diff --git a/libcutils/include/cutils/trace.h b/libcutils/include/cutils/trace.h index 79b4b355b..e12c32cff 100644 --- a/libcutils/include/cutils/trace.h +++ b/libcutils/include/cutils/trace.h @@ -25,7 +25,6 @@ #include #include #include - #include __BEGIN_DECLS @@ -89,6 +88,12 @@ __BEGIN_DECLS #error ATRACE_TAG must be defined to be one of the tags defined in cutils/trace.h #endif +// Set this to 0 to revert to the old Binder-based atrace implementation. +// This is only here in case rollbacks do not apply cleanly. +// TODO(fmayer): Remove this once we are confident this won't need to be +// rolled back, no later than 2020-03-01. +#define ATRACE_SHMEM 1 + /** * Opens the trace file for writing and reads the property for initial tags. * The atrace.tags.enableflags property sets the tags to trace. @@ -116,11 +121,15 @@ void atrace_set_debuggable(bool debuggable); * prevent tracing within the Zygote process. */ void atrace_set_tracing_enabled(bool enabled); - /** - * Flag indicating whether setup has been completed, initialized to 0. - * Nonzero indicates setup has completed. - * Note: This does NOT indicate whether or not setup was successful. + * If !ATRACE_SHMEM: + * Flag indicating whether setup has been completed, initialized to 0. + * Nonzero indicates setup has completed. + * Note: This does NOT indicate whether or not setup was successful. + * If ATRACE_SHMEM: + * This is always set to false. This forces code that uses an old version + * of this header to always call into atrace_setup, in which we call + * atrace_init unconditionally. */ extern atomic_bool atrace_is_ready; @@ -143,6 +152,12 @@ extern int atrace_marker_fd; * This can be explicitly run to avoid setup delay on first trace function. */ #define ATRACE_INIT() atrace_init() +#define ATRACE_GET_ENABLED_TAGS() atrace_get_enabled_tags() + +#if ATRACE_SHMEM +void atrace_init(); +uint64_t atrace_get_enabled_tags(); +#else static inline void atrace_init() { if (CC_UNLIKELY(!atomic_load_explicit(&atrace_is_ready, memory_order_acquire))) { @@ -155,12 +170,12 @@ static inline void atrace_init() * It can be used as a guard condition around more expensive trace calculations. * Every trace function calls this, which ensures atrace_init is run. */ -#define ATRACE_GET_ENABLED_TAGS() atrace_get_enabled_tags() static inline uint64_t atrace_get_enabled_tags() { atrace_init(); return atrace_enabled_tags; } +#endif /** * Test if a given tag is currently enabled. diff --git a/libcutils/trace-container.cpp b/libcutils/trace-container.cpp index d981f8fa5..c23d5e2bd 100644 --- a/libcutils/trace-container.cpp +++ b/libcutils/trace-container.cpp @@ -39,6 +39,11 @@ static int atrace_container_sock_fd = -1; static pthread_mutex_t atrace_enabling_mutex = PTHREAD_MUTEX_INITIALIZER; static pthread_rwlock_t atrace_container_sock_rwlock = PTHREAD_RWLOCK_INITIALIZER; +static void atrace_seq_number_changed(uint32_t, uint32_t seq_no) { + pthread_once(&atrace_once_control, atrace_init_once); + atomic_store_explicit(&last_sequence_number, seq_no, memory_order_relaxed); +} + static bool atrace_init_container_sock() { pthread_rwlock_wrlock(&atrace_container_sock_rwlock); diff --git a/libcutils/trace-dev.cpp b/libcutils/trace-dev.cpp index bff16c174..2ee39d328 100644 --- a/libcutils/trace-dev.cpp +++ b/libcutils/trace-dev.cpp @@ -37,12 +37,39 @@ static void atrace_init_once() } else { atrace_enabled_tags = atrace_get_property(); } +#if !ATRACE_SHMEM atomic_store_explicit(&atrace_is_ready, true, memory_order_release); +#endif +} + +static void atrace_seq_number_changed(uint32_t prev_seq_no, uint32_t seq_no) { + if (!atomic_load_explicit(&atrace_is_enabled, memory_order_acquire)) { + return; + } + + // Someone raced us. + if (!atomic_compare_exchange_strong(&last_sequence_number, &prev_seq_no, seq_no)) { + return; + } + + if (CC_UNLIKELY(prev_seq_no == kSeqNoNotInit)) { +#if defined(__BIONIC__) + const prop_info* new_pi = __system_property_find("debug.atrace.tags.enableflags"); + if (new_pi) atrace_property_info = new_pi; +#endif + pthread_once(&atrace_once_control, atrace_init_once); + } + + atrace_update_tags(); } void atrace_setup() { +#if ATRACE_SHMEM + atrace_init(); +#else pthread_once(&atrace_once_control, atrace_init_once); +#endif } void atrace_begin_body(const char* name) diff --git a/libcutils/trace-dev.inc b/libcutils/trace-dev.inc index e3da77bec..a57a4c59e 100644 --- a/libcutils/trace-dev.inc +++ b/libcutils/trace-dev.inc @@ -34,6 +34,11 @@ #include #include +#if defined(__BIONIC__) +#define _REALLY_INCLUDE_SYS__SYSTEM_PROPERTIES_H_ +#include +#endif + /** * Maximum size of a message that can be logged to the trace buffer. * Note this message includes a tag, the pid, and the string given as the name. @@ -41,12 +46,57 @@ */ #define ATRACE_MESSAGE_LENGTH 1024 -atomic_bool atrace_is_ready = ATOMIC_VAR_INIT(false); -int atrace_marker_fd = -1; -uint64_t atrace_enabled_tags = ATRACE_TAG_NOT_READY; -static bool atrace_is_debuggable = false; -static atomic_bool atrace_is_enabled = ATOMIC_VAR_INIT(true); -static pthread_mutex_t atrace_tags_mutex = PTHREAD_MUTEX_INITIALIZER; +constexpr uint32_t kSeqNoNotInit = static_cast(-1); + +atomic_bool atrace_is_ready = ATOMIC_VAR_INIT(false); +int atrace_marker_fd = -1; +uint64_t atrace_enabled_tags = ATRACE_TAG_NOT_READY; +static bool atrace_is_debuggable = false; +static atomic_bool atrace_is_enabled = ATOMIC_VAR_INIT(true); +static pthread_mutex_t atrace_tags_mutex = PTHREAD_MUTEX_INITIALIZER; + +/** + * Sequence number of debug.atrace.tags.enableflags the last time the enabled + * tags were reloaded. + **/ +static _Atomic(uint32_t) last_sequence_number = ATOMIC_VAR_INIT(kSeqNoNotInit); + +#if defined(__BIONIC__) +// All zero prop_info that has a sequence number of 0. This is easier than +// depending on implementation details of the property implementation. +// +// prop_info is static_assert-ed to be 96 bytes, which cannot change due to +// ABI compatibility. +alignas(uint64_t) static char empty_pi[96]; +static const prop_info* atrace_property_info = reinterpret_cast(empty_pi); +#endif + +#if ATRACE_SHMEM + +/** + * This is called when the sequence number of debug.atrace.tags.enableflags + * changes and we need to reload the enabled tags. + **/ +static void atrace_seq_number_changed(uint32_t prev_seq_no, uint32_t seq_no); + +void atrace_init() { +#if defined(__BIONIC__) + uint32_t seq_no = __system_property_serial(atrace_property_info); // Acquire semantics. +#else + uint32_t seq_no = 0; +#endif + uint32_t prev_seq_no = atomic_load_explicit(&last_sequence_number, memory_order_relaxed); + if (CC_UNLIKELY(seq_no != prev_seq_no)) { + atrace_seq_number_changed(prev_seq_no, seq_no); + } +} + +uint64_t atrace_get_enabled_tags() +{ + atrace_init(); + return atrace_enabled_tags; +} +#endif // Set whether this process is debuggable, which determines whether // application-level tracing is allowed when the ro.debuggable system property @@ -136,7 +186,7 @@ static uint64_t atrace_get_property() void atrace_update_tags() { uint64_t tags; - if (CC_UNLIKELY(atomic_load_explicit(&atrace_is_ready, memory_order_acquire))) { + if (ATRACE_SHMEM || CC_UNLIKELY(atomic_load_explicit(&atrace_is_ready, memory_order_acquire))) { if (atomic_load_explicit(&atrace_is_enabled, memory_order_acquire)) { tags = atrace_get_property(); pthread_mutex_lock(&atrace_tags_mutex); diff --git a/libcutils/trace-host.cpp b/libcutils/trace-host.cpp index d47cc1861..c21d0ee5e 100644 --- a/libcutils/trace-host.cpp +++ b/libcutils/trace-host.cpp @@ -30,3 +30,10 @@ void atrace_async_begin_body(const char* /*name*/, int32_t /*cookie*/) {} void atrace_async_end_body(const char* /*name*/, int32_t /*cookie*/) {} void atrace_int_body(const char* /*name*/, int32_t /*value*/) {} void atrace_int64_body(const char* /*name*/, int64_t /*value*/) {} +#if ATRACE_SHMEM +void atrace_init() {} +uint64_t atrace_get_enabled_tags() +{ + return ATRACE_TAG_NOT_READY; +} +#endif