1 /* Subroutines needed for unwinding stack frames for exception handling. */
2 /* Copyright (C) 1997-2023 Free Software Foundation, Inc.
3 Contributed by Jason Merrill <jason@cygnus.com>.
4
5 This file is part of GCC.
6
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 3, or (at your option) any later
10 version.
11
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
15 for more details.
16
17 Under Section 7 of GPL version 3, you are granted additional
18 permissions described in the GCC Runtime Library Exception, version
19 3.1, as published by the Free Software Foundation.
20
21 You should have received a copy of the GNU General Public License and
22 a copy of the GCC Runtime Library Exception along with this program;
23 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
24 <http://www.gnu.org/licenses/>. */
25
26 #ifndef GCC_UNWIND_DW2_FDE_H
27 #define GCC_UNWIND_DW2_FDE_H
28
29 #ifndef HIDE_EXPORTS
30 #pragma GCC visibility push(default)
31 #endif
32
33 struct fde_vector
34 {
35 const void *orig_data;
36 size_t count;
37 const struct dwarf_fde *array[];
38 };
39
40 struct object
41 {
42 void *pc_begin;
43 void *tbase;
44 void *dbase;
45 union {
46 const struct dwarf_fde *single;
47 struct dwarf_fde **array;
48 struct fde_vector *sort;
49 } u;
50
51 union {
52 struct {
53 unsigned long sorted : 1;
54 unsigned long from_array : 1;
55 unsigned long mixed_encoding : 1;
56 unsigned long encoding : 8;
57 /* ??? Wish there was an easy way to detect a 64-bit host here;
58 we've got 32 bits left to play with... */
59 unsigned long count : 21;
60 } b;
61 size_t i;
62 } s;
63
64 #ifdef DWARF2_OBJECT_END_PTR_EXTENSION
65 char *fde_end;
66 #endif
67
68 struct object *next;
69 };
70
71 /* This is the original definition of struct object. While the struct
72 itself was opaque to users, they did know how large it was, and
73 allocate one statically in crtbegin for each DSO. Keep this around
74 so that we're aware of the static size limitations for the new struct. */
75 struct old_object
76 {
77 void *pc_begin;
78 void *pc_end;
79 struct dwarf_fde *fde_begin;
80 struct dwarf_fde **fde_array;
81 size_t count;
82 struct old_object *next;
83 };
84
85 struct dwarf_eh_bases
86 {
87 void *tbase;
88 void *dbase;
89 void *func;
90 };
91
92
93 extern void __register_frame_info_bases (const void *, struct object *,
94 void *, void *);
95 extern void __register_frame_info (const void *, struct object *);
96 extern void __register_frame (void *);
97 extern void __register_frame_info_table_bases (void *, struct object *,
98 void *, void *);
99 extern void __register_frame_info_table (void *, struct object *);
100 extern void __register_frame_table (void *);
101 extern void *__deregister_frame_info (const void *);
102 extern void *__deregister_frame_info_bases (const void *);
103 extern void __deregister_frame (void *);
104
105
106 typedef int sword __attribute__ ((mode (SI)));
107 typedef unsigned int uword __attribute__ ((mode (SI)));
108 typedef unsigned int uaddr __attribute__ ((mode (pointer)));
109 typedef int saddr __attribute__ ((mode (pointer)));
110 typedef unsigned char ubyte;
111
112 /* Terminology:
113 CIE - Common Information Element
114 FDE - Frame Descriptor Element
115
116 There is one per function, and it describes where the function code
117 is located, and what the register lifetimes and stack layout are
118 within the function.
119
120 The data structures are defined in the DWARF specification, although
121 not in a very readable way (see LITERATURE).
122
123 Every time an exception is thrown, the code needs to locate the FDE
124 for the current function, and starts to look for exception regions
125 from that FDE. This works in a two-level search:
126 a) in a linear search, find the shared image (i.e. DLL) containing
127 the PC
128 b) using the FDE table for that shared object, locate the FDE using
129 binary search (which requires the sorting). */
130
131 /* The first few fields of a CIE. The CIE_id field is 0 for a CIE,
132 to distinguish it from a valid FDE. FDEs are aligned to an addressing
133 unit boundary, but the fields within are unaligned. */
134 struct dwarf_cie
135 {
136 uword length;
137 sword CIE_id;
138 ubyte version;
139 unsigned char augmentation[];
140 } __attribute__ ((packed, aligned (__alignof__ (void *))));
141
142 /* The first few fields of an FDE. */
143 struct dwarf_fde
144 {
145 uword length;
146 sword CIE_delta;
147 unsigned char pc_begin[];
148 } __attribute__ ((packed, aligned (__alignof__ (void *))));
149
150 typedef struct dwarf_fde fde;
151
152 /* Locate the CIE for a given FDE. */
153
154 static inline const struct dwarf_cie *
155 get_cie (const struct dwarf_fde *f)
156 {
157 return (const void *)&f->CIE_delta - f->CIE_delta;
158 }
159
160 static inline const fde *
161 next_fde (const fde *f)
162 {
163 return (const fde *) ((const char *) f + f->length + sizeof (f->length));
164 }
165
166 extern const fde * _Unwind_Find_FDE (void *, struct dwarf_eh_bases *);
167
168 static inline int
169 last_fde (const struct object *obj __attribute__ ((__unused__)), const fde *f)
170 {
171 #ifdef DWARF2_OBJECT_END_PTR_EXTENSION
172 return f == (const fde *) obj->fde_end || f->length == 0;
173 #else
174 return f->length == 0;
175 #endif
176 }
177
178 #ifndef HIDE_EXPORTS
179 #pragma GCC visibility pop
180 #endif
181
182 #endif /* unwind-dw2-fde.h */