1 /* DWARF2 exception handling and frame unwind runtime interface routines.
2 Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002
3 Free Software Foundation, Inc.
4
5 This file is part of GCC.
6
7 GCC is free software; you can redistribute it and/or modify it
8 under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
10 any later version.
11
12 GCC is distributed in the hope that it will be useful, but WITHOUT
13 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
14 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
15 License for more details.
16
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to the Free
19 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
20 02111-1307, USA. */
21
22 #include "tconfig.h"
23 #include "tsystem.h"
24 #include "unwind.h"
25 #include "gthr.h"
26
27 #ifdef __USING_SJLJ_EXCEPTIONS__
28
29 #ifdef DONT_USE_BUILTIN_SETJMP
30 #ifndef inhibit_libc
31 #include <setjmp.h>
32 #else
33 typedef void *jmp_buf[JMP_BUF_SIZE];
34 extern void longjmp(jmp_buf, int) __attribute__((noreturn));
35 #endif
36 #else
37 #define setjmp __builtin_setjmp
38 #define longjmp __builtin_longjmp
39 #endif
40
41 /* This structure is allocated on the stack of the target function.
42 This must match the definition created in except.c:init_eh. */
43 struct SjLj_Function_Context
44 {
45 /* This is the chain through all registered contexts. It is
46 filled in by _Unwind_SjLj_Register. */
47 struct SjLj_Function_Context *prev;
48
49 /* This is assigned in by the target function before every call
50 to the index of the call site in the lsda. It is assigned by
51 the personality routine to the landing pad index. */
52 int call_site;
53
54 /* This is how data is returned from the personality routine to
55 the target function's handler. */
56 _Unwind_Word data[4];
57
58 /* These are filled in once by the target function before any
59 exceptions are expected to be handled. */
60 _Unwind_Personality_Fn personality;
61 void *lsda;
62
63 #ifdef DONT_USE_BUILTIN_SETJMP
64 /* We don't know what sort of alignment requirements the system
65 jmp_buf has. We over estimated in except.c, and now we have
66 to match that here just in case the system *didn't* have more
67 restrictive requirements. */
68 jmp_buf jbuf __attribute__((aligned));
69 #else
70 void *jbuf[];
71 #endif
72 };
73
74 struct _Unwind_Context
75 {
76 struct SjLj_Function_Context *fc;
77 };
78
79 typedef struct
80 {
81 _Unwind_Personality_Fn personality;
82 } _Unwind_FrameState;
83
84
85 /* Manage the chain of registered function contexts. */
86
87 /* Single threaded fallback chain. */
88 static struct SjLj_Function_Context *fc_static;
89
90 #if __GTHREADS
91 static __gthread_key_t fc_key;
92 static int use_fc_key = -1;
93
94 static void
fc_key_dtor(void * ptr)95 fc_key_dtor (void *ptr)
96 {
97 __gthread_key_dtor (fc_key, ptr);
98 }
99
100 static void
fc_key_init(void)101 fc_key_init (void)
102 {
103 use_fc_key = __gthread_key_create (&fc_key, fc_key_dtor) == 0;
104 }
105
106 static void
fc_key_init_once(void)107 fc_key_init_once (void)
108 {
109 static __gthread_once_t once = __GTHREAD_ONCE_INIT;
110 if (__gthread_once (&once, fc_key_init) != 0 || use_fc_key < 0)
111 use_fc_key = 0;
112 }
113 #endif
114
115 void
_Unwind_SjLj_Register(struct SjLj_Function_Context * fc)116 _Unwind_SjLj_Register (struct SjLj_Function_Context *fc)
117 {
118 #if __GTHREADS
119 if (use_fc_key < 0)
120 fc_key_init_once ();
121
122 if (use_fc_key)
123 {
124 fc->prev = __gthread_getspecific (fc_key);
125 __gthread_setspecific (fc_key, fc);
126 }
127 else
128 #endif
129 {
130 fc->prev = fc_static;
131 fc_static = fc;
132 }
133 }
134
135 static inline struct SjLj_Function_Context *
_Unwind_SjLj_GetContext(void)136 _Unwind_SjLj_GetContext (void)
137 {
138 #if __GTHREADS
139 if (use_fc_key < 0)
140 fc_key_init_once ();
141
142 if (use_fc_key)
143 return __gthread_getspecific (fc_key);
144 #endif
145 return fc_static;
146 }
147
148 static inline void
_Unwind_SjLj_SetContext(struct SjLj_Function_Context * fc)149 _Unwind_SjLj_SetContext (struct SjLj_Function_Context *fc)
150 {
151 #if __GTHREADS
152 if (use_fc_key < 0)
153 fc_key_init_once ();
154
155 if (use_fc_key)
156 __gthread_setspecific (fc_key, fc);
157 else
158 #endif
159 fc_static = fc;
160 }
161
162 void
_Unwind_SjLj_Unregister(struct SjLj_Function_Context * fc)163 _Unwind_SjLj_Unregister (struct SjLj_Function_Context *fc)
164 {
165 _Unwind_SjLj_SetContext (fc->prev);
166 }
167
168
169 /* Get/set the return data value at INDEX in CONTEXT. */
170
171 _Unwind_Word
_Unwind_GetGR(struct _Unwind_Context * context,int index)172 _Unwind_GetGR (struct _Unwind_Context *context, int index)
173 {
174 return context->fc->data[index];
175 }
176
177 /* Get the value of the CFA as saved in CONTEXT. */
178
179 _Unwind_Word
_Unwind_GetCFA(struct _Unwind_Context * context)180 _Unwind_GetCFA (struct _Unwind_Context *context)
181 {
182 /* ??? Ideally __builtin_setjmp places the CFA in the jmpbuf. */
183 return NULL;
184 }
185
186 void
_Unwind_SetGR(struct _Unwind_Context * context,int index,_Unwind_Word val)187 _Unwind_SetGR (struct _Unwind_Context *context, int index, _Unwind_Word val)
188 {
189 context->fc->data[index] = val;
190 }
191
192 /* Get the call-site index as saved in CONTEXT. */
193
194 _Unwind_Ptr
_Unwind_GetIP(struct _Unwind_Context * context)195 _Unwind_GetIP (struct _Unwind_Context *context)
196 {
197 return context->fc->call_site + 1;
198 }
199
200 /* Set the return landing pad index in CONTEXT. */
201
202 void
_Unwind_SetIP(struct _Unwind_Context * context,_Unwind_Ptr val)203 _Unwind_SetIP (struct _Unwind_Context *context, _Unwind_Ptr val)
204 {
205 context->fc->call_site = val - 1;
206 }
207
208 void *
_Unwind_GetLanguageSpecificData(struct _Unwind_Context * context)209 _Unwind_GetLanguageSpecificData (struct _Unwind_Context *context)
210 {
211 return context->fc->lsda;
212 }
213
214 _Unwind_Ptr
_Unwind_GetRegionStart(struct _Unwind_Context * context)215 _Unwind_GetRegionStart (struct _Unwind_Context *context __attribute__((unused)) )
216 {
217 return 0;
218 }
219
220 void *
_Unwind_FindEnclosingFunction(void * pc)221 _Unwind_FindEnclosingFunction (void *pc)
222 {
223 return NULL;
224 }
225
226 #ifndef __ia64__
227 _Unwind_Ptr
_Unwind_GetDataRelBase(struct _Unwind_Context * context)228 _Unwind_GetDataRelBase (struct _Unwind_Context *context __attribute__((unused)) )
229 {
230 return 0;
231 }
232
233 _Unwind_Ptr
_Unwind_GetTextRelBase(struct _Unwind_Context * context)234 _Unwind_GetTextRelBase (struct _Unwind_Context *context __attribute__((unused)) )
235 {
236 return 0;
237 }
238 #endif
239
240 static inline _Unwind_Reason_Code
uw_frame_state_for(struct _Unwind_Context * context,_Unwind_FrameState * fs)241 uw_frame_state_for (struct _Unwind_Context *context, _Unwind_FrameState *fs)
242 {
243 if (context->fc == NULL)
244 {
245 fs->personality = NULL;
246 return _URC_END_OF_STACK;
247 }
248 else
249 {
250 fs->personality = context->fc->personality;
251 return _URC_NO_REASON;
252 }
253 }
254
255 static inline void
uw_update_context(struct _Unwind_Context * context,_Unwind_FrameState * fs)256 uw_update_context (struct _Unwind_Context *context,
257 _Unwind_FrameState *fs __attribute__((unused)) )
258 {
259 context->fc = context->fc->prev;
260 }
261
262 static inline void
uw_init_context(struct _Unwind_Context * context)263 uw_init_context (struct _Unwind_Context *context)
264 {
265 context->fc = _Unwind_SjLj_GetContext ();
266 }
267
268 /* ??? There appear to be bugs in integrate.c wrt __builtin_longjmp and
269 virtual-stack-vars. An inline version of this segfaults on SPARC. */
270 #define uw_install_context(CURRENT, TARGET) \
271 do \
272 { \
273 _Unwind_SjLj_SetContext ((TARGET)->fc); \
274 longjmp ((TARGET)->fc->jbuf, 1); \
275 } \
276 while (0)
277
278
279 static inline _Unwind_Ptr
uw_identify_context(struct _Unwind_Context * context)280 uw_identify_context (struct _Unwind_Context *context)
281 {
282 return (_Unwind_Ptr) context->fc;
283 }
284
285
286 /* Play games with unwind symbols so that we can have call frame
287 and sjlj symbols in the same shared library. Not that you can
288 use them simultaneously... */
289 #define _Unwind_RaiseException _Unwind_SjLj_RaiseException
290 #define _Unwind_ForcedUnwind _Unwind_SjLj_ForcedUnwind
291 #define _Unwind_Resume _Unwind_SjLj_Resume
292 #define _Unwind_Resume_or_Rethrow _Unwind_SjLj_Resume_or_Rethrow
293
294 #include "unwind.inc"
295
296 #endif /* USING_SJLJ_EXCEPTIONS */
297