76 lines
2.8 KiB
C
76 lines
2.8 KiB
C
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// Copyright 2019 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef BASE_PROFILER_ARM_CFI_TABLE_H_
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#define BASE_PROFILER_ARM_CFI_TABLE_H_
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#include <memory>
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#include "base/containers/buffer_iterator.h"
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#include "base/containers/span.h"
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#include "base/macros.h"
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#include "base/optional.h"
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namespace base {
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// This class implements methods to read and parse the arm Call Frame
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// Information (CFI) for Chrome, which contains tables for unwinding Chrome
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// functions. For detailed description of the format, see
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// extract_unwind_tables.py.
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class BASE_EXPORT ArmCFITable {
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public:
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// The CFI information that correspond to an instruction. {0, 0} is a valid
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// entry and should be interpreted as the default rule:
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// .cfa: sp; .cfa = lr (link register).
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struct FrameEntry {
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// The offset of the call frame address (CFA) of previous function, relative
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// to the current stack pointer. Rule for unwinding CFA:
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// .cfa: sp + cfa_offset.
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uint16_t cfa_offset = 0;
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// The offset of location of return address (RA), relative to the previous
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// call frame address. Rule for unwinding RA:
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// .ra = *(cfa - ra_offset).
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uint16_t ra_offset = 0;
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};
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// Parses |cfi_data| and creates a ArmCFITable that reads from it.
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// |cfi_data| is required to remain valid for the lifetime of the object.
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static std::unique_ptr<ArmCFITable> Parse(span<const uint8_t> cfi_data);
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ArmCFITable(span<const uint32_t> function_addresses,
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span<const uint16_t> entry_data_indices,
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span<const uint8_t> entry_data);
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~ArmCFITable();
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// Finds the CFI row for the given |address| in terms of offset from the
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// start of the current binary. Concurrent calls are thread safe.
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Optional<FrameEntry> FindEntryForAddress(uintptr_t address) const;
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size_t GetTableSizeForTesting() const { return function_addresses_.size(); }
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private:
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// The UNW_INDEX table allows readers to map functions start addresses to
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// that function's respective entry in the UNW_DATA table.
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// - A function's start address is at 0x123, and
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// - function_addresses_[2] == 0x123, and
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// - entry_data_indices_[2] = 42, then
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// - entry_data_[42] is the corresponding entry in the UNW_DATA table for
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// the function with the start address of 0x123
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//
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// Note that function_addresses is sorted to facilitate easy lookup.
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const span<const uint32_t> function_addresses_;
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const span<const uint16_t> entry_data_indices_;
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// A reference to the UNW_DATA table. Each entry in the UNW_DATA table
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// corresponds to a function, which in turn corresponds to an array of
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// CFIDataRows. (see arm_cfi_reader.cc).
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const span<const uint8_t> entry_data_;
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DISALLOW_COPY_AND_ASSIGN(ArmCFITable);
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};
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} // namespace base
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#endif // BASE_PROFILER_ARM_CFI_TABLE_H_
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