1 //===-- asan_stack.cc -------------------------------------------*- C++ -*-===// 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 // Code for ASan stack trace. 13 //===----------------------------------------------------------------------===// 14 #include "asan_interceptors.h" 15 #include "asan_lock.h" 16 #include "asan_procmaps.h" 17 #include "asan_stack.h" 18 #include "asan_thread.h" 19 #include "asan_thread_registry.h" 20 21 #ifdef ASAN_USE_EXTERNAL_SYMBOLIZER 22 extern bool 23 ASAN_USE_EXTERNAL_SYMBOLIZER(const void *pc, char *out, int out_size); 24 #endif 25 26 namespace __asan { 27 28 // ----------------------- AsanStackTrace ----------------------------- {{{1 29 #if defined(ASAN_USE_EXTERNAL_SYMBOLIZER) 30 void AsanStackTrace::PrintStack(uintptr_t *addr, size_t size) { 31 for (size_t i = 0; i < size && addr[i]; i++) { 32 uintptr_t pc = addr[i]; 33 char buff[4096]; 34 ASAN_USE_EXTERNAL_SYMBOLIZER((void*)pc, buff, sizeof(buff)); 35 Printf(" #%zu 0x%zx %s\n", i, pc, buff); 36 } 37 } 38 39 #else // ASAN_USE_EXTERNAL_SYMBOLIZER 40 void AsanStackTrace::PrintStack(uintptr_t *addr, size_t size) { 41 AsanProcMaps proc_maps; 42 for (size_t i = 0; i < size && addr[i]; i++) { 43 proc_maps.Reset(); 44 uintptr_t pc = addr[i]; 45 uintptr_t offset; 46 char filename[4096]; 47 if (proc_maps.GetObjectNameAndOffset(pc, &offset, 48 filename, sizeof(filename))) { 49 Printf(" #%zu 0x%zx (%s+0x%zx)\n", i, pc, filename, offset); 50 } else { 51 Printf(" #%zu 0x%zx\n", i, pc); 52 } 53 } 54 } 55 #endif // ASAN_USE_EXTERNAL_SYMBOLIZER 56 57 uintptr_t AsanStackTrace::GetCurrentPc() { 58 return GET_CALLER_PC(); 59 } 60 61 void AsanStackTrace::FastUnwindStack(uintptr_t pc, uintptr_t bp) { 62 CHECK(size == 0 && trace[0] == pc); 63 size = 1; 64 if (!asan_inited) return; 65 AsanThread *t = asanThreadRegistry().GetCurrent(); 66 if (!t) return; 67 uintptr_t *frame = (uintptr_t*)bp; 68 uintptr_t *prev_frame = frame; 69 uintptr_t *top = (uintptr_t*)t->stack_top(); 70 uintptr_t *bottom = (uintptr_t*)t->stack_bottom(); 71 while (frame >= prev_frame && 72 frame < top - 2 && 73 frame > bottom && 74 size < max_size) { 75 uintptr_t pc1 = frame[1]; 76 if (pc1 != pc) { 77 trace[size++] = pc1; 78 } 79 prev_frame = frame; 80 frame = (uintptr_t*)frame[0]; 81 } 82 } 83 84 // On 32-bits we don't compress stack traces. 85 // On 64-bits we compress stack traces: if a given pc differes slightly from 86 // the previous one, we record a 31-bit offset instead of the full pc. 87 size_t AsanStackTrace::CompressStack(AsanStackTrace *stack, 88 uint32_t *compressed, size_t size) { 89 #if __WORDSIZE == 32 90 // Don't compress, just copy. 91 size_t res = 0; 92 for (size_t i = 0; i < stack->size && i < size; i++) { 93 compressed[i] = stack->trace[i]; 94 res++; 95 } 96 if (stack->size < size) 97 compressed[stack->size] = 0; 98 #else // 64 bits, compress. 99 uintptr_t prev_pc = 0; 100 const uintptr_t kMaxOffset = (1ULL << 30) - 1; 101 uintptr_t c_index = 0; 102 size_t res = 0; 103 for (size_t i = 0, n = stack->size; i < n; i++) { 104 uintptr_t pc = stack->trace[i]; 105 if (!pc) break; 106 if ((int64_t)pc < 0) break; 107 // Printf("C pc[%zu] %zx\n", i, pc); 108 if (prev_pc - pc < kMaxOffset || pc - prev_pc < kMaxOffset) { 109 uintptr_t offset = (int64_t)(pc - prev_pc); 110 offset |= (1U << 31); 111 if (c_index >= size) break; 112 // Printf("C co[%zu] offset %zx\n", i, offset); 113 compressed[c_index++] = offset; 114 } else { 115 uintptr_t hi = pc >> 32; 116 uintptr_t lo = (pc << 32) >> 32; 117 CHECK((hi & (1 << 31)) == 0); 118 if (c_index + 1 >= size) break; 119 // Printf("C co[%zu] hi/lo: %zx %zx\n", c_index, hi, lo); 120 compressed[c_index++] = hi; 121 compressed[c_index++] = lo; 122 } 123 res++; 124 prev_pc = pc; 125 } 126 if (c_index < size) 127 compressed[c_index] = 0; 128 if (c_index + 1 < size) 129 compressed[c_index + 1] = 0; 130 #endif // __WORDSIZE 131 132 // debug-only code 133 #if 0 134 AsanStackTrace check_stack; 135 UncompressStack(&check_stack, compressed, size); 136 if (res < check_stack.size) { 137 Printf("res %zu check_stack.size %zu; c_size %zu\n", res, 138 check_stack.size, size); 139 } 140 // |res| may be greater than check_stack.size, because 141 // UncompressStack(CompressStack(stack)) eliminates the 0x0 frames. 142 CHECK(res >= check_stack.size); 143 CHECK(0 == REAL(memcmp)(check_stack.trace, stack->trace, 144 check_stack.size * sizeof(uintptr_t))); 145 #endif 146 147 return res; 148 } 149 150 void AsanStackTrace::UncompressStack(AsanStackTrace *stack, 151 uint32_t *compressed, size_t size) { 152 #if __WORDSIZE == 32 153 // Don't uncompress, just copy. 154 stack->size = 0; 155 for (size_t i = 0; i < size && i < kStackTraceMax; i++) { 156 if (!compressed[i]) break; 157 stack->size++; 158 stack->trace[i] = compressed[i]; 159 } 160 #else // 64 bits, uncompress 161 uintptr_t prev_pc = 0; 162 stack->size = 0; 163 for (size_t i = 0; i < size && stack->size < kStackTraceMax; i++) { 164 uint32_t x = compressed[i]; 165 uintptr_t pc = 0; 166 if (x & (1U << 31)) { 167 // Printf("U co[%zu] offset: %x\n", i, x); 168 // this is an offset 169 int32_t offset = x; 170 offset = (offset << 1) >> 1; // remove the 31-byte and sign-extend. 171 pc = prev_pc + offset; 172 CHECK(pc); 173 } else { 174 // CHECK(i + 1 < size); 175 if (i + 1 >= size) break; 176 uintptr_t hi = x; 177 uintptr_t lo = compressed[i+1]; 178 // Printf("U co[%zu] hi/lo: %zx %zx\n", i, hi, lo); 179 i++; 180 pc = (hi << 32) | lo; 181 if (!pc) break; 182 } 183 // Printf("U pc[%zu] %zx\n", stack->size, pc); 184 stack->trace[stack->size++] = pc; 185 prev_pc = pc; 186 } 187 #endif // __WORDSIZE 188 } 189 190 } // namespace __asan 191
