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 
19 namespace __tsan {
20 
21 #define CALLERPC ((uptr)__builtin_return_address(0))
22 
23 struct TagData {
24   const char *object_type;
25   const char *header;
26 };
27 
28 static TagData registered_tags[kExternalTagMax] = {
29   {},
30   {"Swift variable", "Swift access race"},
31 };
32 static atomic_uint32_t used_tags{kExternalTagFirstUserAvailable};
GetTagData(uptr tag)33 static 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 
GetObjectTypeFromTag(uptr tag)39 const char *GetObjectTypeFromTag(uptr tag) {
40   TagData *tag_data = GetTagData(tag);
41   return tag_data ? tag_data->object_type : nullptr;
42 }
43 
GetReportHeaderFromTag(uptr tag)44 const char *GetReportHeaderFromTag(uptr tag) {
45   TagData *tag_data = GetTagData(tag);
46   return tag_data ? tag_data->header : nullptr;
47 }
48 
TagFromShadowStackFrame(uptr pc)49 uptr 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.
PushTag(ThreadState * thr,uptr tag)62 static void PushTag(ThreadState *thr, uptr tag) {
63   FuncEntry(thr, (uptr)&registered_tags[tag]);
64 }
PopTag(ThreadState * thr)65 static void PopTag(ThreadState *thr) { FuncExit(thr); }
66 
ExternalAccess(void * addr,uptr caller_pc,uptr tsan_caller_pc,void * tag,AccessType typ)67 static 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 
82 extern "C" {
83 SANITIZER_INTERFACE_ATTRIBUTE
__tsan_external_register_tag(const char * object_type)84 void *__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 
94 SANITIZER_INTERFACE_ATTRIBUTE
__tsan_external_register_header(void * tag,const char * header)95 void __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 
106 SANITIZER_INTERFACE_ATTRIBUTE
__tsan_external_assign_tag(void * addr,void * tag)107 void __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 
120 SANITIZER_INTERFACE_ATTRIBUTE
__tsan_external_read(void * addr,void * caller_pc,void * tag)121 void __tsan_external_read(void *addr, void *caller_pc, void *tag) {
122   ExternalAccess(addr, STRIP_PAC_PC(caller_pc), CALLERPC, tag, kAccessRead);
123 }
124 
125 SANITIZER_INTERFACE_ATTRIBUTE
__tsan_external_write(void * addr,void * caller_pc,void * tag)126 void __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