diff options
Diffstat (limited to 'compiler-rt/lib/xray/xray_fdr_logging.cc')
| -rw-r--r-- | compiler-rt/lib/xray/xray_fdr_logging.cc | 349 |
1 files changed, 7 insertions, 342 deletions
diff --git a/compiler-rt/lib/xray/xray_fdr_logging.cc b/compiler-rt/lib/xray/xray_fdr_logging.cc index bae7d4c4d07..0a1fb19f0e3 100644 --- a/compiler-rt/lib/xray/xray_fdr_logging.cc +++ b/compiler-rt/lib/xray/xray_fdr_logging.cc @@ -7,7 +7,7 @@ // //===----------------------------------------------------------------------===// // -// This file is a part of XRay, a dynamic runtime instruementation system. +// This file is a part of XRay, a dynamic runtime instrumentation system. // // Here we implement the Flight Data Recorder mode for XRay, where we use // compact structures to store records in memory as well as when writing out the @@ -31,6 +31,7 @@ #include "xray/xray_records.h" #include "xray_buffer_queue.h" #include "xray_defs.h" +#include "xray_fdr_logging_impl.h" #include "xray_flags.h" #include "xray_tsc.h" #include "xray_utils.h" @@ -49,8 +50,8 @@ std::atomic<XRayLogFlushStatus> LogFlushStatus{ std::unique_ptr<FDRLoggingOptions> FDROptions; XRayLogInitStatus fdrLoggingInit(std::size_t BufferSize, std::size_t BufferMax, - void *Options, - size_t OptionsSize) XRAY_NEVER_INSTRUMENT { + void *Options, + size_t OptionsSize) XRAY_NEVER_INSTRUMENT { assert(OptionsSize == sizeof(FDRLoggingOptions)); XRayLogInitStatus CurrentStatus = XRayLogInitStatus::XRAY_LOG_UNINITIALIZED; if (!LoggingStatus.compare_exchange_strong( @@ -174,352 +175,16 @@ XRayLogInitStatus fdrLoggingReset() XRAY_NEVER_INSTRUMENT { return XRayLogInitStatus::XRAY_LOG_UNINITIALIZED; } -namespace { -thread_local BufferQueue::Buffer Buffer; -thread_local char *RecordPtr = nullptr; - -void setupNewBuffer(const BufferQueue::Buffer &Buffer) XRAY_NEVER_INSTRUMENT { - RecordPtr = static_cast<char *>(Buffer.Buffer); - - static constexpr int InitRecordsCount = 2; - std::aligned_storage<sizeof(MetadataRecord)>::type Records[InitRecordsCount]; - { - // Write out a MetadataRecord to signify that this is the start of a new - // buffer, associated with a particular thread, with a new CPU. For the - // data, we have 15 bytes to squeeze as much information as we can. At this - // point we only write down the following bytes: - // - Thread ID (pid_t, 4 bytes) - auto &NewBuffer = *reinterpret_cast<MetadataRecord *>(&Records[0]); - NewBuffer.Type = uint8_t(RecordType::Metadata); - NewBuffer.RecordKind = uint8_t(MetadataRecord::RecordKinds::NewBuffer); - pid_t Tid = syscall(SYS_gettid); - std::memcpy(&NewBuffer.Data, &Tid, sizeof(pid_t)); - } - - // Also write the WalltimeMarker record. - { - static_assert(sizeof(time_t) <= 8, "time_t needs to be at most 8 bytes"); - auto &WalltimeMarker = *reinterpret_cast<MetadataRecord *>(&Records[1]); - WalltimeMarker.Type = uint8_t(RecordType::Metadata); - WalltimeMarker.RecordKind = - uint8_t(MetadataRecord::RecordKinds::WalltimeMarker); - timespec TS{0, 0}; - clock_gettime(CLOCK_MONOTONIC, &TS); - - // We only really need microsecond precision here, and enforce across - // platforms that we need 64-bit seconds and 32-bit microseconds encoded in - // the Metadata record. - int32_t Micros = TS.tv_nsec / 1000; - int64_t Seconds = TS.tv_sec; - std::memcpy(WalltimeMarker.Data, &Seconds, sizeof(Seconds)); - std::memcpy(WalltimeMarker.Data + sizeof(Seconds), &Micros, sizeof(Micros)); - } - std::memcpy(RecordPtr, Records, sizeof(MetadataRecord) * InitRecordsCount); - RecordPtr += sizeof(MetadataRecord) * InitRecordsCount; -} - -void writeNewCPUIdMetadata(uint16_t CPU, uint64_t TSC) XRAY_NEVER_INSTRUMENT { - MetadataRecord NewCPUId; - NewCPUId.Type = uint8_t(RecordType::Metadata); - NewCPUId.RecordKind = uint8_t(MetadataRecord::RecordKinds::NewCPUId); - - // The data for the New CPU will contain the following bytes: - // - CPU ID (uint16_t, 2 bytes) - // - Full TSC (uint64_t, 8 bytes) - // Total = 12 bytes. - std::memcpy(&NewCPUId.Data, &CPU, sizeof(CPU)); - std::memcpy(&NewCPUId.Data[sizeof(CPU)], &TSC, sizeof(TSC)); - std::memcpy(RecordPtr, &NewCPUId, sizeof(MetadataRecord)); - RecordPtr += sizeof(MetadataRecord); -} - -void writeEOBMetadata() XRAY_NEVER_INSTRUMENT { - MetadataRecord EOBMeta; - EOBMeta.Type = uint8_t(RecordType::Metadata); - EOBMeta.RecordKind = uint8_t(MetadataRecord::RecordKinds::EndOfBuffer); - // For now we don't write any bytes into the Data field. - std::memcpy(RecordPtr, &EOBMeta, sizeof(MetadataRecord)); - RecordPtr += sizeof(MetadataRecord); -} - -void writeTSCWrapMetadata(uint64_t TSC) XRAY_NEVER_INSTRUMENT { - MetadataRecord TSCWrap; - TSCWrap.Type = uint8_t(RecordType::Metadata); - TSCWrap.RecordKind = uint8_t(MetadataRecord::RecordKinds::TSCWrap); - - // The data for the TSCWrap record contains the following bytes: - // - Full TSC (uint64_t, 8 bytes) - // Total = 8 bytes. - std::memcpy(&TSCWrap.Data, &TSC, sizeof(TSC)); - std::memcpy(RecordPtr, &TSCWrap, sizeof(MetadataRecord)); - RecordPtr += sizeof(MetadataRecord); -} - -constexpr auto MetadataRecSize = sizeof(MetadataRecord); -constexpr auto FunctionRecSize = sizeof(FunctionRecord); - -class ThreadExitBufferCleanup { - std::weak_ptr<BufferQueue> Buffers; - BufferQueue::Buffer &Buffer; - -public: - explicit ThreadExitBufferCleanup(std::weak_ptr<BufferQueue> BQ, - BufferQueue::Buffer &Buffer) - XRAY_NEVER_INSTRUMENT : Buffers(BQ), - Buffer(Buffer) {} - - ~ThreadExitBufferCleanup() noexcept XRAY_NEVER_INSTRUMENT { - if (RecordPtr == nullptr) - return; - - // We make sure that upon exit, a thread will write out the EOB - // MetadataRecord in the thread-local log, and also release the buffer to - // the queue. - assert((RecordPtr + MetadataRecSize) - static_cast<char *>(Buffer.Buffer) >= - static_cast<ptrdiff_t>(MetadataRecSize)); - if (auto BQ = Buffers.lock()) { - writeEOBMetadata(); - if (auto EC = BQ->releaseBuffer(Buffer)) - Report("Failed to release buffer at %p; error=%s\n", Buffer.Buffer, - EC.message().c_str()); - return; - } - } -}; - -class RecursionGuard { - bool &Running; - const bool Valid; - -public: - explicit RecursionGuard(bool &R) : Running(R), Valid(!R) { - if (Valid) - Running = true; - } - - RecursionGuard(const RecursionGuard &) = delete; - RecursionGuard(RecursionGuard &&) = delete; - RecursionGuard &operator=(const RecursionGuard &) = delete; - RecursionGuard &operator=(RecursionGuard &&) = delete; - - explicit operator bool() const { return Valid; } - - ~RecursionGuard() noexcept { - if (Valid) - Running = false; - } -}; - -inline bool loggingInitialized() { - return LoggingStatus.load(std::memory_order_acquire) == - XRayLogInitStatus::XRAY_LOG_INITIALIZED; -} - -} // namespace - void fdrLoggingHandleArg0(int32_t FuncId, - XRayEntryType Entry) XRAY_NEVER_INSTRUMENT { + XRayEntryType Entry) XRAY_NEVER_INSTRUMENT { // We want to get the TSC as early as possible, so that we can check whether // we've seen this CPU before. We also do it before we load anything else, to // allow for forward progress with the scheduling. unsigned char CPU; uint64_t TSC = __xray::readTSC(CPU); - // Bail out right away if logging is not initialized yet. - if (LoggingStatus.load(std::memory_order_acquire) != - XRayLogInitStatus::XRAY_LOG_INITIALIZED) - return; - - // We use a thread_local variable to keep track of which CPUs we've already - // run, and the TSC times for these CPUs. This allows us to stop repeating the - // CPU field in the function records. - // - // We assume that we'll support only 65536 CPUs for x86_64. - thread_local uint16_t CurrentCPU = std::numeric_limits<uint16_t>::max(); - thread_local uint64_t LastTSC = 0; - - // Make sure a thread that's ever called handleArg0 has a thread-local - // live reference to the buffer queue for this particular instance of - // FDRLogging, and that we're going to clean it up when the thread exits. - thread_local auto LocalBQ = BQ; - thread_local ThreadExitBufferCleanup Cleanup(LocalBQ, Buffer); - - // Prevent signal handler recursion, so in case we're already in a log writing - // mode and the signal handler comes in (and is also instrumented) then we - // don't want to be clobbering potentially partial writes already happening in - // the thread. We use a simple thread_local latch to only allow one on-going - // handleArg0 to happen at any given time. - thread_local bool Running = false; - RecursionGuard Guard{Running}; - if (!Guard) { - assert(Running == true && "RecursionGuard is buggy!"); - return; - } - - if (!loggingInitialized() || LocalBQ->finalizing()) { - writeEOBMetadata(); - if (auto EC = BQ->releaseBuffer(Buffer)) { - Report("Failed to release buffer at %p; error=%s\n", Buffer.Buffer, - EC.message().c_str()); - return; - } - RecordPtr = nullptr; - } - - if (Buffer.Buffer == nullptr) { - if (auto EC = LocalBQ->getBuffer(Buffer)) { - auto LS = LoggingStatus.load(std::memory_order_acquire); - if (LS != XRayLogInitStatus::XRAY_LOG_FINALIZING && - LS != XRayLogInitStatus::XRAY_LOG_FINALIZED) - Report("Failed to acquire a buffer; error=%s\n", EC.message().c_str()); - return; - } - - setupNewBuffer(Buffer); - } - - if (CurrentCPU == std::numeric_limits<uint16_t>::max()) { - // This means this is the first CPU this thread has ever run on. We set the - // current CPU and record this as the first TSC we've seen. - CurrentCPU = CPU; - writeNewCPUIdMetadata(CPU, TSC); - } - - // Before we go setting up writing new function entries, we need to be really - // careful about the pointer math we're doing. This means we need to ensure - // that the record we are about to write is going to fit into the buffer, - // without overflowing the buffer. - // - // To do this properly, we use the following assumptions: - // - // - The least number of bytes we will ever write is 8 - // (sizeof(FunctionRecord)) only if the delta between the previous entry - // and this entry is within 32 bits. - // - The most number of bytes we will ever write is 8 + 16 = 24. This is - // computed by: - // - // sizeof(FunctionRecord) + sizeof(MetadataRecord) - // - // These arise in the following cases: - // - // 1. When the delta between the TSC we get and the previous TSC for the - // same CPU is outside of the uint32_t range, we end up having to - // write a MetadataRecord to indicate a "tsc wrap" before the actual - // FunctionRecord. - // 2. When we learn that we've moved CPUs, we need to write a - // MetadataRecord to indicate a "cpu change", and thus write out the - // current TSC for that CPU before writing out the actual - // FunctionRecord. - // 3. When we learn about a new CPU ID, we need to write down a "new cpu - // id" MetadataRecord before writing out the actual FunctionRecord. - // - // - An End-of-Buffer (EOB) MetadataRecord is 16 bytes. - // - // So the math we need to do is to determine whether writing 24 bytes past the - // current pointer leaves us with enough bytes to write the EOB - // MetadataRecord. If we don't have enough space after writing as much as 24 - // bytes in the end of the buffer, we need to write out the EOB, get a new - // Buffer, set it up properly before doing any further writing. - // - char *BufferStart = static_cast<char *>(Buffer.Buffer); - if ((RecordPtr + (MetadataRecSize + FunctionRecSize)) - BufferStart < - static_cast<ptrdiff_t>(MetadataRecSize)) { - writeEOBMetadata(); - if (auto EC = LocalBQ->releaseBuffer(Buffer)) { - Report("Failed to release buffer at %p; error=%s\n", Buffer.Buffer, - EC.message().c_str()); - return; - } - if (auto EC = LocalBQ->getBuffer(Buffer)) { - Report("Failed to acquire a buffer; error=%s\n", EC.message().c_str()); - return; - } - setupNewBuffer(Buffer); - } - - // By this point, we are now ready to write at most 24 bytes (one metadata - // record and one function record). - BufferStart = static_cast<char *>(Buffer.Buffer); - assert((RecordPtr + (MetadataRecSize + FunctionRecSize)) - BufferStart >= - static_cast<ptrdiff_t>(MetadataRecSize) && - "Misconfigured BufferQueue provided; Buffer size not large enough."); - - std::aligned_storage<sizeof(FunctionRecord), alignof(FunctionRecord)>::type - AlignedFuncRecordBuffer; - auto &FuncRecord = - *reinterpret_cast<FunctionRecord *>(&AlignedFuncRecordBuffer); - FuncRecord.Type = uint8_t(RecordType::Function); - - // Only get the lower 28 bits of the function id. - FuncRecord.FuncId = FuncId & ~(0x0F << 28); - - // Here we compute the TSC Delta. There are a few interesting situations we - // need to account for: - // - // - The thread has migrated to a different CPU. If this is the case, then - // we write down the following records: - // - // 1. A 'NewCPUId' Metadata record. - // 2. A FunctionRecord with a 0 for the TSCDelta field. - // - // - The TSC delta is greater than the 32 bits we can store in a - // FunctionRecord. In this case we write down the following records: - // - // 1. A 'TSCWrap' Metadata record. - // 2. A FunctionRecord with a 0 for the TSCDelta field. - // - // - The TSC delta is representable within the 32 bits we can store in a - // FunctionRecord. In this case we write down just a FunctionRecord with - // the correct TSC delta. - // - FuncRecord.TSCDelta = 0; - if (CPU != CurrentCPU) { - // We've moved to a new CPU. - writeNewCPUIdMetadata(CPU, TSC); - } else { - // If the delta is greater than the range for a uint32_t, then we write out - // the TSC wrap metadata entry with the full TSC, and the TSC for the - // function record be 0. - auto Delta = LastTSC - TSC; - if (Delta > (1ULL << 32) - 1) - writeTSCWrapMetadata(TSC); - else - FuncRecord.TSCDelta = Delta; - } - - // We then update our "LastTSC" and "CurrentCPU" thread-local variables to aid - // us in future computations of this TSC delta value. - LastTSC = TSC; - CurrentCPU = CPU; - - switch (Entry) { - case XRayEntryType::ENTRY: - case XRayEntryType::LOG_ARGS_ENTRY: - FuncRecord.RecordKind = uint8_t(FunctionRecord::RecordKinds::FunctionEnter); - break; - case XRayEntryType::EXIT: - FuncRecord.RecordKind = uint8_t(FunctionRecord::RecordKinds::FunctionExit); - break; - case XRayEntryType::TAIL: - FuncRecord.RecordKind = - uint8_t(FunctionRecord::RecordKinds::FunctionTailExit); - break; - } - - std::memcpy(RecordPtr, &AlignedFuncRecordBuffer, sizeof(FunctionRecord)); - RecordPtr += sizeof(FunctionRecord); - - // If we've exhausted the buffer by this time, we then release the buffer to - // make sure that other threads may start using this buffer. - if ((RecordPtr + MetadataRecSize) - BufferStart == MetadataRecSize) { - writeEOBMetadata(); - if (auto EC = LocalBQ->releaseBuffer(Buffer)) { - Report("Failed releasing buffer at %p; error=%s\n", Buffer.Buffer, - EC.message().c_str()); - return; - } - RecordPtr = nullptr; - } + __xray_fdr_internal::processFunctionHook(FuncId, Entry, TSC, CPU, + clock_gettime, LoggingStatus, BQ); } } // namespace __xray |
