1//===-- xray_AArch64.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 AArch64-specific routines (64-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#include <cassert>
20
21extern "C" void __clear_cache(void *start, void *end);
22
23namespace __xray {
24
25// The machine codes for some instructions used in runtime patching.
26enum class PatchOpcodes : uint32_t {
27  PO_StpX0X30SP_m16e = 0xA9BF7BE0, // STP X0, X30, [SP, #-16]!
28  PO_LdrW0_12 = 0x18000060,        // LDR W0, #12
29  PO_LdrX16_12 = 0x58000070,       // LDR X16, #12
30  PO_BlrX16 = 0xD63F0200,          // BLR X16
31  PO_LdpX0X30SP_16 = 0xA8C17BE0,   // LDP X0, X30, [SP], #16
32  PO_B32 = 0x14000008              // B #32
33};
34
35inline static bool patchSled(const bool Enable, const uint32_t FuncId,
36                             const XRaySledEntry &Sled,
37                             void (*TracingHook)()) XRAY_NEVER_INSTRUMENT {
38  // When |Enable| == true,
39  // We replace the following compile-time stub (sled):
40  //
41  // xray_sled_n:
42  //   B #32
43  //   7 NOPs (24 bytes)
44  //
45  // With the following runtime patch:
46  //
47  // xray_sled_n:
48  //   STP X0, X30, [SP, #-16]! ; PUSH {r0, lr}
49  //   LDR W0, #12 ; W0 := function ID
50  //   LDR X16,#12 ; X16 := address of the trampoline
51  //   BLR X16
52  //   ;DATA: 32 bits of function ID
53  //   ;DATA: lower 32 bits of the address of the trampoline
54  //   ;DATA: higher 32 bits of the address of the trampoline
55  //   LDP X0, X30, [SP], #16 ; POP {r0, lr}
56  //
57  // Replacement of the first 4-byte instruction should be the last and atomic
58  // operation, so that the user code which reaches the sled concurrently
59  // either jumps over the whole sled, or executes the whole sled when the
60  // latter is ready.
61  //
62  // When |Enable|==false, we set back the first instruction in the sled to be
63  //   B #32
64
65  uint32_t *FirstAddress = reinterpret_cast<uint32_t *>(Sled.Address);
66  uint32_t *CurAddress = FirstAddress + 1;
67  if (Enable) {
68    *CurAddress = uint32_t(PatchOpcodes::PO_LdrW0_12);
69    CurAddress++;
70    *CurAddress = uint32_t(PatchOpcodes::PO_LdrX16_12);
71    CurAddress++;
72    *CurAddress = uint32_t(PatchOpcodes::PO_BlrX16);
73    CurAddress++;
74    *CurAddress = FuncId;
75    CurAddress++;
76    *reinterpret_cast<void (**)()>(CurAddress) = TracingHook;
77    CurAddress += 2;
78    *CurAddress = uint32_t(PatchOpcodes::PO_LdpX0X30SP_16);
79    CurAddress++;
80    std::atomic_store_explicit(
81        reinterpret_cast<std::atomic<uint32_t> *>(FirstAddress),
82        uint32_t(PatchOpcodes::PO_StpX0X30SP_m16e), std::memory_order_release);
83  } else {
84    std::atomic_store_explicit(
85        reinterpret_cast<std::atomic<uint32_t> *>(FirstAddress),
86        uint32_t(PatchOpcodes::PO_B32), std::memory_order_release);
87  }
88  __clear_cache(reinterpret_cast<char *>(FirstAddress),
89                reinterpret_cast<char *>(CurAddress));
90  return true;
91}
92
93bool patchFunctionEntry(const bool Enable, const uint32_t FuncId,
94                        const XRaySledEntry &Sled,
95                        void (*Trampoline)()) XRAY_NEVER_INSTRUMENT {
96  return patchSled(Enable, FuncId, Sled, Trampoline);
97}
98
99bool patchFunctionExit(const bool Enable, const uint32_t FuncId,
100                       const XRaySledEntry &Sled) XRAY_NEVER_INSTRUMENT {
101  return patchSled(Enable, FuncId, Sled, __xray_FunctionExit);
102}
103
104bool patchFunctionTailExit(const bool Enable, const uint32_t FuncId,
105                           const XRaySledEntry &Sled) XRAY_NEVER_INSTRUMENT {
106  return patchSled(Enable, FuncId, Sled, __xray_FunctionTailExit);
107}
108
109bool patchCustomEvent(const bool Enable, const uint32_t FuncId,
110                      const XRaySledEntry &Sled)
111    XRAY_NEVER_INSTRUMENT { // FIXME: Implement in aarch64?
112  return false;
113}
114
115bool patchTypedEvent(const bool Enable, const uint32_t FuncId,
116                     const XRaySledEntry &Sled) XRAY_NEVER_INSTRUMENT {
117  // FIXME: Implement in aarch64?
118  return false;
119}
120
121// FIXME: Maybe implement this better?
122bool probeRequiredCPUFeatures() XRAY_NEVER_INSTRUMENT { return true; }
123
124} // namespace __xray
125
126extern "C" void __xray_ArgLoggerEntry() XRAY_NEVER_INSTRUMENT {
127  // FIXME: this will have to be implemented in the trampoline assembly file
128}
129