| // 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. |
| |
| #ifndef COMPONENTS_ZUCCHINI_ARM_UTILS_H_ |
| #define COMPONENTS_ZUCCHINI_ARM_UTILS_H_ |
| |
| #include <stddef.h> |
| #include <stdint.h> |
| |
| #include "base/check_op.h" |
| #include "components/zucchini/address_translator.h" |
| #include "components/zucchini/buffer_view.h" |
| |
| namespace zucchini { |
| |
| // References: |
| // * AArch32 (32-bit ARM, AKA ARM32): |
| // https://static.docs.arm.com/ddi0406/c/DDI0406C_C_arm_architecture_reference_manual.pdf |
| // * AArch64 (64-bit ARM): |
| // https://static.docs.arm.com/ddi0487/da/DDI0487D_a_armv8_arm.pdf |
| |
| // Definitions (used in Zucchini): |
| // * |instr_rva|: Instruction RVA: The RVA where an instruction is located. In |
| // ARM mode and for AArch64 this is 4-byte aligned; in THUMB2 mode this is |
| // 2-byte aligned. |
| // * |code|: Instruction code: ARM instruction code as seen in manual. In ARM |
| // mode and for AArch64, this is a 32-bit int. In THUMB2 mode, this may be a |
| // 16-bit or 32-bit int. |
| // * |disp|: Displacement: For branch instructions (e.g.: B, BL, BLX, and |
| // conditional varieties) this is the value encoded in instruction bytes. |
| // * PC: Program Counter: In ARM mode this is |instr_rva + 8|; in THUMB2 mode |
| // this is |instr_rva + 4|; for AArch64 this is |instr_rva|. |
| // * |target_rva|: Target RVA: The RVA targeted by a branch instruction. |
| // |
| // These are related by: |
| // |code| = Fetch(image data at offset(|instr_rva|)). |
| // |disp| = Decode(|code|). |
| // PC = |instr_rva| + {8 in ARM mode, 4 in THUMB2 mode, 0 for AArch64}. |
| // |target_rva| = PC + |disp| - (see "BLX complication" below) |
| // |
| // Example 1 (ARM mode): |
| // 00103050: 00 01 02 EA B 00183458 |
| // |instr_rva| = 0x00103050 (4-byte aligned). |
| // |code| = 0xEA020100 (little endian fetched from data). |
| // |disp| = 0x00080400 (decoded from |code| with A24 -> B encoding T1). |
| // PC = |instr_rva| + 8 = 0x00103058 (ARM mode). |
| // |target_rva| = PC + |disp| = 0x00183458. |
| // |
| // Example 2 (THUMB2 mode): |
| // 001030A2: 00 F0 01 FA BL 001034A8 |
| // |instr_rva| = 0x001030A2 (2-byte aligned). |
| // |code| = 0xF000FA01 (special THUMB2 mode data fetch). |
| // |disp| = 0x00000402 (decoded from |code| with T24 -> BL encoding T1). |
| // PC = |instr_rva| + 4 = 0x001030A6 (THUMB2 mode). |
| // |target_rva| = PC + |disp| = 0x001034A8. |
| // |
| // Example 3 (AArch64): |
| // 0000000000305070: 03 02 01 14 B 000000000034587C |
| // |instr_rva| = 0x00305070 (4-byte aligned, assumed to fit in 32-bit). |
| // |code| = 0x14010203 (little endian fetchd from data). |
| // |disp| = 0x0004080C (decoded from |code| with Immd -> B). |
| // PC = |instr_rva| = 0x00305070 (AArch64). |
| // |target_rva| = PC + |disp| = 0x0034587C. |
| |
| // BLX complication: BLX transits between ARM mode and THUMB2 mode, and branches |
| // to an address. Therefore |instr_rva| must align by the "old" mode, and |
| // |target_rva| must align by the "new" mode. In particular: |
| // * BLX encoding A2 (ARM -> THUMB2): |instr_rva| is 4-byte aligned with |
| // PC = |instr_rva| + 8; |target_rva| is 2-byte aligned, and so |disp| is |
| // 2-byte aligned. |
| // * BLX encoding T2 (THUMB2 -> ARM): |instr_rva| is 2-byte aligned with |
| // PC = |instr_rva| + 4; |target_rva| is 4-byte aligned. Complication: BLX |
| // encoding T2 stores a bit |H| that corresponds to "2" in binary, but |H| |
| // must be set to 0. Thus the encoded value is effectively 4-byte aligned. So |
| // when computing |target_rva| by adding PC (2-byte aligned) to the stored |
| // value (4-byte aligned), the result must be rounded down to the nearest |
| // 4-byte aligned address. |
| // The last situation creates ambiguity in how |disp| is defined! Alternatives: |
| // (1) |disp| := |target_rva| - PC: So |code| <-> |disp| for BLX encoding T2, |
| // requires |instr_rva| % 4 to be determined, and adjustments made. |
| // (2) |disp| := Value stored in |code|: So |disp| <-> |target_rva| for BLX |
| // encoding T2 requires adjustment: |disp| -> |target_rva| needs to round |
| // down, whereas |target_rva| -> |disp| needs to round up. |
| // We adopt (2) to simplify |code| <-> |disp|, since that gets used. |
| |
| using arm_disp_t = int32_t; |
| |
| // Alignment requirement for |target_rva|, useful for |disp| <-> |target_rva| |
| // (also requires |instr_rva|). Alignment is determined by parsing |code| in |
| // *Decode() functions. kArmAlignFail is also defined to indicate parse failure. |
| // Alignments can be 2 or 4. These values are also used in the enum, so |
| // |x % align| with |x & (align - 1)| to compute alignment. |
| enum ArmAlign : uint32_t { |
| kArmAlignFail = 0U, |
| kArmAlign2 = 2U, |
| kArmAlign4 = 4U, |
| }; |
| |
| // Traits for rel32 address types (technically rel64 for AArch64 -- but we |
| // assume values are small enough), which form collections of strategies to |
| // process each rel32 address type. |
| template <typename ENUM_ADDR_TYPE, |
| ENUM_ADDR_TYPE ADDR_TYPE, |
| typename CODE_T, |
| CODE_T (*FETCH)(ConstBufferView, offset_t), |
| void (*STORE)(MutableBufferView, offset_t, CODE_T), |
| ArmAlign (*DECODE)(CODE_T, arm_disp_t*), |
| bool (*ENCODE)(arm_disp_t, CODE_T*), |
| bool (*READ)(rva_t, CODE_T, rva_t*), |
| bool (*WRITE)(rva_t, rva_t, CODE_T*)> |
| class ArmAddrTraits { |
| public: |
| static constexpr ENUM_ADDR_TYPE addr_type = ADDR_TYPE; |
| using code_t = CODE_T; |
| static constexpr CODE_T (*Fetch)(ConstBufferView, offset_t) = FETCH; |
| static constexpr void (*Store)(MutableBufferView, offset_t, CODE_T) = STORE; |
| static constexpr ArmAlign (*Decode)(CODE_T, arm_disp_t*) = DECODE; |
| static constexpr bool (*Encode)(arm_disp_t, CODE_T*) = ENCODE; |
| static constexpr bool (*Read)(rva_t, CODE_T, rva_t*) = READ; |
| static constexpr bool (*Write)(rva_t, rva_t, CODE_T*) = WRITE; |
| }; |
| |
| // Given THUMB2 instruction |code16|, returns 2 if it's from a 16-bit THUMB2 |
| // instruction, or 4 if it's from a 32-bit THUMB2 instruction. |
| inline int GetThumb2InstructionSize(uint16_t code16) { |
| return ((code16 & 0xF000) == 0xF000 || (code16 & 0xF800) == 0xE800) ? 4 : 2; |
| } |
| |
| // A translator for ARM mode and THUMB2 mode with static functions that |
| // translate among |code|, |disp|, and |target_rva|. |
| class AArch32Rel32Translator { |
| public: |
| // Rel32 address types enumeration. |
| enum AddrType : uint8_t { |
| ADDR_NONE = 0xFF, |
| // Naming: Here "A24" represents ARM mode instructions where |code| |
| // dedicates 24 bits (including sign bit) to specify |disp|. Similarly, "T8" |
| // represents THUMB2 mode instructions with 8 bits for |disp|. Currently |
| // only {A24, T8, T11, T20, T24} are defined. These are not to be confused |
| // with "B encoding A1", "B encoding T3", etc., which are specific encoding |
| // schemes given by the manual for the "B" (or other) instructions (only |
| // {A1, A2, T1, T2, T3, T4} are seen). |
| ADDR_A24 = 0, |
| ADDR_T8, |
| ADDR_T11, |
| ADDR_T20, |
| ADDR_T24, |
| NUM_ADDR_TYPE |
| }; |
| |
| AArch32Rel32Translator(); |
| AArch32Rel32Translator(const AArch32Rel32Translator&) = delete; |
| const AArch32Rel32Translator& operator=(const AArch32Rel32Translator&) = |
| delete; |
| |
| // Fetches the 32-bit ARM instruction |code| at |view[idx]|. |
| static inline uint32_t FetchArmCode32(ConstBufferView view, offset_t idx) { |
| return view.read<uint32_t>(idx); |
| } |
| |
| // Fetches the 16-bit THUMB2 instruction |code| at |view[idx]|. |
| static inline uint16_t FetchThumb2Code16(ConstBufferView view, offset_t idx) { |
| return view.read<uint16_t>(idx); |
| } |
| |
| // Fetches the 32-bit THUMB2 instruction |code| at |view[idx]|. |
| static inline uint32_t FetchThumb2Code32(ConstBufferView view, offset_t idx) { |
| // By convention, 32-bit THUMB2 instructions are written (as seen later) as: |
| // [byte3, byte2, byte1, byte0]. |
| // However (assuming little-endian ARM) the in-memory representation is |
| // [byte2, byte3, byte0, byte1]. |
| return (static_cast<uint32_t>(view.read<uint16_t>(idx)) << 16) | |
| view.read<uint16_t>(idx + 2); |
| } |
| |
| // Stores the 32-bit ARM instruction |code| to |mutable_view[idx]|. |
| static inline void StoreArmCode32(MutableBufferView mutable_view, |
| offset_t idx, |
| uint32_t code) { |
| mutable_view.write<uint32_t>(idx, code); |
| } |
| |
| // Stores the 16-bit THUMB2 instruction |code| to |mutable_view[idx]|. |
| static inline void StoreThumb2Code16(MutableBufferView mutable_view, |
| offset_t idx, |
| uint16_t code) { |
| mutable_view.write<uint16_t>(idx, code); |
| } |
| |
| // Stores the next 32-bit THUMB2 instruction |code| to |mutable_view[idx]|. |
| static inline void StoreThumb2Code32(MutableBufferView mutable_view, |
| offset_t idx, |
| uint32_t code) { |
| mutable_view.write<uint16_t>(idx, static_cast<uint16_t>(code >> 16)); |
| mutable_view.write<uint16_t>(idx + 2, static_cast<uint16_t>(code & 0xFFFF)); |
| } |
| |
| // The following functions convert |code| (16-bit or 32-bit) from/to |disp| |
| // or |target_rva|, for specific branch instruction types. |
| // Read*() and write*() functions convert between |code| and |target_rva|. |
| // * Decode*() determines whether |code16/code32| is a branch instruction |
| // of a specific type. If so, then extracts |*disp| and returns the required |
| // ArmAlign. Otherwise returns kArmAlignFail. |
| // * Encode*() determines whether |*code16/*code32| is a branch instruction of |
| // a specific type, and whether it can accommodate |disp|. If so, then |
| // re-encodes |*code32| using |disp|, and returns true. Otherwise returns |
| // false. |
| // * Read*() is similar to Decode*(), but on success, extracts |*target_rva| |
| // using |instr_rva| as aid, performs the proper alignment, and returns |
| // true. Otherwise returns false. |
| // * Write*() is similar to Encode*(), takes |target_rva| instead, and uses |
| // |instr_rva| as aid. |
| static ArmAlign DecodeA24(uint32_t code32, arm_disp_t* disp); |
| static bool EncodeA24(arm_disp_t disp, uint32_t* code32); |
| // TODO(huangs): Refactor the Read*() functions: These are identical |
| // except for Decode*() and Get*TargetRvaFromDisp(). |
| static bool ReadA24(rva_t instr_rva, uint32_t code32, rva_t* target_rva); |
| static bool WriteA24(rva_t instr_rva, rva_t target_rva, uint32_t* code32); |
| |
| static ArmAlign DecodeT8(uint16_t code16, arm_disp_t* disp); |
| static bool EncodeT8(arm_disp_t disp, uint16_t* code16); |
| static bool ReadT8(rva_t instr_rva, uint16_t code16, rva_t* target_rva); |
| static bool WriteT8(rva_t instr_rva, rva_t target_rva, uint16_t* code16); |
| |
| static ArmAlign DecodeT11(uint16_t code16, arm_disp_t* disp); |
| static bool EncodeT11(arm_disp_t disp, uint16_t* code16); |
| static bool ReadT11(rva_t instr_rva, uint16_t code16, rva_t* target_rva); |
| static bool WriteT11(rva_t instr_rva, rva_t target_rva, uint16_t* code16); |
| |
| static ArmAlign DecodeT20(uint32_t code32, arm_disp_t* disp); |
| static bool EncodeT20(arm_disp_t disp, uint32_t* code32); |
| static bool ReadT20(rva_t instr_rva, uint32_t code32, rva_t* target_rva); |
| static bool WriteT20(rva_t instr_rva, rva_t target_rva, uint32_t* code32); |
| |
| static ArmAlign DecodeT24(uint32_t code32, arm_disp_t* disp); |
| static bool EncodeT24(arm_disp_t disp, uint32_t* code32); |
| static bool ReadT24(rva_t instr_rva, uint32_t code32, rva_t* target_rva); |
| static bool WriteT24(rva_t instr_rva, rva_t target_rva, uint32_t* code32); |
| |
| // Computes |target_rva| from |instr_rva| and |disp| in ARM mode. |
| static inline rva_t GetArmTargetRvaFromDisp(rva_t instr_rva, |
| arm_disp_t disp, |
| ArmAlign align) { |
| rva_t ret = static_cast<rva_t>(instr_rva + 8 + disp); |
| // Align down. |
| DCHECK_NE(align, kArmAlignFail); |
| return ret - (ret & static_cast<rva_t>(align - 1)); |
| } |
| |
| // Computes |target_rva| from |instr_rva| and |disp| in THUMB2 mode. |
| static inline rva_t GetThumb2TargetRvaFromDisp(rva_t instr_rva, |
| arm_disp_t disp, |
| ArmAlign align) { |
| rva_t ret = static_cast<rva_t>(instr_rva + 4 + disp); |
| // Align down. |
| DCHECK_NE(align, kArmAlignFail); |
| return ret - (ret & static_cast<rva_t>(align - 1)); |
| } |
| |
| // Computes |disp| from |instr_rva| and |target_rva| in ARM mode. |
| static inline arm_disp_t GetArmDispFromTargetRva(rva_t instr_rva, |
| rva_t target_rva, |
| ArmAlign align) { |
| // Assumes that |instr_rva + 8| does not overflow. |
| arm_disp_t ret = static_cast<arm_disp_t>(target_rva) - |
| static_cast<arm_disp_t>(instr_rva + 8); |
| // Align up. |
| DCHECK_NE(align, kArmAlignFail); |
| return ret + ((-ret) & static_cast<arm_disp_t>(align - 1)); |
| } |
| |
| // Computes |disp| from |instr_rva| and |target_rva| in THUMB2 mode. |
| static inline arm_disp_t GetThumb2DispFromTargetRva(rva_t instr_rva, |
| rva_t target_rva, |
| ArmAlign align) { |
| // Assumes that |instr_rva + 4| does not overflow. |
| arm_disp_t ret = static_cast<arm_disp_t>(target_rva) - |
| static_cast<arm_disp_t>(instr_rva + 4); |
| // Align up. |
| DCHECK_NE(align, kArmAlignFail); |
| return ret + ((-ret) & static_cast<arm_disp_t>(align - 1)); |
| } |
| |
| // Strategies to process each rel32 address type. |
| using AddrTraits_A24 = ArmAddrTraits<AddrType, |
| ADDR_A24, |
| uint32_t, |
| FetchArmCode32, |
| StoreArmCode32, |
| DecodeA24, |
| EncodeA24, |
| ReadA24, |
| WriteA24>; |
| using AddrTraits_T8 = ArmAddrTraits<AddrType, |
| ADDR_T8, |
| uint16_t, |
| FetchThumb2Code16, |
| StoreThumb2Code16, |
| DecodeT8, |
| EncodeT8, |
| ReadT8, |
| WriteT8>; |
| using AddrTraits_T11 = ArmAddrTraits<AddrType, |
| ADDR_T11, |
| uint16_t, |
| FetchThumb2Code16, |
| StoreThumb2Code16, |
| DecodeT11, |
| EncodeT11, |
| ReadT11, |
| WriteT11>; |
| using AddrTraits_T20 = ArmAddrTraits<AddrType, |
| ADDR_T20, |
| uint32_t, |
| FetchThumb2Code32, |
| StoreThumb2Code32, |
| DecodeT20, |
| EncodeT20, |
| ReadT20, |
| WriteT20>; |
| using AddrTraits_T24 = ArmAddrTraits<AddrType, |
| ADDR_T24, |
| uint32_t, |
| FetchThumb2Code32, |
| StoreThumb2Code32, |
| DecodeT24, |
| EncodeT24, |
| ReadT24, |
| WriteT24>; |
| }; |
| |
| // Translator for AArch64, which is simpler than 32-bit ARM. Although pointers |
| // are 64-bit, displacements are within 32-bit. |
| class AArch64Rel32Translator { |
| public: |
| // Rel64 address types enumeration. |
| enum AddrType : uint8_t { |
| ADDR_NONE = 0xFF, |
| ADDR_IMMD14 = 0, |
| ADDR_IMMD19, |
| ADDR_IMMD26, |
| NUM_ADDR_TYPE |
| }; |
| |
| // Although RVA for 64-bit architecture can be 64-bit in length, we make the |
| // bold assumption that for ELF images that RVA will stay nicely in 32-bit! |
| AArch64Rel32Translator(); |
| AArch64Rel32Translator(const AArch64Rel32Translator&) = delete; |
| const AArch64Rel32Translator& operator=(const AArch64Rel32Translator&) = |
| delete; |
| |
| static inline uint32_t FetchCode32(ConstBufferView view, offset_t idx) { |
| return view.read<uint32_t>(idx); |
| } |
| |
| static inline void StoreCode32(MutableBufferView mutable_view, |
| offset_t idx, |
| uint32_t code) { |
| mutable_view.write<uint32_t>(idx, code); |
| } |
| |
| // Conversion functions for |code32| from/to |disp| or |target_rva|, similar |
| // to the counterparts in AArch32Rel32Translator. |
| static ArmAlign DecodeImmd14(uint32_t code32, arm_disp_t* disp); |
| static bool EncodeImmd14(arm_disp_t disp, uint32_t* code32); |
| // TODO(huangs): Refactor the Read*() functions: These are identical |
| // except for Decode*(). |
| static bool ReadImmd14(rva_t instr_rva, uint32_t code32, rva_t* target_rva); |
| static bool WriteImmd14(rva_t instr_rva, rva_t target_rva, uint32_t* code32); |
| |
| static ArmAlign DecodeImmd19(uint32_t code32, arm_disp_t* disp); |
| static bool EncodeImmd19(arm_disp_t disp, uint32_t* code32); |
| static bool ReadImmd19(rva_t instr_rva, uint32_t code32, rva_t* target_rva); |
| static bool WriteImmd19(rva_t instr_rva, rva_t target_rva, uint32_t* code32); |
| |
| static ArmAlign DecodeImmd26(uint32_t code32, arm_disp_t* disp); |
| static bool EncodeImmd26(arm_disp_t disp, uint32_t* code32); |
| static bool ReadImmd26(rva_t instr_rva, uint32_t code32, rva_t* target_rva); |
| static bool WriteImmd26(rva_t instr_rva, rva_t target_rva, uint32_t* code32); |
| |
| static inline rva_t GetTargetRvaFromDisp(rva_t instr_rva, arm_disp_t disp) { |
| return static_cast<rva_t>(instr_rva + disp); |
| } |
| |
| static inline arm_disp_t GetDispFromTargetRva(rva_t instr_rva, |
| rva_t target_rva) { |
| return static_cast<arm_disp_t>(target_rva - instr_rva); |
| } |
| |
| // Strategies to process each rel32 address type. |
| using AddrTraits_Immd14 = ArmAddrTraits<AddrType, |
| ADDR_IMMD14, |
| uint32_t, |
| FetchCode32, |
| StoreCode32, |
| DecodeImmd14, |
| EncodeImmd14, |
| ReadImmd14, |
| WriteImmd14>; |
| using AddrTraits_Immd19 = ArmAddrTraits<AddrType, |
| ADDR_IMMD19, |
| uint32_t, |
| FetchCode32, |
| StoreCode32, |
| DecodeImmd19, |
| EncodeImmd19, |
| ReadImmd19, |
| WriteImmd19>; |
| using AddrTraits_Immd26 = ArmAddrTraits<AddrType, |
| ADDR_IMMD26, |
| uint32_t, |
| FetchCode32, |
| StoreCode32, |
| DecodeImmd26, |
| EncodeImmd26, |
| ReadImmd26, |
| WriteImmd26>; |
| }; |
| |
| } // namespace zucchini |
| |
| #endif // COMPONENTS_ZUCCHINI_ARM_UTILS_H_ |