libstdc++-v3/libsupc++/unwind-cxx.h

   1 // -*- C++ -*- Exception handling and frame unwind runtime interface routines.
   2 // Copyright (C) 2001-2018 Free Software Foundation, Inc.
   3 //
   4 // This file is part of GCC.
   5 //
   6 // GCC is free software; you can redistribute it and/or modify
   7 // it under the terms of the GNU General Public License as published by
   8 // the Free Software Foundation; either version 3, or (at your option)
   9 // any later version.
  10 //
  11 // GCC is distributed in the hope that it will be useful,
  12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 // GNU General Public License for more details.
  15 //
  16 // Under Section 7 of GPL version 3, you are granted additional
  17 // permissions described in the GCC Runtime Library Exception, version
  18 // 3.1, as published by the Free Software Foundation.
  19
  20 // You should have received a copy of the GNU General Public License and
  21 // a copy of the GCC Runtime Library Exception along with this program;
  22 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  23 // <http://www.gnu.org/licenses/>.
  24
  25 // This is derived from the C++ ABI for IA-64.  Where we diverge
  26 // for cross-architecture compatibility are noted with "@@@".
  27
  28 #ifndef _UNWIND_CXX_H
  29 #define _UNWIND_CXX_H 1
  30
  31 // Level 2: C++ ABI
  32
  33 #include <typeinfo>
  34 #include <exception>
  35 #include <cstddef>
  36 #include "unwind.h"
  37 #include <bits/atomic_word.h>
  38 #include <cxxabi.h>
  39
  40 #ifdef _GLIBCXX_HAVE_SYS_SDT_H
  41 #include <sys/sdt.h>
  42 /* We only want to use stap probes starting with v3.  Earlier versions
  43    added too much startup cost.  */
  44 #if defined (STAP_PROBE2) && _SDT_NOTE_TYPE >= 3
  45 #define PROBE2(name, arg1, arg2) STAP_PROBE2 (libstdcxx, name, arg1, arg2)
  46 #endif
  47 #endif
  48
  49 #ifndef PROBE2
  50 #define PROBE2(name, arg1, arg2)
  51 #endif
  52
  53 #pragma GCC visibility push(default)
  54
  55 namespace __cxxabiv1
  56 {
  57
  58 // A primary C++ exception object consists of a header, which is a wrapper
  59 // around an unwind object header with additional C++ specific information,
  60 // followed by the exception object itself.
  61
  62 struct __cxa_exception
  63 {
  64   // Manage the exception object itself.
  65   std::type_info *exceptionType;
  66   void (_GLIBCXX_CDTOR_CALLABI *exceptionDestructor)(void *);
  67
  68   // The C++ standard has entertaining rules wrt calling set_terminate
  69   // and set_unexpected in the middle of the exception cleanup process.
  70   std::unexpected_handler unexpectedHandler;
  71   std::terminate_handler terminateHandler;
  72
  73   // The caught exception stack threads through here.
  74   __cxa_exception *nextException;
  75
  76   // How many nested handlers have caught this exception.  A negated
  77   // value is a signal that this object has been rethrown.
  78   int handlerCount;
  79
  80 #ifdef __ARM_EABI_UNWINDER__
  81   // Stack of exceptions in cleanups.
  82   __cxa_exception* nextPropagatingException;
  83
  84   // The number of active cleanup handlers for this exception.
  85   int propagationCount;
  86 #else
  87   // Cache parsed handler data from the personality routine Phase 1
  88   // for Phase 2 and __cxa_call_unexpected.
  89   int handlerSwitchValue;
  90   const unsigned char *actionRecord;
  91   const unsigned char *languageSpecificData;
  92   _Unwind_Ptr catchTemp;
  93   void *adjustedPtr;
  94 #endif
  95
  96   // The generic exception header.  Must be last.
  97   _Unwind_Exception unwindHeader;
  98 };
  99
 100 struct __cxa_refcounted_exception
 101 {
 102   // Manage this header.
 103   _Atomic_word referenceCount;
 104   // __cxa_exception must be last, and no padding can be after it.
 105   __cxa_exception exc;
 106 };
 107
 108 // A dependent C++ exception object consists of a wrapper around an unwind
 109 // object header with additional C++ specific information, containing a pointer
 110 // to a primary exception object.
 111
 112 struct __cxa_dependent_exception
 113 {
 114   // The primary exception this thing depends on.
 115   void *primaryException;
 116
 117   // Unused member to get similar layout to __cxa_exception, otherwise the
 118   // alignment requirements of _Unwind_Exception would require padding bytes
 119   // before the unwindHeader member.
 120   void (_GLIBCXX_CDTOR_CALLABI *__padding)(void *);
 121
 122   // The C++ standard has entertaining rules wrt calling set_terminate
 123   // and set_unexpected in the middle of the exception cleanup process.
 124   std::unexpected_handler unexpectedHandler;
 125   std::terminate_handler terminateHandler;
 126
 127   // The caught exception stack threads through here.
 128   __cxa_exception *nextException;
 129
 130   // How many nested handlers have caught this exception.  A negated
 131   // value is a signal that this object has been rethrown.
 132   int handlerCount;
 133
 134 #ifdef __ARM_EABI_UNWINDER__
 135   // Stack of exceptions in cleanups.
 136   __cxa_exception* nextPropagatingException;
 137
 138   // The number of active cleanup handlers for this exception.
 139   int propagationCount;
 140 #else
 141   // Cache parsed handler data from the personality routine Phase 1
 142   // for Phase 2 and __cxa_call_unexpected.
 143   int handlerSwitchValue;
 144   const unsigned char *actionRecord;
 145   const unsigned char *languageSpecificData;
 146   _Unwind_Ptr catchTemp;
 147   void *adjustedPtr;
 148 #endif
 149
 150   // The generic exception header.  Must be last.
 151   _Unwind_Exception unwindHeader;
 152 };
 153
 154 // Each thread in a C++ program has access to a __cxa_eh_globals object.
 155 struct __cxa_eh_globals
 156 {
 157   __cxa_exception *caughtExceptions;
 158   unsigned int uncaughtExceptions;
 159 #ifdef __ARM_EABI_UNWINDER__
 160   __cxa_exception* propagatingExceptions;
 161 #endif
 162 };
 163
 164 // @@@ These are not directly specified by the IA-64 C++ ABI.
 165
 166 // Handles re-checking the exception specification if unexpectedHandler
 167 // throws, and if bad_exception needs to be thrown.  Called from the
 168 // compiler.
 169 extern "C" void __cxa_call_unexpected (void *) __attribute__((__noreturn__));
 170 extern "C" void __cxa_call_terminate (_Unwind_Exception*) throw ()
 171   __attribute__((__noreturn__));
 172
 173 #ifdef __ARM_EABI_UNWINDER__
 174 // Arm EABI specified routines.
 175 typedef enum {
 176   ctm_failed = 0,
 177   ctm_succeeded = 1,
 178   ctm_succeeded_with_ptr_to_base = 2
 179 } __cxa_type_match_result;
 180 extern "C" __cxa_type_match_result __cxa_type_match(_Unwind_Exception*,
 181                                                     const std::type_info*,
 182                                                     bool, void**);
 183 extern "C" bool __cxa_begin_cleanup (_Unwind_Exception*);
 184 extern "C" void __cxa_end_cleanup (void);
 185 #endif
 186
 187 // Handles cleanup from transactional memory restart.
 188 extern "C" void __cxa_tm_cleanup (void *, void *, unsigned int) throw();
 189
 190 // Invokes given handler, dying appropriately if the user handler was
 191 // so inconsiderate as to return.
 192 extern void __terminate(std::terminate_handler) throw ()
 193   __attribute__((__noreturn__));
 194 extern void __unexpected(std::unexpected_handler)
 195   __attribute__((__noreturn__));
 196
 197 // The current installed user handlers.
 198 extern std::terminate_handler __terminate_handler;
 199 extern std::unexpected_handler __unexpected_handler;
 200
 201 // These are explicitly GNU C++ specific.
 202
 203 // Acquire the C++ exception header from the C++ object.
 204 static inline __cxa_exception *
 205 __get_exception_header_from_obj (void *ptr)
 206 {
 207   return reinterpret_cast<__cxa_exception *>(ptr) - 1;
 208 }
 209
 210 // Acquire the C++ exception header from the generic exception header.
 211 static inline __cxa_exception *
 212 __get_exception_header_from_ue (_Unwind_Exception *exc)
 213 {
 214   return reinterpret_cast<__cxa_exception *>(exc + 1) - 1;
 215 }
 216
 217 // Acquire the C++ refcounted exception header from the C++ object.
 218 static inline __cxa_refcounted_exception *
 219 __get_refcounted_exception_header_from_obj (void *ptr)
 220 {
 221   return reinterpret_cast<__cxa_refcounted_exception *>(ptr) - 1;
 222 }
 223
 224 // Acquire the C++ refcounted exception header from the generic exception
 225 // header.
 226 static inline __cxa_refcounted_exception *
 227 __get_refcounted_exception_header_from_ue (_Unwind_Exception *exc)
 228 {
 229   return reinterpret_cast<__cxa_refcounted_exception *>(exc + 1) - 1;
 230 }
 231
 232 static inline __cxa_dependent_exception *
 233 __get_dependent_exception_from_ue (_Unwind_Exception *exc)
 234 {
 235   return reinterpret_cast<__cxa_dependent_exception *>(exc + 1) - 1;
 236 }
 237
 238 #ifdef __ARM_EABI_UNWINDER__
 239 static inline bool
 240 __is_gxx_exception_class(_Unwind_Exception_Class c)
 241 {
 242   // TODO: Take advantage of the fact that c will always be word aligned.
 243   return c[0] == 'G'
 244          && c[1] == 'N'
 245          && c[2] == 'U'
 246          && c[3] == 'C'
 247          && c[4] == 'C'
 248          && c[5] == '+'
 249          && c[6] == '+'
 250          && (c[7] == '\0' || c[7] == '\x01');
 251 }
 252
 253 // Only checks for primary or dependent, but not that it is a C++ exception at
 254 // all.
 255 static inline bool
 256 __is_dependent_exception(_Unwind_Exception_Class c)
 257 {
 258   return c[7] == '\x01';
 259 }
 260
 261 static inline void
 262 __GXX_INIT_PRIMARY_EXCEPTION_CLASS(_Unwind_Exception_Class c)
 263 {
 264   c[0] = 'G';
 265   c[1] = 'N';
 266   c[2] = 'U';
 267   c[3] = 'C';
 268   c[4] = 'C';
 269   c[5] = '+';
 270   c[6] = '+';
 271   c[7] = '\0';
 272 }
 273
 274 static inline void
 275 __GXX_INIT_DEPENDENT_EXCEPTION_CLASS(_Unwind_Exception_Class c)
 276 {
 277   c[0] = 'G';
 278   c[1] = 'N';
 279   c[2] = 'U';
 280   c[3] = 'C';
 281   c[4] = 'C';
 282   c[5] = '+';
 283   c[6] = '+';
 284   c[7] = '\x01';
 285 }
 286
 287 static inline bool
 288 __is_gxx_forced_unwind_class(_Unwind_Exception_Class c)
 289 {
 290   return c[0] == 'G'
 291          && c[1] == 'N'
 292          && c[2] == 'U'
 293          && c[3] == 'C'
 294          && c[4] == 'F'
 295          && c[5] == 'O'
 296          && c[6] == 'R'
 297          && c[7] == '\0';
 298 }
 299
 300 static inline void
 301 __GXX_INIT_FORCED_UNWIND_CLASS(_Unwind_Exception_Class c)
 302 {
 303   c[0] = 'G';
 304   c[1] = 'N';
 305   c[2] = 'U';
 306   c[3] = 'C';
 307   c[4] = 'F';
 308   c[5] = 'O';
 309   c[6] = 'R';
 310   c[7] = '\0';
 311 }
 312
 313 static inline void*
 314 __gxx_caught_object(_Unwind_Exception* eo)
 315 {
 316   return (void*)eo->barrier_cache.bitpattern[0];
 317 }
 318 #else // !__ARM_EABI_UNWINDER__
 319 // This is the primary exception class we report -- "GNUCC++\0".
 320 const _Unwind_Exception_Class __gxx_primary_exception_class
 321 = ((((((((_Unwind_Exception_Class) 'G'
 322          << 8 | (_Unwind_Exception_Class) 'N')
 323         << 8 | (_Unwind_Exception_Class) 'U')
 324        << 8 | (_Unwind_Exception_Class) 'C')
 325       << 8 | (_Unwind_Exception_Class) 'C')
 326      << 8 | (_Unwind_Exception_Class) '+')
 327     << 8 | (_Unwind_Exception_Class) '+')
 328    << 8 | (_Unwind_Exception_Class) '\0');
 329
 330 // This is the dependent (from std::rethrow_exception) exception class we report
 331 // "GNUCC++\x01"
 332 const _Unwind_Exception_Class __gxx_dependent_exception_class
 333 = ((((((((_Unwind_Exception_Class) 'G'
 334          << 8 | (_Unwind_Exception_Class) 'N')
 335         << 8 | (_Unwind_Exception_Class) 'U')
 336        << 8 | (_Unwind_Exception_Class) 'C')
 337       << 8 | (_Unwind_Exception_Class) 'C')
 338      << 8 | (_Unwind_Exception_Class) '+')
 339     << 8 | (_Unwind_Exception_Class) '+')
 340    << 8 | (_Unwind_Exception_Class) '\x01');
 341
 342 static inline bool
 343 __is_gxx_exception_class(_Unwind_Exception_Class c)
 344 {
 345   return c == __gxx_primary_exception_class
 346       || c == __gxx_dependent_exception_class;
 347 }
 348
 349 // Only checks for primary or dependent, but not that it is a C++ exception at
 350 // all.
 351 static inline bool
 352 __is_dependent_exception(_Unwind_Exception_Class c)
 353 {
 354   return (c & 1);
 355 }
 356
 357 #define __GXX_INIT_PRIMARY_EXCEPTION_CLASS(c) c = __gxx_primary_exception_class
 358 #define __GXX_INIT_DEPENDENT_EXCEPTION_CLASS(c) \
 359   c = __gxx_dependent_exception_class
 360
 361 // GNU C++ personality routine, Version 0.
 362 extern "C" _Unwind_Reason_Code __gxx_personality_v0
 363      (int, _Unwind_Action, _Unwind_Exception_Class,
 364       struct _Unwind_Exception *, struct _Unwind_Context *);
 365
 366 // GNU C++ sjlj personality routine, Version 0.
 367 extern "C" _Unwind_Reason_Code __gxx_personality_sj0
 368      (int, _Unwind_Action, _Unwind_Exception_Class,
 369       struct _Unwind_Exception *, struct _Unwind_Context *);
 370
 371 static inline void*
 372 __gxx_caught_object(_Unwind_Exception* eo)
 373 {
 374   // Bad as it looks, this actually works for dependent exceptions too.
 375   __cxa_exception* header = __get_exception_header_from_ue (eo);
 376   return header->adjustedPtr;
 377 }
 378 #endif // !__ARM_EABI_UNWINDER__
 379
 380 static inline void*
 381 __get_object_from_ue(_Unwind_Exception* eo) throw()
 382 {
 383   return __is_dependent_exception (eo->exception_class) ?
 384     __get_dependent_exception_from_ue (eo)->primaryException :
 385     eo + 1;
 386 }
 387
 388 static inline void *
 389 __get_object_from_ambiguous_exception(__cxa_exception *p_or_d) throw()
 390 {
 391         return __get_object_from_ue (&p_or_d->unwindHeader);
 392 }
 393
 394
 395 } /* namespace __cxxabiv1 */
 396
 397 #pragma GCC visibility pop
 398
 399 #endif // _UNWIND_CXX_H