Ryan Macnak
b70685ed17
TEST=ci Bug: https://github.com/dart-lang/sdk/issues/60204 Change-Id: Ib2b5c9e9a8079258143be69a409a141e92a039a5 Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/413560 Reviewed-by: Daco Harkes <dacoharkes@google.com> Commit-Queue: Ryan Macnak <rmacnak@google.com>
41 lines
1.7 KiB
C++
41 lines
1.7 KiB
C++
// Copyright (c) 2019, the Dart project authors. Please see the AUTHORS file
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// for details. All rights reserved. Use of this source code is governed by a
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// BSD-style license that can be found in the LICENSE file.
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#include "vm/bss_relocs.h"
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#include "vm/native_symbol.h"
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#include "vm/runtime_entry.h"
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#include "vm/thread.h"
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namespace dart {
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void BSS::InitializeBSSEntry(BSS::Relocation relocation,
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uword new_value,
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uword* bss_start) {
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std::atomic<uword>* slot = reinterpret_cast<std::atomic<uword>*>(
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&bss_start[BSS::RelocationIndex(relocation)]);
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uword old_value = slot->load(std::memory_order_relaxed);
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// FullSnapshotReader::ReadProgramSnapshot, and thus BSS::Initialize, can
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// get called multiple times for the same isolate in different threads, though
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// the initialized value will be consistent and thus change only once. Avoid
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// calling compare_exchange_strong unless we actually need to change the
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// value, to avoid spurious read/write races by TSAN.
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if (old_value == new_value) return;
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if (!slot->compare_exchange_strong(old_value, new_value,
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std::memory_order_relaxed)) {
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RELEASE_ASSERT(old_value == new_value);
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}
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}
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void BSS::Initialize(Thread* current, uword* bss_start, bool vm) {
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// TODO(https://dartbug.com/52579): Remove.
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InitializeBSSEntry(Relocation::DLRT_GetFfiCallbackMetadata,
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reinterpret_cast<uword>(DLRT_GetFfiCallbackMetadata),
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bss_start);
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InitializeBSSEntry(Relocation::DLRT_ExitTemporaryIsolate,
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reinterpret_cast<uword>(DLRT_ExitTemporaryIsolate),
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bss_start);
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}
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} // namespace dart
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