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diff --git a/src/profiling/common/unwind_support.h b/src/profiling/common/unwind_support.h
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+++ b/src/profiling/common/unwind_support.h
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+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef SRC_PROFILING_COMMON_UNWIND_SUPPORT_H_
+#define SRC_PROFILING_COMMON_UNWIND_SUPPORT_H_
+
+// defines PERFETTO_BUILDFLAG
+#include "perfetto/base/build_config.h"
+
+#include <memory>
+#include <string>
+
+#include <unwindstack/Maps.h>
+#include <unwindstack/Unwinder.h>
+#if PERFETTO_BUILDFLAG(PERFETTO_ANDROID_BUILD)
+#include <unwindstack/DexFiles.h>
+#include <unwindstack/JitDebug.h>
+#endif
+
+#include "perfetto/base/logging.h"
+#include "perfetto/base/time.h"
+#include "perfetto/ext/base/scoped_file.h"
+
+namespace perfetto {
+namespace profiling {
+
+// libunwindstack's FrameData annotated with the build_id.
+struct FrameData {
+  FrameData(unwindstack::FrameData f, std::string id)
+      : frame(std::move(f)), build_id(std::move(id)) {}
+
+  unwindstack::FrameData frame;
+  std::string build_id;
+};
+
+// Read /proc/[pid]/maps from an open file descriptor.
+// TODO(fmayer): Figure out deduplication to other maps.
+class FDMaps : public unwindstack::Maps {
+ public:
+  FDMaps(base::ScopedFile fd);
+
+  FDMaps(const FDMaps&) = delete;
+  FDMaps& operator=(const FDMaps&) = delete;
+
+  FDMaps(FDMaps&& m) : Maps(std::move(m)) { fd_ = std::move(m.fd_); }
+
+  FDMaps& operator=(FDMaps&& m) {
+    if (&m != this)
+      fd_ = std::move(m.fd_);
+    Maps::operator=(std::move(m));
+    return *this;
+  }
+
+  virtual ~FDMaps() override = default;
+
+  bool Parse() override;
+  void Reset();
+
+ private:
+  base::ScopedFile fd_;
+};
+
+class FDMemory : public unwindstack::Memory {
+ public:
+  FDMemory(base::ScopedFile mem_fd);
+  size_t Read(uint64_t addr, void* dst, size_t size) override;
+
+ private:
+  base::ScopedFile mem_fd_;
+};
+
+// Overlays size bytes pointed to by stack for addresses in [sp, sp + size).
+// Addresses outside of that range are read from mem_fd, which should be an fd
+// that opened /proc/[pid]/mem.
+class StackOverlayMemory : public unwindstack::Memory {
+ public:
+  StackOverlayMemory(std::shared_ptr<unwindstack::Memory> mem,
+                     uint64_t sp,
+                     const uint8_t* stack,
+                     size_t size);
+  size_t Read(uint64_t addr, void* dst, size_t size) override;
+
+ private:
+  std::shared_ptr<unwindstack::Memory> mem_;
+  const uint64_t sp_;
+  const uint64_t stack_end_;
+  const uint8_t* const stack_;
+};
+
+struct UnwindingMetadata {
+  UnwindingMetadata(base::ScopedFile maps_fd, base::ScopedFile mem_fd);
+
+  // move-only
+  UnwindingMetadata(const UnwindingMetadata&) = delete;
+  UnwindingMetadata& operator=(const UnwindingMetadata&) = delete;
+
+  UnwindingMetadata(UnwindingMetadata&&) = default;
+  UnwindingMetadata& operator=(UnwindingMetadata&&) = default;
+
+  void ReparseMaps();
+
+  FrameData AnnotateFrame(unwindstack::FrameData frame);
+
+  FDMaps fd_maps;
+  // The API of libunwindstack expects shared_ptr for Memory.
+  std::shared_ptr<unwindstack::Memory> fd_mem;
+  uint64_t reparses = 0;
+  base::TimeMillis last_maps_reparse_time{0};
+#if PERFETTO_BUILDFLAG(PERFETTO_ANDROID_BUILD)
+  std::unique_ptr<unwindstack::JitDebug> jit_debug;
+  std::unique_ptr<unwindstack::DexFiles> dex_files;
+#endif
+};
+
+std::string StringifyLibUnwindstackError(unwindstack::ErrorCode);
+
+}  // namespace profiling
+}  // namespace perfetto
+
+#endif  // SRC_PROFILING_COMMON_UNWIND_SUPPORT_H_