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74bd2300 | 1 | /* Subroutines needed for unwinding stack frames for exception handling. */ |
b168057a | 2 | /* Copyright (C) 1997-2015 Free Software Foundation, Inc. |
74bd2300 UD |
3 | Contributed by Jason Merrill <jason@cygnus.com>. |
4 | ||
df5fd414 | 5 | This file is part of the GNU C Library. |
74bd2300 | 6 | |
df5fd414 RM |
7 | The GNU C Library is free software; you can redistribute it and/or |
8 | modify it under the terms of the GNU Lesser General Public | |
9 | License as published by the Free Software Foundation; either | |
10 | version 2.1 of the License, or (at your option) any later version. | |
74bd2300 | 11 | |
df5fd414 RM |
12 | The GNU C Library is distributed in the hope that it will be useful, |
13 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
15 | Lesser General Public License for more details. | |
74bd2300 | 16 | |
df5fd414 | 17 | You should have received a copy of the GNU Lesser General Public |
59ba27a6 PE |
18 | License along with the GNU C Library; if not, see |
19 | <http://www.gnu.org/licenses/>. */ | |
74bd2300 UD |
20 | |
21 | ||
22 | struct fde_vector | |
23 | { | |
24 | void *orig_data; | |
25 | size_t count; | |
26 | struct dwarf_fde *array __flexarr; | |
27 | }; | |
28 | ||
29 | #ifdef _LIBC | |
30 | #include <gccframe.h> | |
31 | #else | |
32 | struct object | |
33 | { | |
34 | void *pc_begin; | |
35 | void *tbase; | |
36 | void *dbase; | |
37 | union { | |
38 | struct dwarf_fde *single; | |
39 | struct dwarf_fde **array; | |
40 | struct fde_vector *sort; | |
41 | } u; | |
42 | ||
43 | union { | |
44 | struct { | |
45 | unsigned long sorted : 1; | |
46 | unsigned long from_array : 1; | |
47 | unsigned long mixed_encoding : 1; | |
48 | unsigned long encoding : 8; | |
49 | /* ??? Wish there was an easy way to detect a 64-bit host here; | |
6180ac2f | 50 | we've got 32 bits left to play with... */ |
74bd2300 UD |
51 | unsigned long count : 21; |
52 | } b; | |
53 | size_t i; | |
54 | } s; | |
55 | ||
6180ac2f UD |
56 | #ifdef DWARF2_OBJECT_END_PTR_EXTENSION |
57 | char *fde_end; | |
58 | #endif | |
59 | ||
74bd2300 UD |
60 | struct object *next; |
61 | }; | |
62 | #endif | |
63 | ||
64 | /* This is the original definition of struct object. While the struct | |
65 | itself was opaque to users, they did know how large it was, and | |
66 | allocate one statically in crtbegin for each DSO. Keep this around | |
67 | so that we're aware of the static size limitations for the new struct. */ | |
68 | struct old_object | |
69 | { | |
70 | void *pc_begin; | |
71 | void *pc_end; | |
72 | struct dwarf_fde *fde_begin; | |
73 | struct dwarf_fde **fde_array; | |
74 | size_t count; | |
75 | struct old_object *next; | |
76 | }; | |
77 | ||
78 | struct dwarf_eh_bases | |
79 | { | |
80 | void *tbase; | |
81 | void *dbase; | |
82 | void *func; | |
83 | }; | |
84 | ||
85 | ||
86 | extern void __register_frame_info_bases (void *, struct object *, | |
87 | void *, void *); | |
88 | extern void __register_frame_info (void *, struct object *); | |
89 | extern void __register_frame (void *); | |
90 | extern void __register_frame_info_table_bases (void *, struct object *, | |
91 | void *, void *); | |
92 | extern void __register_frame_info_table (void *, struct object *); | |
93 | extern void __register_frame_table (void *); | |
94 | extern void *__deregister_frame_info (void *); | |
95 | extern void *__deregister_frame_info_bases (void *); | |
96 | extern void __deregister_frame (void *); | |
97 | ||
98 | \f | |
99 | typedef int sword __attribute__ ((mode (SI))); | |
100 | typedef unsigned int uword __attribute__ ((mode (SI))); | |
101 | typedef unsigned int uaddr __attribute__ ((mode (pointer))); | |
102 | typedef int saddr __attribute__ ((mode (pointer))); | |
103 | typedef unsigned char ubyte; | |
104 | ||
105 | /* Terminology: | |
106 | CIE - Common Information Element | |
107 | FDE - Frame Descriptor Element | |
108 | ||
109 | There is one per function, and it describes where the function code | |
110 | is located, and what the register lifetimes and stack layout are | |
111 | within the function. | |
112 | ||
6180ac2f | 113 | The data structures are defined in the DWARF specification, although |
74bd2300 UD |
114 | not in a very readable way (see LITERATURE). |
115 | ||
116 | Every time an exception is thrown, the code needs to locate the FDE | |
117 | for the current function, and starts to look for exception regions | |
118 | from that FDE. This works in a two-level search: | |
119 | a) in a linear search, find the shared image (i.e. DLL) containing | |
120 | the PC | |
121 | b) using the FDE table for that shared object, locate the FDE using | |
6180ac2f | 122 | binary search (which requires the sorting). */ |
74bd2300 UD |
123 | |
124 | /* The first few fields of a CIE. The CIE_id field is 0 for a CIE, | |
125 | to distinguish it from a valid FDE. FDEs are aligned to an addressing | |
126 | unit boundary, but the fields within are unaligned. */ | |
127 | struct dwarf_cie | |
128 | { | |
129 | uword length; | |
130 | sword CIE_id; | |
131 | ubyte version; | |
132 | unsigned char augmentation __flexarr; | |
133 | } __attribute__ ((packed, aligned (__alignof__ (void *)))); | |
134 | ||
135 | /* The first few fields of an FDE. */ | |
136 | struct dwarf_fde | |
137 | { | |
138 | uword length; | |
139 | sword CIE_delta; | |
140 | unsigned char pc_begin __flexarr; | |
141 | } __attribute__ ((packed, aligned (__alignof__ (void *)))); | |
142 | ||
143 | typedef struct dwarf_fde fde; | |
144 | ||
145 | /* Locate the CIE for a given FDE. */ | |
146 | ||
147 | static inline struct dwarf_cie * | |
148 | get_cie (struct dwarf_fde *f) | |
149 | { | |
150 | return (void *)&f->CIE_delta - f->CIE_delta; | |
151 | } | |
152 | ||
153 | static inline fde * | |
154 | next_fde (fde *f) | |
155 | { | |
6180ac2f | 156 | return (fde *) ((char *) f + f->length + sizeof (f->length)); |
74bd2300 UD |
157 | } |
158 | ||
159 | extern fde * _Unwind_Find_FDE (void *, struct dwarf_eh_bases *); | |
6180ac2f UD |
160 | |
161 | static inline int | |
162 | last_fde (struct object *obj __attribute__ ((__unused__)), fde *f) | |
163 | { | |
164 | #ifdef DWARF2_OBJECT_END_PTR_EXTENSION | |
165 | return (char *)f == obj->fde_end || f->length == 0; | |
166 | #else | |
167 | return f->length == 0; | |
168 | #endif | |
169 | } |