1 //===--------------------- UnwindLevel1-gcc-ext.c -------------------------===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is dual licensed under the MIT and the University of Illinois Open 6 // Source Licenses. See LICENSE.TXT for details. 7 // 8 // 9 // Implements gcc extensions to the C++ ABI Exception Handling Level 1. 10 // 11 //===----------------------------------------------------------------------===// 12 13 #include <stdint.h> 14 #include <stdbool.h> 15 #include <stdlib.h> 16 #include <stdio.h> 17 18 #include "libunwind.h" 19 #include "unwind.h" 20 #include "libunwind_ext.h" 21 #include "config.h" 22 23 #if _LIBUNWIND_BUILD_ZERO_COST_APIS 24 25 /// Called by __cxa_rethrow(). 26 _LIBUNWIND_EXPORT _Unwind_Reason_Code 27 _Unwind_Resume_or_Rethrow(_Unwind_Exception *exception_object) { 28 _LIBUNWIND_TRACE_API("_Unwind_Resume_or_Rethrow(ex_obj=%p), " 29 "private_1=%ld\n", 30 exception_object, 31 #if LIBCXXABI_ARM_EHABI 32 (long)exception_object->unwinder_cache.reserved1); 33 #else 34 (long)exception_object->private_1); 35 #endif 36 37 #if LIBCXXABI_ARM_EHABI 38 // _Unwind_RaiseException on EHABI will always set the reserved1 field to 0, 39 // which is in the same position as private_1 below. 40 return _Unwind_RaiseException(exception_object); 41 #else 42 // If this is non-forced and a stopping place was found, then this is a 43 // re-throw. 44 // Call _Unwind_RaiseException() as if this was a new exception 45 if (exception_object->private_1 == 0) { 46 return _Unwind_RaiseException(exception_object); 47 // Will return if there is no catch clause, so that __cxa_rethrow can call 48 // std::terminate(). 49 } 50 51 // Call through to _Unwind_Resume() which distiguishes between forced and 52 // regular exceptions. 53 _Unwind_Resume(exception_object); 54 _LIBUNWIND_ABORT("_Unwind_Resume_or_Rethrow() called _Unwind_RaiseException()" 55 " which unexpectedly returned"); 56 #endif 57 } 58 59 60 /// Called by personality handler during phase 2 to get base address for data 61 /// relative encodings. 62 _LIBUNWIND_EXPORT uintptr_t 63 _Unwind_GetDataRelBase(struct _Unwind_Context *context) { 64 (void)context; 65 _LIBUNWIND_TRACE_API("_Unwind_GetDataRelBase(context=%p)\n", context); 66 _LIBUNWIND_ABORT("_Unwind_GetDataRelBase() not implemented"); 67 } 68 69 70 /// Called by personality handler during phase 2 to get base address for text 71 /// relative encodings. 72 _LIBUNWIND_EXPORT uintptr_t 73 _Unwind_GetTextRelBase(struct _Unwind_Context *context) { 74 (void)context; 75 _LIBUNWIND_TRACE_API("_Unwind_GetTextRelBase(context=%p)\n", context); 76 _LIBUNWIND_ABORT("_Unwind_GetTextRelBase() not implemented"); 77 } 78 79 80 /// Scans unwind information to find the function that contains the 81 /// specified code address "pc". 82 _LIBUNWIND_EXPORT void *_Unwind_FindEnclosingFunction(void *pc) { 83 _LIBUNWIND_TRACE_API("_Unwind_FindEnclosingFunction(pc=%p)\n", pc); 84 // This is slow, but works. 85 // We create an unwind cursor then alter the IP to be pc 86 unw_cursor_t cursor; 87 unw_context_t uc; 88 unw_proc_info_t info; 89 unw_getcontext(&uc); 90 unw_init_local(&cursor, &uc); 91 unw_set_reg(&cursor, UNW_REG_IP, (unw_word_t)(long) pc); 92 if (unw_get_proc_info(&cursor, &info) == UNW_ESUCCESS) 93 return (void *)(long) info.start_ip; 94 else 95 return NULL; 96 } 97 98 99 /// Walk every frame and call trace function at each one. If trace function 100 /// returns anything other than _URC_NO_REASON, then walk is terminated. 101 _LIBUNWIND_EXPORT _Unwind_Reason_Code 102 _Unwind_Backtrace(_Unwind_Trace_Fn callback, void *ref) { 103 unw_cursor_t cursor; 104 unw_context_t uc; 105 unw_getcontext(&uc); 106 unw_init_local(&cursor, &uc); 107 108 _LIBUNWIND_TRACE_API("_Unwind_Backtrace(callback=%p)\n", callback); 109 110 // walk each frame 111 while (true) { 112 _Unwind_Reason_Code result; 113 114 // ask libuwind to get next frame (skip over first frame which is 115 // _Unwind_Backtrace()) 116 if (unw_step(&cursor) <= 0) { 117 _LIBUNWIND_TRACE_UNWINDING(" _backtrace: ended because cursor reached " 118 "bottom of stack, returning %d\n", 119 _URC_END_OF_STACK); 120 return _URC_END_OF_STACK; 121 } 122 123 #if LIBCXXABI_ARM_EHABI 124 // Get the information for this frame. 125 unw_proc_info_t frameInfo; 126 if (unw_get_proc_info(&cursor, &frameInfo) != UNW_ESUCCESS) { 127 return _URC_END_OF_STACK; 128 } 129 130 struct _Unwind_Context *context = (struct _Unwind_Context *)&cursor; 131 size_t off; 132 size_t len; 133 uint32_t* unwindInfo = (uint32_t *) frameInfo.unwind_info; 134 unwindInfo = decode_eht_entry(unwindInfo, &off, &len); 135 if (unwindInfo == NULL) { 136 return _URC_FAILURE; 137 } 138 139 result = _Unwind_VRS_Interpret(context, unwindInfo, off, len); 140 if (result != _URC_CONTINUE_UNWIND) { 141 return _URC_END_OF_STACK; 142 } 143 #endif // LIBCXXABI_ARM_EHABI 144 145 // debugging 146 if (_LIBUNWIND_TRACING_UNWINDING) { 147 char functionName[512]; 148 unw_proc_info_t frameInfo; 149 unw_word_t offset; 150 unw_get_proc_name(&cursor, functionName, 512, &offset); 151 unw_get_proc_info(&cursor, &frameInfo); 152 _LIBUNWIND_TRACE_UNWINDING( 153 " _backtrace: start_ip=0x%llX, func=%s, lsda=0x%llX, context=%p\n", 154 (long long)frameInfo.start_ip, functionName, (long long)frameInfo.lsda, 155 &cursor); 156 } 157 158 // call trace function with this frame 159 result = (*callback)((struct _Unwind_Context *)(&cursor), ref); 160 if (result != _URC_NO_REASON) { 161 _LIBUNWIND_TRACE_UNWINDING(" _backtrace: ended because callback " 162 "returned %d\n", 163 result); 164 return result; 165 } 166 } 167 } 168 169 170 /// Find dwarf unwind info for an address 'pc' in some function. 171 _LIBUNWIND_EXPORT const void *_Unwind_Find_FDE(const void *pc, 172 struct dwarf_eh_bases *bases) { 173 // This is slow, but works. 174 // We create an unwind cursor then alter the IP to be pc 175 unw_cursor_t cursor; 176 unw_context_t uc; 177 unw_proc_info_t info; 178 unw_getcontext(&uc); 179 unw_init_local(&cursor, &uc); 180 unw_set_reg(&cursor, UNW_REG_IP, (unw_word_t)(long) pc); 181 unw_get_proc_info(&cursor, &info); 182 bases->tbase = (uintptr_t)info.extra; 183 bases->dbase = 0; // dbase not used on Mac OS X 184 bases->func = (uintptr_t)info.start_ip; 185 _LIBUNWIND_TRACE_API("_Unwind_Find_FDE(pc=%p) => %p\n", pc, 186 (void *)(long) info.unwind_info); 187 return (void *)(long) info.unwind_info; 188 } 189 190 /// Returns the CFA (call frame area, or stack pointer at start of function) 191 /// for the current context. 192 _LIBUNWIND_EXPORT uintptr_t _Unwind_GetCFA(struct _Unwind_Context *context) { 193 unw_cursor_t *cursor = (unw_cursor_t *)context; 194 unw_word_t result; 195 unw_get_reg(cursor, UNW_REG_SP, &result); 196 _LIBUNWIND_TRACE_API("_Unwind_GetCFA(context=%p) => 0x%llX\n", context, 197 (uint64_t) result); 198 return (uintptr_t)result; 199 } 200 201 202 /// Called by personality handler during phase 2 to get instruction pointer. 203 /// ipBefore is a boolean that says if IP is already adjusted to be the call 204 /// site address. Normally IP is the return address. 205 _LIBUNWIND_EXPORT uintptr_t _Unwind_GetIPInfo(struct _Unwind_Context *context, 206 int *ipBefore) { 207 _LIBUNWIND_TRACE_API("_Unwind_GetIPInfo(context=%p)\n", context); 208 *ipBefore = 0; 209 return _Unwind_GetIP(context); 210 } 211 212 #if _LIBUNWIND_SUPPORT_DWARF_UNWIND 213 214 /// Called by programs with dynamic code generators that want 215 /// to register a dynamically generated FDE. 216 /// This function has existed on Mac OS X since 10.4, but 217 /// was broken until 10.6. 218 _LIBUNWIND_EXPORT void __register_frame(const void *fde) { 219 _LIBUNWIND_TRACE_API("__register_frame(%p)\n", fde); 220 _unw_add_dynamic_fde((unw_word_t)(uintptr_t) fde); 221 } 222 223 224 /// Called by programs with dynamic code generators that want 225 /// to unregister a dynamically generated FDE. 226 /// This function has existed on Mac OS X since 10.4, but 227 /// was broken until 10.6. 228 _LIBUNWIND_EXPORT void __deregister_frame(const void *fde) { 229 _LIBUNWIND_TRACE_API("__deregister_frame(%p)\n", fde); 230 _unw_remove_dynamic_fde((unw_word_t)(uintptr_t) fde); 231 } 232 233 234 // The following register/deregister functions are gcc extensions. 235 // They have existed on Mac OS X, but have never worked because Mac OS X 236 // before 10.6 used keymgr to track known FDEs, but these functions 237 // never got updated to use keymgr. 238 // For now, we implement these as do-nothing functions to keep any existing 239 // applications working. We also add the not in 10.6 symbol so that nwe 240 // application won't be able to use them. 241 242 #if _LIBUNWIND_SUPPORT_FRAME_APIS 243 _LIBUNWIND_EXPORT void __register_frame_info_bases(const void *fde, void *ob, 244 void *tb, void *db) { 245 (void)fde; 246 (void)ob; 247 (void)tb; 248 (void)db; 249 _LIBUNWIND_TRACE_API("__register_frame_info_bases(%p,%p, %p, %p)\n", 250 fde, ob, tb, db); 251 // do nothing, this function never worked in Mac OS X 252 } 253 254 _LIBUNWIND_EXPORT void __register_frame_info(const void *fde, void *ob) { 255 (void)fde; 256 (void)ob; 257 _LIBUNWIND_TRACE_API("__register_frame_info(%p, %p)\n", fde, ob); 258 // do nothing, this function never worked in Mac OS X 259 } 260 261 _LIBUNWIND_EXPORT void __register_frame_info_table_bases(const void *fde, 262 void *ob, void *tb, 263 void *db) { 264 (void)fde; 265 (void)ob; 266 (void)tb; 267 (void)db; 268 _LIBUNWIND_TRACE_API("__register_frame_info_table_bases" 269 "(%p,%p, %p, %p)\n", fde, ob, tb, db); 270 // do nothing, this function never worked in Mac OS X 271 } 272 273 _LIBUNWIND_EXPORT void __register_frame_info_table(const void *fde, void *ob) { 274 (void)fde; 275 (void)ob; 276 _LIBUNWIND_TRACE_API("__register_frame_info_table(%p, %p)\n", fde, ob); 277 // do nothing, this function never worked in Mac OS X 278 } 279 280 _LIBUNWIND_EXPORT void __register_frame_table(const void *fde) { 281 (void)fde; 282 _LIBUNWIND_TRACE_API("__register_frame_table(%p)\n", fde); 283 // do nothing, this function never worked in Mac OS X 284 } 285 286 _LIBUNWIND_EXPORT void *__deregister_frame_info(const void *fde) { 287 (void)fde; 288 _LIBUNWIND_TRACE_API("__deregister_frame_info(%p)\n", fde); 289 // do nothing, this function never worked in Mac OS X 290 return NULL; 291 } 292 293 _LIBUNWIND_EXPORT void *__deregister_frame_info_bases(const void *fde) { 294 (void)fde; 295 _LIBUNWIND_TRACE_API("__deregister_frame_info_bases(%p)\n", fde); 296 // do nothing, this function never worked in Mac OS X 297 return NULL; 298 } 299 #endif // _LIBUNWIND_SUPPORT_FRAME_APIS 300 301 #endif // _LIBUNWIND_SUPPORT_DWARF_UNWIND 302 303 #endif // _LIBUNWIND_BUILD_ZERO_COST_APIS 304
