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-rw-r--r--lib/xray/xray_arm.cpp164
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diff --git a/lib/xray/xray_arm.cpp b/lib/xray/xray_arm.cpp
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+//===-- 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
+}