1 //===-- xray_mips.cc --------------------------------------------*- C++ -*-===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This file is a part of XRay, a dynamic runtime instrumentation system. 11 // 12 // Implementation of MIPS-specific routines (32-bit). 13 // 14 //===----------------------------------------------------------------------===// 15 #include "sanitizer_common/sanitizer_common.h" 16 #include "xray_defs.h" 17 #include "xray_interface_internal.h" 18 #include <atomic> 19 20 namespace __xray { 21 22 // The machine codes for some instructions used in runtime patching. 23 enum PatchOpcodes : uint32_t { 24 PO_ADDIU = 0x24000000, // addiu rt, rs, imm 25 PO_SW = 0xAC000000, // sw rt, offset(sp) 26 PO_LUI = 0x3C000000, // lui rs, %hi(address) 27 PO_ORI = 0x34000000, // ori rt, rs, %lo(address) 28 PO_JALR = 0x0000F809, // jalr rs 29 PO_LW = 0x8C000000, // lw rt, offset(address) 30 PO_B44 = 0x1000000b, // b #44 31 PO_NOP = 0x0, // nop 32 }; 33 34 enum RegNum : uint32_t { 35 RN_T0 = 0x8, 36 RN_T9 = 0x19, 37 RN_RA = 0x1F, 38 RN_SP = 0x1D, 39 }; 40 41 inline static uint32_t encodeInstruction(uint32_t Opcode, uint32_t Rs, 42 uint32_t Rt, 43 uint32_t Imm) XRAY_NEVER_INSTRUMENT { 44 return (Opcode | Rs << 21 | Rt << 16 | Imm); 45 } 46 47 inline static uint32_t 48 encodeSpecialInstruction(uint32_t Opcode, uint32_t Rs, uint32_t Rt, uint32_t Rd, 49 uint32_t Imm) XRAY_NEVER_INSTRUMENT { 50 return (Rs << 21 | Rt << 16 | Rd << 11 | Imm << 6 | Opcode); 51 } 52 53 inline static bool patchSled(const bool Enable, const uint32_t FuncId, 54 const XRaySledEntry &Sled, 55 void (*TracingHook)()) XRAY_NEVER_INSTRUMENT { 56 // When |Enable| == true, 57 // We replace the following compile-time stub (sled): 58 // 59 // xray_sled_n: 60 // B .tmpN 61 // 11 NOPs (44 bytes) 62 // .tmpN 63 // ADDIU T9, T9, 44 64 // 65 // With the following runtime patch: 66 // 67 // xray_sled_n (32-bit): 68 // addiu sp, sp, -8 ;create stack frame 69 // nop 70 // sw ra, 4(sp) ;save return address 71 // sw t9, 0(sp) ;save register t9 72 // lui t9, %hi(__xray_FunctionEntry/Exit) 73 // ori t9, t9, %lo(__xray_FunctionEntry/Exit) 74 // lui t0, %hi(function_id) 75 // jalr t9 ;call Tracing hook 76 // ori t0, t0, %lo(function_id) ;pass function id (delay slot) 77 // lw t9, 0(sp) ;restore register t9 78 // lw ra, 4(sp) ;restore return address 79 // addiu sp, sp, 8 ;delete stack frame 80 // 81 // We add 44 bytes to t9 because we want to adjust the function pointer to 82 // the actual start of function i.e. the address just after the noop sled. 83 // We do this because gp displacement relocation is emitted at the start of 84 // of the function i.e after the nop sled and to correctly calculate the 85 // global offset table address, t9 must hold the address of the instruction 86 // containing the gp displacement relocation. 87 // FIXME: Is this correct for the static relocation model? 88 // 89 // Replacement of the first 4-byte instruction should be the last and atomic 90 // operation, so that the user code which reaches the sled concurrently 91 // either jumps over the whole sled, or executes the whole sled when the 92 // latter is ready. 93 // 94 // When |Enable|==false, we set back the first instruction in the sled to be 95 // B #44 96 97 if (Enable) { 98 uint32_t LoTracingHookAddr = 99 reinterpret_cast<int32_t>(TracingHook) & 0xffff; 100 uint32_t HiTracingHookAddr = 101 (reinterpret_cast<int32_t>(TracingHook) >> 16) & 0xffff; 102 uint32_t LoFunctionID = FuncId & 0xffff; 103 uint32_t HiFunctionID = (FuncId >> 16) & 0xffff; 104 *reinterpret_cast<uint32_t *>(Sled.Address + 8) = encodeInstruction( 105 PatchOpcodes::PO_SW, RegNum::RN_SP, RegNum::RN_RA, 0x4); 106 *reinterpret_cast<uint32_t *>(Sled.Address + 12) = encodeInstruction( 107 PatchOpcodes::PO_SW, RegNum::RN_SP, RegNum::RN_T9, 0x0); 108 *reinterpret_cast<uint32_t *>(Sled.Address + 16) = encodeInstruction( 109 PatchOpcodes::PO_LUI, 0x0, RegNum::RN_T9, HiTracingHookAddr); 110 *reinterpret_cast<uint32_t *>(Sled.Address + 20) = encodeInstruction( 111 PatchOpcodes::PO_ORI, RegNum::RN_T9, RegNum::RN_T9, LoTracingHookAddr); 112 *reinterpret_cast<uint32_t *>(Sled.Address + 24) = encodeInstruction( 113 PatchOpcodes::PO_LUI, 0x0, RegNum::RN_T0, HiFunctionID); 114 *reinterpret_cast<uint32_t *>(Sled.Address + 28) = encodeSpecialInstruction( 115 PatchOpcodes::PO_JALR, RegNum::RN_T9, 0x0, RegNum::RN_RA, 0X0); 116 *reinterpret_cast<uint32_t *>(Sled.Address + 32) = encodeInstruction( 117 PatchOpcodes::PO_ORI, RegNum::RN_T0, RegNum::RN_T0, LoFunctionID); 118 *reinterpret_cast<uint32_t *>(Sled.Address + 36) = encodeInstruction( 119 PatchOpcodes::PO_LW, RegNum::RN_SP, RegNum::RN_T9, 0x0); 120 *reinterpret_cast<uint32_t *>(Sled.Address + 40) = encodeInstruction( 121 PatchOpcodes::PO_LW, RegNum::RN_SP, RegNum::RN_RA, 0x4); 122 *reinterpret_cast<uint32_t *>(Sled.Address + 44) = encodeInstruction( 123 PatchOpcodes::PO_ADDIU, RegNum::RN_SP, RegNum::RN_SP, 0x8); 124 uint32_t CreateStackSpaceInstr = encodeInstruction( 125 PatchOpcodes::PO_ADDIU, RegNum::RN_SP, RegNum::RN_SP, 0xFFF8); 126 std::atomic_store_explicit( 127 reinterpret_cast<std::atomic<uint32_t> *>(Sled.Address), 128 uint32_t(CreateStackSpaceInstr), std::memory_order_release); 129 } else { 130 std::atomic_store_explicit( 131 reinterpret_cast<std::atomic<uint32_t> *>(Sled.Address), 132 uint32_t(PatchOpcodes::PO_B44), std::memory_order_release); 133 } 134 return true; 135 } 136 137 bool patchFunctionEntry(const bool Enable, const uint32_t FuncId, 138 const XRaySledEntry &Sled, 139 void (*Trampoline)()) XRAY_NEVER_INSTRUMENT { 140 return patchSled(Enable, FuncId, Sled, Trampoline); 141 } 142 143 bool patchFunctionExit(const bool Enable, const uint32_t FuncId, 144 const XRaySledEntry &Sled) XRAY_NEVER_INSTRUMENT { 145 return patchSled(Enable, FuncId, Sled, __xray_FunctionExit); 146 } 147 148 bool patchFunctionTailExit(const bool Enable, const uint32_t FuncId, 149 const XRaySledEntry &Sled) XRAY_NEVER_INSTRUMENT { 150 // FIXME: In the future we'd need to distinguish between non-tail exits and 151 // tail exits for better information preservation. 152 return patchSled(Enable, FuncId, Sled, __xray_FunctionExit); 153 } 154 155 bool patchCustomEvent(const bool Enable, const uint32_t FuncId, 156 const XRaySledEntry &Sled) XRAY_NEVER_INSTRUMENT { 157 // FIXME: Implement in mips? 158 return false; 159 } 160 161 bool patchTypedEvent(const bool Enable, const uint32_t FuncId, 162 const XRaySledEntry &Sled) XRAY_NEVER_INSTRUMENT { 163 // FIXME: Implement in mips? 164 return false; 165 } 166 167 } // namespace __xray 168 169 extern "C" void __xray_ArgLoggerEntry() XRAY_NEVER_INSTRUMENT { 170 // FIXME: this will have to be implemented in the trampoline assembly file 171 } 172
Indexes created Sat Sep 20 22:09:52 GMT 2025