Repo created

TMessagesProj/jni/voip/webrtc/base/profiler/stack_copier_suspend.cc

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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());
+  }
+
+  delegate->OnThreadResume();
+
+  *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