1// -*- C++ -*- Exception handling and frame unwind runtime interface routines.
2// Copyright (C) 2001-2017 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
55namespace __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
62struct __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
100struct __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
112struct __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.
155struct __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.
169extern "C" void __cxa_call_unexpected (void *) __attribute__((__noreturn__));
170extern "C" void __cxa_call_terminate (_Unwind_Exception*) throw ()
171 __attribute__((__noreturn__));
172
173#ifdef __ARM_EABI_UNWINDER__
174// Arm EABI specified routines.
175typedef enum {
176 ctm_failed = 0,
177 ctm_succeeded = 1,
178 ctm_succeeded_with_ptr_to_base = 2
179} __cxa_type_match_result;
180extern "C" __cxa_type_match_result __cxa_type_match(_Unwind_Exception*,
181 const std::type_info*,
182 bool, void**);
183extern "C" bool __cxa_begin_cleanup (_Unwind_Exception*);
184extern "C" void __cxa_end_cleanup (void);
185#endif
186
187// Handles cleanup from transactional memory restart.
188extern "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.
192extern void __terminate(std::terminate_handler) throw ()
193 __attribute__((__noreturn__));
194extern void __unexpected(std::unexpected_handler)
195 __attribute__((__noreturn__));
196
197// The current installed user handlers.
198extern std::terminate_handler __terminate_handler;
199extern std::unexpected_handler __unexpected_handler;
200
201// These are explicitly GNU C++ specific.
202
203// Acquire the C++ exception header from the C++ object.
204static 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.
211static 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.
218static 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.
226static 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
232static 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__
239static 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.
255static inline bool
256__is_dependent_exception(_Unwind_Exception_Class c)
257{
258 return c[7] == '\x01';
259}
260
261static 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
274static 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
287static 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
300static 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
313static 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".
320const _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"
332const _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
342static 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.
351static 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.
362extern "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.
367extern "C" _Unwind_Reason_Code __gxx_personality_sj0
368 (int, _Unwind_Action, _Unwind_Exception_Class,
369 struct _Unwind_Exception *, struct _Unwind_Context *);
370
371static 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
380static 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
388static 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
400