| //===-- xray_mips.cpp -------------------------------------------*- C++ -*-===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file is a part of XRay, a dynamic runtime instrumentation system. |
| // |
| // Implementation of MIPS-specific routines (32-bit). |
| // |
| //===----------------------------------------------------------------------===// |
| #include "sanitizer_common/sanitizer_common.h" |
| #include "xray_defs.h" |
| #include "xray_interface_internal.h" |
| #include <atomic> |
| |
| namespace __xray { |
| |
| // The machine codes for some instructions used in runtime patching. |
| enum PatchOpcodes : uint32_t { |
| PO_ADDIU = 0x24000000, // addiu rt, rs, imm |
| PO_SW = 0xAC000000, // sw rt, offset(sp) |
| PO_LUI = 0x3C000000, // lui rs, %hi(address) |
| PO_ORI = 0x34000000, // ori rt, rs, %lo(address) |
| PO_JALR = 0x0000F809, // jalr rs |
| PO_LW = 0x8C000000, // lw rt, offset(address) |
| PO_B44 = 0x1000000b, // b #44 |
| PO_NOP = 0x0, // nop |
| }; |
| |
| enum RegNum : uint32_t { |
| RN_T0 = 0x8, |
| RN_T9 = 0x19, |
| RN_RA = 0x1F, |
| RN_SP = 0x1D, |
| }; |
| |
| inline static uint32_t encodeInstruction(uint32_t Opcode, uint32_t Rs, |
| uint32_t Rt, |
| uint32_t Imm) XRAY_NEVER_INSTRUMENT { |
| return (Opcode | Rs << 21 | Rt << 16 | Imm); |
| } |
| |
| inline static uint32_t |
| encodeSpecialInstruction(uint32_t Opcode, uint32_t Rs, uint32_t Rt, uint32_t Rd, |
| uint32_t Imm) XRAY_NEVER_INSTRUMENT { |
| return (Rs << 21 | Rt << 16 | Rd << 11 | Imm << 6 | Opcode); |
| } |
| |
| inline static bool patchSled(const bool Enable, const uint32_t FuncId, |
| const XRaySledEntry &Sled, |
| void (*TracingHook)()) XRAY_NEVER_INSTRUMENT { |
| // When |Enable| == true, |
| // We replace the following compile-time stub (sled): |
| // |
| // xray_sled_n: |
| // B .tmpN |
| // 11 NOPs (44 bytes) |
| // .tmpN |
| // ADDIU T9, T9, 44 |
| // |
| // With the following runtime patch: |
| // |
| // xray_sled_n (32-bit): |
| // addiu sp, sp, -8 ;create stack frame |
| // nop |
| // sw ra, 4(sp) ;save return address |
| // sw t9, 0(sp) ;save register t9 |
| // lui t9, %hi(__xray_FunctionEntry/Exit) |
| // ori t9, t9, %lo(__xray_FunctionEntry/Exit) |
| // lui t0, %hi(function_id) |
| // jalr t9 ;call Tracing hook |
| // ori t0, t0, %lo(function_id) ;pass function id (delay slot) |
| // lw t9, 0(sp) ;restore register t9 |
| // lw ra, 4(sp) ;restore return address |
| // addiu sp, sp, 8 ;delete stack frame |
| // |
| // We add 44 bytes to t9 because we want to adjust the function pointer to |
| // the actual start of function i.e. the address just after the noop sled. |
| // We do this because gp displacement relocation is emitted at the start of |
| // of the function i.e after the nop sled and to correctly calculate the |
| // global offset table address, t9 must hold the address of the instruction |
| // containing the gp displacement relocation. |
| // FIXME: Is this correct for the static relocation model? |
| // |
| // Replacement of the first 4-byte instruction should be the last and atomic |
| // operation, so that the user code which reaches the sled concurrently |
| // either jumps over the whole sled, or executes the whole sled when the |
| // latter is ready. |
| // |
| // When |Enable|==false, we set back the first instruction in the sled to be |
| // B #44 |
| |
| uint32_t *Address = reinterpret_cast<uint32_t *>(Sled.address()); |
| if (Enable) { |
| uint32_t LoTracingHookAddr = |
| reinterpret_cast<int32_t>(TracingHook) & 0xffff; |
| uint32_t HiTracingHookAddr = |
| (reinterpret_cast<int32_t>(TracingHook) >> 16) & 0xffff; |
| uint32_t LoFunctionID = FuncId & 0xffff; |
| uint32_t HiFunctionID = (FuncId >> 16) & 0xffff; |
| Address[2] = encodeInstruction(PatchOpcodes::PO_SW, RegNum::RN_SP, |
| RegNum::RN_RA, 0x4); |
| Address[3] = encodeInstruction(PatchOpcodes::PO_SW, RegNum::RN_SP, |
| RegNum::RN_T9, 0x0); |
| Address[4] = encodeInstruction(PatchOpcodes::PO_LUI, 0x0, RegNum::RN_T9, |
| HiTracingHookAddr); |
| Address[5] = encodeInstruction(PatchOpcodes::PO_ORI, RegNum::RN_T9, |
| RegNum::RN_T9, LoTracingHookAddr); |
| Address[6] = encodeInstruction(PatchOpcodes::PO_LUI, 0x0, RegNum::RN_T0, |
| HiFunctionID); |
| Address[7] = encodeSpecialInstruction(PatchOpcodes::PO_JALR, RegNum::RN_T9, |
| 0x0, RegNum::RN_RA, 0X0); |
| Address[8] = encodeInstruction(PatchOpcodes::PO_ORI, RegNum::RN_T0, |
| RegNum::RN_T0, LoFunctionID); |
| Address[9] = encodeInstruction(PatchOpcodes::PO_LW, RegNum::RN_SP, |
| RegNum::RN_T9, 0x0); |
| Address[10] = encodeInstruction(PatchOpcodes::PO_LW, RegNum::RN_SP, |
| RegNum::RN_RA, 0x4); |
| Address[11] = encodeInstruction(PatchOpcodes::PO_ADDIU, RegNum::RN_SP, |
| RegNum::RN_SP, 0x8); |
| uint32_t CreateStackSpaceInstr = encodeInstruction( |
| PatchOpcodes::PO_ADDIU, RegNum::RN_SP, RegNum::RN_SP, 0xFFF8); |
| std::atomic_store_explicit( |
| reinterpret_cast<std::atomic<uint32_t> *>(Address), |
| uint32_t(CreateStackSpaceInstr), std::memory_order_release); |
| } else { |
| std::atomic_store_explicit( |
| reinterpret_cast<std::atomic<uint32_t> *>(Address), |
| uint32_t(PatchOpcodes::PO_B44), std::memory_order_release); |
| } |
| return true; |
| } |
| |
| bool patchFunctionEntry(const bool Enable, const uint32_t FuncId, |
| const XRaySledEntry &Sled, |
| void (*Trampoline)()) XRAY_NEVER_INSTRUMENT { |
| return patchSled(Enable, FuncId, Sled, Trampoline); |
| } |
| |
| bool patchFunctionExit(const bool Enable, const uint32_t FuncId, |
| const XRaySledEntry &Sled) XRAY_NEVER_INSTRUMENT { |
| return patchSled(Enable, FuncId, Sled, __xray_FunctionExit); |
| } |
| |
| bool patchFunctionTailExit(const bool Enable, const uint32_t FuncId, |
| const XRaySledEntry &Sled) XRAY_NEVER_INSTRUMENT { |
| // FIXME: In the future we'd need to distinguish between non-tail exits and |
| // tail exits for better information preservation. |
| return patchSled(Enable, FuncId, Sled, __xray_FunctionExit); |
| } |
| |
| bool patchCustomEvent(const bool Enable, const uint32_t FuncId, |
| const XRaySledEntry &Sled) XRAY_NEVER_INSTRUMENT { |
| // FIXME: Implement in mips? |
| return false; |
| } |
| |
| bool patchTypedEvent(const bool Enable, const uint32_t FuncId, |
| const XRaySledEntry &Sled) XRAY_NEVER_INSTRUMENT { |
| // FIXME: Implement in mips? |
| return false; |
| } |
| |
| } // namespace __xray |
| |
| extern "C" void __xray_ArgLoggerEntry() XRAY_NEVER_INSTRUMENT { |
| // FIXME: this will have to be implemented in the trampoline assembly file |
| } |
