Import compiler-rt r182741.vendor/compiler-rt/compiler-rt-r182741

1 files changed, 117 insertions, 0 deletions

diff --git a/lib/asan/asan_fake_stack.h b/lib/asan/asan_fake_stack.h
new file mode 100644
index 000000000000..308b4c571832
--- /dev/null
+++ b/lib/asan/asan_fake_stack.h
@@ -0,0 +1,117 @@
+//===-- asan_fake_stack.h ---------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is a part of AddressSanitizer, an address sanity checker.
+//
+// ASan-private header for asan_fake_stack.cc
+//===----------------------------------------------------------------------===//
+
+#ifndef ASAN_FAKE_STACK_H
+#define ASAN_FAKE_STACK_H
+
+namespace __asan {
+
+// Fake stack frame contains local variables of one function.
+struct FakeFrame {
+  uptr magic;  // Modified by the instrumented code.
+  uptr descr;  // Modified by the instrumented code.
+  uptr pc;     // Modified by the instrumented code.
+  u64 real_stack     : 48;
+  u64 size_minus_one : 16;
+  // End of the first 32 bytes.
+  // The rest should not be used when the frame is active.
+  FakeFrame *next;
+};
+
+struct FakeFrameFifo {
+ public:
+  void FifoPush(FakeFrame *node);
+  FakeFrame *FifoPop();
+ private:
+  FakeFrame *first_, *last_;
+};
+
+template<uptr kMaxNumberOfFrames>
+class FakeFrameLifo {
+ public:
+  explicit FakeFrameLifo(LinkerInitialized) {}
+  FakeFrameLifo() : n_frames_(0) {}
+  void LifoPush(FakeFrame *node) {
+    CHECK_LT(n_frames_, kMaxNumberOfFrames);
+    frames_[n_frames_++] = node;
+  }
+  void LifoPop() {
+    CHECK(n_frames_);
+    n_frames_--;
+  }
+  FakeFrame *top() {
+    if (n_frames_ == 0)
+      return 0;
+    return frames_[n_frames_ - 1];
+  }
+ private:
+  uptr n_frames_;
+  FakeFrame *frames_[kMaxNumberOfFrames];
+};
+
+// For each thread we create a fake stack and place stack objects on this fake
+// stack instead of the real stack. The fake stack is not really a stack but
+// a fast malloc-like allocator so that when a function exits the fake stack
+// is not poped but remains there for quite some time until gets used again.
+// So, we poison the objects on the fake stack when function returns.
+// It helps us find use-after-return bugs.
+// We can not rely on __asan_stack_free being called on every function exit,
+// so we maintain a lifo list of all current fake frames and update it on every
+// call to __asan_stack_malloc.
+class FakeStack {
+ public:
+  FakeStack();
+  explicit FakeStack(LinkerInitialized x) : call_stack_(x) {}
+  void Init(uptr stack_size);
+  void StopUsingFakeStack() { alive_ = false; }
+  void Cleanup();
+  uptr AllocateStack(uptr size, uptr real_stack);
+  static void OnFree(uptr ptr, uptr size, uptr real_stack);
+  // Return the bottom of the maped region.
+  uptr AddrIsInFakeStack(uptr addr);
+  bool StackSize() { return stack_size_; }
+
+ private:
+  static const uptr kMinStackFrameSizeLog = 9;  // Min frame is 512B.
+  static const uptr kMaxStackFrameSizeLog = 16;  // Max stack frame is 64K.
+  static const uptr kMaxStackMallocSize = 1 << kMaxStackFrameSizeLog;
+  static const uptr kNumberOfSizeClasses =
+      kMaxStackFrameSizeLog - kMinStackFrameSizeLog + 1;
+  static const uptr kMaxRecursionDepth = 1023;
+
+  bool AddrIsInSizeClass(uptr addr, uptr size_class);
+
+  // Each size class should be large enough to hold all frames.
+  uptr ClassMmapSize(uptr size_class);
+
+  uptr ClassSize(uptr size_class) {
+    return 1UL << (size_class + kMinStackFrameSizeLog);
+  }
+
+  void DeallocateFrame(FakeFrame *fake_frame);
+
+  uptr ComputeSizeClass(uptr alloc_size);
+  void AllocateOneSizeClass(uptr size_class);
+
+  uptr stack_size_;
+  bool   alive_;
+
+  uptr allocated_size_classes_[kNumberOfSizeClasses];
+  FakeFrameFifo size_classes_[kNumberOfSizeClasses];
+  FakeFrameLifo<kMaxRecursionDepth> call_stack_;
+};
+
+}  // namespace __asan
+
+#endif  // ASAN_FAKE_STACK_H