1//===-- tsan_external.cpp -------------------------------------------------===//
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 ThreadSanitizer (TSan), a race detector.
10//
11//===----------------------------------------------------------------------===//
12#include "tsan_rtl.h"
13#include "sanitizer_common/sanitizer_ptrauth.h"
14
15#if !SANITIZER_GO
16#  include "tsan_interceptors.h"
17#endif
18
19namespace __tsan {
20
21#define CALLERPC ((uptr)__builtin_return_address(0))
22
23struct TagData {
24  const char *object_type;
25  const char *header;
26};
27
28static TagData registered_tags[kExternalTagMax] = {
29  {},
30  {"Swift variable", "Swift access race"},
31};
32static atomic_uint32_t used_tags{kExternalTagFirstUserAvailable};
33static TagData *GetTagData(uptr tag) {
34  // Invalid/corrupted tag?  Better return NULL and let the caller deal with it.
35  if (tag >= atomic_load(&used_tags, memory_order_relaxed)) return nullptr;
36  return &registered_tags[tag];
37}
38
39const char *GetObjectTypeFromTag(uptr tag) {
40  TagData *tag_data = GetTagData(tag);
41  return tag_data ? tag_data->object_type : nullptr;
42}
43
44const char *GetReportHeaderFromTag(uptr tag) {
45  TagData *tag_data = GetTagData(tag);
46  return tag_data ? tag_data->header : nullptr;
47}
48
49uptr TagFromShadowStackFrame(uptr pc) {
50  uptr tag_count = atomic_load(&used_tags, memory_order_relaxed);
51  void *pc_ptr = (void *)pc;
52  if (pc_ptr < GetTagData(0) || pc_ptr > GetTagData(tag_count - 1))
53    return 0;
54  return (TagData *)pc_ptr - GetTagData(0);
55}
56
57#if !SANITIZER_GO
58
59// We need to track tags for individual memory accesses, but there is no space
60// in the shadow cells for them.  Instead we push/pop them onto the thread
61// traces and ignore the extra tag frames when printing reports.
62static void PushTag(ThreadState *thr, uptr tag) {
63  FuncEntry(thr, (uptr)&registered_tags[tag]);
64}
65static void PopTag(ThreadState *thr) { FuncExit(thr); }
66
67static void ExternalAccess(void *addr, uptr caller_pc, uptr tsan_caller_pc,
68                           void *tag, AccessType typ) {
69  CHECK_LT(tag, atomic_load(&used_tags, memory_order_relaxed));
70  bool in_ignored_lib;
71  if (caller_pc && libignore()->IsIgnored(caller_pc, &in_ignored_lib))
72    return;
73
74  ThreadState *thr = cur_thread();
75  if (caller_pc) FuncEntry(thr, caller_pc);
76  PushTag(thr, (uptr)tag);
77  MemoryAccess(thr, tsan_caller_pc, (uptr)addr, 1, typ);
78  PopTag(thr);
79  if (caller_pc) FuncExit(thr);
80}
81
82extern "C" {
83SANITIZER_INTERFACE_ATTRIBUTE
84void *__tsan_external_register_tag(const char *object_type) {
85  uptr new_tag = atomic_fetch_add(&used_tags, 1, memory_order_relaxed);
86  CHECK_LT(new_tag, kExternalTagMax);
87  GetTagData(new_tag)->object_type = internal_strdup(object_type);
88  char header[127] = {0};
89  internal_snprintf(header, sizeof(header), "race on %s", object_type);
90  GetTagData(new_tag)->header = internal_strdup(header);
91  return (void *)new_tag;
92}
93
94SANITIZER_INTERFACE_ATTRIBUTE
95void __tsan_external_register_header(void *tag, const char *header) {
96  CHECK_GE((uptr)tag, kExternalTagFirstUserAvailable);
97  CHECK_LT((uptr)tag, kExternalTagMax);
98  atomic_uintptr_t *header_ptr =
99      (atomic_uintptr_t *)&GetTagData((uptr)tag)->header;
100  header = internal_strdup(header);
101  char *old_header =
102      (char *)atomic_exchange(header_ptr, (uptr)header, memory_order_seq_cst);
103  Free(old_header);
104}
105
106SANITIZER_INTERFACE_ATTRIBUTE
107void __tsan_external_assign_tag(void *addr, void *tag) {
108  CHECK_LT(tag, atomic_load(&used_tags, memory_order_relaxed));
109  Allocator *a = allocator();
110  MBlock *b = nullptr;
111  if (a->PointerIsMine((void *)addr)) {
112    void *block_begin = a->GetBlockBegin((void *)addr);
113    if (block_begin) b = ctx->metamap.GetBlock((uptr)block_begin);
114  }
115  if (b) {
116    b->tag = (uptr)tag;
117  }
118}
119
120SANITIZER_INTERFACE_ATTRIBUTE
121void __tsan_external_read(void *addr, void *caller_pc, void *tag) {
122  ExternalAccess(addr, STRIP_PAC_PC(caller_pc), CALLERPC, tag, kAccessRead);
123}
124
125SANITIZER_INTERFACE_ATTRIBUTE
126void __tsan_external_write(void *addr, void *caller_pc, void *tag) {
127  ExternalAccess(addr, STRIP_PAC_PC(caller_pc), CALLERPC, tag, kAccessWrite);
128}
129}  // extern "C"
130
131#endif  // !SANITIZER_GO
132
133}  // namespace __tsan
134