1 //===-- sanitizer_stacktrace.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 shared between AddressSanitizer and ThreadSanitizer
11 // run-time libraries.
12 //===----------------------------------------------------------------------===//
13
14 #include "sanitizer_common.h"
15 #include "sanitizer_procmaps.h"
16 #include "sanitizer_stacktrace.h"
17 #include "sanitizer_symbolizer.h"
18
19 namespace __sanitizer {
StripPathPrefix(const char * filepath,const char * strip_file_prefix)20 const char *StripPathPrefix(const char *filepath,
21 const char *strip_file_prefix) {
22 if (filepath == 0) return 0;
23 const char *prefix_beg = internal_strstr(filepath, strip_file_prefix);
24 if (prefix_beg)
25 return prefix_beg + internal_strlen(strip_file_prefix);
26 return filepath;
27 }
28
29 // ----------------------- StackTrace ----------------------------- {{{1
GetPreviousInstructionPc(uptr pc)30 uptr StackTrace::GetPreviousInstructionPc(uptr pc) {
31 #ifdef __arm__
32 // Cancel Thumb bit.
33 pc = pc & (~1);
34 #endif
35 #if defined(__powerpc__) || defined(__powerpc64__)
36 // PCs are always 4 byte aligned.
37 return pc - 4;
38 #elif defined(__sparc__)
39 return pc - 8;
40 #else
41 return pc - 1;
42 #endif
43 }
44
PrintStackFramePrefix(uptr frame_num,uptr pc)45 static void PrintStackFramePrefix(uptr frame_num, uptr pc) {
46 Printf(" #%zu 0x%zx", frame_num, pc);
47 }
48
PrintSourceLocation(const char * file,int line,int column,const char * strip_file_prefix)49 static void PrintSourceLocation(const char *file, int line, int column,
50 const char *strip_file_prefix) {
51 CHECK(file);
52 Printf(" %s", StripPathPrefix(file, strip_file_prefix));
53 if (line > 0) {
54 Printf(":%d", line);
55 if (column > 0)
56 Printf(":%d", column);
57 }
58 }
59
PrintModuleAndOffset(const char * module,uptr offset,const char * strip_file_prefix)60 static void PrintModuleAndOffset(const char *module, uptr offset,
61 const char *strip_file_prefix) {
62 Printf(" (%s+0x%zx)", StripPathPrefix(module, strip_file_prefix), offset);
63 }
64
PrintStack(const uptr * addr,uptr size,bool symbolize,const char * strip_file_prefix,SymbolizeCallback symbolize_callback)65 void StackTrace::PrintStack(const uptr *addr, uptr size,
66 bool symbolize, const char *strip_file_prefix,
67 SymbolizeCallback symbolize_callback ) {
68 MemoryMappingLayout proc_maps(/*cache_enabled*/true);
69 InternalScopedBuffer<char> buff(GetPageSizeCached() * 2);
70 InternalScopedBuffer<AddressInfo> addr_frames(64);
71 uptr frame_num = 0;
72 for (uptr i = 0; i < size && addr[i]; i++) {
73 // PCs in stack traces are actually the return addresses, that is,
74 // addresses of the next instructions after the call.
75 uptr pc = GetPreviousInstructionPc(addr[i]);
76 uptr addr_frames_num = 0; // The number of stack frames for current
77 // instruction address.
78 if (symbolize_callback) {
79 if (symbolize_callback((void*)pc, buff.data(), buff.size())) {
80 addr_frames_num = 1;
81 PrintStackFramePrefix(frame_num, pc);
82 // We can't know anything about the string returned by external
83 // symbolizer, but if it starts with filename, try to strip path prefix
84 // from it.
85 Printf(" %s\n", StripPathPrefix(buff.data(), strip_file_prefix));
86 frame_num++;
87 }
88 }
89 if (symbolize && addr_frames_num == 0 && &SymbolizeCode) {
90 // Use our own (online) symbolizer, if necessary.
91 addr_frames_num = SymbolizeCode(pc, addr_frames.data(),
92 addr_frames.size());
93 for (uptr j = 0; j < addr_frames_num; j++) {
94 AddressInfo &info = addr_frames[j];
95 PrintStackFramePrefix(frame_num, pc);
96 if (info.function) {
97 Printf(" in %s", info.function);
98 }
99 if (info.file) {
100 PrintSourceLocation(info.file, info.line, info.column,
101 strip_file_prefix);
102 } else if (info.module) {
103 PrintModuleAndOffset(info.module, info.module_offset,
104 strip_file_prefix);
105 }
106 Printf("\n");
107 info.Clear();
108 frame_num++;
109 }
110 }
111 if (addr_frames_num == 0) {
112 // If online symbolization failed, try to output at least module and
113 // offset for instruction.
114 PrintStackFramePrefix(frame_num, pc);
115 uptr offset;
116 if (proc_maps.GetObjectNameAndOffset(pc, &offset,
117 buff.data(), buff.size(),
118 /* protection */0)) {
119 PrintModuleAndOffset(buff.data(), offset, strip_file_prefix);
120 }
121 Printf("\n");
122 frame_num++;
123 }
124 }
125 }
126
GetCurrentPc()127 uptr StackTrace::GetCurrentPc() {
128 return GET_CALLER_PC();
129 }
130
FastUnwindStack(uptr pc,uptr bp,uptr stack_top,uptr stack_bottom)131 void StackTrace::FastUnwindStack(uptr pc, uptr bp,
132 uptr stack_top, uptr stack_bottom) {
133 CHECK(size == 0 && trace[0] == pc);
134 size = 1;
135 uhwptr *frame = (uhwptr *)bp;
136 uhwptr *prev_frame = frame - 1;
137 if (stack_top < 4096) return; // Sanity check for stack top.
138 // Avoid infinite loop when frame == frame[0] by using frame > prev_frame.
139 while (frame > prev_frame &&
140 frame < (uhwptr *)stack_top - 2 &&
141 frame > (uhwptr *)stack_bottom &&
142 IsAligned((uptr)frame, sizeof(*frame)) &&
143 size < max_size) {
144 uhwptr pc1 = frame[1];
145 if (pc1 != pc) {
146 trace[size++] = (uptr) pc1;
147 }
148 prev_frame = frame;
149 frame = (uhwptr *)frame[0];
150 }
151 }
152
PopStackFrames(uptr count)153 void StackTrace::PopStackFrames(uptr count) {
154 CHECK(size >= count);
155 size -= count;
156 for (uptr i = 0; i < size; i++) {
157 trace[i] = trace[i + count];
158 }
159 }
160
161 // On 32-bits we don't compress stack traces.
162 // On 64-bits we compress stack traces: if a given pc differes slightly from
163 // the previous one, we record a 31-bit offset instead of the full pc.
164 SANITIZER_INTERFACE_ATTRIBUTE
CompressStack(StackTrace * stack,u32 * compressed,uptr size)165 uptr StackTrace::CompressStack(StackTrace *stack, u32 *compressed, uptr size) {
166 #if SANITIZER_WORDSIZE == 32
167 // Don't compress, just copy.
168 uptr res = 0;
169 for (uptr i = 0; i < stack->size && i < size; i++) {
170 compressed[i] = stack->trace[i];
171 res++;
172 }
173 if (stack->size < size)
174 compressed[stack->size] = 0;
175 #else // 64 bits, compress.
176 uptr prev_pc = 0;
177 const uptr kMaxOffset = (1ULL << 30) - 1;
178 uptr c_index = 0;
179 uptr res = 0;
180 for (uptr i = 0, n = stack->size; i < n; i++) {
181 uptr pc = stack->trace[i];
182 if (!pc) break;
183 if ((s64)pc < 0) break;
184 // Printf("C pc[%zu] %zx\n", i, pc);
185 if (prev_pc - pc < kMaxOffset || pc - prev_pc < kMaxOffset) {
186 uptr offset = (s64)(pc - prev_pc);
187 offset |= (1U << 31);
188 if (c_index >= size) break;
189 // Printf("C co[%zu] offset %zx\n", i, offset);
190 compressed[c_index++] = offset;
191 } else {
192 uptr hi = pc >> 32;
193 uptr lo = (pc << 32) >> 32;
194 CHECK_EQ((hi & (1 << 31)), 0);
195 if (c_index + 1 >= size) break;
196 // Printf("C co[%zu] hi/lo: %zx %zx\n", c_index, hi, lo);
197 compressed[c_index++] = hi;
198 compressed[c_index++] = lo;
199 }
200 res++;
201 prev_pc = pc;
202 }
203 if (c_index < size)
204 compressed[c_index] = 0;
205 if (c_index + 1 < size)
206 compressed[c_index + 1] = 0;
207 #endif // SANITIZER_WORDSIZE
208
209 // debug-only code
210 #if 0
211 StackTrace check_stack;
212 UncompressStack(&check_stack, compressed, size);
213 if (res < check_stack.size) {
214 Printf("res %zu check_stack.size %zu; c_size %zu\n", res,
215 check_stack.size, size);
216 }
217 // |res| may be greater than check_stack.size, because
218 // UncompressStack(CompressStack(stack)) eliminates the 0x0 frames.
219 CHECK(res >= check_stack.size);
220 CHECK_EQ(0, REAL(memcmp)(check_stack.trace, stack->trace,
221 check_stack.size * sizeof(uptr)));
222 #endif
223
224 return res;
225 }
226
227 SANITIZER_INTERFACE_ATTRIBUTE
UncompressStack(StackTrace * stack,u32 * compressed,uptr size)228 void StackTrace::UncompressStack(StackTrace *stack,
229 u32 *compressed, uptr size) {
230 #if SANITIZER_WORDSIZE == 32
231 // Don't uncompress, just copy.
232 stack->size = 0;
233 for (uptr i = 0; i < size && i < kStackTraceMax; i++) {
234 if (!compressed[i]) break;
235 stack->size++;
236 stack->trace[i] = compressed[i];
237 }
238 #else // 64 bits, uncompress
239 uptr prev_pc = 0;
240 stack->size = 0;
241 for (uptr i = 0; i < size && stack->size < kStackTraceMax; i++) {
242 u32 x = compressed[i];
243 uptr pc = 0;
244 if (x & (1U << 31)) {
245 // Printf("U co[%zu] offset: %x\n", i, x);
246 // this is an offset
247 s32 offset = x;
248 offset = (offset << 1) >> 1; // remove the 31-byte and sign-extend.
249 pc = prev_pc + offset;
250 CHECK(pc);
251 } else {
252 // CHECK(i + 1 < size);
253 if (i + 1 >= size) break;
254 uptr hi = x;
255 uptr lo = compressed[i+1];
256 // Printf("U co[%zu] hi/lo: %zx %zx\n", i, hi, lo);
257 i++;
258 pc = (hi << 32) | lo;
259 if (!pc) break;
260 }
261 // Printf("U pc[%zu] %zx\n", stack->size, pc);
262 stack->trace[stack->size++] = pc;
263 prev_pc = pc;
264 }
265 #endif // SANITIZER_WORDSIZE
266 }
267
268 } // namespace __sanitizer
269