1//===- FuzzerTraceState.cpp - Trace-based fuzzer mutator ------------------===//
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// This file implements a mutation algorithm based on instruction traces and
10// on taint analysis feedback from DFSan.
11//
12// Instruction traces are special hooks inserted by the compiler around
13// interesting instructions. Currently supported traces:
14//   * __sanitizer_cov_trace_cmp -- inserted before every ICMP instruction,
15//    receives the type, size and arguments of ICMP.
16//
17// Every time a traced event is intercepted we analyse the data involved
18// in the event and suggest a mutation for future executions.
19// For example if 4 bytes of data that derive from input bytes {4,5,6,7}
20// are compared with a constant 12345,
21// we try to insert 12345, 12344, 12346 into bytes
22// {4,5,6,7} of the next fuzzed inputs.
23//
24// The fuzzer can work only with the traces, or with both traces and DFSan.
25//
26// DataFlowSanitizer (DFSan) is a tool for
27// generalised dynamic data flow (taint) analysis:
28// http://clang.llvm.org/docs/DataFlowSanitizer.html .
29//
30// The approach with DFSan-based fuzzing has some similarity to
31// "Taint-based Directed Whitebox Fuzzing"
32// by Vijay Ganesh & Tim Leek & Martin Rinard:
33// http://dspace.mit.edu/openaccess-disseminate/1721.1/59320,
34// but it uses a full blown LLVM IR taint analysis and separate instrumentation
35// to analyze all of the "attack points" at once.
36//
37// Workflow with DFSan:
38//   * lib/Fuzzer/Fuzzer*.cpp is compiled w/o any instrumentation.
39//   * The code under test is compiled with DFSan *and* with instruction traces.
40//   * Every call to HOOK(a,b) is replaced by DFSan with
41//     __dfsw_HOOK(a, b, label(a), label(b)) so that __dfsw_HOOK
42//     gets all the taint labels for the arguments.
43//   * At the Fuzzer startup we assign a unique DFSan label
44//     to every byte of the input string (Fuzzer::CurrentUnit) so that for any
45//     chunk of data we know which input bytes it has derived from.
46//   * The __dfsw_* functions (implemented in this file) record the
47//     parameters (i.e. the application data and the corresponding taint labels)
48//     in a global state.
49//   * Fuzzer::ApplyTraceBasedMutation() tries to use the data recorded
50//     by __dfsw_* hooks to guide the fuzzing towards new application states.
51//
52// Parts of this code will not function when DFSan is not linked in.
53// Instead of using ifdefs and thus requiring a separate build of lib/Fuzzer
54// we redeclare the dfsan_* interface functions as weak and check if they
55// are nullptr before calling.
56// If this approach proves to be useful we may add attribute(weak) to the
57// dfsan declarations in dfsan_interface.h
58//
59// This module is in the "proof of concept" stage.
60// It is capable of solving only the simplest puzzles
61// like test/dfsan/DFSanSimpleCmpTest.cpp.
62//===----------------------------------------------------------------------===//
63
64/* Example of manual usage (-fsanitize=dataflow is optional):
65(
66  cd $LLVM/lib/Fuzzer/
67  clang  -fPIC -c -g -O2 -std=c++11 Fuzzer*.cpp
68  clang++ -O0 -std=c++11 -fsanitize-coverage=edge,trace-cmp \
69    -fsanitize=dataflow \
70    test/SimpleCmpTest.cpp Fuzzer*.o
71  ./a.out -use_traces=1
72)
73*/
74
75#include "FuzzerDFSan.h"
76#include "FuzzerInternal.h"
77
78#include <algorithm>
79#include <cstring>
80#include <unordered_map>
81
82#if !LLVM_FUZZER_SUPPORTS_DFSAN
83// Stubs for dfsan for platforms where dfsan does not exist and weak
84// functions don't work.
85extern "C" {
86dfsan_label dfsan_create_label(const char *desc, void *userdata) { return 0; }
87void dfsan_set_label(dfsan_label label, void *addr, size_t size) {}
88void dfsan_add_label(dfsan_label label, void *addr, size_t size) {}
89const struct dfsan_label_info *dfsan_get_label_info(dfsan_label label) {
90  return nullptr;
91}
92dfsan_label dfsan_read_label(const void *addr, size_t size) { return 0; }
93}  // extern "C"
94#endif  // !LLVM_FUZZER_SUPPORTS_DFSAN
95
96namespace fuzzer {
97
98// These values are copied from include/llvm/IR/InstrTypes.h.
99// We do not include the LLVM headers here to remain independent.
100// If these values ever change, an assertion in ComputeCmp will fail.
101enum Predicate {
102  ICMP_EQ = 32,  ///< equal
103  ICMP_NE = 33,  ///< not equal
104  ICMP_UGT = 34, ///< unsigned greater than
105  ICMP_UGE = 35, ///< unsigned greater or equal
106  ICMP_ULT = 36, ///< unsigned less than
107  ICMP_ULE = 37, ///< unsigned less or equal
108  ICMP_SGT = 38, ///< signed greater than
109  ICMP_SGE = 39, ///< signed greater or equal
110  ICMP_SLT = 40, ///< signed less than
111  ICMP_SLE = 41, ///< signed less or equal
112};
113
114template <class U, class S>
115bool ComputeCmp(size_t CmpType, U Arg1, U Arg2) {
116  switch(CmpType) {
117    case ICMP_EQ : return Arg1 == Arg2;
118    case ICMP_NE : return Arg1 != Arg2;
119    case ICMP_UGT: return Arg1 > Arg2;
120    case ICMP_UGE: return Arg1 >= Arg2;
121    case ICMP_ULT: return Arg1 < Arg2;
122    case ICMP_ULE: return Arg1 <= Arg2;
123    case ICMP_SGT: return (S)Arg1 > (S)Arg2;
124    case ICMP_SGE: return (S)Arg1 >= (S)Arg2;
125    case ICMP_SLT: return (S)Arg1 < (S)Arg2;
126    case ICMP_SLE: return (S)Arg1 <= (S)Arg2;
127    default: assert(0 && "unsupported CmpType");
128  }
129  return false;
130}
131
132static bool ComputeCmp(size_t CmpSize, size_t CmpType, uint64_t Arg1,
133                       uint64_t Arg2) {
134  if (CmpSize == 8) return ComputeCmp<uint64_t, int64_t>(CmpType, Arg1, Arg2);
135  if (CmpSize == 4) return ComputeCmp<uint32_t, int32_t>(CmpType, Arg1, Arg2);
136  if (CmpSize == 2) return ComputeCmp<uint16_t, int16_t>(CmpType, Arg1, Arg2);
137  if (CmpSize == 1) return ComputeCmp<uint8_t, int8_t>(CmpType, Arg1, Arg2);
138  // Other size, ==
139  if (CmpType == ICMP_EQ) return Arg1 == Arg2;
140  // assert(0 && "unsupported cmp and type size combination");
141  return true;
142}
143
144// As a simplification we use the range of input bytes instead of a set of input
145// bytes.
146struct LabelRange {
147  uint16_t Beg, End;  // Range is [Beg, End), thus Beg==End is an empty range.
148
149  LabelRange(uint16_t Beg = 0, uint16_t End = 0) : Beg(Beg), End(End) {}
150
151  static LabelRange Join(LabelRange LR1, LabelRange LR2) {
152    if (LR1.Beg == LR1.End) return LR2;
153    if (LR2.Beg == LR2.End) return LR1;
154    return {std::min(LR1.Beg, LR2.Beg), std::max(LR1.End, LR2.End)};
155  }
156  LabelRange &Join(LabelRange LR) {
157    return *this = Join(*this, LR);
158  }
159  static LabelRange Singleton(const dfsan_label_info *LI) {
160    uint16_t Idx = (uint16_t)(uintptr_t)LI->userdata;
161    assert(Idx > 0);
162    return {(uint16_t)(Idx - 1), Idx};
163  }
164};
165
166// For now, very simple: put Size bytes of Data at position Pos.
167struct TraceBasedMutation {
168  size_t Pos;
169  size_t Size;
170  uint64_t Data;
171};
172
173class TraceState {
174 public:
175   TraceState(const Fuzzer::FuzzingOptions &Options, const Unit &CurrentUnit)
176       : Options(Options), CurrentUnit(CurrentUnit) {}
177
178  LabelRange GetLabelRange(dfsan_label L);
179  void DFSanCmpCallback(uintptr_t PC, size_t CmpSize, size_t CmpType,
180                        uint64_t Arg1, uint64_t Arg2, dfsan_label L1,
181                        dfsan_label L2);
182  void DFSanSwitchCallback(uint64_t PC, size_t ValSizeInBits, uint64_t Val,
183                           size_t NumCases, uint64_t *Cases, dfsan_label L);
184  void TraceCmpCallback(uintptr_t PC, size_t CmpSize, size_t CmpType,
185                        uint64_t Arg1, uint64_t Arg2);
186
187  void TraceSwitchCallback(uintptr_t PC, size_t ValSizeInBits, uint64_t Val,
188                           size_t NumCases, uint64_t *Cases);
189  int TryToAddDesiredData(uint64_t PresentData, uint64_t DesiredData,
190                           size_t DataSize);
191
192  void StartTraceRecording() {
193    if (!Options.UseTraces) return;
194    RecordingTraces = true;
195    Mutations.clear();
196  }
197
198  size_t StopTraceRecording(FuzzerRandomBase &Rand) {
199    RecordingTraces = false;
200    return Mutations.size();
201  }
202
203  void ApplyTraceBasedMutation(size_t Idx, fuzzer::Unit *U);
204
205 private:
206  bool IsTwoByteData(uint64_t Data) {
207    int64_t Signed = static_cast<int64_t>(Data);
208    Signed >>= 16;
209    return Signed == 0 || Signed == -1L;
210  }
211  bool RecordingTraces = false;
212  std::vector<TraceBasedMutation> Mutations;
213  LabelRange LabelRanges[1 << (sizeof(dfsan_label) * 8)];
214  const Fuzzer::FuzzingOptions &Options;
215  const Unit &CurrentUnit;
216};
217
218LabelRange TraceState::GetLabelRange(dfsan_label L) {
219  LabelRange &LR = LabelRanges[L];
220  if (LR.Beg < LR.End || L == 0)
221    return LR;
222  const dfsan_label_info *LI = dfsan_get_label_info(L);
223  if (LI->l1 || LI->l2)
224    return LR = LabelRange::Join(GetLabelRange(LI->l1), GetLabelRange(LI->l2));
225  return LR = LabelRange::Singleton(LI);
226}
227
228void TraceState::ApplyTraceBasedMutation(size_t Idx, fuzzer::Unit *U) {
229  assert(Idx < Mutations.size());
230  auto &M = Mutations[Idx];
231  if (Options.Verbosity >= 3)
232    Printf("TBM %zd %zd %zd\n", M.Pos, M.Size, M.Data);
233  if (M.Pos + M.Size > U->size()) return;
234  memcpy(U->data() + M.Pos, &M.Data, M.Size);
235}
236
237void TraceState::DFSanCmpCallback(uintptr_t PC, size_t CmpSize, size_t CmpType,
238                                  uint64_t Arg1, uint64_t Arg2, dfsan_label L1,
239                                  dfsan_label L2) {
240  assert(ReallyHaveDFSan());
241  if (!RecordingTraces) return;
242  if (L1 == 0 && L2 == 0)
243    return;  // Not actionable.
244  if (L1 != 0 && L2 != 0)
245    return;  // Probably still actionable.
246  bool Res = ComputeCmp(CmpSize, CmpType, Arg1, Arg2);
247  uint64_t Data = L1 ? Arg2 : Arg1;
248  LabelRange LR = L1 ? GetLabelRange(L1) : GetLabelRange(L2);
249
250  for (size_t Pos = LR.Beg; Pos + CmpSize <= LR.End; Pos++) {
251    Mutations.push_back({Pos, CmpSize, Data});
252    Mutations.push_back({Pos, CmpSize, Data + 1});
253    Mutations.push_back({Pos, CmpSize, Data - 1});
254  }
255
256  if (CmpSize > LR.End - LR.Beg)
257    Mutations.push_back({LR.Beg, (unsigned)(LR.End - LR.Beg), Data});
258
259
260  if (Options.Verbosity >= 3)
261    Printf("DFSanCmpCallback: PC %lx S %zd T %zd A1 %llx A2 %llx R %d L1 %d L2 "
262           "%d MU %zd\n",
263           PC, CmpSize, CmpType, Arg1, Arg2, Res, L1, L2, Mutations.size());
264}
265
266void TraceState::DFSanSwitchCallback(uint64_t PC, size_t ValSizeInBits,
267                                     uint64_t Val, size_t NumCases,
268                                     uint64_t *Cases, dfsan_label L) {
269  assert(ReallyHaveDFSan());
270  if (!RecordingTraces) return;
271  if (!L) return;  // Not actionable.
272  LabelRange LR = GetLabelRange(L);
273  size_t ValSize = ValSizeInBits / 8;
274  bool TryShort = IsTwoByteData(Val);
275  for (size_t i = 0; i < NumCases; i++)
276    TryShort &= IsTwoByteData(Cases[i]);
277
278  for (size_t Pos = LR.Beg; Pos + ValSize <= LR.End; Pos++)
279    for (size_t i = 0; i < NumCases; i++)
280      Mutations.push_back({Pos, ValSize, Cases[i]});
281
282  if (TryShort)
283    for (size_t Pos = LR.Beg; Pos + 2 <= LR.End; Pos++)
284      for (size_t i = 0; i < NumCases; i++)
285        Mutations.push_back({Pos, 2, Cases[i]});
286
287  if (Options.Verbosity >= 3)
288    Printf("DFSanSwitchCallback: PC %lx Val %zd SZ %zd # %zd L %d: {%d, %d} "
289           "TryShort %d\n",
290           PC, Val, ValSize, NumCases, L, LR.Beg, LR.End, TryShort);
291}
292
293int TraceState::TryToAddDesiredData(uint64_t PresentData, uint64_t DesiredData,
294                                    size_t DataSize) {
295  int Res = 0;
296  const uint8_t *Beg = CurrentUnit.data();
297  const uint8_t *End = Beg + CurrentUnit.size();
298  for (const uint8_t *Cur = Beg; Cur < End; Cur++) {
299    Cur = (uint8_t *)memmem(Cur, End - Cur, &PresentData, DataSize);
300    if (!Cur)
301      break;
302    size_t Pos = Cur - Beg;
303    assert(Pos < CurrentUnit.size());
304    if (Mutations.size() > 100000U) return Res;  // Just in case.
305    Mutations.push_back({Pos, DataSize, DesiredData});
306    Mutations.push_back({Pos, DataSize, DesiredData + 1});
307    Mutations.push_back({Pos, DataSize, DesiredData - 1});
308    Res++;
309  }
310  return Res;
311}
312
313void TraceState::TraceCmpCallback(uintptr_t PC, size_t CmpSize, size_t CmpType,
314                                  uint64_t Arg1, uint64_t Arg2) {
315  if (!RecordingTraces) return;
316  int Added = 0;
317  if (Options.Verbosity >= 3)
318    Printf("TraceCmp %zd/%zd: %p %zd %zd\n", CmpSize, CmpType, PC, Arg1, Arg2);
319  Added += TryToAddDesiredData(Arg1, Arg2, CmpSize);
320  Added += TryToAddDesiredData(Arg2, Arg1, CmpSize);
321  if (!Added && CmpSize == 4 && IsTwoByteData(Arg1) && IsTwoByteData(Arg2)) {
322    Added += TryToAddDesiredData(Arg1, Arg2, 2);
323    Added += TryToAddDesiredData(Arg2, Arg1, 2);
324  }
325}
326
327void TraceState::TraceSwitchCallback(uintptr_t PC, size_t ValSizeInBits,
328                                     uint64_t Val, size_t NumCases,
329                                     uint64_t *Cases) {
330  if (!RecordingTraces) return;
331  size_t ValSize = ValSizeInBits / 8;
332  bool TryShort = IsTwoByteData(Val);
333  for (size_t i = 0; i < NumCases; i++)
334    TryShort &= IsTwoByteData(Cases[i]);
335
336  if (Options.Verbosity >= 3)
337    Printf("TraceSwitch: %p %zd # %zd; TryShort %d\n", PC, Val, NumCases,
338           TryShort);
339
340  for (size_t i = 0; i < NumCases; i++) {
341    TryToAddDesiredData(Val, Cases[i], ValSize);
342    if (TryShort)
343      TryToAddDesiredData(Val, Cases[i], 2);
344  }
345
346}
347
348static TraceState *TS;
349
350void Fuzzer::StartTraceRecording() {
351  if (!TS) return;
352  if (ReallyHaveDFSan())
353    for (size_t i = 0; i < static_cast<size_t>(Options.MaxLen); i++)
354      dfsan_set_label(i + 1, &CurrentUnit[i], 1);
355  TS->StartTraceRecording();
356}
357
358size_t Fuzzer::StopTraceRecording() {
359  if (!TS) return 0;
360  return TS->StopTraceRecording(USF.GetRand());
361}
362
363void Fuzzer::ApplyTraceBasedMutation(size_t Idx, Unit *U) {
364  assert(TS);
365  TS->ApplyTraceBasedMutation(Idx, U);
366}
367
368void Fuzzer::InitializeTraceState() {
369  if (!Options.UseTraces) return;
370  TS = new TraceState(Options, CurrentUnit);
371  CurrentUnit.resize(Options.MaxLen);
372  // The rest really requires DFSan.
373  if (!ReallyHaveDFSan()) return;
374  for (size_t i = 0; i < static_cast<size_t>(Options.MaxLen); i++) {
375    dfsan_label L = dfsan_create_label("input", (void*)(i + 1));
376    // We assume that no one else has called dfsan_create_label before.
377    if (L != i + 1) {
378      Printf("DFSan labels are not starting from 1, exiting\n");
379      exit(1);
380    }
381  }
382}
383
384static size_t InternalStrnlen(const char *S, size_t MaxLen) {
385  size_t Len = 0;
386  for (; Len < MaxLen && S[Len]; Len++) {}
387  return Len;
388}
389
390}  // namespace fuzzer
391
392using fuzzer::TS;
393
394extern "C" {
395void __dfsw___sanitizer_cov_trace_cmp(uint64_t SizeAndType, uint64_t Arg1,
396                                      uint64_t Arg2, dfsan_label L0,
397                                      dfsan_label L1, dfsan_label L2) {
398  if (!TS) return;
399  assert(L0 == 0);
400  uintptr_t PC = reinterpret_cast<uintptr_t>(__builtin_return_address(0));
401  uint64_t CmpSize = (SizeAndType >> 32) / 8;
402  uint64_t Type = (SizeAndType << 32) >> 32;
403  TS->DFSanCmpCallback(PC, CmpSize, Type, Arg1, Arg2, L1, L2);
404}
405
406void __dfsw___sanitizer_cov_trace_switch(uint64_t Val, uint64_t *Cases,
407                                         dfsan_label L1, dfsan_label L2) {
408  if (!TS) return;
409  uintptr_t PC = reinterpret_cast<uintptr_t>(__builtin_return_address(0));
410  TS->DFSanSwitchCallback(PC, Cases[1], Val, Cases[0], Cases+2, L1);
411}
412
413void dfsan_weak_hook_memcmp(void *caller_pc, const void *s1, const void *s2,
414                            size_t n, dfsan_label s1_label,
415                            dfsan_label s2_label, dfsan_label n_label) {
416  if (!TS) return;
417  uintptr_t PC = reinterpret_cast<uintptr_t>(caller_pc);
418  uint64_t S1 = 0, S2 = 0;
419  // Simplification: handle only first 8 bytes.
420  memcpy(&S1, s1, std::min(n, sizeof(S1)));
421  memcpy(&S2, s2, std::min(n, sizeof(S2)));
422  dfsan_label L1 = dfsan_read_label(s1, n);
423  dfsan_label L2 = dfsan_read_label(s2, n);
424  TS->DFSanCmpCallback(PC, n, fuzzer::ICMP_EQ, S1, S2, L1, L2);
425}
426
427void dfsan_weak_hook_strncmp(void *caller_pc, const char *s1, const char *s2,
428                             size_t n, dfsan_label s1_label,
429                             dfsan_label s2_label, dfsan_label n_label) {
430  if (!TS) return;
431  uintptr_t PC = reinterpret_cast<uintptr_t>(caller_pc);
432  uint64_t S1 = 0, S2 = 0;
433  n = std::min(n, fuzzer::InternalStrnlen(s1, n));
434  n = std::min(n, fuzzer::InternalStrnlen(s2, n));
435  // Simplification: handle only first 8 bytes.
436  memcpy(&S1, s1, std::min(n, sizeof(S1)));
437  memcpy(&S2, s2, std::min(n, sizeof(S2)));
438  dfsan_label L1 = dfsan_read_label(s1, n);
439  dfsan_label L2 = dfsan_read_label(s2, n);
440  TS->DFSanCmpCallback(PC, n, fuzzer::ICMP_EQ, S1, S2, L1, L2);
441}
442
443void dfsan_weak_hook_strcmp(void *caller_pc, const char *s1, const char *s2,
444                            dfsan_label s1_label, dfsan_label s2_label) {
445  if (!TS) return;
446  uintptr_t PC = reinterpret_cast<uintptr_t>(caller_pc);
447  uint64_t S1 = 0, S2 = 0;
448  size_t Len1 = strlen(s1);
449  size_t Len2 = strlen(s2);
450  size_t N = std::min(Len1, Len2);
451  if (N <= 1) return;  // Not interesting.
452  // Simplification: handle only first 8 bytes.
453  memcpy(&S1, s1, std::min(N, sizeof(S1)));
454  memcpy(&S2, s2, std::min(N, sizeof(S2)));
455  dfsan_label L1 = dfsan_read_label(s1, Len1);
456  dfsan_label L2 = dfsan_read_label(s2, Len2);
457  TS->DFSanCmpCallback(PC, N, fuzzer::ICMP_EQ, S1, S2, L1, L2);
458}
459
460void __sanitizer_weak_hook_memcmp(void *caller_pc, const void *s1,
461                                  const void *s2, size_t n) {
462  if (!TS) return;
463  uintptr_t PC = reinterpret_cast<uintptr_t>(caller_pc);
464  uint64_t S1 = 0, S2 = 0;
465  // Simplification: handle only first 8 bytes.
466  memcpy(&S1, s1, std::min(n, sizeof(S1)));
467  memcpy(&S2, s2, std::min(n, sizeof(S2)));
468  TS->TraceCmpCallback(PC, n, fuzzer::ICMP_EQ, S1, S2);
469}
470
471void __sanitizer_weak_hook_strncmp(void *caller_pc, const char *s1,
472                                   const char *s2, size_t n) {
473  if (!TS) return;
474  uintptr_t PC = reinterpret_cast<uintptr_t>(caller_pc);
475  uint64_t S1 = 0, S2 = 0;
476  size_t Len1 = fuzzer::InternalStrnlen(s1, n);
477  size_t Len2 = fuzzer::InternalStrnlen(s2, n);
478  n = std::min(n, Len1);
479  n = std::min(n, Len2);
480  if (n <= 1) return;  // Not interesting.
481  // Simplification: handle only first 8 bytes.
482  memcpy(&S1, s1, std::min(n, sizeof(S1)));
483  memcpy(&S2, s2, std::min(n, sizeof(S2)));
484  TS->TraceCmpCallback(PC, n, fuzzer::ICMP_EQ, S1, S2);
485}
486
487void __sanitizer_weak_hook_strcmp(void *caller_pc, const char *s1,
488                                   const char *s2) {
489  if (!TS) return;
490  uintptr_t PC = reinterpret_cast<uintptr_t>(caller_pc);
491  uint64_t S1 = 0, S2 = 0;
492  size_t Len1 = strlen(s1);
493  size_t Len2 = strlen(s2);
494  size_t N = std::min(Len1, Len2);
495  if (N <= 1) return;  // Not interesting.
496  // Simplification: handle only first 8 bytes.
497  memcpy(&S1, s1, std::min(N, sizeof(S1)));
498  memcpy(&S2, s2, std::min(N, sizeof(S2)));
499  TS->TraceCmpCallback(PC, N, fuzzer::ICMP_EQ, S1, S2);
500}
501
502__attribute__((visibility("default")))
503void __sanitizer_cov_trace_cmp(uint64_t SizeAndType, uint64_t Arg1,
504                               uint64_t Arg2) {
505  if (!TS) return;
506  uintptr_t PC = reinterpret_cast<uintptr_t>(__builtin_return_address(0));
507  uint64_t CmpSize = (SizeAndType >> 32) / 8;
508  uint64_t Type = (SizeAndType << 32) >> 32;
509  TS->TraceCmpCallback(PC, CmpSize, Type, Arg1, Arg2);
510}
511
512__attribute__((visibility("default")))
513void __sanitizer_cov_trace_switch(uint64_t Val, uint64_t *Cases) {
514  if (!TS) return;
515  uintptr_t PC = reinterpret_cast<uintptr_t>(__builtin_return_address(0));
516  TS->TraceSwitchCallback(PC, Cases[1], Val, Cases[0], Cases + 2);
517}
518
519}  // extern "C"
520