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-rw-r--r--lib/xray/xray_profiling.cpp519
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diff --git a/lib/xray/xray_profiling.cpp b/lib/xray/xray_profiling.cpp
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+//===-- xray_profiling.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.
+//
+// This is the implementation of a profiling handler.
+//
+//===----------------------------------------------------------------------===//
+#include <memory>
+#include <time.h>
+
+#include "sanitizer_common/sanitizer_atomic.h"
+#include "sanitizer_common/sanitizer_flags.h"
+#include "xray/xray_interface.h"
+#include "xray/xray_log_interface.h"
+#include "xray_buffer_queue.h"
+#include "xray_flags.h"
+#include "xray_profile_collector.h"
+#include "xray_profiling_flags.h"
+#include "xray_recursion_guard.h"
+#include "xray_tsc.h"
+#include "xray_utils.h"
+#include <pthread.h>
+
+namespace __xray {
+
+namespace {
+
+static atomic_sint32_t ProfilerLogFlushStatus = {
+ XRayLogFlushStatus::XRAY_LOG_NOT_FLUSHING};
+
+static atomic_sint32_t ProfilerLogStatus = {
+ XRayLogInitStatus::XRAY_LOG_UNINITIALIZED};
+
+static SpinMutex ProfilerOptionsMutex;
+
+struct ProfilingData {
+ atomic_uintptr_t Allocators;
+ atomic_uintptr_t FCT;
+};
+
+static pthread_key_t ProfilingKey;
+
+// We use a global buffer queue, which gets initialized once at initialisation
+// time, and gets reset when profiling is "done".
+static std::aligned_storage<sizeof(BufferQueue), alignof(BufferQueue)>::type
+ BufferQueueStorage;
+static BufferQueue *BQ = nullptr;
+
+thread_local FunctionCallTrie::Allocators::Buffers ThreadBuffers;
+thread_local std::aligned_storage<sizeof(FunctionCallTrie::Allocators),
+ alignof(FunctionCallTrie::Allocators)>::type
+ AllocatorsStorage;
+thread_local std::aligned_storage<sizeof(FunctionCallTrie),
+ alignof(FunctionCallTrie)>::type
+ FunctionCallTrieStorage;
+thread_local ProfilingData TLD{{0}, {0}};
+thread_local atomic_uint8_t ReentranceGuard{0};
+
+// We use a separate guard for ensuring that for this thread, if we're already
+// cleaning up, that any signal handlers don't attempt to cleanup nor
+// initialise.
+thread_local atomic_uint8_t TLDInitGuard{0};
+
+// We also use a separate latch to signal that the thread is exiting, and
+// non-essential work should be ignored (things like recording events, etc.).
+thread_local atomic_uint8_t ThreadExitingLatch{0};
+
+static ProfilingData *getThreadLocalData() XRAY_NEVER_INSTRUMENT {
+ thread_local auto ThreadOnce = []() XRAY_NEVER_INSTRUMENT {
+ pthread_setspecific(ProfilingKey, &TLD);
+ return false;
+ }();
+ (void)ThreadOnce;
+
+ RecursionGuard TLDInit(TLDInitGuard);
+ if (!TLDInit)
+ return nullptr;
+
+ if (atomic_load_relaxed(&ThreadExitingLatch))
+ return nullptr;
+
+ uptr Allocators = 0;
+ if (atomic_compare_exchange_strong(&TLD.Allocators, &Allocators, 1,
+ memory_order_acq_rel)) {
+ bool Success = false;
+ auto AllocatorsUndo = at_scope_exit([&]() XRAY_NEVER_INSTRUMENT {
+ if (!Success)
+ atomic_store(&TLD.Allocators, 0, memory_order_release);
+ });
+
+ // Acquire a set of buffers for this thread.
+ if (BQ == nullptr)
+ return nullptr;
+
+ if (BQ->getBuffer(ThreadBuffers.NodeBuffer) != BufferQueue::ErrorCode::Ok)
+ return nullptr;
+ auto NodeBufferUndo = at_scope_exit([&]() XRAY_NEVER_INSTRUMENT {
+ if (!Success)
+ BQ->releaseBuffer(ThreadBuffers.NodeBuffer);
+ });
+
+ if (BQ->getBuffer(ThreadBuffers.RootsBuffer) != BufferQueue::ErrorCode::Ok)
+ return nullptr;
+ auto RootsBufferUndo = at_scope_exit([&]() XRAY_NEVER_INSTRUMENT {
+ if (!Success)
+ BQ->releaseBuffer(ThreadBuffers.RootsBuffer);
+ });
+
+ if (BQ->getBuffer(ThreadBuffers.ShadowStackBuffer) !=
+ BufferQueue::ErrorCode::Ok)
+ return nullptr;
+ auto ShadowStackBufferUndo = at_scope_exit([&]() XRAY_NEVER_INSTRUMENT {
+ if (!Success)
+ BQ->releaseBuffer(ThreadBuffers.ShadowStackBuffer);
+ });
+
+ if (BQ->getBuffer(ThreadBuffers.NodeIdPairBuffer) !=
+ BufferQueue::ErrorCode::Ok)
+ return nullptr;
+
+ Success = true;
+ new (&AllocatorsStorage) FunctionCallTrie::Allocators(
+ FunctionCallTrie::InitAllocatorsFromBuffers(ThreadBuffers));
+ Allocators = reinterpret_cast<uptr>(
+ reinterpret_cast<FunctionCallTrie::Allocators *>(&AllocatorsStorage));
+ atomic_store(&TLD.Allocators, Allocators, memory_order_release);
+ }
+
+ if (Allocators == 1)
+ return nullptr;
+
+ uptr FCT = 0;
+ if (atomic_compare_exchange_strong(&TLD.FCT, &FCT, 1, memory_order_acq_rel)) {
+ new (&FunctionCallTrieStorage)
+ FunctionCallTrie(*reinterpret_cast<FunctionCallTrie::Allocators *>(
+ atomic_load_relaxed(&TLD.Allocators)));
+ FCT = reinterpret_cast<uptr>(
+ reinterpret_cast<FunctionCallTrie *>(&FunctionCallTrieStorage));
+ atomic_store(&TLD.FCT, FCT, memory_order_release);
+ }
+
+ if (FCT == 1)
+ return nullptr;
+
+ return &TLD;
+}
+
+static void cleanupTLD() XRAY_NEVER_INSTRUMENT {
+ auto FCT = atomic_exchange(&TLD.FCT, 0, memory_order_acq_rel);
+ if (FCT == reinterpret_cast<uptr>(reinterpret_cast<FunctionCallTrie *>(
+ &FunctionCallTrieStorage)))
+ reinterpret_cast<FunctionCallTrie *>(FCT)->~FunctionCallTrie();
+
+ auto Allocators = atomic_exchange(&TLD.Allocators, 0, memory_order_acq_rel);
+ if (Allocators ==
+ reinterpret_cast<uptr>(
+ reinterpret_cast<FunctionCallTrie::Allocators *>(&AllocatorsStorage)))
+ reinterpret_cast<FunctionCallTrie::Allocators *>(Allocators)->~Allocators();
+}
+
+static void postCurrentThreadFCT(ProfilingData &T) XRAY_NEVER_INSTRUMENT {
+ RecursionGuard TLDInit(TLDInitGuard);
+ if (!TLDInit)
+ return;
+
+ uptr P = atomic_exchange(&T.FCT, 0, memory_order_acq_rel);
+ if (P != reinterpret_cast<uptr>(
+ reinterpret_cast<FunctionCallTrie *>(&FunctionCallTrieStorage)))
+ return;
+
+ auto FCT = reinterpret_cast<FunctionCallTrie *>(P);
+ DCHECK_NE(FCT, nullptr);
+
+ uptr A = atomic_exchange(&T.Allocators, 0, memory_order_acq_rel);
+ if (A !=
+ reinterpret_cast<uptr>(
+ reinterpret_cast<FunctionCallTrie::Allocators *>(&AllocatorsStorage)))
+ return;
+
+ auto Allocators = reinterpret_cast<FunctionCallTrie::Allocators *>(A);
+ DCHECK_NE(Allocators, nullptr);
+
+ // Always move the data into the profile collector.
+ profileCollectorService::post(BQ, std::move(*FCT), std::move(*Allocators),
+ std::move(ThreadBuffers), GetTid());
+
+ // Re-initialize the ThreadBuffers object to a known "default" state.
+ ThreadBuffers = FunctionCallTrie::Allocators::Buffers{};
+}
+
+} // namespace
+
+const char *profilingCompilerDefinedFlags() XRAY_NEVER_INSTRUMENT {
+#ifdef XRAY_PROFILER_DEFAULT_OPTIONS
+ return SANITIZER_STRINGIFY(XRAY_PROFILER_DEFAULT_OPTIONS);
+#else
+ return "";
+#endif
+}
+
+XRayLogFlushStatus profilingFlush() XRAY_NEVER_INSTRUMENT {
+ if (atomic_load(&ProfilerLogStatus, memory_order_acquire) !=
+ XRayLogInitStatus::XRAY_LOG_FINALIZED) {
+ if (Verbosity())
+ Report("Not flushing profiles, profiling not been finalized.\n");
+ return XRayLogFlushStatus::XRAY_LOG_NOT_FLUSHING;
+ }
+
+ RecursionGuard SignalGuard(ReentranceGuard);
+ if (!SignalGuard) {
+ if (Verbosity())
+ Report("Cannot finalize properly inside a signal handler!\n");
+ atomic_store(&ProfilerLogFlushStatus,
+ XRayLogFlushStatus::XRAY_LOG_NOT_FLUSHING,
+ memory_order_release);
+ return XRayLogFlushStatus::XRAY_LOG_NOT_FLUSHING;
+ }
+
+ s32 Previous = atomic_exchange(&ProfilerLogFlushStatus,
+ XRayLogFlushStatus::XRAY_LOG_FLUSHING,
+ memory_order_acq_rel);
+ if (Previous == XRayLogFlushStatus::XRAY_LOG_FLUSHING) {
+ if (Verbosity())
+ Report("Not flushing profiles, implementation still flushing.\n");
+ return XRayLogFlushStatus::XRAY_LOG_FLUSHING;
+ }
+
+ // At this point, we'll create the file that will contain the profile, but
+ // only if the options say so.
+ if (!profilingFlags()->no_flush) {
+ // First check whether we have data in the profile collector service
+ // before we try and write anything down.
+ XRayBuffer B = profileCollectorService::nextBuffer({nullptr, 0});
+ if (B.Data == nullptr) {
+ if (Verbosity())
+ Report("profiling: No data to flush.\n");
+ } else {
+ LogWriter *LW = LogWriter::Open();
+ if (LW == nullptr) {
+ if (Verbosity())
+ Report("profiling: Failed to flush to file, dropping data.\n");
+ } else {
+ // Now for each of the buffers, write out the profile data as we would
+ // see it in memory, verbatim.
+ while (B.Data != nullptr && B.Size != 0) {
+ LW->WriteAll(reinterpret_cast<const char *>(B.Data),
+ reinterpret_cast<const char *>(B.Data) + B.Size);
+ B = profileCollectorService::nextBuffer(B);
+ }
+ }
+ LogWriter::Close(LW);
+ }
+ }
+
+ profileCollectorService::reset();
+
+ atomic_store(&ProfilerLogFlushStatus, XRayLogFlushStatus::XRAY_LOG_FLUSHED,
+ memory_order_release);
+ atomic_store(&ProfilerLogStatus, XRayLogInitStatus::XRAY_LOG_UNINITIALIZED,
+ memory_order_release);
+
+ return XRayLogFlushStatus::XRAY_LOG_FLUSHED;
+}
+
+void profilingHandleArg0(int32_t FuncId,
+ XRayEntryType Entry) XRAY_NEVER_INSTRUMENT {
+ unsigned char CPU;
+ auto TSC = readTSC(CPU);
+ RecursionGuard G(ReentranceGuard);
+ if (!G)
+ return;
+
+ auto Status = atomic_load(&ProfilerLogStatus, memory_order_acquire);
+ if (UNLIKELY(Status == XRayLogInitStatus::XRAY_LOG_UNINITIALIZED ||
+ Status == XRayLogInitStatus::XRAY_LOG_INITIALIZING))
+ return;
+
+ if (UNLIKELY(Status == XRayLogInitStatus::XRAY_LOG_FINALIZED ||
+ Status == XRayLogInitStatus::XRAY_LOG_FINALIZING)) {
+ postCurrentThreadFCT(TLD);
+ return;
+ }
+
+ auto T = getThreadLocalData();
+ if (T == nullptr)
+ return;
+
+ auto FCT = reinterpret_cast<FunctionCallTrie *>(atomic_load_relaxed(&T->FCT));
+ switch (Entry) {
+ case XRayEntryType::ENTRY:
+ case XRayEntryType::LOG_ARGS_ENTRY:
+ FCT->enterFunction(FuncId, TSC, CPU);
+ break;
+ case XRayEntryType::EXIT:
+ case XRayEntryType::TAIL:
+ FCT->exitFunction(FuncId, TSC, CPU);
+ break;
+ default:
+ // FIXME: Handle bugs.
+ break;
+ }
+}
+
+void profilingHandleArg1(int32_t FuncId, XRayEntryType Entry,
+ uint64_t) XRAY_NEVER_INSTRUMENT {
+ return profilingHandleArg0(FuncId, Entry);
+}
+
+XRayLogInitStatus profilingFinalize() XRAY_NEVER_INSTRUMENT {
+ s32 CurrentStatus = XRayLogInitStatus::XRAY_LOG_INITIALIZED;
+ if (!atomic_compare_exchange_strong(&ProfilerLogStatus, &CurrentStatus,
+ XRayLogInitStatus::XRAY_LOG_FINALIZING,
+ memory_order_release)) {
+ if (Verbosity())
+ Report("Cannot finalize profile, the profiling is not initialized.\n");
+ return static_cast<XRayLogInitStatus>(CurrentStatus);
+ }
+
+ // Mark then finalize the current generation of buffers. This allows us to let
+ // the threads currently holding onto new buffers still use them, but let the
+ // last reference do the memory cleanup.
+ DCHECK_NE(BQ, nullptr);
+ BQ->finalize();
+
+ // Wait a grace period to allow threads to see that we're finalizing.
+ SleepForMillis(profilingFlags()->grace_period_ms);
+
+ // If we for some reason are entering this function from an instrumented
+ // handler, we bail out.
+ RecursionGuard G(ReentranceGuard);
+ if (!G)
+ return static_cast<XRayLogInitStatus>(CurrentStatus);
+
+ // Post the current thread's data if we have any.
+ postCurrentThreadFCT(TLD);
+
+ // Then we force serialize the log data.
+ profileCollectorService::serialize();
+
+ atomic_store(&ProfilerLogStatus, XRayLogInitStatus::XRAY_LOG_FINALIZED,
+ memory_order_release);
+ return XRayLogInitStatus::XRAY_LOG_FINALIZED;
+}
+
+XRayLogInitStatus
+profilingLoggingInit(size_t, size_t, void *Options,
+ size_t OptionsSize) XRAY_NEVER_INSTRUMENT {
+ RecursionGuard G(ReentranceGuard);
+ if (!G)
+ return XRayLogInitStatus::XRAY_LOG_UNINITIALIZED;
+
+ s32 CurrentStatus = XRayLogInitStatus::XRAY_LOG_UNINITIALIZED;
+ if (!atomic_compare_exchange_strong(&ProfilerLogStatus, &CurrentStatus,
+ XRayLogInitStatus::XRAY_LOG_INITIALIZING,
+ memory_order_acq_rel)) {
+ if (Verbosity())
+ Report("Cannot initialize already initialised profiling "
+ "implementation.\n");
+ return static_cast<XRayLogInitStatus>(CurrentStatus);
+ }
+
+ {
+ SpinMutexLock Lock(&ProfilerOptionsMutex);
+ FlagParser ConfigParser;
+ ProfilerFlags Flags;
+ Flags.setDefaults();
+ registerProfilerFlags(&ConfigParser, &Flags);
+ ConfigParser.ParseString(profilingCompilerDefinedFlags());
+ const char *Env = GetEnv("XRAY_PROFILING_OPTIONS");
+ if (Env == nullptr)
+ Env = "";
+ ConfigParser.ParseString(Env);
+
+ // Then parse the configuration string provided.
+ ConfigParser.ParseString(static_cast<const char *>(Options));
+ if (Verbosity())
+ ReportUnrecognizedFlags();
+ *profilingFlags() = Flags;
+ }
+
+ // We need to reset the profile data collection implementation now.
+ profileCollectorService::reset();
+
+ // Then also reset the buffer queue implementation.
+ if (BQ == nullptr) {
+ bool Success = false;
+ new (&BufferQueueStorage)
+ BufferQueue(profilingFlags()->per_thread_allocator_max,
+ profilingFlags()->buffers_max, Success);
+ if (!Success) {
+ if (Verbosity())
+ Report("Failed to initialize preallocated memory buffers!");
+ atomic_store(&ProfilerLogStatus,
+ XRayLogInitStatus::XRAY_LOG_UNINITIALIZED,
+ memory_order_release);
+ return XRayLogInitStatus::XRAY_LOG_UNINITIALIZED;
+ }
+
+ // If we've succeded, set the global pointer to the initialised storage.
+ BQ = reinterpret_cast<BufferQueue *>(&BufferQueueStorage);
+ } else {
+ BQ->finalize();
+ auto InitStatus = BQ->init(profilingFlags()->per_thread_allocator_max,
+ profilingFlags()->buffers_max);
+
+ if (InitStatus != BufferQueue::ErrorCode::Ok) {
+ if (Verbosity())
+ Report("Failed to initialize preallocated memory buffers; error: %s",
+ BufferQueue::getErrorString(InitStatus));
+ atomic_store(&ProfilerLogStatus,
+ XRayLogInitStatus::XRAY_LOG_UNINITIALIZED,
+ memory_order_release);
+ return XRayLogInitStatus::XRAY_LOG_UNINITIALIZED;
+ }
+
+ DCHECK(!BQ->finalizing());
+ }
+
+ // We need to set up the exit handlers.
+ static pthread_once_t Once = PTHREAD_ONCE_INIT;
+ pthread_once(
+ &Once, +[] {
+ pthread_key_create(
+ &ProfilingKey, +[](void *P) XRAY_NEVER_INSTRUMENT {
+ if (atomic_exchange(&ThreadExitingLatch, 1, memory_order_acq_rel))
+ return;
+
+ if (P == nullptr)
+ return;
+
+ auto T = reinterpret_cast<ProfilingData *>(P);
+ if (atomic_load_relaxed(&T->Allocators) == 0)
+ return;
+
+ {
+ // If we're somehow executing this while inside a
+ // non-reentrant-friendly context, we skip attempting to post
+ // the current thread's data.
+ RecursionGuard G(ReentranceGuard);
+ if (!G)
+ return;
+
+ postCurrentThreadFCT(*T);
+ }
+ });
+
+ // We also need to set up an exit handler, so that we can get the
+ // profile information at exit time. We use the C API to do this, to not
+ // rely on C++ ABI functions for registering exit handlers.
+ Atexit(+[]() XRAY_NEVER_INSTRUMENT {
+ if (atomic_exchange(&ThreadExitingLatch, 1, memory_order_acq_rel))
+ return;
+
+ auto Cleanup =
+ at_scope_exit([]() XRAY_NEVER_INSTRUMENT { cleanupTLD(); });
+
+ // Finalize and flush.
+ if (profilingFinalize() != XRAY_LOG_FINALIZED ||
+ profilingFlush() != XRAY_LOG_FLUSHED)
+ return;
+
+ if (Verbosity())
+ Report("XRay Profile flushed at exit.");
+ });
+ });
+
+ __xray_log_set_buffer_iterator(profileCollectorService::nextBuffer);
+ __xray_set_handler(profilingHandleArg0);
+ __xray_set_handler_arg1(profilingHandleArg1);
+
+ atomic_store(&ProfilerLogStatus, XRayLogInitStatus::XRAY_LOG_INITIALIZED,
+ memory_order_release);
+ if (Verbosity())
+ Report("XRay Profiling init successful.\n");
+
+ return XRayLogInitStatus::XRAY_LOG_INITIALIZED;
+}
+
+bool profilingDynamicInitializer() XRAY_NEVER_INSTRUMENT {
+ // Set up the flag defaults from the static defaults and the
+ // compiler-provided defaults.
+ {
+ SpinMutexLock Lock(&ProfilerOptionsMutex);
+ auto *F = profilingFlags();
+ F->setDefaults();
+ FlagParser ProfilingParser;
+ registerProfilerFlags(&ProfilingParser, F);
+ ProfilingParser.ParseString(profilingCompilerDefinedFlags());
+ }
+
+ XRayLogImpl Impl{
+ profilingLoggingInit,
+ profilingFinalize,
+ profilingHandleArg0,
+ profilingFlush,
+ };
+ auto RegistrationResult = __xray_log_register_mode("xray-profiling", Impl);
+ if (RegistrationResult != XRayLogRegisterStatus::XRAY_REGISTRATION_OK) {
+ if (Verbosity())
+ Report("Cannot register XRay Profiling mode to 'xray-profiling'; error = "
+ "%d\n",
+ RegistrationResult);
+ return false;
+ }
+
+ if (!internal_strcmp(flags()->xray_mode, "xray-profiling"))
+ __xray_log_select_mode("xray_profiling");
+ return true;
+}
+
+} // namespace __xray
+
+static auto UNUSED Unused = __xray::profilingDynamicInitializer();