1 /* SJLJ exception handling and frame unwind runtime interface routines. 2 Copyright (C) 1997-2018 Free Software Foundation, Inc. 3 4 This file is part of GCC. 5 6 GCC is free software; you can redistribute it and/or modify it 7 under the terms of the GNU General Public License as published by 8 the Free Software Foundation; either version 3, or (at your option) 9 any later version. 10 11 GCC is distributed in the hope that it will be useful, but WITHOUT 12 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 13 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public 14 License for more details. 15 16 Under Section 7 of GPL version 3, you are granted additional 17 permissions described in the GCC Runtime Library Exception, version 18 3.1, as published by the Free Software Foundation. 19 20 You should have received a copy of the GNU General Public License and 21 a copy of the GCC Runtime Library Exception along with this program; 22 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 23 <http://www.gnu.org/licenses/>. */ 24 25 #include "tconfig.h" 26 #include "tsystem.h" 27 #include "coretypes.h" 28 #include "tm.h" 29 #include "libgcc_tm.h" 30 #include "unwind.h" 31 #include "gthr.h" 32 33 #ifdef __USING_SJLJ_EXCEPTIONS__ 34 35 #ifdef __LIBGCC_DONT_USE_BUILTIN_SETJMP__ 36 #ifndef inhibit_libc 37 #include <setjmp.h> 38 #else 39 typedef void *jmp_buf[__LIBGCC_JMP_BUF_SIZE__]; 40 extern void longjmp(jmp_buf, int) __attribute__((noreturn)); 41 #endif 42 #else 43 #define longjmp __builtin_longjmp 44 #endif 45 46 /* The setjmp side is dealt with in the except.c file. */ 47 #undef setjmp 48 #define setjmp setjmp_should_not_be_used_in_this_file 49 50 51 /* This structure is allocated on the stack of the target function. 52 This must match the definition created in except.c:init_eh. */ 53 struct SjLj_Function_Context 54 { 55 /* This is the chain through all registered contexts. It is 56 filled in by _Unwind_SjLj_Register. */ 57 struct SjLj_Function_Context *prev; 58 59 /* This is assigned in by the target function before every call 60 to the index of the call site in the lsda. It is assigned by 61 the personality routine to the landing pad index. */ 62 int call_site; 63 64 /* This is how data is returned from the personality routine to 65 the target function's handler. */ 66 _Unwind_Word data[4]; 67 68 /* These are filled in once by the target function before any 69 exceptions are expected to be handled. */ 70 _Unwind_Personality_Fn personality; 71 void *lsda; 72 73 #ifdef __LIBGCC_DONT_USE_BUILTIN_SETJMP__ 74 /* We don't know what sort of alignment requirements the system 75 jmp_buf has. We over estimated in except.c, and now we have 76 to match that here just in case the system *didn't* have more 77 restrictive requirements. */ 78 jmp_buf jbuf __attribute__((aligned)); 79 #else 80 void *jbuf[]; 81 #endif 82 }; 83 84 struct _Unwind_Context 85 { 86 struct SjLj_Function_Context *fc; 87 }; 88 89 typedef struct 90 { 91 _Unwind_Personality_Fn personality; 92 } _Unwind_FrameState; 93 94 95 /* Manage the chain of registered function contexts. */ 96 97 /* Single threaded fallback chain. */ 98 static struct SjLj_Function_Context *fc_static; 99 100 #if __GTHREADS 101 static __gthread_key_t fc_key; 102 static int use_fc_key = -1; 103 104 static void 105 fc_key_init (void) 106 { 107 use_fc_key = __gthread_key_create (&fc_key, 0) == 0; 108 } 109 110 static void 111 fc_key_init_once (void) 112 { 113 static __gthread_once_t once = __GTHREAD_ONCE_INIT; 114 if (__gthread_once (&once, fc_key_init) != 0 || use_fc_key < 0) 115 use_fc_key = 0; 116 } 117 #endif 118 119 void 120 _Unwind_SjLj_Register (struct SjLj_Function_Context *fc) 121 { 122 #if __GTHREADS 123 if (use_fc_key < 0) 124 fc_key_init_once (); 125 126 if (use_fc_key) 127 { 128 fc->prev = __gthread_getspecific (fc_key); 129 __gthread_setspecific (fc_key, fc); 130 } 131 else 132 #endif 133 { 134 fc->prev = fc_static; 135 fc_static = fc; 136 } 137 } 138 139 static inline struct SjLj_Function_Context * 140 _Unwind_SjLj_GetContext (void) 141 { 142 #if __GTHREADS 143 if (use_fc_key < 0) 144 fc_key_init_once (); 145 146 if (use_fc_key) 147 return __gthread_getspecific (fc_key); 148 #endif 149 return fc_static; 150 } 151 152 static inline void 153 _Unwind_SjLj_SetContext (struct SjLj_Function_Context *fc) 154 { 155 #if __GTHREADS 156 if (use_fc_key < 0) 157 fc_key_init_once (); 158 159 if (use_fc_key) 160 __gthread_setspecific (fc_key, fc); 161 else 162 #endif 163 fc_static = fc; 164 } 165 166 void 167 _Unwind_SjLj_Unregister (struct SjLj_Function_Context *fc) 168 { 169 _Unwind_SjLj_SetContext (fc->prev); 170 } 171 172 173 /* Get/set the return data value at INDEX in CONTEXT. */ 174 175 _Unwind_Word 176 _Unwind_GetGR (struct _Unwind_Context *context, int index) 177 { 178 return context->fc->data[index]; 179 } 180 181 /* Get the value of the CFA as saved in CONTEXT. */ 182 183 _Unwind_Word 184 _Unwind_GetCFA (struct _Unwind_Context *context __attribute__((unused))) 185 { 186 /* ??? Ideally __builtin_setjmp places the CFA in the jmpbuf. */ 187 188 #ifndef __LIBGCC_DONT_USE_BUILTIN_SETJMP__ 189 /* This is a crude imitation of the CFA: the saved stack pointer. 190 This is roughly the CFA of the frame before CONTEXT. When using the 191 DWARF-2 unwinder _Unwind_GetCFA returns the CFA of the frame described 192 by CONTEXT instead; but for DWARF-2 the cleanups associated with 193 CONTEXT have already been run, and for SJLJ they have not yet been. */ 194 if (context->fc != NULL) 195 return (_Unwind_Word) context->fc->jbuf[2]; 196 #endif 197 198 /* Otherwise we're out of luck for now. */ 199 return (_Unwind_Word) 0; 200 } 201 202 void 203 _Unwind_SetGR (struct _Unwind_Context *context, int index, _Unwind_Word val) 204 { 205 context->fc->data[index] = val; 206 } 207 208 /* Get the call-site index as saved in CONTEXT. */ 209 210 _Unwind_Ptr 211 _Unwind_GetIP (struct _Unwind_Context *context) 212 { 213 return context->fc->call_site + 1; 214 } 215 216 _Unwind_Ptr 217 _Unwind_GetIPInfo (struct _Unwind_Context *context, int *ip_before_insn) 218 { 219 *ip_before_insn = 0; 220 if (context->fc != NULL) 221 return context->fc->call_site + 1; 222 else 223 return 0; 224 } 225 226 /* Set the return landing pad index in CONTEXT. */ 227 228 void 229 _Unwind_SetIP (struct _Unwind_Context *context, _Unwind_Ptr val) 230 { 231 context->fc->call_site = val - 1; 232 } 233 234 void * 235 _Unwind_GetLanguageSpecificData (struct _Unwind_Context *context) 236 { 237 return context->fc->lsda; 238 } 239 240 _Unwind_Ptr 241 _Unwind_GetRegionStart (struct _Unwind_Context *context __attribute__((unused)) ) 242 { 243 return 0; 244 } 245 246 void * 247 _Unwind_FindEnclosingFunction (void *pc __attribute__((unused))) 248 { 249 return NULL; 250 } 251 252 #ifndef __ia64__ 253 _Unwind_Ptr 254 _Unwind_GetDataRelBase (struct _Unwind_Context *context __attribute__((unused)) ) 255 { 256 return 0; 257 } 258 259 _Unwind_Ptr 260 _Unwind_GetTextRelBase (struct _Unwind_Context *context __attribute__((unused)) ) 261 { 262 return 0; 263 } 264 #endif 265 266 static inline _Unwind_Reason_Code 267 uw_frame_state_for (struct _Unwind_Context *context, _Unwind_FrameState *fs) 268 { 269 if (context->fc == NULL) 270 { 271 fs->personality = NULL; 272 return _URC_END_OF_STACK; 273 } 274 else 275 { 276 fs->personality = context->fc->personality; 277 return _URC_NO_REASON; 278 } 279 } 280 281 static inline void 282 uw_update_context (struct _Unwind_Context *context, 283 _Unwind_FrameState *fs __attribute__((unused)) ) 284 { 285 context->fc = context->fc->prev; 286 } 287 288 static void 289 uw_advance_context (struct _Unwind_Context *context, _Unwind_FrameState *fs) 290 { 291 _Unwind_SjLj_Unregister (context->fc); 292 uw_update_context (context, fs); 293 } 294 295 static inline void 296 uw_init_context (struct _Unwind_Context *context) 297 { 298 context->fc = _Unwind_SjLj_GetContext (); 299 } 300 301 static void __attribute__((noreturn)) 302 uw_install_context (struct _Unwind_Context *current __attribute__((unused)), 303 struct _Unwind_Context *target, 304 unsigned long frames __attribute__((unused))) 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