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 = 256; 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_MAC 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(__powerpc__) || defined(__powerpc64__) || defined(__aarch64__) 92 // PCs are always 4 byte aligned. 93 return pc - 4; 94 #elif defined(__sparc__) || defined(__mips__) 95 return pc - 8; 96 #elif SANITIZER_RISCV64 97 // RV-64 has variable instruciton length... 98 // C extentions gives us 2-byte instructoins 99 // RV-64 has 4-byte instructions 100 // + RISCV architecture allows instructions up to 8 bytes 101 // It seems difficult to figure out the exact instruction length - 102 // pc - 2 seems like a safe option for the purposes of stack tracing 103 return pc - 2; 104 #else 105 return pc - 1; 106 #endif 107 } 108 109 // StackTrace that owns the buffer used to store the addresses. 110 struct BufferedStackTrace : public StackTrace { 111 uptr trace_buffer[kStackTraceMax]; 112 uptr top_frame_bp; // Optional bp of a top frame. 113 114 BufferedStackTrace() : StackTrace(trace_buffer, 0), top_frame_bp(0) {} 115 116 void Init(const uptr *pcs, uptr cnt, uptr extra_top_pc = 0); 117 118 // Get the stack trace with the given pc and bp. 119 // The pc will be in the position 0 of the resulting stack trace. 120 // The bp may refer to the current frame or to the caller's frame. 121 void Unwind(uptr pc, uptr bp, void *context, bool request_fast, 122 u32 max_depth = kStackTraceMax) { 123 top_frame_bp = (max_depth > 0) ? bp : 0; 124 // Small max_depth optimization 125 if (max_depth <= 1) { 126 if (max_depth == 1) 127 trace_buffer[0] = pc; 128 size = max_depth; 129 return; 130 } 131 UnwindImpl(pc, bp, context, request_fast, max_depth); 132 } 133 134 void Unwind(u32 max_depth, uptr pc, uptr bp, void *context, uptr stack_top, 135 uptr stack_bottom, bool request_fast_unwind); 136 137 void Reset() { 138 *static_cast<StackTrace *>(this) = StackTrace(trace_buffer, 0); 139 top_frame_bp = 0; 140 } 141 142 private: 143 // Every runtime defines its own implementation of this method 144 void UnwindImpl(uptr pc, uptr bp, void *context, bool request_fast, 145 u32 max_depth); 146 147 // UnwindFast/Slow have platform-specific implementations 148 void UnwindFast(uptr pc, uptr bp, uptr stack_top, uptr stack_bottom, 149 u32 max_depth); 150 void UnwindSlow(uptr pc, u32 max_depth); 151 void UnwindSlow(uptr pc, void *context, u32 max_depth); 152 153 void PopStackFrames(uptr count); 154 uptr LocatePcInTrace(uptr pc); 155 156 BufferedStackTrace(const BufferedStackTrace &) = delete; 157 void operator=(const BufferedStackTrace &) = delete; 158 159 friend class FastUnwindTest; 160 }; 161 162 #if defined(__s390x__) 163 static const uptr kFrameSize = 160; 164 #elif defined(__s390__) 165 static const uptr kFrameSize = 96; 166 #else 167 static const uptr kFrameSize = 2 * sizeof(uhwptr); 168 #endif 169 170 // Check if given pointer points into allocated stack area. 171 static inline bool IsValidFrame(uptr frame, uptr stack_top, uptr stack_bottom) { 172 return frame > stack_bottom && frame < stack_top - kFrameSize; 173 } 174 175 } // namespace __sanitizer 176 177 // Use this macro if you want to print stack trace with the caller 178 // of the current function in the top frame. 179 #define GET_CALLER_PC_BP \ 180 uptr bp = GET_CURRENT_FRAME(); \ 181 uptr pc = GET_CALLER_PC(); 182 183 #define GET_CALLER_PC_BP_SP \ 184 GET_CALLER_PC_BP; \ 185 uptr local_stack; \ 186 uptr sp = (uptr)&local_stack 187 188 // Use this macro if you want to print stack trace with the current 189 // function in the top frame. 190 #define GET_CURRENT_PC_BP \ 191 uptr bp = GET_CURRENT_FRAME(); \ 192 uptr pc = StackTrace::GetCurrentPc() 193 194 #define GET_CURRENT_PC_BP_SP \ 195 GET_CURRENT_PC_BP; \ 196 uptr local_stack; \ 197 uptr sp = (uptr)&local_stack 198 199 // GET_CURRENT_PC() is equivalent to StackTrace::GetCurrentPc(). 200 // Optimized x86 version is faster than GetCurrentPc because 201 // it does not involve a function call, instead it reads RIP register. 202 // Reads of RIP by an instruction return RIP pointing to the next 203 // instruction, which is exactly what we want here, thus 0 offset. 204 // It needs to be a macro because otherwise we will get the name 205 // of this function on the top of most stacks. Attribute artificial 206 // does not do what it claims to do, unfortunatley. And attribute 207 // __nodebug__ is clang-only. If we would have an attribute that 208 // would remove this function from debug info, we could simply make 209 // StackTrace::GetCurrentPc() faster. 210 #if defined(__x86_64__) 211 # define GET_CURRENT_PC() \ 212 ({ \ 213 uptr pc; \ 214 asm("lea 0(%%rip), %0" : "=r"(pc)); \ 215 pc; \ 216 }) 217 #else 218 # define GET_CURRENT_PC() StackTrace::GetCurrentPc() 219 #endif 220 221 #endif // SANITIZER_STACKTRACE_H 222