1 /* Exception handling and frame unwind runtime interface routines.
2 Copyright (C) 2001-2023 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 it
7 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, but WITHOUT
12 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
13 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
14 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_H
29 #define _UNWIND_H
30
31 #if defined (__SEH__) && !defined (__USING_SJLJ_EXCEPTIONS__)
32 /* Only for _GCC_specific_handler. */
33 #define WIN32_LEAN_AND_MEAN
34 #include <windows.h>
35 #endif
36
37 #ifndef HIDE_EXPORTS
38 #pragma GCC visibility push(default)
39 #endif
40
41 #ifdef __cplusplus
42 extern "C" {
43 #endif
44
45 /* Level 1: Base ABI */
46
47 /* @@@ The IA-64 ABI uses uint64 throughout. Most places this is
48 inefficient for 32-bit and smaller machines. */
49 typedef unsigned _Unwind_Word __attribute__((__mode__(__unwind_word__)));
50 typedef signed _Unwind_Sword __attribute__((__mode__(__unwind_word__)));
51 #if defined(__ia64__) && defined(__hpux__)
52 typedef unsigned _Unwind_Ptr __attribute__((__mode__(__word__)));
53 #else
54 typedef unsigned _Unwind_Ptr __attribute__((__mode__(__pointer__)));
55 #endif
56 typedef unsigned _Unwind_Internal_Ptr __attribute__((__mode__(__pointer__)));
57
58 /* @@@ The IA-64 ABI uses a 64-bit word to identify the producer and
59 consumer of an exception. We'll go along with this for now even on
60 32-bit machines. We'll need to provide some other option for
61 16-bit machines and for machines with > 8 bits per byte. */
62 typedef unsigned _Unwind_Exception_Class __attribute__((__mode__(__DI__)));
63
64 /* The unwind interface uses reason codes in several contexts to
65 identify the reasons for failures or other actions. */
66 typedef enum
67 {
68 _URC_NO_REASON = 0,
69 _URC_FOREIGN_EXCEPTION_CAUGHT = 1,
70 _URC_FATAL_PHASE2_ERROR = 2,
71 _URC_FATAL_PHASE1_ERROR = 3,
72 _URC_NORMAL_STOP = 4,
73 _URC_END_OF_STACK = 5,
74 _URC_HANDLER_FOUND = 6,
75 _URC_INSTALL_CONTEXT = 7,
76 _URC_CONTINUE_UNWIND = 8
77 } _Unwind_Reason_Code;
78
79
80 /* The unwind interface uses a pointer to an exception header object
81 as its representation of an exception being thrown. In general, the
82 full representation of an exception object is language- and
83 implementation-specific, but it will be prefixed by a header
84 understood by the unwind interface. */
85
86 struct _Unwind_Exception;
87
88 typedef void (*_Unwind_Exception_Cleanup_Fn) (_Unwind_Reason_Code,
89 struct _Unwind_Exception *);
90
91 struct _Unwind_Exception
92 {
93 _Unwind_Exception_Class exception_class;
94 _Unwind_Exception_Cleanup_Fn exception_cleanup;
95
96 #if !defined (__USING_SJLJ_EXCEPTIONS__) && defined (__SEH__)
97 _Unwind_Word private_[6];
98 #else
99 _Unwind_Word private_1;
100 _Unwind_Word private_2;
101 #endif
102
103 /* @@@ The IA-64 ABI says that this structure must be double-word aligned.
104 Taking that literally does not make much sense generically. Instead we
105 provide the maximum alignment required by any type for the machine. */
106 } __attribute__((__aligned__));
107
108
109 /* The ACTIONS argument to the personality routine is a bitwise OR of one
110 or more of the following constants. */
111 typedef int _Unwind_Action;
112
113 #define _UA_SEARCH_PHASE 1
114 #define _UA_CLEANUP_PHASE 2
115 #define _UA_HANDLER_FRAME 4
116 #define _UA_FORCE_UNWIND 8
117 #define _UA_END_OF_STACK 16
118
119 /* The target can override this macro to define any back-end-specific
120 attributes required for the lowest-level stack frame. */
121 #ifndef LIBGCC2_UNWIND_ATTRIBUTE
122 #define LIBGCC2_UNWIND_ATTRIBUTE
123 #endif
124
125 /* This is an opaque type used to refer to a system-specific data
126 structure used by the system unwinder. This context is created and
127 destroyed by the system, and passed to the personality routine
128 during unwinding. */
129 struct _Unwind_Context;
130
131 /* Raise an exception, passing along the given exception object. */
132 extern _Unwind_Reason_Code LIBGCC2_UNWIND_ATTRIBUTE
133 _Unwind_RaiseException (struct _Unwind_Exception *);
134
135 /* Raise an exception for forced unwinding. */
136
137 typedef _Unwind_Reason_Code (*_Unwind_Stop_Fn)
138 (int, _Unwind_Action, _Unwind_Exception_Class,
139 struct _Unwind_Exception *, struct _Unwind_Context *, void *);
140
141 extern _Unwind_Reason_Code LIBGCC2_UNWIND_ATTRIBUTE
142 _Unwind_ForcedUnwind (struct _Unwind_Exception *, _Unwind_Stop_Fn, void *);
143
144 /* Helper to invoke the exception_cleanup routine. */
145 extern void _Unwind_DeleteException (struct _Unwind_Exception *);
146
147 /* Resume propagation of an existing exception. This is used after
148 e.g. executing cleanup code, and not to implement rethrowing. */
149 extern void LIBGCC2_UNWIND_ATTRIBUTE
150 _Unwind_Resume (struct _Unwind_Exception *);
151
152 /* @@@ Resume propagation of a FORCE_UNWIND exception, or to rethrow
153 a normal exception that was handled. */
154 extern _Unwind_Reason_Code LIBGCC2_UNWIND_ATTRIBUTE
155 _Unwind_Resume_or_Rethrow (struct _Unwind_Exception *);
156
157 /* @@@ Use unwind data to perform a stack backtrace. The trace callback
158 is called for every stack frame in the call chain, but no cleanup
159 actions are performed. */
160 typedef _Unwind_Reason_Code (*_Unwind_Trace_Fn)
161 (struct _Unwind_Context *, void *);
162
163 extern _Unwind_Reason_Code LIBGCC2_UNWIND_ATTRIBUTE
164 _Unwind_Backtrace (_Unwind_Trace_Fn, void *);
165
166 /* These functions are used for communicating information about the unwind
167 context (i.e. the unwind descriptors and the user register state) between
168 the unwind library and the personality routine and landing pad. Only
169 selected registers may be manipulated. */
170
171 extern _Unwind_Word _Unwind_GetGR (struct _Unwind_Context *, int);
172 extern void _Unwind_SetGR (struct _Unwind_Context *, int, _Unwind_Word);
173
174 extern _Unwind_Ptr _Unwind_GetIP (struct _Unwind_Context *);
175 extern _Unwind_Ptr _Unwind_GetIPInfo (struct _Unwind_Context *, int *);
176 extern void _Unwind_SetIP (struct _Unwind_Context *, _Unwind_Ptr);
177
178 /* @@@ Retrieve the CFA of the given context. */
179 extern _Unwind_Word _Unwind_GetCFA (struct _Unwind_Context *);
180
181 extern void *_Unwind_GetLanguageSpecificData (struct _Unwind_Context *);
182
183 extern _Unwind_Ptr _Unwind_GetRegionStart (struct _Unwind_Context *);
184
185
186 /* The personality routine is the function in the C++ (or other language)
187 runtime library which serves as an interface between the system unwind
188 library and language-specific exception handling semantics. It is
189 specific to the code fragment described by an unwind info block, and
190 it is always referenced via the pointer in the unwind info block, and
191 hence it has no ABI-specified name.
192
193 Note that this implies that two different C++ implementations can
194 use different names, and have different contents in the language
195 specific data area. Moreover, that the language specific data
196 area contains no version info because name of the function invoked
197 provides more effective versioning by detecting at link time the
198 lack of code to handle the different data format. */
199
200 typedef _Unwind_Reason_Code (*_Unwind_Personality_Fn)
201 (int, _Unwind_Action, _Unwind_Exception_Class,
202 struct _Unwind_Exception *, struct _Unwind_Context *);
203
204 /* @@@ The following alternate entry points are for setjmp/longjmp
205 based unwinding. */
206
207 struct SjLj_Function_Context;
208 extern void _Unwind_SjLj_Register (struct SjLj_Function_Context *);
209 extern void _Unwind_SjLj_Unregister (struct SjLj_Function_Context *);
210
211 extern _Unwind_Reason_Code LIBGCC2_UNWIND_ATTRIBUTE
212 _Unwind_SjLj_RaiseException (struct _Unwind_Exception *);
213 extern _Unwind_Reason_Code LIBGCC2_UNWIND_ATTRIBUTE
214 _Unwind_SjLj_ForcedUnwind (struct _Unwind_Exception *, _Unwind_Stop_Fn, void *);
215 extern void LIBGCC2_UNWIND_ATTRIBUTE
216 _Unwind_SjLj_Resume (struct _Unwind_Exception *);
217 extern _Unwind_Reason_Code LIBGCC2_UNWIND_ATTRIBUTE
218 _Unwind_SjLj_Resume_or_Rethrow (struct _Unwind_Exception *);
219
220 /* @@@ The following provide access to the base addresses for text
221 and data-relative addressing in the LDSA. In order to stay link
222 compatible with the standard ABI for IA-64, we inline these. */
223
224 #ifdef __ia64__
225 static inline _Unwind_Ptr
226 _Unwind_GetDataRelBase (struct _Unwind_Context *_C)
227 {
228 /* The GP is stored in R1. */
229 return _Unwind_GetGR (_C, 1);
230 }
231
232 static inline _Unwind_Ptr
233 _Unwind_GetTextRelBase (struct _Unwind_Context *_C __attribute__ ((__unused__)))
234 {
235 __builtin_abort ();
236 return 0;
237 }
238
239 /* @@@ Retrieve the Backing Store Pointer of the given context. */
240 extern _Unwind_Word _Unwind_GetBSP (struct _Unwind_Context *);
241 #else
242 extern _Unwind_Ptr _Unwind_GetDataRelBase (struct _Unwind_Context *);
243 extern _Unwind_Ptr _Unwind_GetTextRelBase (struct _Unwind_Context *);
244 #endif
245
246 /* @@@ Given an address, return the entry point of the function that
247 contains it. */
248 extern void * _Unwind_FindEnclosingFunction (void *pc);
249
250 #ifndef __SIZEOF_LONG__
251 #error "__SIZEOF_LONG__ macro not defined"
252 #endif
253
254 #ifndef __SIZEOF_POINTER__
255 #error "__SIZEOF_POINTER__ macro not defined"
256 #endif
257
258
259 /* leb128 type numbers have a potentially unlimited size.
260 The target of the following definitions of _sleb128_t and _uleb128_t
261 is to have efficient data types large enough to hold the leb128 type
262 numbers used in the unwind code.
263 Mostly these types will simply be defined to long and unsigned long
264 except when a unsigned long data type on the target machine is not
265 capable of storing a pointer. */
266
267 #if __SIZEOF_LONG__ >= __SIZEOF_POINTER__
268 typedef long _sleb128_t;
269 typedef unsigned long _uleb128_t;
270 #elif __SIZEOF_LONG_LONG__ >= __SIZEOF_POINTER__
271 typedef long long _sleb128_t;
272 typedef unsigned long long _uleb128_t;
273 #else
274 # error "What type shall we use for _sleb128_t?"
275 #endif
276
277 #if defined (__SEH__) && !defined (__USING_SJLJ_EXCEPTIONS__)
278 /* Handles the mapping from SEH to GCC interfaces. */
279 EXCEPTION_DISPOSITION _GCC_specific_handler (PEXCEPTION_RECORD, void *,
280 PCONTEXT, PDISPATCHER_CONTEXT,
281 _Unwind_Personality_Fn);
282 #endif
283
284 #ifdef __cplusplus
285 }
286 #endif
287
288 #ifndef HIDE_EXPORTS
289 #pragma GCC visibility pop
290 #endif
291
292 /* Additional actions to unwind number of stack frames. */
293 #define _Unwind_Frames_Extra(frames)
294
295 /* Increment frame count. */
296 #define _Unwind_Frames_Increment(exc, context, frames) frames++
297
298 #endif /* unwind.h */