| //===-- xray_arm.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 ARM-specific routines (32-bit). |
| // |
| //===----------------------------------------------------------------------===// |
| #include "sanitizer_common/sanitizer_common.h" |
| #include "xray_defs.h" |
| #include "xray_interface_internal.h" |
| #include <atomic> |
| #include <cassert> |
| |
| extern "C" void __clear_cache(void *start, void *end); |
| |
| namespace __xray { |
| |
| // The machine codes for some instructions used in runtime patching. |
| enum class PatchOpcodes : uint32_t { |
| PO_PushR0Lr = 0xE92D4001, // PUSH {r0, lr} |
| PO_BlxIp = 0xE12FFF3C, // BLX ip |
| PO_PopR0Lr = 0xE8BD4001, // POP {r0, lr} |
| PO_B20 = 0xEA000005 // B #20 |
| }; |
| |
| // 0xUUUUWXYZ -> 0x000W0XYZ |
| inline static uint32_t getMovwMask(const uint32_t Value) XRAY_NEVER_INSTRUMENT { |
| return (Value & 0xfff) | ((Value & 0xf000) << 4); |
| } |
| |
| // 0xWXYZUUUU -> 0x000W0XYZ |
| inline static uint32_t getMovtMask(const uint32_t Value) XRAY_NEVER_INSTRUMENT { |
| return getMovwMask(Value >> 16); |
| } |
| |
| // Writes the following instructions: |
| // MOVW R<regNo>, #<lower 16 bits of the |Value|> |
| // MOVT R<regNo>, #<higher 16 bits of the |Value|> |
| inline static uint32_t * |
| write32bitLoadReg(uint8_t regNo, uint32_t *Address, |
| const uint32_t Value) XRAY_NEVER_INSTRUMENT { |
| // This is a fatal error: we cannot just report it and continue execution. |
| assert(regNo <= 15 && "Register number must be 0 to 15."); |
| // MOVW R, #0xWXYZ in machine code is 0xE30WRXYZ |
| *Address = (0xE3000000 | (uint32_t(regNo) << 12) | getMovwMask(Value)); |
| Address++; |
| // MOVT R, #0xWXYZ in machine code is 0xE34WRXYZ |
| *Address = (0xE3400000 | (uint32_t(regNo) << 12) | getMovtMask(Value)); |
| return Address + 1; |
| } |
| |
| // Writes the following instructions: |
| // MOVW r0, #<lower 16 bits of the |Value|> |
| // MOVT r0, #<higher 16 bits of the |Value|> |
| inline static uint32_t * |
| write32bitLoadR0(uint32_t *Address, |
| const uint32_t Value) XRAY_NEVER_INSTRUMENT { |
| return write32bitLoadReg(0, Address, Value); |
| } |
| |
| // Writes the following instructions: |
| // MOVW ip, #<lower 16 bits of the |Value|> |
| // MOVT ip, #<higher 16 bits of the |Value|> |
| inline static uint32_t * |
| write32bitLoadIP(uint32_t *Address, |
| const uint32_t Value) XRAY_NEVER_INSTRUMENT { |
| return write32bitLoadReg(12, Address, Value); |
| } |
| |
| 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 #20 |
| // 6 NOPs (24 bytes) |
| // |
| // With the following runtime patch: |
| // |
| // xray_sled_n: |
| // PUSH {r0, lr} |
| // MOVW r0, #<lower 16 bits of function ID> |
| // MOVT r0, #<higher 16 bits of function ID> |
| // MOVW ip, #<lower 16 bits of address of TracingHook> |
| // MOVT ip, #<higher 16 bits of address of TracingHook> |
| // BLX ip |
| // POP {r0, lr} |
| // |
| // 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 #20 |
| |
| uint32_t *FirstAddress = reinterpret_cast<uint32_t *>(Sled.address()); |
| uint32_t *CurAddress = FirstAddress + 1; |
| if (Enable) { |
| CurAddress = |
| write32bitLoadR0(CurAddress, reinterpret_cast<uint32_t>(FuncId)); |
| CurAddress = |
| write32bitLoadIP(CurAddress, reinterpret_cast<uint32_t>(TracingHook)); |
| *CurAddress = uint32_t(PatchOpcodes::PO_BlxIp); |
| CurAddress++; |
| *CurAddress = uint32_t(PatchOpcodes::PO_PopR0Lr); |
| CurAddress++; |
| std::atomic_store_explicit( |
| reinterpret_cast<std::atomic<uint32_t> *>(FirstAddress), |
| uint32_t(PatchOpcodes::PO_PushR0Lr), std::memory_order_release); |
| } else { |
| std::atomic_store_explicit( |
| reinterpret_cast<std::atomic<uint32_t> *>(FirstAddress), |
| uint32_t(PatchOpcodes::PO_B20), std::memory_order_release); |
| } |
| __clear_cache(reinterpret_cast<char *>(FirstAddress), |
| reinterpret_cast<char *>(CurAddress)); |
| 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 { |
| return patchSled(Enable, FuncId, Sled, __xray_FunctionTailExit); |
| } |
| |
| bool patchCustomEvent(const bool Enable, const uint32_t FuncId, |
| const XRaySledEntry &Sled) |
| XRAY_NEVER_INSTRUMENT { // FIXME: Implement in arm? |
| return false; |
| } |
| |
| bool patchTypedEvent(const bool Enable, const uint32_t FuncId, |
| const XRaySledEntry &Sled) XRAY_NEVER_INSTRUMENT { |
| // FIXME: Implement in arm? |
| return false; |
| } |
| |
| // FIXME: Maybe implement this better? |
| bool probeRequiredCPUFeatures() XRAY_NEVER_INSTRUMENT { return true; } |
| |
| } // namespace __xray |
| |
| extern "C" void __xray_ArgLoggerEntry() XRAY_NEVER_INSTRUMENT { |
| // FIXME: this will have to be implemented in the trampoline assembly file |
| } |