libsanitizer/sanitizer_common/sanitizer_stacktrace.h

   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 instruction length...
  95   // C extentions gives us 2-byte instructoins
  96   // RV-64 has 4-byte instructions
  97   // + RISC-V 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