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e5ece81cc9
We shouldn't be using stat() or dlsym() in the freestanding runtime. rdar://111214571 rdar://106555012
125 lines
3.8 KiB
C++
125 lines
3.8 KiB
C++
//===--- ThreadSanitizer.h - Thread Sanitizer support --------- -*- C++ -*-===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2023 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See https://swift.org/LICENSE.txt for license information
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// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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//
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// Helper functions for code that needs to integrate with the thread
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// sanitizer. In particular, TSan can't see inside the runtime libraries,
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// so we occasionally need to give it a hint that we're doing synchronization
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// in order to avoid false positives.
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//
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//===----------------------------------------------------------------------===//
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#ifndef SWIFT_THREADING_THREAD_SANITIZER_H
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#define SWIFT_THREADING_THREAD_SANITIZER_H
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#include "swift/shims/Visibility.h"
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namespace swift {
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#if SWIFT_THREADING_NONE \
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|| defined(_WIN32) || defined(__wasi__) \
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|| !__has_include(<dlfcn.h>) \
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|| (defined(SWIFT_STDLIB_HAS_DLSYM) && !SWIFT_STDLIB_HAS_DLSYM)
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#define SWIFT_THREADING_TSAN_SUPPORT 0
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namespace tsan {
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inline bool enabled() { return false; }
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template <typename T> T *acquire(T *ptr) { return ptr; }
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template <typename T> T *release(T *ptr) { return ptr; }
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} // namespace tsan
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#else
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#define SWIFT_THREADING_TSAN_SUPPORT 1
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// If we're static linking to libswiftThreading.a, these symbols can come
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// from there. If, on the other hand, we're dynamically linked, we want
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// to get them from libswiftCore.dylib instead.
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#if SWIFT_THREADING_STATIC
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#define SWIFT_THREADING_EXPORT extern "C"
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#else
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#define SWIFT_THREADING_EXPORT SWIFT_RUNTIME_EXPORT
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#endif
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namespace threading_impl {
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SWIFT_THREADING_EXPORT bool _swift_tsan_enabled;
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SWIFT_THREADING_EXPORT void (*_swift_tsan_acquire)(const void *ptr);
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SWIFT_THREADING_EXPORT void (*_swift_tsan_release)(const void *ptr);
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} // namespace threading_impl
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namespace tsan {
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/// Returns true if TSan is enabled
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inline bool enabled() {
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return threading_impl::_swift_tsan_enabled;
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}
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/// Inform TSan about a synchronization operation.
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///
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/// This is used when TSan cannot see the synchronization operation, for
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/// example, if it is using a custom primitive for which TSan doesn't have
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/// a built-in interceptor. This does not necessarily mean a lock or a C(++)
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/// atomic operation - it could be any kind of synchronization mechanism.
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///
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/// An acquire-release pair using the same address establishes an ordering
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/// constraint in TSan's happens-before graph, which TSan uses to determine
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/// whether two memory accesses from different threads have a well-defined
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/// order.
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///
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/// For instance, in
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///
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/// Thread 1 Thread 2
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///
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/// access to y
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/// tsan::release(x)
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/// lock given away
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///
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/// --> sync point -->
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///
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/// lock taken
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/// tsan::acquire(x)
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/// access to y
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///
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/// the access to y from Thread 2 is safe relative to the preceding access to
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/// y on Thread 1 because it is preceded by an acquire of x that was itself
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/// preceded by a release of x.
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template <typename T>
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T *acquire(T *ptr) {
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if (threading_impl::_swift_tsan_acquire) {
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threading_impl::_swift_tsan_acquire(ptr);
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}
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return ptr;
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}
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/// Inform TSan about a synchronization operation.
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///
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/// This is the counterpart to tsan::acquire.
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template <typename T>
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T *release(T *ptr) {
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if (threading_impl::_swift_tsan_release) {
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threading_impl::_swift_tsan_release(ptr);
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}
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return ptr;
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}
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} // namespace tsan
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#endif
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} // namespace swift
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#endif
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