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_internal_defs.h"
16 #include "sanitizer_platform.h"
17
18 namespace __sanitizer {
19
20 struct BufferedStackTrace;
21
22 static const u32 kStackTraceMax = 256;
23
24 #if SANITIZER_LINUX && defined(__mips__)
25 # define SANITIZER_CAN_FAST_UNWIND 0
26 #elif SANITIZER_WINDOWS
27 # define SANITIZER_CAN_FAST_UNWIND 0
28 #else
29 # define SANITIZER_CAN_FAST_UNWIND 1
30 #endif
31
32 // Fast unwind is the only option on Mac for now; we will need to
33 // revisit this macro when slow unwind works on Mac, see
34 // https://github.com/google/sanitizers/issues/137
35 #if SANITIZER_MAC || SANITIZER_RTEMS
36 # define SANITIZER_CAN_SLOW_UNWIND 0
37 #else
38 # define SANITIZER_CAN_SLOW_UNWIND 1
39 #endif
40
41 struct StackTrace {
42 const uptr *trace;
43 u32 size;
44 u32 tag;
45
46 static const int TAG_UNKNOWN = 0;
47 static const int TAG_ALLOC = 1;
48 static const int TAG_DEALLOC = 2;
49 static const int TAG_CUSTOM = 100; // Tool specific tags start here.
50
StackTraceStackTrace51 StackTrace() : trace(nullptr), size(0), tag(0) {}
StackTraceStackTrace52 StackTrace(const uptr *trace, u32 size) : trace(trace), size(size), tag(0) {}
StackTraceStackTrace53 StackTrace(const uptr *trace, u32 size, u32 tag)
54 : trace(trace), size(size), tag(tag) {}
55
56 // Prints a symbolized stacktrace, followed by an empty line.
57 void Print() const;
58
WillUseFastUnwindStackTrace59 static bool WillUseFastUnwind(bool request_fast_unwind) {
60 if (!SANITIZER_CAN_FAST_UNWIND)
61 return false;
62 if (!SANITIZER_CAN_SLOW_UNWIND)
63 return true;
64 return request_fast_unwind;
65 }
66
67 static uptr GetCurrentPc();
68 static inline uptr GetPreviousInstructionPc(uptr pc);
69 static uptr GetNextInstructionPc(uptr pc);
70 typedef bool (*SymbolizeCallback)(const void *pc, char *out_buffer,
71 int out_size);
72 };
73
74 // Performance-critical, must be in the header.
75 ALWAYS_INLINE
GetPreviousInstructionPc(uptr pc)76 uptr StackTrace::GetPreviousInstructionPc(uptr pc) {
77 #if defined(__arm__)
78 // T32 (Thumb) branch instructions might be 16 or 32 bit long,
79 // so we return (pc-2) in that case in order to be safe.
80 // For A32 mode we return (pc-4) because all instructions are 32 bit long.
81 return (pc - 3) & (~1);
82 #elif defined(__powerpc__) || defined(__powerpc64__) || defined(__aarch64__)
83 // PCs are always 4 byte aligned.
84 return pc - 4;
85 #elif defined(__sparc__) || defined(__mips__)
86 return pc - 8;
87 #elif SANITIZER_RISCV64
88 // RV-64 has variable instruciton length...
89 // C extentions gives us 2-byte instructoins
90 // RV-64 has 4-byte instructions
91 // + RISCV architecture allows instructions up to 8 bytes
92 // It seems difficult to figure out the exact instruction length -
93 // pc - 2 seems like a safe option for the purposes of stack tracing
94 return pc - 2;
95 #else
96 return pc - 1;
97 #endif
98 }
99
100 // StackTrace that owns the buffer used to store the addresses.
101 struct BufferedStackTrace : public StackTrace {
102 uptr trace_buffer[kStackTraceMax];
103 uptr top_frame_bp; // Optional bp of a top frame.
104
BufferedStackTraceBufferedStackTrace105 BufferedStackTrace() : StackTrace(trace_buffer, 0), top_frame_bp(0) {}
106
107 void Init(const uptr *pcs, uptr cnt, uptr extra_top_pc = 0);
108
109 // Get the stack trace with the given pc and bp.
110 // The pc will be in the position 0 of the resulting stack trace.
111 // The bp may refer to the current frame or to the caller's frame.
112 void Unwind(uptr pc, uptr bp, void *context, bool request_fast,
113 u32 max_depth = kStackTraceMax) {
114 top_frame_bp = (max_depth > 0) ? bp : 0;
115 // Small max_depth optimization
116 if (max_depth <= 1) {
117 if (max_depth == 1)
118 trace_buffer[0] = pc;
119 size = max_depth;
120 return;
121 }
122 UnwindImpl(pc, bp, context, request_fast, max_depth);
123 }
124
125 void Unwind(u32 max_depth, uptr pc, uptr bp, void *context, uptr stack_top,
126 uptr stack_bottom, bool request_fast_unwind);
127
ResetBufferedStackTrace128 void Reset() {
129 *static_cast<StackTrace *>(this) = StackTrace(trace_buffer, 0);
130 top_frame_bp = 0;
131 }
132
133 private:
134 // Every runtime defines its own implementation of this method
135 void UnwindImpl(uptr pc, uptr bp, void *context, bool request_fast,
136 u32 max_depth);
137
138 // UnwindFast/Slow have platform-specific implementations
139 void UnwindFast(uptr pc, uptr bp, uptr stack_top, uptr stack_bottom,
140 u32 max_depth);
141 void UnwindSlow(uptr pc, u32 max_depth);
142 void UnwindSlow(uptr pc, void *context, u32 max_depth);
143
144 void PopStackFrames(uptr count);
145 uptr LocatePcInTrace(uptr pc);
146
147 BufferedStackTrace(const BufferedStackTrace &) = delete;
148 void operator=(const BufferedStackTrace &) = delete;
149
150 friend class FastUnwindTest;
151 };
152
153 #if defined(__s390x__)
154 static const uptr kFrameSize = 160;
155 #elif defined(__s390__)
156 static const uptr kFrameSize = 96;
157 #else
158 static const uptr kFrameSize = 2 * sizeof(uhwptr);
159 #endif
160
161 // Check if given pointer points into allocated stack area.
IsValidFrame(uptr frame,uptr stack_top,uptr stack_bottom)162 static inline bool IsValidFrame(uptr frame, uptr stack_top, uptr stack_bottom) {
163 return frame > stack_bottom && frame < stack_top - kFrameSize;
164 }
165
166 } // namespace __sanitizer
167
168 // Use this macro if you want to print stack trace with the caller
169 // of the current function in the top frame.
170 #define GET_CALLER_PC_BP \
171 uptr bp = GET_CURRENT_FRAME(); \
172 uptr pc = GET_CALLER_PC();
173
174 #define GET_CALLER_PC_BP_SP \
175 GET_CALLER_PC_BP; \
176 uptr local_stack; \
177 uptr sp = (uptr)&local_stack
178
179 // Use this macro if you want to print stack trace with the current
180 // function in the top frame.
181 #define GET_CURRENT_PC_BP \
182 uptr bp = GET_CURRENT_FRAME(); \
183 uptr pc = StackTrace::GetCurrentPc()
184
185 #define GET_CURRENT_PC_BP_SP \
186 GET_CURRENT_PC_BP; \
187 uptr local_stack; \
188 uptr sp = (uptr)&local_stack
189
190
191 #endif // SANITIZER_STACKTRACE_H
192