rel32_finder.h | Explore in Territory

// Copyright 2017 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef COMPONENTS_ZUCCHINI_REL32_FINDER_H_
#define COMPONENTS_ZUCCHINI_REL32_FINDER_H_

#include <stddef.h>

#include <deque>

#include "components/zucchini/address_translator.h"
#include "components/zucchini/arm_utils.h"
#include "components/zucchini/buffer_view.h"
#include "components/zucchini/image_utils.h"

namespace zucchini {

// See README.md for definitions on abs32 and rel32 references. The following
// are assumed:
// * Abs32 reference bodies have fixed widths.
// * Rel32 locations can be identified by heuristically disassembling machine
//   code, and errors are tolerated.
// * The collection all abs32 and rel32 reference bodies do not overlap.

// A class to visit non-empty contiguous gaps in |region| that lie outside of
// |abs32_locations| elements, each with a body that spans |abs32_width_| bytes.
// For example, given:
//   region = [base_ + 4, base_ + 26),
//   abs32_locations = {2, 6, 15, 20, 27},
//   abs32_width_ = 4,
// the following is obtained:
//             111111111122222222223   -> offsets
//   0123456789012345678901234567890
//   ....**********************.....   -> region = *
//     ^   ^        ^    ^      ^      -> abs32 locations
//     aaaaaaaa     aaaa aaaa   aaaa   -> abs32 bodies
//   ....------*****----*----**.....   -> regions excluding abs32 -> 3 gaps
// The resulting gaps (non-empty, so [6, 6) is excluded) are:
//   [10, 15), [19, 20), [24, 26).
// These gaps can then be passed to Rel32Finder (below) to find rel32 references
// with bodies that are guaranteed to not overlap with any abs32 bodies.
class Abs32GapFinder { … };

// A class to scan regions within an image to find successive rel32 references.
// Architecture-specific parsing and result extraction are delegated to
// inherited classes (say, Rel32Finder_Impl). Sample extraction loop, combined
// with Abs32GapFinder usage:
//
//   Abs32GapFinder gap_finder(...);
//   Rel32Finder_Impl finder(...);
//   while (gap_finder.FindNext()) {
//     rel_finder.SetRegion(gap_finder.GetGap());
//     while (rel_finder.FindNext()) {
//       auto rel32 = rel_finder.GetRel32();  // In Rel32Finder_Impl.
//       if (architecture_specific_validation(rel32)) {
//         rel_finder.Accept();
//         // Store rel32.
//       }
//     }
//   }
class Rel32Finder { … };

// Parsing for X86 or X64: we perform naive scan for opcodes that have rel32 as
// an argument, and disregard instruction alignment.
class Rel32FinderIntel : public Rel32Finder { … };

// X86 instructions.
class Rel32FinderX86 : public Rel32FinderIntel { … };

// X64 instructions.
class Rel32FinderX64 : public Rel32FinderIntel { … };

// Base class for ARM (AArch32 and AArch64) instructions.
template <typename ADDR_TYPE>
class Rel32FinderArm : public Rel32Finder { … };

// AArch32 instructions.
class Rel32FinderAArch32
    : public Rel32FinderArm<AArch32Rel32Translator::AddrType> { … };

// AArch64 instructions.
class Rel32FinderAArch64
    : public Rel32FinderArm<AArch64Rel32Translator::AddrType> { … };

}  // namespace zucchini

#endif  // COMPONENTS_ZUCCHINI_REL32_FINDER_H_
chromium/components/zucchini/rel32_finder.h
