field_e, string) * - * * Array sequence of signed integer values * + * * Array sequence of signed integer values * * ctf_array(long, field_f, arg4, FIXED_LEN4) * ctf_sequence(long, field_g, arg4, size_t, arg4_len) * )