blob: 867d82a6112b9d855067394dccc65c08ed76b575 [file] [log] [blame]
// Copyright (c) 2019, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
#include "vm/bss_relocs.h"
#include "vm/native_symbol.h"
#include "vm/runtime_entry.h"
#include "vm/thread.h"
namespace dart {
void BSS::InitializeBSSEntry(BSS::Relocation relocation,
uword new_value,
uword* bss_start) {
std::atomic<uword>* slot = reinterpret_cast<std::atomic<uword>*>(
uword old_value = slot->load(std::memory_order_relaxed);
// FullSnapshotReader::ReadProgramSnapshot, and thus BSS::Initialize, can
// get called multiple times for the same isolate in different threads, though
// the initialized value will be consistent and thus change only once. Avoid
// calling compare_exchange_strong unless we actually need to change the
// value, to avoid spurious read/write races by TSAN.
if (old_value == new_value) return;
if (!slot->compare_exchange_strong(old_value, new_value,
std::memory_order_relaxed)) {
RELEASE_ASSERT(old_value == new_value);
void BSS::Initialize(Thread* current, uword* bss_start, bool vm) {
auto const instructions = reinterpret_cast<uword>(
uword dso_base;
// Needed for assembly snapshots. For ELF snapshots, we set up the relocated
// address information directly in the text segment InstructionsSection.
if (NativeSymbolResolver::LookupSharedObject(instructions, &dso_base)) {
instructions - dso_base, bss_start);
if (!vm) {
// Fill values at isolate-only indices.
} // namespace dart