1 //===-- sanitizer_deadlock_detector1.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 // Deadlock detector implementation based on NxN adjacency bit matrix. 10 // 11 //===----------------------------------------------------------------------===// 12 13 #include "sanitizer_deadlock_detector_interface.h" 14 #include "sanitizer_deadlock_detector.h" 15 #include "sanitizer_allocator_internal.h" 16 #include "sanitizer_placement_new.h" 17 #include "sanitizer_mutex.h" 18 19 #if SANITIZER_DEADLOCK_DETECTOR_VERSION == 1 20 21 namespace __sanitizer { 22 23 typedef TwoLevelBitVector<> DDBV; // DeadlockDetector's bit vector. 24 25 struct DDPhysicalThread { 26 }; 27 28 struct DDLogicalThread { 29 u64 ctx; 30 DeadlockDetectorTLS<DDBV> dd; 31 DDReport rep; 32 bool report_pending; 33 }; 34 35 struct DD : public DDetector { 36 SpinMutex mtx; 37 DeadlockDetector<DDBV> dd; 38 DDFlags flags; 39 40 explicit DD(const DDFlags *flags); 41 42 DDPhysicalThread *CreatePhysicalThread() override; 43 void DestroyPhysicalThread(DDPhysicalThread *pt) override; 44 45 DDLogicalThread *CreateLogicalThread(u64 ctx) override; 46 void DestroyLogicalThread(DDLogicalThread *lt) override; 47 48 void MutexInit(DDCallback *cb, DDMutex *m) override; 49 void MutexBeforeLock(DDCallback *cb, DDMutex *m, bool wlock) override; 50 void MutexAfterLock(DDCallback *cb, DDMutex *m, bool wlock, 51 bool trylock) override; 52 void MutexBeforeUnlock(DDCallback *cb, DDMutex *m, bool wlock) override; 53 void MutexDestroy(DDCallback *cb, DDMutex *m) override; 54 55 DDReport *GetReport(DDCallback *cb) override; 56 57 void MutexEnsureID(DDLogicalThread *lt, DDMutex *m); 58 void ReportDeadlock(DDCallback *cb, DDMutex *m); 59 }; 60 61 DDetector *DDetector::Create(const DDFlags *flags) { 62 (void)flags; 63 void *mem = MmapOrDie(sizeof(DD), "deadlock detector"); 64 return new(mem) DD(flags); 65 } 66 67 DD::DD(const DDFlags *flags) 68 : flags(*flags) { 69 dd.clear(); 70 } 71 72 DDPhysicalThread* DD::CreatePhysicalThread() { 73 return nullptr; 74 } 75 76 void DD::DestroyPhysicalThread(DDPhysicalThread *pt) { 77 } 78 79 DDLogicalThread* DD::CreateLogicalThread(u64 ctx) { 80 DDLogicalThread *lt = (DDLogicalThread*)InternalAlloc(sizeof(*lt)); 81 lt->ctx = ctx; 82 lt->dd.clear(); 83 lt->report_pending = false; 84 return lt; 85 } 86 87 void DD::DestroyLogicalThread(DDLogicalThread *lt) { 88 lt->~DDLogicalThread(); 89 InternalFree(lt); 90 } 91 92 void DD::MutexInit(DDCallback *cb, DDMutex *m) { 93 m->id = 0; 94 m->stk = cb->Unwind(); 95 } 96 97 void DD::MutexEnsureID(DDLogicalThread *lt, DDMutex *m) { 98 if (!dd.nodeBelongsToCurrentEpoch(m->id)) 99 m->id = dd.newNode(reinterpret_cast<uptr>(m)); 100 dd.ensureCurrentEpoch(<->dd); 101 } 102 103 void DD::MutexBeforeLock(DDCallback *cb, 104 DDMutex *m, bool wlock) { 105 DDLogicalThread *lt = cb->lt; 106 if (lt->dd.empty()) return; // This will be the first lock held by lt. 107 if (dd.hasAllEdges(<->dd, m->id)) return; // We already have all edges. 108 SpinMutexLock lk(&mtx); 109 MutexEnsureID(lt, m); 110 if (dd.isHeld(<->dd, m->id)) 111 return; // FIXME: allow this only for recursive locks. 112 if (dd.onLockBefore(<->dd, m->id)) { 113 // Actually add this edge now so that we have all the stack traces. 114 dd.addEdges(<->dd, m->id, cb->Unwind(), cb->UniqueTid()); 115 ReportDeadlock(cb, m); 116 } 117 } 118 119 void DD::ReportDeadlock(DDCallback *cb, DDMutex *m) { 120 DDLogicalThread *lt = cb->lt; 121 uptr path[20]; 122 uptr len = dd.findPathToLock(<->dd, m->id, path, ARRAY_SIZE(path)); 123 if (len == 0U) { 124 // A cycle of 20+ locks? Well, that's a bit odd... 125 Printf("WARNING: too long mutex cycle found\n"); 126 return; 127 } 128 CHECK_EQ(m->id, path[0]); 129 lt->report_pending = true; 130 len = Min<uptr>(len, DDReport::kMaxLoopSize); 131 DDReport *rep = <->rep; 132 rep->n = len; 133 for (uptr i = 0; i < len; i++) { 134 uptr from = path[i]; 135 uptr to = path[(i + 1) % len]; 136 DDMutex *m0 = (DDMutex*)dd.getData(from); 137 DDMutex *m1 = (DDMutex*)dd.getData(to); 138 139 u32 stk_from = -1U, stk_to = -1U; 140 int unique_tid = 0; 141 dd.findEdge(from, to, &stk_from, &stk_to, &unique_tid); 142 // Printf("Edge: %zd=>%zd: %u/%u T%d\n", from, to, stk_from, stk_to, 143 // unique_tid); 144 rep->loop[i].thr_ctx = unique_tid; 145 rep->loop[i].mtx_ctx0 = m0->ctx; 146 rep->loop[i].mtx_ctx1 = m1->ctx; 147 rep->loop[i].stk[0] = stk_to; 148 rep->loop[i].stk[1] = stk_from; 149 } 150 } 151 152 void DD::MutexAfterLock(DDCallback *cb, DDMutex *m, bool wlock, bool trylock) { 153 DDLogicalThread *lt = cb->lt; 154 u32 stk = 0; 155 if (flags.second_deadlock_stack) 156 stk = cb->Unwind(); 157 // Printf("T%p MutexLock: %zx stk %u\n", lt, m->id, stk); 158 if (dd.onFirstLock(<->dd, m->id, stk)) 159 return; 160 if (dd.onLockFast(<->dd, m->id, stk)) 161 return; 162 163 SpinMutexLock lk(&mtx); 164 MutexEnsureID(lt, m); 165 if (wlock) // Only a recursive rlock may be held. 166 CHECK(!dd.isHeld(<->dd, m->id)); 167 if (!trylock) 168 dd.addEdges(<->dd, m->id, stk ? stk : cb->Unwind(), cb->UniqueTid()); 169 dd.onLockAfter(<->dd, m->id, stk); 170 } 171 172 void DD::MutexBeforeUnlock(DDCallback *cb, DDMutex *m, bool wlock) { 173 // Printf("T%p MutexUnLock: %zx\n", cb->lt, m->id); 174 dd.onUnlock(&cb->lt->dd, m->id); 175 } 176 177 void DD::MutexDestroy(DDCallback *cb, 178 DDMutex *m) { 179 if (!m->id) return; 180 SpinMutexLock lk(&mtx); 181 if (dd.nodeBelongsToCurrentEpoch(m->id)) 182 dd.removeNode(m->id); 183 m->id = 0; 184 } 185 186 DDReport *DD::GetReport(DDCallback *cb) { 187 if (!cb->lt->report_pending) 188 return nullptr; 189 cb->lt->report_pending = false; 190 return &cb->lt->rep; 191 } 192 193 } // namespace __sanitizer 194 #endif // #if SANITIZER_DEADLOCK_DETECTOR_VERSION == 1 195