1//===-- asan_thread.h -------------------------------------------*- 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 AddressSanitizer, an address sanity checker.
10//
11// ASan-private header for asan_thread.cpp.
12//===----------------------------------------------------------------------===//
13
14#ifndef ASAN_THREAD_H
15#define ASAN_THREAD_H
16
17#include "asan_allocator.h"
18#include "asan_fake_stack.h"
19#include "asan_internal.h"
20#include "asan_stats.h"
21#include "sanitizer_common/sanitizer_common.h"
22#include "sanitizer_common/sanitizer_libc.h"
23#include "sanitizer_common/sanitizer_thread_arg_retval.h"
24#include "sanitizer_common/sanitizer_thread_registry.h"
25
26namespace __sanitizer {
27struct DTLS;
28} // namespace __sanitizer
29
30namespace __asan {
31
32class AsanThread;
33
34// These objects are created for every thread and are never deleted,
35// so we can find them by tid even if the thread is long dead.
36class AsanThreadContext final : public ThreadContextBase {
37 public:
38 explicit AsanThreadContext(int tid)
39 : ThreadContextBase(tid),
40 announced(false),
41 destructor_iterations(GetPthreadDestructorIterations()),
42 thread(nullptr) {}
43 bool announced;
44 u8 destructor_iterations;
45 AsanThread *thread;
46
47 void OnCreated(void *arg) override;
48 void OnFinished() override;
49};
50
51// AsanThreadContext objects are never freed, so we need many of them.
52COMPILER_CHECK(sizeof(AsanThreadContext) <= 256);
53
54#if defined(_MSC_VER) && !defined(__clang__)
55// MSVC raises a warning about a nonstandard extension being used for the 0
56// sized element in this array. Disable this for warn-as-error builds.
57# pragma warning(push)
58# pragma warning(disable : 4200)
59#endif
60
61// AsanThread are stored in TSD and destroyed when the thread dies.
62class AsanThread {
63 public:
64 template <typename T>
65 static AsanThread *Create(const T &data, u32 parent_tid, StackTrace *stack,
66 bool detached) {
67 return Create(&data, sizeof(data), parent_tid, stack, detached);
68 }
69 static AsanThread *Create(u32 parent_tid, StackTrace *stack, bool detached) {
70 return Create(start_data: nullptr, data_size: 0, parent_tid, stack, detached);
71 }
72 static void TSDDtor(void *tsd);
73 void Destroy();
74
75 struct InitOptions;
76 void Init(const InitOptions *options = nullptr);
77
78 void ThreadStart(tid_t os_id);
79 thread_return_t RunThread();
80
81 uptr stack_top();
82 uptr stack_bottom();
83 uptr stack_size();
84 uptr tls_begin() { return tls_begin_; }
85 uptr tls_end() { return tls_end_; }
86 DTLS *dtls() { return dtls_; }
87 u32 tid() { return context_->tid; }
88 AsanThreadContext *context() { return context_; }
89 void set_context(AsanThreadContext *context) { context_ = context; }
90
91 struct StackFrameAccess {
92 uptr offset;
93 uptr frame_pc;
94 const char *frame_descr;
95 };
96 bool GetStackFrameAccessByAddr(uptr addr, StackFrameAccess *access);
97
98 // Returns a pointer to the start of the stack variable's shadow memory.
99 uptr GetStackVariableShadowStart(uptr addr);
100
101 bool AddrIsInStack(uptr addr);
102
103 void DeleteFakeStack(int tid) {
104 if (!fake_stack_) return;
105 FakeStack *t = fake_stack_;
106 fake_stack_ = nullptr;
107 SetTLSFakeStack(nullptr);
108 t->Destroy(tid);
109 }
110
111 void StartSwitchFiber(FakeStack **fake_stack_save, uptr bottom, uptr size);
112 void FinishSwitchFiber(FakeStack *fake_stack_save, uptr *bottom_old,
113 uptr *size_old);
114
115 FakeStack *get_fake_stack() {
116 if (atomic_load(a: &stack_switching_, mo: memory_order_relaxed))
117 return nullptr;
118 if (reinterpret_cast<uptr>(fake_stack_) <= 1)
119 return nullptr;
120 return fake_stack_;
121 }
122
123 FakeStack *get_or_create_fake_stack() {
124 if (atomic_load(a: &stack_switching_, mo: memory_order_relaxed))
125 return nullptr;
126 if (reinterpret_cast<uptr>(fake_stack_) <= 1)
127 return AsyncSignalSafeLazyInitFakeStack();
128 return fake_stack_;
129 }
130
131 // True is this thread is currently unwinding stack (i.e. collecting a stack
132 // trace). Used to prevent deadlocks on platforms where libc unwinder calls
133 // malloc internally. See PR17116 for more details.
134 bool isUnwinding() const { return unwinding_; }
135 void setUnwinding(bool b) { unwinding_ = b; }
136
137 AsanThreadLocalMallocStorage &malloc_storage() { return malloc_storage_; }
138 AsanStats &stats() { return stats_; }
139
140 void *extra_spill_area() { return &extra_spill_area_; }
141
142 template <typename T>
143 void GetStartData(T &data) const {
144 GetStartData(&data, sizeof(data));
145 }
146
147 private:
148 // NOTE: There is no AsanThread constructor. It is allocated
149 // via mmap() and *must* be valid in zero-initialized state.
150
151 static AsanThread *Create(const void *start_data, uptr data_size,
152 u32 parent_tid, StackTrace *stack, bool detached);
153
154 void SetThreadStackAndTls(const InitOptions *options);
155
156 void ClearShadowForThreadStackAndTLS();
157 FakeStack *AsyncSignalSafeLazyInitFakeStack();
158
159 struct StackBounds {
160 uptr bottom;
161 uptr top;
162 };
163 StackBounds GetStackBounds() const;
164
165 void GetStartData(void *out, uptr out_size) const;
166
167 AsanThreadContext *context_;
168
169 uptr stack_top_;
170 uptr stack_bottom_;
171 // these variables are used when the thread is about to switch stack
172 uptr next_stack_top_;
173 uptr next_stack_bottom_;
174 // true if switching is in progress
175 atomic_uint8_t stack_switching_;
176
177 uptr tls_begin_;
178 uptr tls_end_;
179 DTLS *dtls_;
180
181 FakeStack *fake_stack_;
182 AsanThreadLocalMallocStorage malloc_storage_;
183 AsanStats stats_;
184 bool unwinding_;
185 uptr extra_spill_area_;
186
187 char start_data_[];
188};
189
190#if defined(_MSC_VER) && !defined(__clang__)
191# pragma warning(pop)
192#endif
193
194// Returns a single instance of registry.
195ThreadRegistry &asanThreadRegistry();
196ThreadArgRetval &asanThreadArgRetval();
197
198// Must be called under ThreadRegistryLock.
199AsanThreadContext *GetThreadContextByTidLocked(u32 tid);
200
201// Get the current thread. May return 0.
202AsanThread *GetCurrentThread();
203void SetCurrentThread(AsanThread *t);
204u32 GetCurrentTidOrInvalid();
205AsanThread *FindThreadByStackAddress(uptr addr);
206
207// Used to handle fork().
208void EnsureMainThreadIDIsCorrect();
209} // namespace __asan
210
211#endif // ASAN_THREAD_H
212