1 files changed, 757 insertions, 0 deletions
diff --git a/contrib/llvm-project/compiler-rt/lib/xray/xray_fdr_logging.cpp b/contrib/llvm-project/compiler-rt/lib/xray/xray_fdr_logging.cpp
new file mode 100644
index 000000000000..16ce483502f0
--- /dev/null
+++ b/contrib/llvm-project/compiler-rt/lib/xray/xray_fdr_logging.cpp
@@ -0,0 +1,757 @@
+//===-- xray_fdr_logging.cpp -----------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// 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
+// data to files.
+//
+//===----------------------------------------------------------------------===//
+#include "xray_fdr_logging.h"
+#include <cassert>
+#include <errno.h>
+#include <limits>
+#include <memory>
+#include <pthread.h>
+#include <sys/time.h>
+#include <time.h>
+#include <unistd.h>
+
+#include "sanitizer_common/sanitizer_allocator_internal.h"
+#include "sanitizer_common/sanitizer_atomic.h"
+#include "sanitizer_common/sanitizer_common.h"
+#include "xray/xray_interface.h"
+#include "xray/xray_records.h"
+#include "xray_allocator.h"
+#include "xray_buffer_queue.h"
+#include "xray_defs.h"
+#include "xray_fdr_controller.h"
+#include "xray_fdr_flags.h"
+#include "xray_fdr_log_writer.h"
+#include "xray_flags.h"
+#include "xray_recursion_guard.h"
+#include "xray_tsc.h"
+#include "xray_utils.h"
+
+namespace __xray {
+
+static atomic_sint32_t LoggingStatus = {
+    XRayLogInitStatus::XRAY_LOG_UNINITIALIZED};
+
+namespace {
+
+// Group together thread-local-data in a struct, then hide it behind a function
+// call so that it can be initialized on first use instead of as a global. We
+// force the alignment to 64-bytes for x86 cache line alignment, as this
+// structure is used in the hot path of implementation.
+struct XRAY_TLS_ALIGNAS(64) ThreadLocalData {
+  BufferQueue::Buffer Buffer{};
+  BufferQueue *BQ = nullptr;
+
+  using LogWriterStorage =
+      typename std::aligned_storage<sizeof(FDRLogWriter),
+                                    alignof(FDRLogWriter)>::type;
+
+  LogWriterStorage LWStorage;
+  FDRLogWriter *Writer = nullptr;
+
+  using ControllerStorage =
+      typename std::aligned_storage<sizeof(FDRController<>),
+                                    alignof(FDRController<>)>::type;
+  ControllerStorage CStorage;
+  FDRController<> *Controller = nullptr;
+};
+
+} // namespace
+
+static_assert(std::is_trivially_destructible<ThreadLocalData>::value,
+              "ThreadLocalData must be trivially destructible");
+
+// Use a global pthread key to identify thread-local data for logging.
+static pthread_key_t Key;
+
+// Global BufferQueue.
+static std::aligned_storage<sizeof(BufferQueue)>::type BufferQueueStorage;
+static BufferQueue *BQ = nullptr;
+
+// Global thresholds for function durations.
+static atomic_uint64_t ThresholdTicks{0};
+
+// Global for ticks per second.
+static atomic_uint64_t TicksPerSec{0};
+
+static atomic_sint32_t LogFlushStatus = {
+    XRayLogFlushStatus::XRAY_LOG_NOT_FLUSHING};
+
+// This function will initialize the thread-local data structure used by the FDR
+// logging implementation and return a reference to it. The implementation
+// details require a bit of care to maintain.
+//
+// First, some requirements on the implementation in general:
+//
+//   - XRay handlers should not call any memory allocation routines that may
+//     delegate to an instrumented implementation. This means functions like
+//     malloc() and free() should not be called while instrumenting.
+//
+//   - We would like to use some thread-local data initialized on first-use of
+//     the XRay instrumentation. These allow us to implement unsynchronized
+//     routines that access resources associated with the thread.
+//
+// The implementation here uses a few mechanisms that allow us to provide both
+// the requirements listed above. We do this by:
+//
+//   1. Using a thread-local aligned storage buffer for representing the
+//      ThreadLocalData struct. This data will be uninitialized memory by
+//      design.
+//
+//   2. Not requiring a thread exit handler/implementation, keeping the
+//      thread-local as purely a collection of references/data that do not
+//      require cleanup.
+//
+// We're doing this to avoid using a `thread_local` object that has a
+// non-trivial destructor, because the C++ runtime might call std::malloc(...)
+// to register calls to destructors. Deadlocks may arise when, for example, an
+// externally provided malloc implementation is XRay instrumented, and
+// initializing the thread-locals involves calling into malloc. A malloc
+// implementation that does global synchronization might be holding a lock for a
+// critical section, calling a function that might be XRay instrumented (and
+// thus in turn calling into malloc by virtue of registration of the
+// thread_local's destructor).
+#if XRAY_HAS_TLS_ALIGNAS
+static_assert(alignof(ThreadLocalData) >= 64,
+              "ThreadLocalData must be cache line aligned.");
+#endif
+static ThreadLocalData &getThreadLocalData() {
+  thread_local typename std::aligned_storage<
+      sizeof(ThreadLocalData), alignof(ThreadLocalData)>::type TLDStorage{};
+
+  if (pthread_getspecific(Key) == NULL) {
+    new (reinterpret_cast<ThreadLocalData *>(&TLDStorage)) ThreadLocalData{};
+    pthread_setspecific(Key, &TLDStorage);
+  }
+
+  return *reinterpret_cast<ThreadLocalData *>(&TLDStorage);
+}
+
+static XRayFileHeader &fdrCommonHeaderInfo() {
+  static std::aligned_storage<sizeof(XRayFileHeader)>::type HStorage;
+  static pthread_once_t OnceInit = PTHREAD_ONCE_INIT;
+  static bool TSCSupported = true;
+  static uint64_t CycleFrequency = NanosecondsPerSecond;
+  pthread_once(
+      &OnceInit, +[] {
+        XRayFileHeader &H = reinterpret_cast<XRayFileHeader &>(HStorage);
+        // Version 2 of the log writes the extents of the buffer, instead of
+        // relying on an end-of-buffer record.
+        // Version 3 includes PID metadata record.
+        // Version 4 includes CPU data in the custom event records.
+        // Version 5 uses relative deltas for custom and typed event records,
+        // and removes the CPU data in custom event records (similar to how
+        // function records use deltas instead of full TSCs and rely on other
+        // metadata records for TSC wraparound and CPU migration).
+        H.Version = 5;
+        H.Type = FileTypes::FDR_LOG;
+
+        // Test for required CPU features and cache the cycle frequency
+        TSCSupported = probeRequiredCPUFeatures();
+        if (TSCSupported)
+          CycleFrequency = getTSCFrequency();
+        H.CycleFrequency = CycleFrequency;
+
+        // FIXME: Actually check whether we have 'constant_tsc' and
+        // 'nonstop_tsc' before setting the values in the header.
+        H.ConstantTSC = 1;
+        H.NonstopTSC = 1;
+      });
+  return reinterpret_cast<XRayFileHeader &>(HStorage);
+}
+
+// This is the iterator implementation, which knows how to handle FDR-mode
+// specific buffers. This is used as an implementation of the iterator function
+// needed by __xray_set_buffer_iterator(...). It maintains a global state of the
+// buffer iteration for the currently installed FDR mode buffers. In particular:
+//
+//   - If the argument represents the initial state of XRayBuffer ({nullptr, 0})
+//     then the iterator returns the header information.
+//   - If the argument represents the header information ({address of header
+//     info, size of the header info}) then it returns the first FDR buffer's
+//     address and extents.
+//   - It will keep returning the next buffer and extents as there are more
+//     buffers to process. When the input represents the last buffer, it will
+//     return the initial state to signal completion ({nullptr, 0}).
+//
+// See xray/xray_log_interface.h for more details on the requirements for the
+// implementations of __xray_set_buffer_iterator(...) and
+// __xray_log_process_buffers(...).
+XRayBuffer fdrIterator(const XRayBuffer B) {
+  DCHECK(internal_strcmp(__xray_log_get_current_mode(), "xray-fdr") == 0);
+  DCHECK(BQ->finalizing());
+
+  if (BQ == nullptr || !BQ->finalizing()) {
+    if (Verbosity())
+      Report(
+          "XRay FDR: Failed global buffer queue is null or not finalizing!\n");
+    return {nullptr, 0};
+  }
+
+  // We use a global scratch-pad for the header information, which only gets
+  // initialized the first time this function is called. We'll update one part
+  // of this information with some relevant data (in particular the number of
+  // buffers to expect).
+  static std::aligned_storage<sizeof(XRayFileHeader)>::type HeaderStorage;
+  static pthread_once_t HeaderOnce = PTHREAD_ONCE_INIT;
+  pthread_once(
+      &HeaderOnce, +[] {
+        reinterpret_cast<XRayFileHeader &>(HeaderStorage) =
+            fdrCommonHeaderInfo();
+      });
+
+  // We use a convenience alias for code referring to Header from here on out.
+  auto &Header = reinterpret_cast<XRayFileHeader &>(HeaderStorage);
+  if (B.Data == nullptr && B.Size == 0) {
+    Header.FdrData = FdrAdditionalHeaderData{BQ->ConfiguredBufferSize()};
+    return XRayBuffer{static_cast<void *>(&Header), sizeof(Header)};
+  }
+
+  static BufferQueue::const_iterator It{};
+  static BufferQueue::const_iterator End{};
+  static uint8_t *CurrentBuffer{nullptr};
+  static size_t SerializedBufferSize = 0;
+  if (B.Data == static_cast<void *>(&Header) && B.Size == sizeof(Header)) {
+    // From this point on, we provide raw access to the raw buffer we're getting
+    // from the BufferQueue. We're relying on the iterators from the current
+    // Buffer queue.
+    It = BQ->cbegin();
+    End = BQ->cend();
+  }
+
+  if (CurrentBuffer != nullptr) {
+    deallocateBuffer(CurrentBuffer, SerializedBufferSize);
+    CurrentBuffer = nullptr;
+  }
+
+  if (It == End)
+    return {nullptr, 0};
+
+  // Set up the current buffer to contain the extents like we would when writing
+  // out to disk. The difference here would be that we still write "empty"
+  // buffers, or at least go through the iterators faithfully to let the
+  // handlers see the empty buffers in the queue.
+  //
+  // We need this atomic fence here to ensure that writes happening to the
+  // buffer have been committed before we load the extents atomically. Because
+  // the buffer is not explicitly synchronised across threads, we rely on the
+  // fence ordering to ensure that writes we expect to have been completed
+  // before the fence are fully committed before we read the extents.
+  atomic_thread_fence(memory_order_acquire);
+  auto BufferSize = atomic_load(It->Extents, memory_order_acquire);
+  SerializedBufferSize = BufferSize + sizeof(MetadataRecord);
+  CurrentBuffer = allocateBuffer(SerializedBufferSize);
+  if (CurrentBuffer == nullptr)
+    return {nullptr, 0};
+
+  // Write out the extents as a Metadata Record into the CurrentBuffer.
+  MetadataRecord ExtentsRecord;
+  ExtentsRecord.Type = uint8_t(RecordType::Metadata);
+  ExtentsRecord.RecordKind =
+      uint8_t(MetadataRecord::RecordKinds::BufferExtents);
+  internal_memcpy(ExtentsRecord.Data, &BufferSize, sizeof(BufferSize));
+  auto AfterExtents =
+      static_cast<char *>(internal_memcpy(CurrentBuffer, &ExtentsRecord,
+                                          sizeof(MetadataRecord))) +
+      sizeof(MetadataRecord);
+  internal_memcpy(AfterExtents, It->Data, BufferSize);
+
+  XRayBuffer Result;
+  Result.Data = CurrentBuffer;
+  Result.Size = SerializedBufferSize;
+  ++It;
+  return Result;
+}
+
+// Must finalize before flushing.
+XRayLogFlushStatus fdrLoggingFlush() XRAY_NEVER_INSTRUMENT {
+  if (atomic_load(&LoggingStatus, memory_order_acquire) !=
+      XRayLogInitStatus::XRAY_LOG_FINALIZED) {
+    if (Verbosity())
+      Report("Not flushing log, implementation is not finalized.\n");
+    return XRayLogFlushStatus::XRAY_LOG_NOT_FLUSHING;
+  }
+
+  s32 Result = XRayLogFlushStatus::XRAY_LOG_NOT_FLUSHING;
+  if (!atomic_compare_exchange_strong(&LogFlushStatus, &Result,
+                                      XRayLogFlushStatus::XRAY_LOG_FLUSHING,
+                                      memory_order_release)) {
+    if (Verbosity())
+      Report("Not flushing log, implementation is still finalizing.\n");
+    return static_cast<XRayLogFlushStatus>(Result);
+  }
+
+  if (BQ == nullptr) {
+    if (Verbosity())
+      Report("Cannot flush when global buffer queue is null.\n");
+    return XRayLogFlushStatus::XRAY_LOG_NOT_FLUSHING;
+  }
+
+  // We wait a number of milliseconds to allow threads to see that we've
+  // finalised before attempting to flush the log.
+  SleepForMillis(fdrFlags()->grace_period_ms);
+
+  // At this point, we're going to uninstall the iterator implementation, before
+  // we decide to do anything further with the global buffer queue.
+  __xray_log_remove_buffer_iterator();
+
+  // Once flushed, we should set the global status of the logging implementation
+  // to "uninitialized" to allow for FDR-logging multiple runs.
+  auto ResetToUnitialized = at_scope_exit([] {
+    atomic_store(&LoggingStatus, XRayLogInitStatus::XRAY_LOG_UNINITIALIZED,
+                 memory_order_release);
+  });
+
+  auto CleanupBuffers = at_scope_exit([] {
+    auto &TLD = getThreadLocalData();
+    if (TLD.Controller != nullptr)
+      TLD.Controller->flush();
+  });
+
+  if (fdrFlags()->no_file_flush) {
+    if (Verbosity())
+      Report("XRay FDR: Not flushing to file, 'no_file_flush=true'.\n");
+
+    atomic_store(&LogFlushStatus, XRayLogFlushStatus::XRAY_LOG_FLUSHED,
+                 memory_order_release);
+    return XRayLogFlushStatus::XRAY_LOG_FLUSHED;
+  }
+
+  // We write out the file in the following format:
+  //
+  //   1) We write down the XRay file header with version 1, type FDR_LOG.
+  //   2) Then we use the 'apply' member of the BufferQueue that's live, to
+  //      ensure that at this point in time we write down the buffers that have
+  //      been released (and marked "used") -- we dump the full buffer for now
+  //      (fixed-sized) and let the tools reading the buffers deal with the data
+  //      afterwards.
+  //
+  LogWriter *LW = LogWriter::Open();
+  if (LW == nullptr) {
+    auto Result = XRayLogFlushStatus::XRAY_LOG_NOT_FLUSHING;
+    atomic_store(&LogFlushStatus, Result, memory_order_release);
+    return Result;
+  }
+
+  XRayFileHeader Header = fdrCommonHeaderInfo();
+  Header.FdrData = FdrAdditionalHeaderData{BQ->ConfiguredBufferSize()};
+  LW->WriteAll(reinterpret_cast<char *>(&Header),
+               reinterpret_cast<char *>(&Header) + sizeof(Header));
+
+  // Release the current thread's buffer before we attempt to write out all the
+  // buffers. This ensures that in case we had only a single thread going, that
+  // we are able to capture the data nonetheless.
+  auto &TLD = getThreadLocalData();
+  if (TLD.Controller != nullptr)
+    TLD.Controller->flush();
+
+  BQ->apply([&](const BufferQueue::Buffer &B) {
+    // Starting at version 2 of the FDR logging implementation, we only write
+    // the records identified by the extents of the buffer. We use the Extents
+    // from the Buffer and write that out as the first record in the buffer.  We
+    // still use a Metadata record, but fill in the extents instead for the
+    // data.
+    MetadataRecord ExtentsRecord;
+    auto BufferExtents = atomic_load(B.Extents, memory_order_acquire);
+    DCHECK(BufferExtents <= B.Size);
+    ExtentsRecord.Type = uint8_t(RecordType::Metadata);
+    ExtentsRecord.RecordKind =
+        uint8_t(MetadataRecord::RecordKinds::BufferExtents);
+    internal_memcpy(ExtentsRecord.Data, &BufferExtents, sizeof(BufferExtents));
+    if (BufferExtents > 0) {
+      LW->WriteAll(reinterpret_cast<char *>(&ExtentsRecord),
+                   reinterpret_cast<char *>(&ExtentsRecord) +
+                       sizeof(MetadataRecord));
+      LW->WriteAll(reinterpret_cast<char *>(B.Data),
+                   reinterpret_cast<char *>(B.Data) + BufferExtents);
+    }
+  });
+
+  atomic_store(&LogFlushStatus, XRayLogFlushStatus::XRAY_LOG_FLUSHED,
+               memory_order_release);
+  return XRayLogFlushStatus::XRAY_LOG_FLUSHED;
+}
+
+XRayLogInitStatus fdrLoggingFinalize() XRAY_NEVER_INSTRUMENT {
+  s32 CurrentStatus = XRayLogInitStatus::XRAY_LOG_INITIALIZED;
+  if (!atomic_compare_exchange_strong(&LoggingStatus, &CurrentStatus,
+                                      XRayLogInitStatus::XRAY_LOG_FINALIZING,
+                                      memory_order_release)) {
+    if (Verbosity())
+      Report("Cannot finalize log, implementation not initialized.\n");
+    return static_cast<XRayLogInitStatus>(CurrentStatus);
+  }
+
+  // Do special things to make the log finalize itself, and not allow any more
+  // operations to be performed until re-initialized.
+  if (BQ == nullptr) {
+    if (Verbosity())
+      Report("Attempting to finalize an uninitialized global buffer!\n");
+  } else {
+    BQ->finalize();
+  }
+
+  atomic_store(&LoggingStatus, XRayLogInitStatus::XRAY_LOG_FINALIZED,
+               memory_order_release);
+  return XRayLogInitStatus::XRAY_LOG_FINALIZED;
+}
+
+struct TSCAndCPU {
+  uint64_t TSC = 0;
+  unsigned char CPU = 0;
+};
+
+static TSCAndCPU getTimestamp() 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.
+  TSCAndCPU Result;
+
+  // Test once for required CPU features
+  static pthread_once_t OnceProbe = PTHREAD_ONCE_INIT;
+  static bool TSCSupported = true;
+  pthread_once(
+      &OnceProbe, +[] { TSCSupported = probeRequiredCPUFeatures(); });
+
+  if (TSCSupported) {
+    Result.TSC = __xray::readTSC(Result.CPU);
+  } else {
+    // FIXME: This code needs refactoring as it appears in multiple locations
+    timespec TS;
+    int result = clock_gettime(CLOCK_REALTIME, &TS);
+    if (result != 0) {
+      Report("clock_gettime(2) return %d, errno=%d", result, int(errno));
+      TS = {0, 0};
+    }
+    Result.CPU = 0;
+    Result.TSC = TS.tv_sec * __xray::NanosecondsPerSecond + TS.tv_nsec;
+  }
+  return Result;
+}
+
+thread_local atomic_uint8_t Running{0};
+
+static bool setupTLD(ThreadLocalData &TLD) XRAY_NEVER_INSTRUMENT {
+  // Check if we're finalizing, before proceeding.
+  {
+    auto Status = atomic_load(&LoggingStatus, memory_order_acquire);
+    if (Status == XRayLogInitStatus::XRAY_LOG_FINALIZING ||
+        Status == XRayLogInitStatus::XRAY_LOG_FINALIZED) {
+      if (TLD.Controller != nullptr) {
+        TLD.Controller->flush();
+        TLD.Controller = nullptr;
+      }
+      return false;
+    }
+  }
+
+  if (UNLIKELY(TLD.Controller == nullptr)) {
+    // Set up the TLD buffer queue.
+    if (UNLIKELY(BQ == nullptr))
+      return false;
+    TLD.BQ = BQ;
+
+    // Check that we have a valid buffer.
+    if (TLD.Buffer.Generation != BQ->generation() &&
+        TLD.BQ->releaseBuffer(TLD.Buffer) != BufferQueue::ErrorCode::Ok)
+      return false;
+
+    // Set up a buffer, before setting up the log writer. Bail out on failure.
+    if (TLD.BQ->getBuffer(TLD.Buffer) != BufferQueue::ErrorCode::Ok)
+      return false;
+
+    // Set up the Log Writer for this thread.
+    if (UNLIKELY(TLD.Writer == nullptr)) {
+      auto *LWStorage = reinterpret_cast<FDRLogWriter *>(&TLD.LWStorage);
+      new (LWStorage) FDRLogWriter(TLD.Buffer);
+      TLD.Writer = LWStorage;
+    } else {
+      TLD.Writer->resetRecord();
+    }
+
+    auto *CStorage = reinterpret_cast<FDRController<> *>(&TLD.CStorage);
+    new (CStorage)
+        FDRController<>(TLD.BQ, TLD.Buffer, *TLD.Writer, clock_gettime,
+                        atomic_load_relaxed(&ThresholdTicks));
+    TLD.Controller = CStorage;
+  }
+
+  DCHECK_NE(TLD.Controller, nullptr);
+  return true;
+}
+
+void fdrLoggingHandleArg0(int32_t FuncId,
+                          XRayEntryType Entry) XRAY_NEVER_INSTRUMENT {
+  auto TC = getTimestamp();
+  auto &TSC = TC.TSC;
+  auto &CPU = TC.CPU;
+  RecursionGuard Guard{Running};
+  if (!Guard)
+    return;
+
+  auto &TLD = getThreadLocalData();
+  if (!setupTLD(TLD))
+    return;
+
+  switch (Entry) {
+  case XRayEntryType::ENTRY:
+  case XRayEntryType::LOG_ARGS_ENTRY:
+    TLD.Controller->functionEnter(FuncId, TSC, CPU);
+    return;
+  case XRayEntryType::EXIT:
+    TLD.Controller->functionExit(FuncId, TSC, CPU);
+    return;
+  case XRayEntryType::TAIL:
+    TLD.Controller->functionTailExit(FuncId, TSC, CPU);
+    return;
+  case XRayEntryType::CUSTOM_EVENT:
+  case XRayEntryType::TYPED_EVENT:
+    break;
+  }
+}
+
+void fdrLoggingHandleArg1(int32_t FuncId, XRayEntryType Entry,
+                          uint64_t Arg) XRAY_NEVER_INSTRUMENT {
+  auto TC = getTimestamp();
+  auto &TSC = TC.TSC;
+  auto &CPU = TC.CPU;
+  RecursionGuard Guard{Running};
+  if (!Guard)
+    return;
+
+  auto &TLD = getThreadLocalData();
+  if (!setupTLD(TLD))
+    return;
+
+  switch (Entry) {
+  case XRayEntryType::ENTRY:
+  case XRayEntryType::LOG_ARGS_ENTRY:
+    TLD.Controller->functionEnterArg(FuncId, TSC, CPU, Arg);
+    return;
+  case XRayEntryType::EXIT:
+    TLD.Controller->functionExit(FuncId, TSC, CPU);
+    return;
+  case XRayEntryType::TAIL:
+    TLD.Controller->functionTailExit(FuncId, TSC, CPU);
+    return;
+  case XRayEntryType::CUSTOM_EVENT:
+  case XRayEntryType::TYPED_EVENT:
+    break;
+  }
+}
+
+void fdrLoggingHandleCustomEvent(void *Event,
+                                 std::size_t EventSize) XRAY_NEVER_INSTRUMENT {
+  auto TC = getTimestamp();
+  auto &TSC = TC.TSC;
+  auto &CPU = TC.CPU;
+  RecursionGuard Guard{Running};
+  if (!Guard)
+    return;
+
+  // Complain when we ever get at least one custom event that's larger than what
+  // we can possibly support.
+  if (EventSize >
+      static_cast<std::size_t>(std::numeric_limits<int32_t>::max())) {
+    static pthread_once_t Once = PTHREAD_ONCE_INIT;
+    pthread_once(
+        &Once, +[] {
+          Report("Custom event size too large; truncating to %d.\n",
+                 std::numeric_limits<int32_t>::max());
+        });
+  }
+
+  auto &TLD = getThreadLocalData();
+  if (!setupTLD(TLD))
+    return;
+
+  int32_t ReducedEventSize = static_cast<int32_t>(EventSize);
+  TLD.Controller->customEvent(TSC, CPU, Event, ReducedEventSize);
+}
+
+void fdrLoggingHandleTypedEvent(
+    uint16_t EventType, const void *Event,
+    std::size_t EventSize) noexcept XRAY_NEVER_INSTRUMENT {
+  auto TC = getTimestamp();
+  auto &TSC = TC.TSC;
+  auto &CPU = TC.CPU;
+  RecursionGuard Guard{Running};
+  if (!Guard)
+    return;
+
+  // Complain when we ever get at least one typed event that's larger than what
+  // we can possibly support.
+  if (EventSize >
+      static_cast<std::size_t>(std::numeric_limits<int32_t>::max())) {
+    static pthread_once_t Once = PTHREAD_ONCE_INIT;
+    pthread_once(
+        &Once, +[] {
+          Report("Typed event size too large; truncating to %d.\n",
+                 std::numeric_limits<int32_t>::max());
+        });
+  }
+
+  auto &TLD = getThreadLocalData();
+  if (!setupTLD(TLD))
+    return;
+
+  int32_t ReducedEventSize = static_cast<int32_t>(EventSize);
+  TLD.Controller->typedEvent(TSC, CPU, EventType, Event, ReducedEventSize);
+}
+
+XRayLogInitStatus fdrLoggingInit(size_t, size_t, void *Options,
+                                 size_t OptionsSize) XRAY_NEVER_INSTRUMENT {
+  if (Options == nullptr)
+    return XRayLogInitStatus::XRAY_LOG_UNINITIALIZED;
+
+  s32 CurrentStatus = XRayLogInitStatus::XRAY_LOG_UNINITIALIZED;
+  if (!atomic_compare_exchange_strong(&LoggingStatus, &CurrentStatus,
+                                      XRayLogInitStatus::XRAY_LOG_INITIALIZING,
+                                      memory_order_release)) {
+    if (Verbosity())
+      Report("Cannot initialize already initialized implementation.\n");
+    return static_cast<XRayLogInitStatus>(CurrentStatus);
+  }
+
+  if (Verbosity())
+    Report("Initializing FDR mode with options: %s\n",
+           static_cast<const char *>(Options));
+
+  // TODO: Factor out the flags specific to the FDR mode implementation. For
+  // now, use the global/single definition of the flags, since the FDR mode
+  // flags are already defined there.
+  FlagParser FDRParser;
+  FDRFlags FDRFlags;
+  registerXRayFDRFlags(&FDRParser, &FDRFlags);
+  FDRFlags.setDefaults();
+
+  // Override first from the general XRAY_DEFAULT_OPTIONS compiler-provided
+  // options until we migrate everyone to use the XRAY_FDR_OPTIONS
+  // compiler-provided options.
+  FDRParser.ParseString(useCompilerDefinedFlags());
+  FDRParser.ParseString(useCompilerDefinedFDRFlags());
+  auto *EnvOpts = GetEnv("XRAY_FDR_OPTIONS");
+  if (EnvOpts == nullptr)
+    EnvOpts = "";
+  FDRParser.ParseString(EnvOpts);
+
+  // FIXME: Remove this when we fully remove the deprecated flags.
+  if (internal_strlen(EnvOpts) == 0) {
+    FDRFlags.func_duration_threshold_us =
+        flags()->xray_fdr_log_func_duration_threshold_us;
+    FDRFlags.grace_period_ms = flags()->xray_fdr_log_grace_period_ms;
+  }
+
+  // The provided options should always override the compiler-provided and
+  // environment-variable defined options.
+  FDRParser.ParseString(static_cast<const char *>(Options));
+  *fdrFlags() = FDRFlags;
+  auto BufferSize = FDRFlags.buffer_size;
+  auto BufferMax = FDRFlags.buffer_max;
+
+  if (BQ == nullptr) {
+    bool Success = false;
+    BQ = reinterpret_cast<BufferQueue *>(&BufferQueueStorage);
+    new (BQ) BufferQueue(BufferSize, BufferMax, Success);
+    if (!Success) {
+      Report("BufferQueue init failed.\n");
+      return XRayLogInitStatus::XRAY_LOG_UNINITIALIZED;
+    }
+  } else {
+    if (BQ->init(BufferSize, BufferMax) != BufferQueue::ErrorCode::Ok) {
+      if (Verbosity())
+        Report("Failed to re-initialize global buffer queue. Init failed.\n");
+      return XRayLogInitStatus::XRAY_LOG_UNINITIALIZED;
+    }
+  }
+
+  static pthread_once_t OnceInit = PTHREAD_ONCE_INIT;
+  pthread_once(
+      &OnceInit, +[] {
+        atomic_store(&TicksPerSec,
+                     probeRequiredCPUFeatures() ? getTSCFrequency()
+                                                : __xray::NanosecondsPerSecond,
+                     memory_order_release);
+        pthread_key_create(
+            &Key, +[](void *TLDPtr) {
+              if (TLDPtr == nullptr)
+                return;
+              auto &TLD = *reinterpret_cast<ThreadLocalData *>(TLDPtr);
+              if (TLD.BQ == nullptr)
+                return;
+              if (TLD.Buffer.Data == nullptr)
+                return;
+              auto EC = TLD.BQ->releaseBuffer(TLD.Buffer);
+              if (EC != BufferQueue::ErrorCode::Ok)
+                Report("At thread exit, failed to release buffer at %p; "
+                       "error=%s\n",
+                       TLD.Buffer.Data, BufferQueue::getErrorString(EC));
+            });
+      });
+
+  atomic_store(&ThresholdTicks,
+               atomic_load_relaxed(&TicksPerSec) *
+                   fdrFlags()->func_duration_threshold_us / 1000000,
+               memory_order_release);
+  // Arg1 handler should go in first to avoid concurrent code accidentally
+  // falling back to arg0 when it should have ran arg1.
+  __xray_set_handler_arg1(fdrLoggingHandleArg1);
+  // Install the actual handleArg0 handler after initialising the buffers.
+  __xray_set_handler(fdrLoggingHandleArg0);
+  __xray_set_customevent_handler(fdrLoggingHandleCustomEvent);
+  __xray_set_typedevent_handler(fdrLoggingHandleTypedEvent);
+
+  // Install the buffer iterator implementation.
+  __xray_log_set_buffer_iterator(fdrIterator);
+
+  atomic_store(&LoggingStatus, XRayLogInitStatus::XRAY_LOG_INITIALIZED,
+               memory_order_release);
+
+  if (Verbosity())
+    Report("XRay FDR init successful.\n");
+  return XRayLogInitStatus::XRAY_LOG_INITIALIZED;
+}
+
+bool fdrLogDynamicInitializer() XRAY_NEVER_INSTRUMENT {
+  XRayLogImpl Impl{
+      fdrLoggingInit,
+      fdrLoggingFinalize,
+      fdrLoggingHandleArg0,
+      fdrLoggingFlush,
+  };
+  auto RegistrationResult = __xray_log_register_mode("xray-fdr", Impl);
+  if (RegistrationResult != XRayLogRegisterStatus::XRAY_REGISTRATION_OK &&
+      Verbosity()) {
+    Report("Cannot register XRay FDR mode to 'xray-fdr'; error = %d\n",
+           RegistrationResult);
+    return false;
+  }
+
+  if (flags()->xray_fdr_log ||
+      !internal_strcmp(flags()->xray_mode, "xray-fdr")) {
+    auto SelectResult = __xray_log_select_mode("xray-fdr");
+    if (SelectResult != XRayLogRegisterStatus::XRAY_REGISTRATION_OK &&
+        Verbosity()) {
+      Report("Cannot select XRay FDR mode as 'xray-fdr'; error = %d\n",
+             SelectResult);
+      return false;
+    }
+  }
+  return true;
+}
+
+} // namespace __xray
+
+static auto UNUSED Unused = __xray::fdrLogDynamicInitializer();