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// Copyright 2015 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 "third_party/blink/renderer/platform/heap/stack_frame_depth.h"
#include "third_party/blink/public/platform/platform.h"
#include "third_party/blink/renderer/platform/wtf/stack_util.h"
#if defined(OS_WIN)
#include <stddef.h>
#include <windows.h>
#include <winnt.h>
#elif defined(__GLIBC__)
extern "C" void* __libc_stack_end; // NOLINT
#endif
namespace blink {
static const char* g_avoid_optimization = nullptr;
// NOINLINE ensures that |dummy| array on configureLimit() is not optimized
// away, and the stack frame base register is adjusted |kSafeStackFrameSize|.
NOINLINE static uintptr_t CurrentStackFrameBaseOnCallee(const char* dummy) {
g_avoid_optimization = dummy;
return StackFrameDepth::CurrentStackFrame();
}
uintptr_t StackFrameDepth::GetFallbackStackLimit() {
// Allocate an |kSafeStackFrameSize|-sized object on stack and query
// stack frame base after it.
char dummy[kSafeStackFrameSize];
// Check that the stack frame can be used.
dummy[sizeof(dummy) - 1] = 0;
return CurrentStackFrameBaseOnCallee(dummy);
}
void StackFrameDepth::EnableStackLimit() {
// All supported platforms will currently return a non-zero estimate,
// except if ASan is enabled.
size_t stack_size = WTF::GetUnderestimatedStackSize();
if (!stack_size) {
stack_frame_limit_ = GetFallbackStackLimit();
return;
}
// Adjust the following when running out of stack space in between turns of
// checking |IsSafeToRecurse()|. The required room size depends on the actions
// performed between turns and how well compiler optimizations apply.
static const int kStackRoomSize = 4096;
Address stack_base = reinterpret_cast<Address>(WTF::GetStackStart());
CHECK_GT(stack_size, static_cast<const size_t>(kStackRoomSize));
size_t stack_room = stack_size - kStackRoomSize;
CHECK_GT(stack_base, reinterpret_cast<Address>(stack_room));
stack_frame_limit_ = reinterpret_cast<uintptr_t>(stack_base - stack_room);
// If current stack use is already exceeding estimated limit, mark as
// disabled.
if (!IsSafeToRecurse())
DisableStackLimit();
}
} // namespace blink
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