1 //===-- sanitizer_stacktrace.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 shared between AddressSanitizer and ThreadSanitizer
10 // run-time libraries.
11 //===----------------------------------------------------------------------===//
12 #ifndef SANITIZER_STACKTRACE_H
13 #define SANITIZER_STACKTRACE_H
14
15 #include "sanitizer_common.h"
16 #include "sanitizer_internal_defs.h"
17 #include "sanitizer_platform.h"
18
19 namespace __sanitizer {
20
21 struct BufferedStackTrace;
22
23 static const u32 kStackTraceMax = 255;
24
25 #if SANITIZER_LINUX && defined(__mips__)
26 # define SANITIZER_CAN_FAST_UNWIND 0
27 #elif SANITIZER_WINDOWS
28 # define SANITIZER_CAN_FAST_UNWIND 0
29 #else
30 # define SANITIZER_CAN_FAST_UNWIND 1
31 #endif
32
33 // Fast unwind is the only option on Mac for now; we will need to
34 // revisit this macro when slow unwind works on Mac, see
35 // https://github.com/google/sanitizers/issues/137
36 #if SANITIZER_APPLE
37 # define SANITIZER_CAN_SLOW_UNWIND 0
38 #else
39 # define SANITIZER_CAN_SLOW_UNWIND 1
40 #endif
41
42 struct StackTrace {
43 const uptr *trace;
44 u32 size;
45 u32 tag;
46
47 static const int TAG_UNKNOWN = 0;
48 static const int TAG_ALLOC = 1;
49 static const int TAG_DEALLOC = 2;
50 static const int TAG_CUSTOM = 100; // Tool specific tags start here.
51
52 StackTrace() : trace(nullptr), size(0), tag(0) {}
53 StackTrace(const uptr *trace, u32 size) : trace(trace), size(size), tag(0) {}
54 StackTrace(const uptr *trace, u32 size, u32 tag)
55 : trace(trace), size(size), tag(tag) {}
56
57 // Prints a symbolized stacktrace, followed by an empty line.
58 void Print() const;
59
60 // Prints a symbolized stacktrace to the output string, followed by an empty
61 // line.
62 void PrintTo(InternalScopedString *output) const;
63
64 // Prints a symbolized stacktrace to the output buffer, followed by an empty
65 // line. Returns the number of symbols that should have been written to buffer
66 // (not including trailing '\0'). Thus, the string is truncated iff return
67 // value is not less than "out_buf_size".
68 uptr PrintTo(char *out_buf, uptr out_buf_size) const;
69
70 static bool WillUseFastUnwind(bool request_fast_unwind) {
71 if (!SANITIZER_CAN_FAST_UNWIND)
72 return false;
73 if (!SANITIZER_CAN_SLOW_UNWIND)
74 return true;
75 return request_fast_unwind;
76 }
77
78 static uptr GetCurrentPc();
79 static inline uptr GetPreviousInstructionPc(uptr pc);
80 static uptr GetNextInstructionPc(uptr pc);
81 };
82
83 // Performance-critical, must be in the header.
84 ALWAYS_INLINE
85 uptr StackTrace::GetPreviousInstructionPc(uptr pc) {
86 #if defined(__arm__)
87 // T32 (Thumb) branch instructions might be 16 or 32 bit long,
88 // so we return (pc-2) in that case in order to be safe.
89 // For A32 mode we return (pc-4) because all instructions are 32 bit long.
90 return (pc - 3) & (~1);
91 #elif defined(__sparc__) || defined(__mips__)
92 return pc - 8;
93 #elif SANITIZER_RISCV64
94 // RV-64 has variable instruciton length...
95 // C extentions gives us 2-byte instructoins
96 // RV-64 has 4-byte instructions
97 // + RISCV architecture allows instructions up to 8 bytes
98 // It seems difficult to figure out the exact instruction length -
99 // pc - 2 seems like a safe option for the purposes of stack tracing
100 return pc - 2;
101 #elif SANITIZER_S390 || SANITIZER_I386 || SANITIZER_X32 || SANITIZER_X64
102 return pc - 1;
103 #else
104 return pc - 4;
105 #endif
106 }
107
108 // StackTrace that owns the buffer used to store the addresses.
109 struct BufferedStackTrace : public StackTrace {
110 uptr trace_buffer[kStackTraceMax];
111 uptr top_frame_bp; // Optional bp of a top frame.
112
113 BufferedStackTrace() : StackTrace(trace_buffer, 0), top_frame_bp(0) {}
114
115 void Init(const uptr *pcs, uptr cnt, uptr extra_top_pc = 0);
116
117 // Get the stack trace with the given pc and bp.
118 // The pc will be in the position 0 of the resulting stack trace.
119 // The bp may refer to the current frame or to the caller's frame.
120 void Unwind(uptr pc, uptr bp, void *context, bool request_fast,
121 u32 max_depth = kStackTraceMax) {
122 top_frame_bp = (max_depth > 0) ? bp : 0;
123 // Small max_depth optimization
124 if (max_depth <= 1) {
125 if (max_depth == 1)
126 trace_buffer[0] = pc;
127 size = max_depth;
128 return;
129 }
130 UnwindImpl(pc, bp, context, request_fast, max_depth);
131 }
132
133 void Unwind(u32 max_depth, uptr pc, uptr bp, void *context, uptr stack_top,
134 uptr stack_bottom, bool request_fast_unwind);
135
136 void Reset() {
137 *static_cast<StackTrace *>(this) = StackTrace(trace_buffer, 0);
138 top_frame_bp = 0;
139 }
140
141 private:
142 // Every runtime defines its own implementation of this method
143 void UnwindImpl(uptr pc, uptr bp, void *context, bool request_fast,
144 u32 max_depth);
145
146 // UnwindFast/Slow have platform-specific implementations
147 void UnwindFast(uptr pc, uptr bp, uptr stack_top, uptr stack_bottom,
148 u32 max_depth);
149 void UnwindSlow(uptr pc, u32 max_depth);
150 void UnwindSlow(uptr pc, void *context, u32 max_depth);
151
152 void PopStackFrames(uptr count);
153 uptr LocatePcInTrace(uptr pc);
154
155 BufferedStackTrace(const BufferedStackTrace &) = delete;
156 void operator=(const BufferedStackTrace &) = delete;
157
158 friend class FastUnwindTest;
159 };
160
161 #if defined(__s390x__)
162 static const uptr kFrameSize = 160;
163 #elif defined(__s390__)
164 static const uptr kFrameSize = 96;
165 #else
166 static const uptr kFrameSize = 2 * sizeof(uhwptr);
167 #endif
168
169 // Check if given pointer points into allocated stack area.
170 static inline bool IsValidFrame(uptr frame, uptr stack_top, uptr stack_bottom) {
171 return frame > stack_bottom && frame < stack_top - kFrameSize;
172 }
173
174 } // namespace __sanitizer
175
176 // Use this macro if you want to print stack trace with the caller
177 // of the current function in the top frame.
178 #define GET_CALLER_PC_BP \
179 uptr bp = GET_CURRENT_FRAME(); \
180 uptr pc = GET_CALLER_PC();
181
182 #define GET_CALLER_PC_BP_SP \
183 GET_CALLER_PC_BP; \
184 uptr local_stack; \
185 uptr sp = (uptr)&local_stack
186
187 // Use this macro if you want to print stack trace with the current
188 // function in the top frame.
189 #define GET_CURRENT_PC_BP \
190 uptr bp = GET_CURRENT_FRAME(); \
191 uptr pc = StackTrace::GetCurrentPc()
192
193 #define GET_CURRENT_PC_BP_SP \
194 GET_CURRENT_PC_BP; \
195 uptr local_stack; \
196 uptr sp = (uptr)&local_stack
197
198 // GET_CURRENT_PC() is equivalent to StackTrace::GetCurrentPc().
199 // Optimized x86 version is faster than GetCurrentPc because
200 // it does not involve a function call, instead it reads RIP register.
201 // Reads of RIP by an instruction return RIP pointing to the next
202 // instruction, which is exactly what we want here, thus 0 offset.
203 // It needs to be a macro because otherwise we will get the name
204 // of this function on the top of most stacks. Attribute artificial
205 // does not do what it claims to do, unfortunatley. And attribute
206 // __nodebug__ is clang-only. If we would have an attribute that
207 // would remove this function from debug info, we could simply make
208 // StackTrace::GetCurrentPc() faster.
209 #if defined(__x86_64__)
210 # define GET_CURRENT_PC() \
211 (__extension__({ \
212 uptr pc; \
213 asm("lea 0(%%rip), %0" : "=r"(pc)); \
214 pc; \
215 }))
216 #else
217 # define GET_CURRENT_PC() StackTrace::GetCurrentPc()
218 #endif
219
220 #endif // SANITIZER_STACKTRACE_H