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 <inttypes.h> 14 #include <stdbool.h> 15 #include <stdint.h> 16 #include <stdio.h> 17 #include <stdlib.h> 18 #include <string.h> 19 20 #include "config.h" 21 #include "libunwind_ext.h" 22 #include "libunwind.h" 23 #include "Unwind-EHABI.h" 24 #include "unwind.h" 25 26 #if defined(_LIBUNWIND_BUILD_ZERO_COST_APIS) 27 28 /// Called by __cxa_rethrow(). 29 _LIBUNWIND_EXPORT _Unwind_Reason_Code 30 _Unwind_Resume_or_Rethrow(_Unwind_Exception *exception_object) { 31 #if defined(_LIBUNWIND_ARM_EHABI) 32 _LIBUNWIND_TRACE_API("_Unwind_Resume_or_Rethrow(ex_obj=%p), private_1=%ld", 33 (void *)exception_object, 34 (long)exception_object->unwinder_cache.reserved1); 35 #else 36 _LIBUNWIND_TRACE_API("_Unwind_Resume_or_Rethrow(ex_obj=%p), private_1=%ld", 37 (void *)exception_object, 38 (long)exception_object->private_1); 39 #endif 40 41 #if defined(_LIBUNWIND_ARM_EHABI) 42 // _Unwind_RaiseException on EHABI will always set the reserved1 field to 0, 43 // which is in the same position as private_1 below. 44 return _Unwind_RaiseException(exception_object); 45 #else 46 // If this is non-forced and a stopping place was found, then this is a 47 // re-throw. 48 // Call _Unwind_RaiseException() as if this was a new exception 49 if (exception_object->private_1 == 0) { 50 return _Unwind_RaiseException(exception_object); 51 // Will return if there is no catch clause, so that __cxa_rethrow can call 52 // std::terminate(). 53 } 54 55 // Call through to _Unwind_Resume() which distiguishes between forced and 56 // regular exceptions. 57 _Unwind_Resume(exception_object); 58 _LIBUNWIND_ABORT("_Unwind_Resume_or_Rethrow() called _Unwind_RaiseException()" 59 " which unexpectedly returned"); 60 #endif 61 } 62 63 64 /// Called by personality handler during phase 2 to get base address for data 65 /// relative encodings. 66 _LIBUNWIND_EXPORT uintptr_t 67 _Unwind_GetDataRelBase(struct _Unwind_Context *context) { 68 (void)context; 69 _LIBUNWIND_TRACE_API("_Unwind_GetDataRelBase(context=%p)", (void *)context); 70 _LIBUNWIND_ABORT("_Unwind_GetDataRelBase() not implemented"); 71 } 72 73 74 /// Called by personality handler during phase 2 to get base address for text 75 /// relative encodings. 76 _LIBUNWIND_EXPORT uintptr_t 77 _Unwind_GetTextRelBase(struct _Unwind_Context *context) { 78 (void)context; 79 _LIBUNWIND_TRACE_API("_Unwind_GetTextRelBase(context=%p)", (void *)context); 80 _LIBUNWIND_ABORT("_Unwind_GetTextRelBase() not implemented"); 81 } 82 83 84 /// Scans unwind information to find the function that contains the 85 /// specified code address "pc". 86 _LIBUNWIND_EXPORT void *_Unwind_FindEnclosingFunction(void *pc) { 87 _LIBUNWIND_TRACE_API("_Unwind_FindEnclosingFunction(pc=%p)", pc); 88 // This is slow, but works. 89 // We create an unwind cursor then alter the IP to be pc 90 unw_cursor_t cursor; 91 unw_context_t uc; 92 unw_proc_info_t info; 93 unw_getcontext(&uc); 94 unw_init_local(&cursor, &uc); 95 unw_set_reg(&cursor, UNW_REG_IP, (unw_word_t)(long) pc); 96 if (unw_get_proc_info(&cursor, &info) == UNW_ESUCCESS) 97 return (void *)(long) info.start_ip; 98 else 99 return NULL; 100 } 101 102 /// Walk every frame and call trace function at each one. If trace function 103 /// returns anything other than _URC_NO_REASON, then walk is terminated. 104 _LIBUNWIND_EXPORT _Unwind_Reason_Code 105 _Unwind_Backtrace(_Unwind_Trace_Fn callback, void *ref) { 106 unw_cursor_t cursor; 107 unw_context_t uc; 108 unw_getcontext(&uc); 109 unw_init_local(&cursor, &uc); 110 111 _LIBUNWIND_TRACE_API("_Unwind_Backtrace(callback=%p)", 112 (void *)(uintptr_t)callback); 113 114 #if defined(_LIBUNWIND_ARM_EHABI) 115 // Create a mock exception object for force unwinding. 116 _Unwind_Exception ex; 117 memset(&ex, '\0', sizeof(ex)); 118 ex.exception_class = 0x434C4E47554E5700; // CLNGUNW\0 119 #endif 120 121 // walk each frame 122 while (true) { 123 _Unwind_Reason_Code result; 124 125 #if !defined(_LIBUNWIND_ARM_EHABI) 126 // ask libunwind to get next frame (skip over first frame which is 127 // _Unwind_Backtrace()) 128 if (unw_step(&cursor) <= 0) { 129 _LIBUNWIND_TRACE_UNWINDING(" _backtrace: ended because cursor reached " 130 "bottom of stack, returning %d", 131 _URC_END_OF_STACK); 132 return _URC_END_OF_STACK; 133 } 134 #else 135 // Get the information for this frame. 136 unw_proc_info_t frameInfo; 137 if (unw_get_proc_info(&cursor, &frameInfo) != UNW_ESUCCESS) { 138 return _URC_END_OF_STACK; 139 } 140 141 // Update the pr_cache in the mock exception object. 142 const uint32_t* unwindInfo = (uint32_t *) frameInfo.unwind_info; 143 ex.pr_cache.fnstart = frameInfo.start_ip; 144 ex.pr_cache.ehtp = (_Unwind_EHT_Header *) unwindInfo; 145 ex.pr_cache.additional= frameInfo.flags; 146 147 struct _Unwind_Context *context = (struct _Unwind_Context *)&cursor; 148 // Get and call the personality function to unwind the frame. 149 __personality_routine handler = (__personality_routine) frameInfo.handler; 150 if (handler == NULL) { 151 return _URC_END_OF_STACK; 152 } 153 if (handler(_US_VIRTUAL_UNWIND_FRAME | _US_FORCE_UNWIND, &ex, context) != 154 _URC_CONTINUE_UNWIND) { 155 return _URC_END_OF_STACK; 156 } 157 #endif // defined(_LIBUNWIND_ARM_EHABI) 158 159 // debugging 160 if (_LIBUNWIND_TRACING_UNWINDING) { 161 char functionName[512]; 162 unw_proc_info_t frame; 163 unw_word_t offset; 164 unw_get_proc_name(&cursor, functionName, 512, &offset); 165 unw_get_proc_info(&cursor, &frame); 166 _LIBUNWIND_TRACE_UNWINDING( 167 " _backtrace: start_ip=0x%" PRIxPTR ", func=%s, lsda=0x%" PRIxPTR ", context=%p", 168 frame.start_ip, functionName, frame.lsda, 169 (void *)&cursor); 170 } 171 172 // call trace function with this frame 173 result = (*callback)((struct _Unwind_Context *)(&cursor), ref); 174 if (result != _URC_NO_REASON) { 175 _LIBUNWIND_TRACE_UNWINDING( 176 " _backtrace: ended because callback returned %d", result); 177 return result; 178 } 179 } 180 } 181 182 183 /// Find DWARF unwind info for an address 'pc' in some function. 184 _LIBUNWIND_EXPORT const void *_Unwind_Find_FDE(const void *pc, 185 struct dwarf_eh_bases *bases) { 186 // This is slow, but works. 187 // We create an unwind cursor then alter the IP to be pc 188 unw_cursor_t cursor; 189 unw_context_t uc; 190 unw_proc_info_t info; 191 unw_getcontext(&uc); 192 unw_init_local(&cursor, &uc); 193 unw_set_reg(&cursor, UNW_REG_IP, (unw_word_t)(long) pc); 194 unw_get_proc_info(&cursor, &info); 195 bases->tbase = (uintptr_t)info.extra; 196 bases->dbase = 0; // dbase not used on Mac OS X 197 bases->func = (uintptr_t)info.start_ip; 198 _LIBUNWIND_TRACE_API("_Unwind_Find_FDE(pc=%p) => %p", pc, 199 (void *)(long) info.unwind_info); 200 return (void *)(long) info.unwind_info; 201 } 202 203 /// Returns the CFA (call frame area, or stack pointer at start of function) 204 /// for the current context. 205 _LIBUNWIND_EXPORT uintptr_t _Unwind_GetCFA(struct _Unwind_Context *context) { 206 unw_cursor_t *cursor = (unw_cursor_t *)context; 207 unw_word_t result; 208 unw_get_reg(cursor, UNW_REG_SP, &result); 209 _LIBUNWIND_TRACE_API("_Unwind_GetCFA(context=%p) => 0x%" PRIxPTR, 210 (void *)context, result); 211 return (uintptr_t)result; 212 } 213 214 215 /// Called by personality handler during phase 2 to get instruction pointer. 216 /// ipBefore is a boolean that says if IP is already adjusted to be the call 217 /// site address. Normally IP is the return address. 218 _LIBUNWIND_EXPORT uintptr_t _Unwind_GetIPInfo(struct _Unwind_Context *context, 219 int *ipBefore) { 220 _LIBUNWIND_TRACE_API("_Unwind_GetIPInfo(context=%p)", (void *)context); 221 *ipBefore = 0; 222 return _Unwind_GetIP(context); 223 } 224 225 #if defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND) 226 227 /// Called by programs with dynamic code generators that want 228 /// to register a dynamically generated FDE. 229 /// This function has existed on Mac OS X since 10.4, but 230 /// was broken until 10.6. 231 _LIBUNWIND_EXPORT void __register_frame(const void *fde) { 232 _LIBUNWIND_TRACE_API("__register_frame(%p)", fde); 233 _unw_add_dynamic_fde((unw_word_t)(uintptr_t) fde); 234 } 235 236 237 /// Called by programs with dynamic code generators that want 238 /// to unregister a dynamically generated FDE. 239 /// This function has existed on Mac OS X since 10.4, but 240 /// was broken until 10.6. 241 _LIBUNWIND_EXPORT void __deregister_frame(const void *fde) { 242 _LIBUNWIND_TRACE_API("__deregister_frame(%p)", fde); 243 _unw_remove_dynamic_fde((unw_word_t)(uintptr_t) fde); 244 } 245 246 247 // The following register/deregister functions are gcc extensions. 248 // They have existed on Mac OS X, but have never worked because Mac OS X 249 // before 10.6 used keymgr to track known FDEs, but these functions 250 // never got updated to use keymgr. 251 // For now, we implement these as do-nothing functions to keep any existing 252 // applications working. We also add the not in 10.6 symbol so that nwe 253 // application won't be able to use them. 254 255 #if defined(_LIBUNWIND_SUPPORT_FRAME_APIS) 256 _LIBUNWIND_EXPORT void __register_frame_info_bases(const void *fde, void *ob, 257 void *tb, void *db) { 258 (void)fde; 259 (void)ob; 260 (void)tb; 261 (void)db; 262 _LIBUNWIND_TRACE_API("__register_frame_info_bases(%p,%p, %p, %p)", 263 fde, ob, tb, db); 264 // do nothing, this function never worked in Mac OS X 265 } 266 267 _LIBUNWIND_EXPORT void __register_frame_info(const void *fde, void *ob) { 268 (void)fde; 269 (void)ob; 270 _LIBUNWIND_TRACE_API("__register_frame_info(%p, %p)", fde, ob); 271 // do nothing, this function never worked in Mac OS X 272 } 273 274 _LIBUNWIND_EXPORT void __register_frame_info_table_bases(const void *fde, 275 void *ob, void *tb, 276 void *db) { 277 (void)fde; 278 (void)ob; 279 (void)tb; 280 (void)db; 281 _LIBUNWIND_TRACE_API("__register_frame_info_table_bases" 282 "(%p,%p, %p, %p)", fde, ob, tb, db); 283 // do nothing, this function never worked in Mac OS X 284 } 285 286 _LIBUNWIND_EXPORT void __register_frame_info_table(const void *fde, void *ob) { 287 (void)fde; 288 (void)ob; 289 _LIBUNWIND_TRACE_API("__register_frame_info_table(%p, %p)", fde, ob); 290 // do nothing, this function never worked in Mac OS X 291 } 292 293 _LIBUNWIND_EXPORT void __register_frame_table(const void *fde) { 294 (void)fde; 295 _LIBUNWIND_TRACE_API("__register_frame_table(%p)", fde); 296 // do nothing, this function never worked in Mac OS X 297 } 298 299 _LIBUNWIND_EXPORT void *__deregister_frame_info(const void *fde) { 300 (void)fde; 301 _LIBUNWIND_TRACE_API("__deregister_frame_info(%p)", fde); 302 // do nothing, this function never worked in Mac OS X 303 return NULL; 304 } 305 306 _LIBUNWIND_EXPORT void *__deregister_frame_info_bases(const void *fde) { 307 (void)fde; 308 _LIBUNWIND_TRACE_API("__deregister_frame_info_bases(%p)", fde); 309 // do nothing, this function never worked in Mac OS X 310 return NULL; 311 } 312 #endif // defined(_LIBUNWIND_SUPPORT_FRAME_APIS) 313 314 #endif // defined(_LIBUNWIND_SUPPORT_DWARF_UNWIND) 315 316 #endif // defined(_LIBUNWIND_BUILD_ZERO_COST_APIS) 317
