asan_thread.cc revision 717ece58e18190c4aef50bd16254db1d74036395 
1//===-- asan_thread.cc ----------------------------------------------------===//
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//
10// This file is a part of AddressSanitizer, an address sanity checker.
11//
12// Thread-related code.
13//===----------------------------------------------------------------------===//
14#include "asan_allocator.h"
15#include "asan_interceptors.h"
16#include "asan_poisoning.h"
17#include "asan_stack.h"
18#include "asan_thread.h"
19#include "asan_mapping.h"
20#include "sanitizer_common/sanitizer_common.h"
21#include "sanitizer_common/sanitizer_placement_new.h"
22#include "lsan/lsan_common.h"
23
24namespace __asan {
25
26// AsanThreadContext implementation.
27
28void AsanThreadContext::OnCreated(void *arg) {
29  CreateThreadContextArgs *args = static_cast<CreateThreadContextArgs*>(arg);
30  if (args->stack) {
31    internal_memcpy(&stack, args->stack, sizeof(stack));
32  }
33  thread = args->thread;
34  thread->set_context(this);
35}
36
37void AsanThreadContext::OnFinished() {
38  // Drop the link to the AsanThread object.
39  thread = 0;
40}
41
42// MIPS requires aligned address
43static ALIGNED(16) char thread_registry_placeholder[sizeof(ThreadRegistry)];
44static ThreadRegistry *asan_thread_registry;
45
46static ThreadContextBase *GetAsanThreadContext(u32 tid) {
47  void *mem = MmapOrDie(sizeof(AsanThreadContext), "AsanThreadContext");
48  return new(mem) AsanThreadContext(tid);
49}
50
51ThreadRegistry &asanThreadRegistry() {
52  static bool initialized;
53  // Don't worry about thread_safety - this should be called when there is
54  // a single thread.
55  if (!initialized) {
56    // Never reuse ASan threads: we store pointer to AsanThreadContext
57    // in TSD and can't reliably tell when no more TSD destructors will
58    // be called. It would be wrong to reuse AsanThreadContext for another
59    // thread before all TSD destructors will be called for it.
60    asan_thread_registry = new(thread_registry_placeholder) ThreadRegistry(
61        GetAsanThreadContext, kMaxNumberOfThreads, kMaxNumberOfThreads);
62    initialized = true;
63  }
64  return *asan_thread_registry;
65}
66
67AsanThreadContext *GetThreadContextByTidLocked(u32 tid) {
68  return static_cast<AsanThreadContext *>(
69      asanThreadRegistry().GetThreadLocked(tid));
70}
71
72// AsanThread implementation.
73
74AsanThread *AsanThread::Create(thread_callback_t start_routine,
75                               void *arg) {
76  uptr PageSize = GetPageSizeCached();
77  uptr size = RoundUpTo(sizeof(AsanThread), PageSize);
78  AsanThread *thread = (AsanThread*)MmapOrDie(size, __FUNCTION__);
79  thread->start_routine_ = start_routine;
80  thread->arg_ = arg;
81  thread->context_ = 0;
82
83  return thread;
84}
85
86void AsanThread::TSDDtor(void *tsd) {
87  AsanThreadContext *context = (AsanThreadContext*)tsd;
88  if (flags()->verbosity >= 1)
89    Report("T%d TSDDtor\n", context->tid);
90  if (context->thread)
91    context->thread->Destroy();
92}
93
94void AsanThread::Destroy() {
95  if (flags()->verbosity >= 1) {
96    Report("T%d exited\n", tid());
97  }
98
99  asanThreadRegistry().FinishThread(tid());
100  FlushToDeadThreadStats(&stats_);
101  // We also clear the shadow on thread destruction because
102  // some code may still be executing in later TSD destructors
103  // and we don't want it to have any poisoned stack.
104  ClearShadowForThreadStackAndTLS();
105  DeleteFakeStack();
106  uptr size = RoundUpTo(sizeof(AsanThread), GetPageSizeCached());
107  UnmapOrDie(this, size);
108}
109
110void AsanThread::Init() {
111  SetThreadStackAndTls();
112  CHECK(AddrIsInMem(stack_bottom_));
113  CHECK(AddrIsInMem(stack_top_ - 1));
114  ClearShadowForThreadStackAndTLS();
115  if (flags()->verbosity >= 1) {
116    int local = 0;
117    Report("T%d: stack [%p,%p) size 0x%zx; local=%p\n",
118           tid(), (void*)stack_bottom_, (void*)stack_top_,
119           stack_top_ - stack_bottom_, &local);
120  }
121  fake_stack_ = 0;  // Will be initialized lazily if needed.
122  AsanPlatformThreadInit();
123}
124
125thread_return_t AsanThread::ThreadStart(uptr os_id) {
126  Init();
127  asanThreadRegistry().StartThread(tid(), os_id, 0);
128  if (flags()->use_sigaltstack) SetAlternateSignalStack();
129
130  if (!start_routine_) {
131    // start_routine_ == 0 if we're on the main thread or on one of the
132    // OS X libdispatch worker threads. But nobody is supposed to call
133    // ThreadStart() for the worker threads.
134    CHECK_EQ(tid(), 0);
135    return 0;
136  }
137
138  thread_return_t res = start_routine_(arg_);
139  malloc_storage().CommitBack();
140  if (flags()->use_sigaltstack) UnsetAlternateSignalStack();
141
142  this->Destroy();
143
144  return res;
145}
146
147void AsanThread::SetThreadStackAndTls() {
148  uptr stack_size = 0, tls_size = 0;
149  GetThreadStackAndTls(tid() == 0, &stack_bottom_, &stack_size, &tls_begin_,
150                       &tls_size);
151  stack_top_ = stack_bottom_ + stack_size;
152  tls_end_ = tls_begin_ + tls_size;
153
154  int local;
155  CHECK(AddrIsInStack((uptr)&local));
156}
157
158void AsanThread::ClearShadowForThreadStackAndTLS() {
159  PoisonShadow(stack_bottom_, stack_top_ - stack_bottom_, 0);
160  if (tls_begin_ != tls_end_)
161    PoisonShadow(tls_begin_, tls_end_ - tls_begin_, 0);
162}
163
164const char *AsanThread::GetFrameNameByAddr(uptr addr, uptr *offset,
165                                           uptr *frame_pc) {
166  uptr bottom = 0;
167  if (AddrIsInStack(addr)) {
168    bottom = stack_bottom();
169  } else if (fake_stack()) {
170    bottom = fake_stack()->AddrIsInFakeStack(addr);
171    CHECK(bottom);
172    *offset = addr - bottom;
173    *frame_pc = ((uptr*)bottom)[2];
174    return  (const char *)((uptr*)bottom)[1];
175  }
176  uptr aligned_addr = addr & ~(SANITIZER_WORDSIZE/8 - 1);  // align addr.
177  u8 *shadow_ptr = (u8*)MemToShadow(aligned_addr);
178  u8 *shadow_bottom = (u8*)MemToShadow(bottom);
179
180  while (shadow_ptr >= shadow_bottom &&
181         *shadow_ptr != kAsanStackLeftRedzoneMagic) {
182    shadow_ptr--;
183  }
184
185  while (shadow_ptr >= shadow_bottom &&
186         *shadow_ptr == kAsanStackLeftRedzoneMagic) {
187    shadow_ptr--;
188  }
189
190  if (shadow_ptr < shadow_bottom) {
191    *offset = 0;
192    return "UNKNOWN";
193  }
194
195  uptr* ptr = (uptr*)SHADOW_TO_MEM((uptr)(shadow_ptr + 1));
196  CHECK(ptr[0] == kCurrentStackFrameMagic);
197  *offset = addr - (uptr)ptr;
198  *frame_pc = ptr[2];
199  return (const char*)ptr[1];
200}
201
202static bool ThreadStackContainsAddress(ThreadContextBase *tctx_base,
203                                       void *addr) {
204  AsanThreadContext *tctx = static_cast<AsanThreadContext*>(tctx_base);
205  AsanThread *t = tctx->thread;
206  if (!t) return false;
207  if (t->AddrIsInStack((uptr)addr)) return true;
208  if (t->fake_stack() && t->fake_stack()->AddrIsInFakeStack((uptr)addr))
209    return true;
210  return false;
211}
212
213AsanThread *GetCurrentThread() {
214  AsanThreadContext *context =
215      reinterpret_cast<AsanThreadContext *>(AsanTSDGet());
216  if (!context) {
217    if (SANITIZER_ANDROID) {
218      // On Android, libc constructor is called _after_ asan_init, and cleans up
219      // TSD. Try to figure out if this is still the main thread by the stack
220      // address. We are not entirely sure that we have correct main thread
221      // limits, so only do this magic on Android, and only if the found thread
222      // is the main thread.
223      AsanThreadContext *tctx = GetThreadContextByTidLocked(0);
224      if (ThreadStackContainsAddress(tctx, &context)) {
225        SetCurrentThread(tctx->thread);
226        return tctx->thread;
227      }
228    }
229    return 0;
230  }
231  return context->thread;
232}
233
234void SetCurrentThread(AsanThread *t) {
235  CHECK(t->context());
236  if (flags()->verbosity >= 2) {
237    Report("SetCurrentThread: %p for thread %p\n",
238           t->context(), (void*)GetThreadSelf());
239  }
240  // Make sure we do not reset the current AsanThread.
241  CHECK_EQ(0, AsanTSDGet());
242  AsanTSDSet(t->context());
243  CHECK_EQ(t->context(), AsanTSDGet());
244}
245
246u32 GetCurrentTidOrInvalid() {
247  AsanThread *t = GetCurrentThread();
248  return t ? t->tid() : kInvalidTid;
249}
250
251AsanThread *FindThreadByStackAddress(uptr addr) {
252  asanThreadRegistry().CheckLocked();
253  AsanThreadContext *tctx = static_cast<AsanThreadContext *>(
254      asanThreadRegistry().FindThreadContextLocked(ThreadStackContainsAddress,
255                                                   (void *)addr));
256  return tctx ? tctx->thread : 0;
257}
258
259void EnsureMainThreadIDIsCorrect() {
260  AsanThreadContext *context =
261      reinterpret_cast<AsanThreadContext *>(AsanTSDGet());
262  if (context && (context->tid == 0))
263    context->os_id = GetTid();
264}
265}  // namespace __asan
266
267// --- Implementation of LSan-specific functions --- {{{1
268namespace __lsan {
269bool GetThreadRangesLocked(uptr os_id, uptr *stack_begin, uptr *stack_end,
270                           uptr *tls_begin, uptr *tls_end,
271                           uptr *cache_begin, uptr *cache_end) {
272  __asan::AsanThreadContext *context = static_cast<__asan::AsanThreadContext *>(
273      __asan::asanThreadRegistry().FindThreadContextByOsIDLocked(os_id));
274  if (!context) return false;
275  __asan::AsanThread *t = context->thread;
276  if (!t) return false;
277  *stack_begin = t->stack_bottom();
278  *stack_end = t->stack_top();
279  *tls_begin = t->tls_begin();
280  *tls_end = t->tls_end();
281  // ASan doesn't keep allocator caches in TLS, so these are unused.
282  *cache_begin = 0;
283  *cache_end = 0;
284  return true;
285}
286
287void LockThreadRegistry() {
288  __asan::asanThreadRegistry().Lock();
289}
290
291void UnlockThreadRegistry() {
292  __asan::asanThreadRegistry().Unlock();
293}
294
295void EnsureMainThreadIDIsCorrect() {
296  __asan::EnsureMainThreadIDIsCorrect();
297}
298}  // namespace __lsan
299