1 //===-- xray_AArch64.cpp ----------------------------------------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file is a part of XRay, a dynamic runtime instrumentation system.
10 //
11 // Implementation of AArch64-specific routines (64-bit).
12 //
13 //===----------------------------------------------------------------------===//
14 #include "sanitizer_common/sanitizer_common.h"
15 #include "xray_defs.h"
16 #include "xray_interface_internal.h"
17 #include <atomic>
18 #include <cassert>
19
20 extern "C" void __clear_cache(void *start, void *end);
21
22 namespace __xray {
23
24 // The machine codes for some instructions used in runtime patching.
25 enum class PatchOpcodes : uint32_t {
26 PO_StpX0X30SP_m16e = 0xA9BF7BE0, // STP X0, X30, [SP, #-16]!
27 PO_LdrW0_12 = 0x18000060, // LDR W0, #12
28 PO_LdrX16_12 = 0x58000070, // LDR X16, #12
29 PO_BlrX16 = 0xD63F0200, // BLR X16
30 PO_LdpX0X30SP_16 = 0xA8C17BE0, // LDP X0, X30, [SP], #16
31 PO_B32 = 0x14000008 // B #32
32 };
33
patchSled(const bool Enable,const uint32_t FuncId,const XRaySledEntry & Sled,void (* TracingHook)())34 inline static bool patchSled(const bool Enable, const uint32_t FuncId,
35 const XRaySledEntry &Sled,
36 void (*TracingHook)()) XRAY_NEVER_INSTRUMENT {
37 // When |Enable| == true,
38 // We replace the following compile-time stub (sled):
39 //
40 // xray_sled_n:
41 // B #32
42 // 7 NOPs (24 bytes)
43 //
44 // With the following runtime patch:
45 //
46 // xray_sled_n:
47 // STP X0, X30, [SP, #-16]! ; PUSH {r0, lr}
48 // LDR W0, #12 ; W0 := function ID
49 // LDR X16,#12 ; X16 := address of the trampoline
50 // BLR X16
51 // ;DATA: 32 bits of function ID
52 // ;DATA: lower 32 bits of the address of the trampoline
53 // ;DATA: higher 32 bits of the address of the trampoline
54 // LDP X0, X30, [SP], #16 ; POP {r0, lr}
55 //
56 // Replacement of the first 4-byte instruction should be the last and atomic
57 // operation, so that the user code which reaches the sled concurrently
58 // either jumps over the whole sled, or executes the whole sled when the
59 // latter is ready.
60 //
61 // When |Enable|==false, we set back the first instruction in the sled to be
62 // B #32
63
64 uint32_t *FirstAddress = reinterpret_cast<uint32_t *>(Sled.address());
65 uint32_t *CurAddress = FirstAddress + 1;
66 if (Enable) {
67 *CurAddress = uint32_t(PatchOpcodes::PO_LdrW0_12);
68 CurAddress++;
69 *CurAddress = uint32_t(PatchOpcodes::PO_LdrX16_12);
70 CurAddress++;
71 *CurAddress = uint32_t(PatchOpcodes::PO_BlrX16);
72 CurAddress++;
73 *CurAddress = FuncId;
74 CurAddress++;
75 *reinterpret_cast<void (**)()>(CurAddress) = TracingHook;
76 CurAddress += 2;
77 *CurAddress = uint32_t(PatchOpcodes::PO_LdpX0X30SP_16);
78 CurAddress++;
79 std::atomic_store_explicit(
80 reinterpret_cast<std::atomic<uint32_t> *>(FirstAddress),
81 uint32_t(PatchOpcodes::PO_StpX0X30SP_m16e), std::memory_order_release);
82 } else {
83 std::atomic_store_explicit(
84 reinterpret_cast<std::atomic<uint32_t> *>(FirstAddress),
85 uint32_t(PatchOpcodes::PO_B32), std::memory_order_release);
86 }
87 __clear_cache(reinterpret_cast<char *>(FirstAddress),
88 reinterpret_cast<char *>(CurAddress));
89 return true;
90 }
91
patchFunctionEntry(const bool Enable,const uint32_t FuncId,const XRaySledEntry & Sled,void (* Trampoline)())92 bool patchFunctionEntry(const bool Enable, const uint32_t FuncId,
93 const XRaySledEntry &Sled,
94 void (*Trampoline)()) XRAY_NEVER_INSTRUMENT {
95 return patchSled(Enable, FuncId, Sled, Trampoline);
96 }
97
patchFunctionExit(const bool Enable,const uint32_t FuncId,const XRaySledEntry & Sled)98 bool patchFunctionExit(const bool Enable, const uint32_t FuncId,
99 const XRaySledEntry &Sled) XRAY_NEVER_INSTRUMENT {
100 return patchSled(Enable, FuncId, Sled, __xray_FunctionExit);
101 }
102
patchFunctionTailExit(const bool Enable,const uint32_t FuncId,const XRaySledEntry & Sled)103 bool patchFunctionTailExit(const bool Enable, const uint32_t FuncId,
104 const XRaySledEntry &Sled) XRAY_NEVER_INSTRUMENT {
105 return patchSled(Enable, FuncId, Sled, __xray_FunctionTailExit);
106 }
107
patchCustomEvent(const bool Enable,const uint32_t FuncId,const XRaySledEntry & Sled)108 bool patchCustomEvent(const bool Enable, const uint32_t FuncId,
109 const XRaySledEntry &Sled)
110 XRAY_NEVER_INSTRUMENT { // FIXME: Implement in aarch64?
111 return false;
112 }
113
patchTypedEvent(const bool Enable,const uint32_t FuncId,const XRaySledEntry & Sled)114 bool patchTypedEvent(const bool Enable, const uint32_t FuncId,
115 const XRaySledEntry &Sled) XRAY_NEVER_INSTRUMENT {
116 // FIXME: Implement in aarch64?
117 return false;
118 }
119
120 // FIXME: Maybe implement this better?
probeRequiredCPUFeatures()121 bool probeRequiredCPUFeatures() XRAY_NEVER_INSTRUMENT { return true; }
122
123 } // namespace __xray
124
__xray_ArgLoggerEntry()125 extern "C" void __xray_ArgLoggerEntry() XRAY_NEVER_INSTRUMENT {
126 // FIXME: this will have to be implemented in the trampoline assembly file
127 }
128