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- // Copyright 2019 The Chromium Authors. All rights reserved.
- // Use of this source code is governed by a BSD-style license that can be
- // found in the LICENSE file.
- #include "base/profiler/stack_copier_suspend.h"
- #include "base/profiler/stack_buffer.h"
- #include "base/profiler/suspendable_thread_delegate.h"
- namespace base {
- StackCopierSuspend::StackCopierSuspend(
- std::unique_ptr<SuspendableThreadDelegate> thread_delegate)
- : thread_delegate_(std::move(thread_delegate)) {}
- StackCopierSuspend::~StackCopierSuspend() = default;
- // Suspends the thread, copies the stack state, and resumes the thread. The
- // copied stack state includes the stack itself, the top address of the stack
- // copy, and the register context. Returns true on success, and returns the
- // copied state via the params.
- //
- // NO HEAP ALLOCATIONS within the ScopedSuspendThread scope.
- bool StackCopierSuspend::CopyStack(StackBuffer* stack_buffer,
- uintptr_t* stack_top,
- TimeTicks* timestamp,
- RegisterContext* thread_context,
- Delegate* delegate) {
- const uintptr_t top = thread_delegate_->GetStackBaseAddress();
- uintptr_t bottom = 0;
- const uint8_t* stack_copy_bottom = nullptr;
- {
- // Allocation of the ScopedSuspendThread object itself is OK since it
- // necessarily occurs before the thread is suspended by the object.
- std::unique_ptr<SuspendableThreadDelegate::ScopedSuspendThread>
- suspend_thread = thread_delegate_->CreateScopedSuspendThread();
- // TimeTicks::Now() is implemented in terms of reads to the timer tick
- // counter or TSC register on x86/x86_64 so is reentrant.
- *timestamp = TimeTicks::Now();
- if (!suspend_thread->WasSuccessful())
- return false;
- if (!thread_delegate_->GetThreadContext(thread_context))
- return false;
- bottom = RegisterContextStackPointer(thread_context);
- // The StackBuffer allocation is expected to be at least as large as the
- // largest stack region allocation on the platform, but check just in case
- // it isn't *and* the actual stack itself exceeds the buffer allocation
- // size.
- if ((top - bottom) > stack_buffer->size())
- return false;
- if (!thread_delegate_->CanCopyStack(bottom))
- return false;
- delegate->OnStackCopy();
- stack_copy_bottom = CopyStackContentsAndRewritePointers(
- reinterpret_cast<uint8_t*>(bottom), reinterpret_cast<uintptr_t*>(top),
- StackBuffer::kPlatformStackAlignment, stack_buffer->buffer());
- }
- *stack_top = reinterpret_cast<uintptr_t>(stack_copy_bottom) + (top - bottom);
- for (uintptr_t* reg :
- thread_delegate_->GetRegistersToRewrite(thread_context)) {
- *reg = RewritePointerIfInOriginalStack(reinterpret_cast<uint8_t*>(bottom),
- reinterpret_cast<uintptr_t*>(top),
- stack_copy_bottom, *reg);
- }
- return true;
- }
- } // namespace base
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