1 files changed, 105 insertions, 0 deletions
diff --git a/lib/xray/xray_AArch64.cc b/lib/xray/xray_AArch64.cc
new file mode 100644
index 000000000..c2d33a200
--- /dev/null
+++ b/lib/xray/xray_AArch64.cc
@@ -0,0 +1,105 @@
+//===-- xray_AArch64.cc -----------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is a part of XRay, a dynamic runtime instrumentation system.
+//
+// Implementation of AArch64-specific routines (64-bit).
+//
+//===----------------------------------------------------------------------===//
+#include "sanitizer_common/sanitizer_common.h"
+#include "xray_defs.h"
+#include "xray_interface_internal.h"
+#include <atomic>
+#include <cassert>
+
+namespace __xray {
+
+// The machine codes for some instructions used in runtime patching.
+enum class PatchOpcodes : uint32_t {
+  PO_StpX0X30SP_m16e = 0xA9BF7BE0, // STP X0, X30, [SP, #-16]!
+  PO_LdrW0_12 = 0x18000060,        // LDR W0, #12
+  PO_LdrX16_12 = 0x58000070,       // LDR X16, #12
+  PO_BlrX16 = 0xD63F0200,          // BLR X16
+  PO_LdpX0X30SP_16 = 0xA8C17BE0,   // LDP X0, X30, [SP], #16
+  PO_B32 = 0x14000008              // B #32
+};
+
+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 #32
+  //   7 NOPs (24 bytes)
+  //
+  // With the following runtime patch:
+  //
+  // xray_sled_n:
+  //   STP X0, X30, [SP, #-16]! ; PUSH {r0, lr}
+  //   LDR W0, #12 ; W0 := function ID
+  //   LDR X16,#12 ; X16 := address of the trampoline
+  //   BLR X16
+  //   ;DATA: 32 bits of function ID
+  //   ;DATA: lower 32 bits of the address of the trampoline
+  //   ;DATA: higher 32 bits of the address of the trampoline
+  //   LDP X0, X30, [SP], #16 ; 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 #32
+
+  uint32_t *FirstAddress = reinterpret_cast<uint32_t *>(Sled.Address);
+  if (Enable) {
+    uint32_t *CurAddress = FirstAddress + 1;
+    *CurAddress = uint32_t(PatchOpcodes::PO_LdrW0_12);
+    CurAddress++;
+    *CurAddress = uint32_t(PatchOpcodes::PO_LdrX16_12);
+    CurAddress++;
+    *CurAddress = uint32_t(PatchOpcodes::PO_BlrX16);
+    CurAddress++;
+    *CurAddress = FuncId;
+    CurAddress++;
+    *reinterpret_cast<void (**)()>(CurAddress) = TracingHook;
+    CurAddress += 2;
+    *CurAddress = uint32_t(PatchOpcodes::PO_LdpX0X30SP_16);
+    std::atomic_store_explicit(
+        reinterpret_cast<std::atomic<uint32_t> *>(FirstAddress),
+        uint32_t(PatchOpcodes::PO_StpX0X30SP_m16e), std::memory_order_release);
+  } else {
+    std::atomic_store_explicit(
+        reinterpret_cast<std::atomic<uint32_t> *>(FirstAddress),
+        uint32_t(PatchOpcodes::PO_B32), std::memory_order_release);
+  }
+  return true;
+}
+
+bool patchFunctionEntry(const bool Enable, const uint32_t FuncId,
+                        const XRaySledEntry &Sled) XRAY_NEVER_INSTRUMENT {
+  return patchSled(Enable, FuncId, Sled, __xray_FunctionEntry);
+}
+
+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);
+}
+
+} // namespace __xray