1 /* SJLJ exception handling and frame unwind runtime interface routines. 2 Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2006, 3 2009, 2011 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 3, 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 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 #include "tconfig.h" 27 #include "tsystem.h" 28 #include "coretypes.h" 29 #include "tm.h" 30 #include "libgcc_tm.h" 31 #include "unwind.h" 32 #include "gthr.h" 33 34 #ifdef __USING_SJLJ_EXCEPTIONS__ 35 36 #ifdef DONT_USE_BUILTIN_SETJMP 37 #ifndef inhibit_libc 38 #include <setjmp.h> 39 #else 40 typedef void *jmp_buf[JMP_BUF_SIZE]; 41 extern void longjmp(jmp_buf, int) __attribute__((noreturn)); 42 #endif 43 #else 44 #define longjmp __builtin_longjmp 45 #endif 46 47 /* The setjmp side is dealt with in the except.c file. */ 48 #undef setjmp 49 #define setjmp setjmp_should_not_be_used_in_this_file 50 51 52 /* This structure is allocated on the stack of the target function. 53 This must match the definition created in except.c:init_eh. */ 54 struct SjLj_Function_Context 55 { 56 /* This is the chain through all registered contexts. It is 57 filled in by _Unwind_SjLj_Register. */ 58 struct SjLj_Function_Context *prev; 59 60 /* This is assigned in by the target function before every call 61 to the index of the call site in the lsda. It is assigned by 62 the personality routine to the landing pad index. */ 63 int call_site; 64 65 /* This is how data is returned from the personality routine to 66 the target function's handler. */ 67 _Unwind_Word data[4]; 68 69 /* These are filled in once by the target function before any 70 exceptions are expected to be handled. */ 71 _Unwind_Personality_Fn personality; 72 void *lsda; 73 74 #ifdef DONT_USE_BUILTIN_SETJMP 75 /* We don't know what sort of alignment requirements the system 76 jmp_buf has. We over estimated in except.c, and now we have 77 to match that here just in case the system *didn't* have more 78 restrictive requirements. */ 79 jmp_buf jbuf __attribute__((aligned)); 80 #else 81 void *jbuf[]; 82 #endif 83 }; 84 85 struct _Unwind_Context 86 { 87 struct SjLj_Function_Context *fc; 88 }; 89 90 typedef struct 91 { 92 _Unwind_Personality_Fn personality; 93 } _Unwind_FrameState; 94 95 96 /* Manage the chain of registered function contexts. */ 97 98 /* Single threaded fallback chain. */ 99 static struct SjLj_Function_Context *fc_static; 100 101 #if __GTHREADS 102 static __gthread_key_t fc_key; 103 static int use_fc_key = -1; 104 105 static void 106 fc_key_init (void) 107 { 108 use_fc_key = __gthread_key_create (&fc_key, 0) == 0; 109 } 110 111 static void 112 fc_key_init_once (void) 113 { 114 static __gthread_once_t once = __GTHREAD_ONCE_INIT; 115 if (__gthread_once (&once, fc_key_init) != 0 || use_fc_key < 0) 116 use_fc_key = 0; 117 } 118 #endif 119 120 void 121 _Unwind_SjLj_Register (struct SjLj_Function_Context *fc) 122 { 123 #if __GTHREADS 124 if (use_fc_key < 0) 125 fc_key_init_once (); 126 127 if (use_fc_key) 128 { 129 fc->prev = __gthread_getspecific (fc_key); 130 __gthread_setspecific (fc_key, fc); 131 } 132 else 133 #endif 134 { 135 fc->prev = fc_static; 136 fc_static = fc; 137 } 138 } 139 140 static inline struct SjLj_Function_Context * 141 _Unwind_SjLj_GetContext (void) 142 { 143 #if __GTHREADS 144 if (use_fc_key < 0) 145 fc_key_init_once (); 146 147 if (use_fc_key) 148 return __gthread_getspecific (fc_key); 149 #endif 150 return fc_static; 151 } 152 153 static inline void 154 _Unwind_SjLj_SetContext (struct SjLj_Function_Context *fc) 155 { 156 #if __GTHREADS 157 if (use_fc_key < 0) 158 fc_key_init_once (); 159 160 if (use_fc_key) 161 __gthread_setspecific (fc_key, fc); 162 else 163 #endif 164 fc_static = fc; 165 } 166 167 void 168 _Unwind_SjLj_Unregister (struct SjLj_Function_Context *fc) 169 { 170 _Unwind_SjLj_SetContext (fc->prev); 171 } 172 173 174 /* Get/set the return data value at INDEX in CONTEXT. */ 175 176 _Unwind_Word 177 _Unwind_GetGR (struct _Unwind_Context *context, int index) 178 { 179 return context->fc->data[index]; 180 } 181 182 /* Get the value of the CFA as saved in CONTEXT. */ 183 184 _Unwind_Word 185 _Unwind_GetCFA (struct _Unwind_Context *context __attribute__((unused))) 186 { 187 /* ??? Ideally __builtin_setjmp places the CFA in the jmpbuf. */ 188 189 #ifndef DONT_USE_BUILTIN_SETJMP 190 /* This is a crude imitation of the CFA: the saved stack pointer. 191 This is roughly the CFA of the frame before CONTEXT. When using the 192 DWARF-2 unwinder _Unwind_GetCFA returns the CFA of the frame described 193 by CONTEXT instead; but for DWARF-2 the cleanups associated with 194 CONTEXT have already been run, and for SJLJ they have not yet been. */ 195 if (context->fc != NULL) 196 return (_Unwind_Word) context->fc->jbuf[2]; 197 #endif 198 199 /* Otherwise we're out of luck for now. */ 200 return (_Unwind_Word) 0; 201 } 202 203 void 204 _Unwind_SetGR (struct _Unwind_Context *context, int index, _Unwind_Word val) 205 { 206 context->fc->data[index] = val; 207 } 208 209 /* Get the call-site index as saved in CONTEXT. */ 210 211 _Unwind_Ptr 212 _Unwind_GetIP (struct _Unwind_Context *context) 213 { 214 return context->fc->call_site + 1; 215 } 216 217 _Unwind_Ptr 218 _Unwind_GetIPInfo (struct _Unwind_Context *context, int *ip_before_insn) 219 { 220 *ip_before_insn = 0; 221 if (context->fc != NULL) 222 return context->fc->call_site + 1; 223 else 224 return 0; 225 } 226 227 /* Set the return landing pad index in CONTEXT. */ 228 229 void 230 _Unwind_SetIP (struct _Unwind_Context *context, _Unwind_Ptr val) 231 { 232 context->fc->call_site = val - 1; 233 } 234 235 void * 236 _Unwind_GetLanguageSpecificData (struct _Unwind_Context *context) 237 { 238 return context->fc->lsda; 239 } 240 241 _Unwind_Ptr 242 _Unwind_GetRegionStart (struct _Unwind_Context *context __attribute__((unused)) ) 243 { 244 return 0; 245 } 246 247 void * 248 _Unwind_FindEnclosingFunction (void *pc __attribute__((unused))) 249 { 250 return NULL; 251 } 252 253 #ifndef __ia64__ 254 _Unwind_Ptr 255 _Unwind_GetDataRelBase (struct _Unwind_Context *context __attribute__((unused)) ) 256 { 257 return 0; 258 } 259 260 _Unwind_Ptr 261 _Unwind_GetTextRelBase (struct _Unwind_Context *context __attribute__((unused)) ) 262 { 263 return 0; 264 } 265 #endif 266 267 static inline _Unwind_Reason_Code 268 uw_frame_state_for (struct _Unwind_Context *context, _Unwind_FrameState *fs) 269 { 270 if (context->fc == NULL) 271 { 272 fs->personality = NULL; 273 return _URC_END_OF_STACK; 274 } 275 else 276 { 277 fs->personality = context->fc->personality; 278 return _URC_NO_REASON; 279 } 280 } 281 282 static inline void 283 uw_update_context (struct _Unwind_Context *context, 284 _Unwind_FrameState *fs __attribute__((unused)) ) 285 { 286 context->fc = context->fc->prev; 287 } 288 289 static void 290 uw_advance_context (struct _Unwind_Context *context, _Unwind_FrameState *fs) 291 { 292 _Unwind_SjLj_Unregister (context->fc); 293 uw_update_context (context, fs); 294 } 295 296 static inline void 297 uw_init_context (struct _Unwind_Context *context) 298 { 299 context->fc = _Unwind_SjLj_GetContext (); 300 } 301 302 static void __attribute__((noreturn)) 303 uw_install_context (struct _Unwind_Context *current __attribute__((unused)), 304 struct _Unwind_Context *target) 305 { 306 _Unwind_SjLj_SetContext (target->fc); 307 longjmp (target->fc->jbuf, 1); 308 } 309 310 static inline _Unwind_Ptr 311 uw_identify_context (struct _Unwind_Context *context) 312 { 313 return (_Unwind_Ptr) context->fc; 314 } 315 316 317 /* Play games with unwind symbols so that we can have call frame 318 and sjlj symbols in the same shared library. Not that you can 319 use them simultaneously... */ 320 #define _Unwind_RaiseException _Unwind_SjLj_RaiseException 321 #define _Unwind_ForcedUnwind _Unwind_SjLj_ForcedUnwind 322 #define _Unwind_Resume _Unwind_SjLj_Resume 323 #define _Unwind_Resume_or_Rethrow _Unwind_SjLj_Resume_or_Rethrow 324 325 #include "unwind.inc" 326 327 #endif /* USING_SJLJ_EXCEPTIONS */ 328