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Diffstat (limited to 'lib/xray/xray_mips.cpp')
-rw-r--r-- | lib/xray/xray_mips.cpp | 170 |
1 files changed, 170 insertions, 0 deletions
diff --git a/lib/xray/xray_mips.cpp b/lib/xray/xray_mips.cpp new file mode 100644 index 000000000000..26fc50374471 --- /dev/null +++ b/lib/xray/xray_mips.cpp @@ -0,0 +1,170 @@ +//===-- 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 + + 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; + *reinterpret_cast<uint32_t *>(Sled.Address + 8) = encodeInstruction( + PatchOpcodes::PO_SW, RegNum::RN_SP, RegNum::RN_RA, 0x4); + *reinterpret_cast<uint32_t *>(Sled.Address + 12) = encodeInstruction( + PatchOpcodes::PO_SW, RegNum::RN_SP, RegNum::RN_T9, 0x0); + *reinterpret_cast<uint32_t *>(Sled.Address + 16) = encodeInstruction( + PatchOpcodes::PO_LUI, 0x0, RegNum::RN_T9, HiTracingHookAddr); + *reinterpret_cast<uint32_t *>(Sled.Address + 20) = encodeInstruction( + PatchOpcodes::PO_ORI, RegNum::RN_T9, RegNum::RN_T9, LoTracingHookAddr); + *reinterpret_cast<uint32_t *>(Sled.Address + 24) = encodeInstruction( + PatchOpcodes::PO_LUI, 0x0, RegNum::RN_T0, HiFunctionID); + *reinterpret_cast<uint32_t *>(Sled.Address + 28) = encodeSpecialInstruction( + PatchOpcodes::PO_JALR, RegNum::RN_T9, 0x0, RegNum::RN_RA, 0X0); + *reinterpret_cast<uint32_t *>(Sled.Address + 32) = encodeInstruction( + PatchOpcodes::PO_ORI, RegNum::RN_T0, RegNum::RN_T0, LoFunctionID); + *reinterpret_cast<uint32_t *>(Sled.Address + 36) = encodeInstruction( + PatchOpcodes::PO_LW, RegNum::RN_SP, RegNum::RN_T9, 0x0); + *reinterpret_cast<uint32_t *>(Sled.Address + 40) = encodeInstruction( + PatchOpcodes::PO_LW, RegNum::RN_SP, RegNum::RN_RA, 0x4); + *reinterpret_cast<uint32_t *>(Sled.Address + 44) = 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> *>(Sled.Address), + uint32_t(CreateStackSpaceInstr), std::memory_order_release); + } else { + std::atomic_store_explicit( + reinterpret_cast<std::atomic<uint32_t> *>(Sled.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 +} |