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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 <memory>
#include "base/containers/buffer_iterator.h"
#include "base/containers/span.h"
#include "base/macros.h"
#include "base/optional.h"
namespace base {
// This class implements methods to read and parse the arm Call Frame
// Information (CFI) for Chrome, which contains tables for unwinding Chrome
// functions. For detailed description of the format, see
class BASE_EXPORT ArmCFITable {
// The CFI information that correspond to an instruction. {0, 0} is a valid
// entry and should be interpreted as the default rule:
// .cfa: sp; .cfa = lr (link register).
struct FrameEntry {
// The offset of the call frame address (CFA) of previous function, relative
// to the current stack pointer. Rule for unwinding CFA:
// .cfa: sp + cfa_offset.
uint16_t cfa_offset = 0;
// The offset of location of return address (RA), relative to the previous
// call frame address. Rule for unwinding RA:
// .ra = *(cfa - ra_offset).
uint16_t ra_offset = 0;
// Parses |cfi_data| and creates a ArmCFITable that reads from it.
// |cfi_data| is required to remain valid for the lifetime of the object.
static std::unique_ptr<ArmCFITable> Parse(span<const uint8_t> cfi_data);
ArmCFITable(span<const uint32_t> function_addresses,
span<const uint16_t> entry_data_indices,
span<const uint8_t> entry_data);
// Finds the CFI row for the given |address| in terms of offset from the
// start of the current binary. Concurrent calls are thread safe.
Optional<FrameEntry> FindEntryForAddress(uintptr_t address) const;
size_t GetTableSizeForTesting() const { return function_addresses_.size(); }
// The UNW_INDEX table allows readers to map functions start addresses to
// that function's respective entry in the UNW_DATA table.
// - A function's start address is at 0x123, and
// - function_addresses_[2] == 0x123, and
// - entry_data_indices_[2] = 42, then
// - entry_data_[42] is the corresponding entry in the UNW_DATA table for
// the function with the start address of 0x123
// Note that function_addresses is sorted to facilitate easy lookup.
const span<const uint32_t> function_addresses_;
const span<const uint16_t> entry_data_indices_;
// A reference to the UNW_DATA table. Each entry in the UNW_DATA table
// corresponds to a function, which in turn corresponds to an array of
// CFIDataRows. (see
const span<const uint8_t> entry_data_;
} // namespace base