1 /* Exception handling and frame unwind runtime interface routines.
2 Copyright (C) 2001-2024 Free Software Foundation, Inc.
4 This file is part of the GNU C Library.
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
11 The GNU C Library 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 GNU
14 Lesser General Public License for more details.
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, see
18 <https://www.gnu.org/licenses/>. */
20 /* This is derived from the C++ ABI for IA-64. Where we diverge
21 for cross-architecture compatibility are noted with "@@@". */
30 /* Level 1: Base ABI */
32 /* @@@ The IA-64 ABI uses uint64 throughout. Most places this is
33 inefficient for 32-bit and smaller machines. */
34 typedef unsigned _Unwind_Word
__attribute__((__mode__(__unwind_word__
)));
35 typedef signed _Unwind_Sword
__attribute__((__mode__(__unwind_word__
)));
36 typedef unsigned _Unwind_Ptr
__attribute__((__mode__(__pointer__
)));
37 typedef unsigned _Unwind_Internal_Ptr
__attribute__((__mode__(__pointer__
)));
39 /* @@@ The IA-64 ABI uses a 64-bit word to identify the producer and
40 consumer of an exception. We'll go along with this for now even on
41 32-bit machines. We'll need to provide some other option for
42 16-bit machines and for machines with > 8 bits per byte. */
43 typedef unsigned _Unwind_Exception_Class
__attribute__((__mode__(__DI__
)));
45 /* The unwind interface uses reason codes in several contexts to
46 identify the reasons for failures or other actions. */
50 _URC_FOREIGN_EXCEPTION_CAUGHT
= 1,
51 _URC_FATAL_PHASE2_ERROR
= 2,
52 _URC_FATAL_PHASE1_ERROR
= 3,
54 _URC_END_OF_STACK
= 5,
55 _URC_HANDLER_FOUND
= 6,
56 _URC_INSTALL_CONTEXT
= 7,
57 _URC_CONTINUE_UNWIND
= 8
58 } _Unwind_Reason_Code
;
61 /* The unwind interface uses a pointer to an exception header object
62 as its representation of an exception being thrown. In general, the
63 full representation of an exception object is language- and
64 implementation-specific, but it will be prefixed by a header
65 understood by the unwind interface. */
67 struct _Unwind_Exception
;
69 typedef void (*_Unwind_Exception_Cleanup_Fn
) (_Unwind_Reason_Code
,
70 struct _Unwind_Exception
*);
72 struct _Unwind_Exception
78 _Unwind_Exception_Class exception_class
;
79 _Unwind_Exception_Cleanup_Fn exception_cleanup
;
80 _Unwind_Word private_1
;
81 _Unwind_Word private_2
;
84 /* The IA-64 ABI says that this structure must be double-word aligned. */
85 _Unwind_Word unwind_exception_align
[2]
86 __attribute__ ((__aligned__ (2 * sizeof (_Unwind_Word
))));
91 /* The ACTIONS argument to the personality routine is a bitwise OR of one
92 or more of the following constants. */
93 typedef int _Unwind_Action
;
95 #define _UA_SEARCH_PHASE 1
96 #define _UA_CLEANUP_PHASE 2
97 #define _UA_HANDLER_FRAME 4
98 #define _UA_FORCE_UNWIND 8
99 #define _UA_END_OF_STACK 16
101 /* This is an opaque type used to refer to a system-specific data
102 structure used by the system unwinder. This context is created and
103 destroyed by the system, and passed to the personality routine
105 struct _Unwind_Context
;
107 /* Raise an exception, passing along the given exception object. */
108 extern _Unwind_Reason_Code
_Unwind_RaiseException (struct _Unwind_Exception
*);
110 /* Raise an exception for forced unwinding. */
112 typedef _Unwind_Reason_Code (*_Unwind_Stop_Fn
)
113 (int, _Unwind_Action
, _Unwind_Exception_Class
,
114 struct _Unwind_Exception
*, struct _Unwind_Context
*, void *);
116 extern _Unwind_Reason_Code
_Unwind_ForcedUnwind (struct _Unwind_Exception
*,
120 /* Helper to invoke the exception_cleanup routine. */
121 extern void _Unwind_DeleteException (struct _Unwind_Exception
*);
123 /* Resume propagation of an existing exception. This is used after
124 e.g. executing cleanup code, and not to implement rethrowing. */
125 extern void _Unwind_Resume (struct _Unwind_Exception
*);
127 /* @@@ Use unwind data to perform a stack backtrace. The trace callback
128 is called for every stack frame in the call chain, but no cleanup
129 actions are performed. */
130 typedef _Unwind_Reason_Code (*_Unwind_Trace_Fn
)
131 (struct _Unwind_Context
*, void *);
133 extern _Unwind_Reason_Code
_Unwind_Backtrace (_Unwind_Trace_Fn
, void *);
135 /* These functions are used for communicating information about the unwind
136 context (i.e. the unwind descriptors and the user register state) between
137 the unwind library and the personality routine and landing pad. Only
138 selected registers maybe manipulated. */
140 extern _Unwind_Word
_Unwind_GetGR (struct _Unwind_Context
*, int);
141 extern void _Unwind_SetGR (struct _Unwind_Context
*, int, _Unwind_Word
);
143 extern _Unwind_Ptr
_Unwind_GetIP (struct _Unwind_Context
*);
144 extern void _Unwind_SetIP (struct _Unwind_Context
*, _Unwind_Ptr
);
146 /* @@@ Retrieve the CFA of the given context. */
147 extern _Unwind_Word
_Unwind_GetCFA (struct _Unwind_Context
*);
149 extern void *_Unwind_GetLanguageSpecificData (struct _Unwind_Context
*);
151 extern _Unwind_Ptr
_Unwind_GetRegionStart (struct _Unwind_Context
*);
154 /* The personality routine is the function in the C++ (or other language)
155 runtime library which serves as an interface between the system unwind
156 library and language-specific exception handling semantics. It is
157 specific to the code fragment described by an unwind info block, and
158 it is always referenced via the pointer in the unwind info block, and
159 hence it has no ABI-specified name.
161 Note that this implies that two different C++ implementations can
162 use different names, and have different contents in the language
163 specific data area. Moreover, that the language specific data
164 area contains no version info because name of the function invoked
165 provides more effective versioning by detecting at link time the
166 lack of code to handle the different data format. */
168 typedef _Unwind_Reason_Code (*_Unwind_Personality_Fn
)
169 (int, _Unwind_Action
, _Unwind_Exception_Class
,
170 struct _Unwind_Exception
*, struct _Unwind_Context
*);
172 /* @@@ The following alternate entry points are for setjmp/longjmp
175 struct SjLj_Function_Context
;
176 extern void _Unwind_SjLj_Register (struct SjLj_Function_Context
*);
177 extern void _Unwind_SjLj_Unregister (struct SjLj_Function_Context
*);
179 extern _Unwind_Reason_Code _Unwind_SjLj_RaiseException
180 (struct _Unwind_Exception
*);
181 extern _Unwind_Reason_Code _Unwind_SjLj_ForcedUnwind
182 (struct _Unwind_Exception
*, _Unwind_Stop_Fn
, void *);
183 extern void _Unwind_SjLj_Resume (struct _Unwind_Exception
*);
185 /* @@@ The following provide access to the base addresses for text
186 and data-relative addressing in the LDSA. In order to stay link
187 compatible with the standard ABI for IA-64, we inline these. */
189 extern _Unwind_Ptr
_Unwind_GetDataRelBase (struct _Unwind_Context
*);
190 extern _Unwind_Ptr
_Unwind_GetTextRelBase (struct _Unwind_Context
*);
192 /* @@@ Given an address, return the entry point of the function that
194 extern void * _Unwind_FindEnclosingFunction (void *pc
);
200 #endif /* unwind.h */