1 /* 2 * Copyright 2010-2011 PathScale, Inc. All rights reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions are met: 6 * 7 * 1. Redistributions of source code must retain the above copyright notice, 8 * this list of conditions and the following disclaimer. 9 * 10 * 2. Redistributions in binary form must reproduce the above copyright notice, 11 * this list of conditions and the following disclaimer in the documentation 12 * and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS 15 * IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, 16 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 17 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR 18 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 19 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 20 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; 21 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 22 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR 23 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF 24 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27 #include <stdlib.h> 28 #include <dlfcn.h> 29 #include <stdio.h> 30 #include <string.h> 31 #include <stdint.h> 32 #include <pthread.h> 33 #include "typeinfo.h" 34 #include "dwarf_eh.h" 35 #include "atomic.h" 36 #include "cxxabi.h" 37 38 #pragma weak pthread_key_create 39 #pragma weak pthread_setspecific 40 #pragma weak pthread_getspecific 41 #pragma weak pthread_once 42 #ifdef LIBCXXRT_WEAK_LOCKS 43 #pragma weak pthread_mutex_lock 44 #define pthread_mutex_lock(mtx) do {\ 45 if (pthread_mutex_lock) pthread_mutex_lock(mtx);\ 46 } while(0) 47 #pragma weak pthread_mutex_unlock 48 #define pthread_mutex_unlock(mtx) do {\ 49 if (pthread_mutex_unlock) pthread_mutex_unlock(mtx);\ 50 } while(0) 51 #pragma weak pthread_cond_signal 52 #define pthread_cond_signal(cv) do {\ 53 if (pthread_cond_signal) pthread_cond_signal(cv);\ 54 } while(0) 55 #pragma weak pthread_cond_wait 56 #define pthread_cond_wait(cv, mtx) do {\ 57 if (pthread_cond_wait) pthread_cond_wait(cv, mtx);\ 58 } while(0) 59 #endif 60 61 using namespace ABI_NAMESPACE; 62 63 /** 64 * Saves the result of the landing pad that we have found. For ARM, this is 65 * stored in the generic unwind structure, while on other platforms it is 66 * stored in the C++ exception. 67 */ 68 static void saveLandingPad(struct _Unwind_Context *context, 69 struct _Unwind_Exception *ucb, 70 struct __cxa_exception *ex, 71 int selector, 72 dw_eh_ptr_t landingPad) 73 { 74 #if defined(__arm__) && !defined(__ARM_DWARF_EH__) 75 // On ARM, we store the saved exception in the generic part of the structure 76 ucb->barrier_cache.sp = _Unwind_GetGR(context, 13); 77 ucb->barrier_cache.bitpattern[1] = static_cast<uint32_t>(selector); 78 ucb->barrier_cache.bitpattern[3] = reinterpret_cast<uint32_t>(landingPad); 79 #endif 80 // Cache the results for the phase 2 unwind, if we found a handler 81 // and this is not a foreign exception. 82 if (ex) 83 { 84 ex->handlerSwitchValue = selector; 85 ex->catchTemp = landingPad; 86 } 87 } 88 89 /** 90 * Loads the saved landing pad. Returns 1 on success, 0 on failure. 91 */ 92 static int loadLandingPad(struct _Unwind_Context *context, 93 struct _Unwind_Exception *ucb, 94 struct __cxa_exception *ex, 95 unsigned long *selector, 96 dw_eh_ptr_t *landingPad) 97 { 98 #if defined(__arm__) && !defined(__ARM_DWARF_EH__) 99 *selector = ucb->barrier_cache.bitpattern[1]; 100 *landingPad = reinterpret_cast<dw_eh_ptr_t>(ucb->barrier_cache.bitpattern[3]); 101 return 1; 102 #else 103 if (ex) 104 { 105 *selector = ex->handlerSwitchValue; 106 *landingPad = reinterpret_cast<dw_eh_ptr_t>(ex->catchTemp); 107 return 0; 108 } 109 return 0; 110 #endif 111 } 112 113 static inline _Unwind_Reason_Code continueUnwinding(struct _Unwind_Exception *ex, 114 struct _Unwind_Context *context) 115 { 116 #if defined(__arm__) && !defined(__ARM_DWARF_EH__) 117 if (__gnu_unwind_frame(ex, context) != _URC_OK) { return _URC_FAILURE; } 118 #endif 119 return _URC_CONTINUE_UNWIND; 120 } 121 122 123 extern "C" void __cxa_free_exception(void *thrown_exception); 124 extern "C" void __cxa_free_dependent_exception(void *thrown_exception); 125 extern "C" void* __dynamic_cast(const void *sub, 126 const __class_type_info *src, 127 const __class_type_info *dst, 128 ptrdiff_t src2dst_offset); 129 130 /** 131 * The type of a handler that has been found. 132 */ 133 typedef enum 134 { 135 /** No handler. */ 136 handler_none, 137 /** 138 * A cleanup - the exception will propagate through this frame, but code 139 * must be run when this happens. 140 */ 141 handler_cleanup, 142 /** 143 * A catch statement. The exception will not propagate past this frame 144 * (without an explicit rethrow). 145 */ 146 handler_catch 147 } handler_type; 148 149 /** 150 * Per-thread info required by the runtime. We store a single structure 151 * pointer in thread-local storage, because this tends to be a scarce resource 152 * and it's impolite to steal all of it and not leave any for the rest of the 153 * program. 154 * 155 * Instances of this structure are allocated lazily - at most one per thread - 156 * and are destroyed on thread termination. 157 */ 158 struct __cxa_thread_info 159 { 160 /** The termination handler for this thread. */ 161 terminate_handler terminateHandler; 162 /** The unexpected exception handler for this thread. */ 163 unexpected_handler unexpectedHandler; 164 /** 165 * The number of emergency buffers held by this thread. This is 0 in 166 * normal operation - the emergency buffers are only used when malloc() 167 * fails to return memory for allocating an exception. Threads are not 168 * permitted to hold more than 4 emergency buffers (as per recommendation 169 * in ABI spec [3.3.1]). 170 */ 171 int emergencyBuffersHeld; 172 /** 173 * The exception currently running in a cleanup. 174 */ 175 _Unwind_Exception *currentCleanup; 176 /** 177 * Our state with respect to foreign exceptions. Usually none, set to 178 * caught if we have just caught an exception and rethrown if we are 179 * rethrowing it. 180 */ 181 enum 182 { 183 none, 184 caught, 185 rethrown 186 } foreign_exception_state; 187 /** 188 * The public part of this structure, accessible from outside of this 189 * module. 190 */ 191 __cxa_eh_globals globals; 192 }; 193 /** 194 * Dependent exception. This 195 */ 196 struct __cxa_dependent_exception 197 { 198 #if __LP64__ 199 void *primaryException; 200 #endif 201 std::type_info *exceptionType; 202 void (*exceptionDestructor) (void *); 203 unexpected_handler unexpectedHandler; 204 terminate_handler terminateHandler; 205 __cxa_exception *nextException; 206 int handlerCount; 207 #if defined(__arm__) && !defined(__ARM_DWARF_EH__) 208 _Unwind_Exception *nextCleanup; 209 int cleanupCount; 210 #endif 211 int handlerSwitchValue; 212 const char *actionRecord; 213 const char *languageSpecificData; 214 void *catchTemp; 215 void *adjustedPtr; 216 #if !__LP64__ 217 void *primaryException; 218 #endif 219 _Unwind_Exception unwindHeader; 220 }; 221 222 223 namespace std 224 { 225 void unexpected(); 226 class exception 227 { 228 public: 229 virtual ~exception() throw(); 230 virtual const char* what() const throw(); 231 }; 232 233 } 234 235 /** 236 * Class of exceptions to distinguish between this and other exception types. 237 * 238 * The first four characters are the vendor ID. Currently, we use GNUC, 239 * because we aim for ABI-compatibility with the GNU implementation, and 240 * various checks may test for equality of the class, which is incorrect. 241 */ 242 static const uint64_t exception_class = 243 EXCEPTION_CLASS('G', 'N', 'U', 'C', 'C', '+', '+', '\0'); 244 /** 245 * Class used for dependent exceptions. 246 */ 247 static const uint64_t dependent_exception_class = 248 EXCEPTION_CLASS('G', 'N', 'U', 'C', 'C', '+', '+', '\x01'); 249 /** 250 * The low four bytes of the exception class, indicating that we conform to the 251 * Itanium C++ ABI. This is currently unused, but should be used in the future 252 * if we change our exception class, to allow this library and libsupc++ to be 253 * linked to the same executable and both to interoperate. 254 */ 255 static const uint32_t abi_exception_class = 256 GENERIC_EXCEPTION_CLASS('C', '+', '+', '\0'); 257 258 static bool isCXXException(uint64_t cls) 259 { 260 return (cls == exception_class) || (cls == dependent_exception_class); 261 } 262 263 static bool isDependentException(uint64_t cls) 264 { 265 return cls == dependent_exception_class; 266 } 267 268 static __cxa_exception *exceptionFromPointer(void *ex) 269 { 270 return reinterpret_cast<__cxa_exception*>(static_cast<char*>(ex) - 271 offsetof(struct __cxa_exception, unwindHeader)); 272 } 273 static __cxa_exception *realExceptionFromException(__cxa_exception *ex) 274 { 275 if (!isDependentException(ex->unwindHeader.exception_class)) { return ex; } 276 return reinterpret_cast<__cxa_exception*>((reinterpret_cast<__cxa_dependent_exception*>(ex))->primaryException)-1; 277 } 278 279 280 namespace std 281 { 282 // Forward declaration of standard library terminate() function used to 283 // abort execution. 284 void terminate(void); 285 } 286 287 using namespace ABI_NAMESPACE; 288 289 290 291 /** The global termination handler. */ 292 static terminate_handler terminateHandler = abort; 293 /** The global unexpected exception handler. */ 294 static unexpected_handler unexpectedHandler = std::terminate; 295 296 /** Key used for thread-local data. */ 297 static pthread_key_t eh_key; 298 299 300 /** 301 * Cleanup function, allowing foreign exception handlers to correctly destroy 302 * this exception if they catch it. 303 */ 304 static void exception_cleanup(_Unwind_Reason_Code reason, 305 struct _Unwind_Exception *ex) 306 { 307 // Exception layout: 308 // [__cxa_exception [_Unwind_Exception]] [exception object] 309 // 310 // __cxa_free_exception expects a pointer to the exception object 311 __cxa_free_exception(static_cast<void*>(ex + 1)); 312 } 313 static void dependent_exception_cleanup(_Unwind_Reason_Code reason, 314 struct _Unwind_Exception *ex) 315 { 316 317 __cxa_free_dependent_exception(static_cast<void*>(ex + 1)); 318 } 319 320 /** 321 * Recursively walk a list of exceptions and delete them all in post-order. 322 */ 323 static void free_exception_list(__cxa_exception *ex) 324 { 325 if (0 != ex->nextException) 326 { 327 free_exception_list(ex->nextException); 328 } 329 // __cxa_free_exception() expects to be passed the thrown object, which 330 // immediately follows the exception, not the exception itself 331 __cxa_free_exception(ex+1); 332 } 333 334 /** 335 * Cleanup function called when a thread exists to make certain that all of the 336 * per-thread data is deleted. 337 */ 338 static void thread_cleanup(void* thread_info) 339 { 340 __cxa_thread_info *info = static_cast<__cxa_thread_info*>(thread_info); 341 if (info->globals.caughtExceptions) 342 { 343 // If this is a foreign exception, ask it to clean itself up. 344 if (info->foreign_exception_state != __cxa_thread_info::none) 345 { 346 _Unwind_Exception *e = reinterpret_cast<_Unwind_Exception*>(info->globals.caughtExceptions); 347 if (e->exception_cleanup) 348 e->exception_cleanup(_URC_FOREIGN_EXCEPTION_CAUGHT, e); 349 } 350 else 351 { 352 free_exception_list(info->globals.caughtExceptions); 353 } 354 } 355 free(thread_info); 356 } 357 358 359 /** 360 * Once control used to protect the key creation. 361 */ 362 static pthread_once_t once_control = PTHREAD_ONCE_INIT; 363 364 /** 365 * We may not be linked against a full pthread implementation. If we're not, 366 * then we need to fake the thread-local storage by storing 'thread-local' 367 * things in a global. 368 */ 369 static bool fakeTLS; 370 /** 371 * Thread-local storage for a single-threaded program. 372 */ 373 static __cxa_thread_info singleThreadInfo; 374 /** 375 * Initialise eh_key. 376 */ 377 static void init_key(void) 378 { 379 if ((0 == pthread_key_create) || 380 (0 == pthread_setspecific) || 381 (0 == pthread_getspecific)) 382 { 383 fakeTLS = true; 384 return; 385 } 386 pthread_key_create(&eh_key, thread_cleanup); 387 pthread_setspecific(eh_key, reinterpret_cast<void *>(0x42)); 388 fakeTLS = (pthread_getspecific(eh_key) != reinterpret_cast<void *>(0x42)); 389 pthread_setspecific(eh_key, 0); 390 } 391 392 /** 393 * Returns the thread info structure, creating it if it is not already created. 394 */ 395 static __cxa_thread_info *thread_info() 396 { 397 if ((0 == pthread_once) || pthread_once(&once_control, init_key)) 398 { 399 fakeTLS = true; 400 } 401 if (fakeTLS) { return &singleThreadInfo; } 402 __cxa_thread_info *info = static_cast<__cxa_thread_info*>(pthread_getspecific(eh_key)); 403 if (0 == info) 404 { 405 info = static_cast<__cxa_thread_info*>(calloc(1, sizeof(__cxa_thread_info))); 406 pthread_setspecific(eh_key, info); 407 } 408 return info; 409 } 410 /** 411 * Fast version of thread_info(). May fail if thread_info() is not called on 412 * this thread at least once already. 413 */ 414 static __cxa_thread_info *thread_info_fast() 415 { 416 if (fakeTLS) { return &singleThreadInfo; } 417 return static_cast<__cxa_thread_info*>(pthread_getspecific(eh_key)); 418 } 419 /** 420 * ABI function returning the __cxa_eh_globals structure. 421 */ 422 extern "C" __cxa_eh_globals *ABI_NAMESPACE::__cxa_get_globals(void) 423 { 424 return &(thread_info()->globals); 425 } 426 /** 427 * Version of __cxa_get_globals() assuming that __cxa_get_globals() has already 428 * been called at least once by this thread. 429 */ 430 extern "C" __cxa_eh_globals *ABI_NAMESPACE::__cxa_get_globals_fast(void) 431 { 432 return &(thread_info_fast()->globals); 433 } 434 435 /** 436 * An emergency allocation reserved for when malloc fails. This is treated as 437 * 16 buffers of 1KB each. 438 */ 439 static char emergency_buffer[16384]; 440 /** 441 * Flag indicating whether each buffer is allocated. 442 */ 443 static bool buffer_allocated[16]; 444 /** 445 * Lock used to protect emergency allocation. 446 */ 447 static pthread_mutex_t emergency_malloc_lock = PTHREAD_MUTEX_INITIALIZER; 448 /** 449 * Condition variable used to wait when two threads are both trying to use the 450 * emergency malloc() buffer at once. 451 */ 452 static pthread_cond_t emergency_malloc_wait = PTHREAD_COND_INITIALIZER; 453 454 /** 455 * Allocates size bytes from the emergency allocation mechanism, if possible. 456 * This function will fail if size is over 1KB or if this thread already has 4 457 * emergency buffers. If all emergency buffers are allocated, it will sleep 458 * until one becomes available. 459 */ 460 static char *emergency_malloc(size_t size) 461 { 462 if (size > 1024) { return 0; } 463 464 __cxa_thread_info *info = thread_info(); 465 // Only 4 emergency buffers allowed per thread! 466 if (info->emergencyBuffersHeld > 3) { return 0; } 467 468 pthread_mutex_lock(&emergency_malloc_lock); 469 int buffer = -1; 470 while (buffer < 0) 471 { 472 // While we were sleeping on the lock, another thread might have free'd 473 // enough memory for us to use, so try the allocation again - no point 474 // using the emergency buffer if there is some real memory that we can 475 // use... 476 void *m = calloc(1, size); 477 if (0 != m) 478 { 479 pthread_mutex_unlock(&emergency_malloc_lock); 480 return static_cast<char*>(m); 481 } 482 for (int i=0 ; i<16 ; i++) 483 { 484 if (!buffer_allocated[i]) 485 { 486 buffer = i; 487 buffer_allocated[i] = true; 488 break; 489 } 490 } 491 // If there still isn't a buffer available, then sleep on the condition 492 // variable. This will be signalled when another thread releases one 493 // of the emergency buffers. 494 if (buffer < 0) 495 { 496 pthread_cond_wait(&emergency_malloc_wait, &emergency_malloc_lock); 497 } 498 } 499 pthread_mutex_unlock(&emergency_malloc_lock); 500 info->emergencyBuffersHeld++; 501 return emergency_buffer + (1024 * buffer); 502 } 503 504 /** 505 * Frees a buffer returned by emergency_malloc(). 506 * 507 * Note: Neither this nor emergency_malloc() is particularly efficient. This 508 * should not matter, because neither will be called in normal operation - they 509 * are only used when the program runs out of memory, which should not happen 510 * often. 511 */ 512 static void emergency_malloc_free(char *ptr) 513 { 514 int buffer = -1; 515 // Find the buffer corresponding to this pointer. 516 for (int i=0 ; i<16 ; i++) 517 { 518 if (ptr == static_cast<void*>(emergency_buffer + (1024 * i))) 519 { 520 buffer = i; 521 break; 522 } 523 } 524 assert(buffer >= 0 && 525 "Trying to free something that is not an emergency buffer!"); 526 // emergency_malloc() is expected to return 0-initialized data. We don't 527 // zero the buffer when allocating it, because the static buffers will 528 // begin life containing 0 values. 529 memset(ptr, 0, 1024); 530 // Signal the condition variable to wake up any threads that are blocking 531 // waiting for some space in the emergency buffer 532 pthread_mutex_lock(&emergency_malloc_lock); 533 // In theory, we don't need to do this with the lock held. In practice, 534 // our array of bools will probably be updated using 32-bit or 64-bit 535 // memory operations, so this update may clobber adjacent values. 536 buffer_allocated[buffer] = false; 537 pthread_cond_signal(&emergency_malloc_wait); 538 pthread_mutex_unlock(&emergency_malloc_lock); 539 } 540 541 static char *alloc_or_die(size_t size) 542 { 543 char *buffer = static_cast<char*>(calloc(1, size)); 544 545 // If calloc() doesn't want to give us any memory, try using an emergency 546 // buffer. 547 if (0 == buffer) 548 { 549 buffer = emergency_malloc(size); 550 // This is only reached if the allocation is greater than 1KB, and 551 // anyone throwing objects that big really should know better. 552 if (0 == buffer) 553 { 554 fprintf(stderr, "Out of memory attempting to allocate exception\n"); 555 std::terminate(); 556 } 557 } 558 return buffer; 559 } 560 static void free_exception(char *e) 561 { 562 // If this allocation is within the address range of the emergency buffer, 563 // don't call free() because it was not allocated with malloc() 564 if ((e >= emergency_buffer) && 565 (e < (emergency_buffer + sizeof(emergency_buffer)))) 566 { 567 emergency_malloc_free(e); 568 } 569 else 570 { 571 free(e); 572 } 573 } 574 575 #ifdef __LP64__ 576 /** 577 * There's an ABI bug in __cxa_exception: unwindHeader requires 16-byte 578 * alignment but it was broken by the addition of the referenceCount. 579 * The unwindHeader is at offset 0x58 in __cxa_exception. In order to keep 580 * compatibility with consumers of the broken __cxa_exception, explicitly add 581 * padding on allocation (and account for it on free). 582 */ 583 static const int exception_alignment_padding = 8; 584 #else 585 static const int exception_alignment_padding = 0; 586 #endif 587 588 /** 589 * Allocates an exception structure. Returns a pointer to the space that can 590 * be used to store an object of thrown_size bytes. This function will use an 591 * emergency buffer if malloc() fails, and may block if there are no such 592 * buffers available. 593 */ 594 extern "C" void *__cxa_allocate_exception(size_t thrown_size) 595 { 596 size_t size = exception_alignment_padding + sizeof(__cxa_exception) + 597 thrown_size; 598 char *buffer = alloc_or_die(size); 599 return buffer + exception_alignment_padding + sizeof(__cxa_exception); 600 } 601 602 extern "C" void *__cxa_allocate_dependent_exception(void) 603 { 604 size_t size = exception_alignment_padding + 605 sizeof(__cxa_dependent_exception); 606 char *buffer = alloc_or_die(size); 607 return buffer + exception_alignment_padding + 608 sizeof(__cxa_dependent_exception); 609 } 610 611 /** 612 * __cxa_free_exception() is called when an exception was thrown in between 613 * calling __cxa_allocate_exception() and actually throwing the exception. 614 * This happens when the object's copy constructor throws an exception. 615 * 616 * In this implementation, it is also called by __cxa_end_catch() and during 617 * thread cleanup. 618 */ 619 extern "C" void __cxa_free_exception(void *thrown_exception) 620 { 621 __cxa_exception *ex = reinterpret_cast<__cxa_exception*>(thrown_exception) - 1; 622 // Free the object that was thrown, calling its destructor 623 if (0 != ex->exceptionDestructor) 624 { 625 try 626 { 627 ex->exceptionDestructor(thrown_exception); 628 } 629 catch(...) 630 { 631 // FIXME: Check that this is really what the spec says to do. 632 std::terminate(); 633 } 634 } 635 636 free_exception(reinterpret_cast<char*>(ex) - 637 exception_alignment_padding); 638 } 639 640 static void releaseException(__cxa_exception *exception) 641 { 642 if (isDependentException(exception->unwindHeader.exception_class)) 643 { 644 __cxa_free_dependent_exception(exception+1); 645 return; 646 } 647 if (__sync_sub_and_fetch(&exception->referenceCount, 1) == 0) 648 { 649 // __cxa_free_exception() expects to be passed the thrown object, 650 // which immediately follows the exception, not the exception 651 // itself 652 __cxa_free_exception(exception+1); 653 } 654 } 655 656 void __cxa_free_dependent_exception(void *thrown_exception) 657 { 658 __cxa_dependent_exception *ex = reinterpret_cast<__cxa_dependent_exception*>(thrown_exception) - 1; 659 assert(isDependentException(ex->unwindHeader.exception_class)); 660 if (ex->primaryException) 661 { 662 releaseException(realExceptionFromException(reinterpret_cast<__cxa_exception*>(ex))); 663 } 664 free_exception(reinterpret_cast<char*>(ex) - 665 exception_alignment_padding); 666 } 667 668 /** 669 * Callback function used with _Unwind_Backtrace(). 670 * 671 * Prints a stack trace. Used only for debugging help. 672 * 673 * Note: As of FreeBSD 8.1, dladd() still doesn't work properly, so this only 674 * correctly prints function names from public, relocatable, symbols. 675 */ 676 static _Unwind_Reason_Code trace(struct _Unwind_Context *context, void *c) 677 { 678 Dl_info myinfo; 679 int mylookup = 680 dladdr(reinterpret_cast<void *>(__cxa_current_exception_type), &myinfo); 681 void *ip = reinterpret_cast<void*>(_Unwind_GetIP(context)); 682 Dl_info info; 683 if (dladdr(ip, &info) != 0) 684 { 685 if (mylookup == 0 || strcmp(info.dli_fname, myinfo.dli_fname) != 0) 686 { 687 printf("%p:%s() in %s\n", ip, info.dli_sname, info.dli_fname); 688 } 689 } 690 return _URC_CONTINUE_UNWIND; 691 } 692 693 /** 694 * Report a failure that occurred when attempting to throw an exception. 695 * 696 * If the failure happened by falling off the end of the stack without finding 697 * a handler, prints a back trace before aborting. 698 */ 699 #if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 4) 700 extern "C" void *__cxa_begin_catch(void *e) throw(); 701 #else 702 extern "C" void *__cxa_begin_catch(void *e); 703 #endif 704 static void report_failure(_Unwind_Reason_Code err, __cxa_exception *thrown_exception) 705 { 706 switch (err) 707 { 708 default: break; 709 case _URC_FATAL_PHASE1_ERROR: 710 fprintf(stderr, "Fatal error during phase 1 unwinding\n"); 711 break; 712 #if !defined(__arm__) || defined(__ARM_DWARF_EH__) 713 case _URC_FATAL_PHASE2_ERROR: 714 fprintf(stderr, "Fatal error during phase 2 unwinding\n"); 715 break; 716 #endif 717 case _URC_END_OF_STACK: 718 __cxa_begin_catch (&(thrown_exception->unwindHeader)); 719 std::terminate(); 720 fprintf(stderr, "Terminating due to uncaught exception %p", 721 static_cast<void*>(thrown_exception)); 722 thrown_exception = realExceptionFromException(thrown_exception); 723 static const __class_type_info *e_ti = 724 static_cast<const __class_type_info*>(&typeid(std::exception)); 725 const __class_type_info *throw_ti = 726 dynamic_cast<const __class_type_info*>(thrown_exception->exceptionType); 727 if (throw_ti) 728 { 729 std::exception *e = 730 static_cast<std::exception*>(e_ti->cast_to(static_cast<void*>(thrown_exception+1), 731 throw_ti)); 732 if (e) 733 { 734 fprintf(stderr, " '%s'", e->what()); 735 } 736 } 737 738 size_t bufferSize = 128; 739 char *demangled = static_cast<char*>(malloc(bufferSize)); 740 const char *mangled = thrown_exception->exceptionType->name(); 741 int status; 742 demangled = __cxa_demangle(mangled, demangled, &bufferSize, &status); 743 fprintf(stderr, " of type %s\n", 744 status == 0 ? demangled : mangled); 745 if (status == 0) { free(demangled); } 746 // Print a back trace if no handler is found. 747 // TODO: Make this optional 748 #ifndef __arm__ 749 _Unwind_Backtrace(trace, 0); 750 #endif 751 752 // Just abort. No need to call std::terminate for the second time 753 abort(); 754 break; 755 } 756 std::terminate(); 757 } 758 759 static void throw_exception(__cxa_exception *ex) 760 { 761 __cxa_thread_info *info = thread_info(); 762 ex->unexpectedHandler = info->unexpectedHandler; 763 if (0 == ex->unexpectedHandler) 764 { 765 ex->unexpectedHandler = unexpectedHandler; 766 } 767 ex->terminateHandler = info->terminateHandler; 768 if (0 == ex->terminateHandler) 769 { 770 ex->terminateHandler = terminateHandler; 771 } 772 info->globals.uncaughtExceptions++; 773 774 _Unwind_Reason_Code err = _Unwind_RaiseException(&ex->unwindHeader); 775 // The _Unwind_RaiseException() function should not return, it should 776 // unwind the stack past this function. If it does return, then something 777 // has gone wrong. 778 report_failure(err, ex); 779 } 780 781 782 /** 783 * ABI function for throwing an exception. Takes the object to be thrown (the 784 * pointer returned by __cxa_allocate_exception()), the type info for the 785 * pointee, and the destructor (if there is one) as arguments. 786 */ 787 extern "C" void __cxa_throw(void *thrown_exception, 788 std::type_info *tinfo, 789 void(*dest)(void*)) 790 { 791 __cxa_exception *ex = reinterpret_cast<__cxa_exception*>(thrown_exception) - 1; 792 793 ex->referenceCount = 1; 794 ex->exceptionType = tinfo; 795 796 ex->exceptionDestructor = dest; 797 798 ex->unwindHeader.exception_class = exception_class; 799 ex->unwindHeader.exception_cleanup = exception_cleanup; 800 801 throw_exception(ex); 802 } 803 804 extern "C" void __cxa_rethrow_primary_exception(void* thrown_exception) 805 { 806 if (NULL == thrown_exception) { return; } 807 808 __cxa_exception *original = exceptionFromPointer(thrown_exception); 809 __cxa_dependent_exception *ex = reinterpret_cast<__cxa_dependent_exception*>(__cxa_allocate_dependent_exception())-1; 810 811 ex->primaryException = thrown_exception; 812 __cxa_increment_exception_refcount(thrown_exception); 813 814 ex->exceptionType = original->exceptionType; 815 ex->unwindHeader.exception_class = dependent_exception_class; 816 ex->unwindHeader.exception_cleanup = dependent_exception_cleanup; 817 818 throw_exception(reinterpret_cast<__cxa_exception*>(ex)); 819 } 820 821 extern "C" void *__cxa_current_primary_exception(void) 822 { 823 __cxa_eh_globals* globals = __cxa_get_globals(); 824 __cxa_exception *ex = globals->caughtExceptions; 825 826 if (0 == ex) { return NULL; } 827 ex = realExceptionFromException(ex); 828 __sync_fetch_and_add(&ex->referenceCount, 1); 829 return ex + 1; 830 } 831 832 extern "C" void __cxa_increment_exception_refcount(void* thrown_exception) 833 { 834 if (NULL == thrown_exception) { return; } 835 __cxa_exception *ex = static_cast<__cxa_exception*>(thrown_exception) - 1; 836 if (isDependentException(ex->unwindHeader.exception_class)) { return; } 837 __sync_fetch_and_add(&ex->referenceCount, 1); 838 } 839 extern "C" void __cxa_decrement_exception_refcount(void* thrown_exception) 840 { 841 if (NULL == thrown_exception) { return; } 842 __cxa_exception *ex = static_cast<__cxa_exception*>(thrown_exception) - 1; 843 releaseException(ex); 844 } 845 846 /** 847 * ABI function. Rethrows the current exception. Does not remove the 848 * exception from the stack or decrement its handler count - the compiler is 849 * expected to set the landing pad for this function to the end of the catch 850 * block, and then call _Unwind_Resume() to continue unwinding once 851 * __cxa_end_catch() has been called and any cleanup code has been run. 852 */ 853 extern "C" void __cxa_rethrow() 854 { 855 __cxa_thread_info *ti = thread_info(); 856 __cxa_eh_globals *globals = &ti->globals; 857 // Note: We don't remove this from the caught list here, because 858 // __cxa_end_catch will be called when we unwind out of the try block. We 859 // could probably make this faster by providing an alternative rethrow 860 // function and ensuring that all cleanup code is run before calling it, so 861 // we can skip the top stack frame when unwinding. 862 __cxa_exception *ex = globals->caughtExceptions; 863 864 if (0 == ex) 865 { 866 fprintf(stderr, 867 "Attempting to rethrow an exception that doesn't exist!\n"); 868 std::terminate(); 869 } 870 871 if (ti->foreign_exception_state != __cxa_thread_info::none) 872 { 873 ti->foreign_exception_state = __cxa_thread_info::rethrown; 874 _Unwind_Exception *e = reinterpret_cast<_Unwind_Exception*>(ex); 875 _Unwind_Reason_Code err = _Unwind_Resume_or_Rethrow(e); 876 report_failure(err, ex); 877 return; 878 } 879 880 assert(ex->handlerCount > 0 && "Rethrowing uncaught exception!"); 881 882 // ex->handlerCount will be decremented in __cxa_end_catch in enclosing 883 // catch block 884 885 // Make handler count negative. This will tell __cxa_end_catch that 886 // exception was rethrown and exception object should not be destroyed 887 // when handler count become zero 888 ex->handlerCount = -ex->handlerCount; 889 890 // Continue unwinding the stack with this exception. This should unwind to 891 // the place in the caller where __cxa_end_catch() is called. The caller 892 // will then run cleanup code and bounce the exception back with 893 // _Unwind_Resume(). 894 _Unwind_Reason_Code err = _Unwind_Resume_or_Rethrow(&ex->unwindHeader); 895 report_failure(err, ex); 896 } 897 898 /** 899 * Returns the type_info object corresponding to the filter. 900 */ 901 static std::type_info *get_type_info_entry(_Unwind_Context *context, 902 dwarf_eh_lsda *lsda, 903 int filter) 904 { 905 // Get the address of the record in the table. 906 dw_eh_ptr_t record = lsda->type_table - 907 dwarf_size_of_fixed_size_field(lsda->type_table_encoding)*filter; 908 //record -= 4; 909 dw_eh_ptr_t start = record; 910 // Read the value, but it's probably an indirect reference... 911 int64_t offset = read_value(lsda->type_table_encoding, &record); 912 913 // (If the entry is 0, don't try to dereference it. That would be bad.) 914 if (offset == 0) { return 0; } 915 916 // ...so we need to resolve it 917 return reinterpret_cast<std::type_info*>(resolve_indirect_value(context, 918 lsda->type_table_encoding, offset, start)); 919 } 920 921 922 923 /** 924 * Checks the type signature found in a handler against the type of the thrown 925 * object. If ex is 0 then it is assumed to be a foreign exception and only 926 * matches cleanups. 927 */ 928 static bool check_type_signature(__cxa_exception *ex, 929 const std::type_info *type, 930 void *&adjustedPtr) 931 { 932 void *exception_ptr = static_cast<void*>(ex+1); 933 const std::type_info *ex_type = ex ? ex->exceptionType : 0; 934 935 bool is_ptr = ex ? ex_type->__is_pointer_p() : false; 936 if (is_ptr) 937 { 938 exception_ptr = *static_cast<void**>(exception_ptr); 939 } 940 // Always match a catchall, even with a foreign exception 941 // 942 // Note: A 0 here is a catchall, not a cleanup, so we return true to 943 // indicate that we found a catch. 944 if (0 == type) 945 { 946 if (ex) 947 { 948 adjustedPtr = exception_ptr; 949 } 950 return true; 951 } 952 953 if (0 == ex) { return false; } 954 955 // If the types are the same, no casting is needed. 956 if (*type == *ex_type) 957 { 958 adjustedPtr = exception_ptr; 959 return true; 960 } 961 962 963 if (type->__do_catch(ex_type, &exception_ptr, 1)) 964 { 965 adjustedPtr = exception_ptr; 966 return true; 967 } 968 969 return false; 970 } 971 /** 972 * Checks whether the exception matches the type specifiers in this action 973 * record. If the exception only matches cleanups, then this returns false. 974 * If it matches a catch (including a catchall) then it returns true. 975 * 976 * The selector argument is used to return the selector that is passed in the 977 * second exception register when installing the context. 978 */ 979 static handler_type check_action_record(_Unwind_Context *context, 980 dwarf_eh_lsda *lsda, 981 dw_eh_ptr_t action_record, 982 __cxa_exception *ex, 983 unsigned long *selector, 984 void *&adjustedPtr) 985 { 986 if (!action_record) { return handler_cleanup; } 987 handler_type found = handler_none; 988 while (action_record) 989 { 990 int filter = read_sleb128(&action_record); 991 dw_eh_ptr_t action_record_offset_base = action_record; 992 int displacement = read_sleb128(&action_record); 993 action_record = displacement ? 994 action_record_offset_base + displacement : 0; 995 // We only check handler types for C++ exceptions - foreign exceptions 996 // are only allowed for cleanups and catchalls. 997 if (filter > 0) 998 { 999 std::type_info *handler_type = get_type_info_entry(context, lsda, filter); 1000 if (check_type_signature(ex, handler_type, adjustedPtr)) 1001 { 1002 *selector = filter; 1003 return handler_catch; 1004 } 1005 } 1006 else if (filter < 0 && 0 != ex) 1007 { 1008 bool matched = false; 1009 *selector = filter; 1010 #if defined(__arm__) && !defined(__ARM_DWARF_EH__) 1011 filter++; 1012 std::type_info *handler_type = get_type_info_entry(context, lsda, filter--); 1013 while (handler_type) 1014 { 1015 if (check_type_signature(ex, handler_type, adjustedPtr)) 1016 { 1017 matched = true; 1018 break; 1019 } 1020 handler_type = get_type_info_entry(context, lsda, filter--); 1021 } 1022 #else 1023 unsigned char *type_index = reinterpret_cast<unsigned char*>(lsda->type_table) - filter - 1; 1024 while (*type_index) 1025 { 1026 std::type_info *handler_type = get_type_info_entry(context, lsda, *(type_index++)); 1027 // If the exception spec matches a permitted throw type for 1028 // this function, don't report a handler - we are allowed to 1029 // propagate this exception out. 1030 if (check_type_signature(ex, handler_type, adjustedPtr)) 1031 { 1032 matched = true; 1033 break; 1034 } 1035 } 1036 #endif 1037 if (matched) { continue; } 1038 // If we don't find an allowed exception spec, we need to install 1039 // the context for this action. The landing pad will then call the 1040 // unexpected exception function. Treat this as a catch 1041 return handler_catch; 1042 } 1043 else if (filter == 0) 1044 { 1045 *selector = filter; 1046 found = handler_cleanup; 1047 } 1048 } 1049 return found; 1050 } 1051 1052 static void pushCleanupException(_Unwind_Exception *exceptionObject, 1053 __cxa_exception *ex) 1054 { 1055 #if defined(__arm__) && !defined(__ARM_DWARF_EH__) 1056 __cxa_thread_info *info = thread_info_fast(); 1057 if (ex) 1058 { 1059 ex->cleanupCount++; 1060 if (ex->cleanupCount > 1) 1061 { 1062 assert(exceptionObject == info->currentCleanup); 1063 return; 1064 } 1065 ex->nextCleanup = info->currentCleanup; 1066 } 1067 info->currentCleanup = exceptionObject; 1068 #endif 1069 } 1070 1071 /** 1072 * The exception personality function. This is referenced in the unwinding 1073 * DWARF metadata and is called by the unwind library for each C++ stack frame 1074 * containing catch or cleanup code. 1075 */ 1076 extern "C" 1077 BEGIN_PERSONALITY_FUNCTION(__gxx_personality_v0) 1078 // This personality function is for version 1 of the ABI. If you use it 1079 // with a future version of the ABI, it won't know what to do, so it 1080 // reports a fatal error and give up before it breaks anything. 1081 if (1 != version) 1082 { 1083 return _URC_FATAL_PHASE1_ERROR; 1084 } 1085 __cxa_exception *ex = 0; 1086 __cxa_exception *realEx = 0; 1087 1088 // If this exception is throw by something else then we can't make any 1089 // assumptions about its layout beyond the fields declared in 1090 // _Unwind_Exception. 1091 bool foreignException = !isCXXException(exceptionClass); 1092 1093 // If this isn't a foreign exception, then we have a C++ exception structure 1094 if (!foreignException) 1095 { 1096 ex = exceptionFromPointer(exceptionObject); 1097 realEx = realExceptionFromException(ex); 1098 } 1099 1100 #if defined(__arm__) && !defined(__ARM_DWARF_EH__) 1101 unsigned char *lsda_addr = 1102 static_cast<unsigned char*>(_Unwind_GetLanguageSpecificData(context)); 1103 #else 1104 unsigned char *lsda_addr = 1105 reinterpret_cast<unsigned char*>(static_cast<uintptr_t>(_Unwind_GetLanguageSpecificData(context))); 1106 #endif 1107 1108 // No LSDA implies no landing pads - try the next frame 1109 if (0 == lsda_addr) { return continueUnwinding(exceptionObject, context); } 1110 1111 // These two variables define how the exception will be handled. 1112 dwarf_eh_action action = {0}; 1113 unsigned long selector = 0; 1114 1115 // During the search phase, we do a complete lookup. If we return 1116 // _URC_HANDLER_FOUND, then the phase 2 unwind will call this function with 1117 // a _UA_HANDLER_FRAME action, telling us to install the handler frame. If 1118 // we return _URC_CONTINUE_UNWIND, we may be called again later with a 1119 // _UA_CLEANUP_PHASE action for this frame. 1120 // 1121 // The point of the two-stage unwind allows us to entirely avoid any stack 1122 // unwinding if there is no handler. If there are just cleanups found, 1123 // then we can just panic call an abort function. 1124 // 1125 // Matching a handler is much more expensive than matching a cleanup, 1126 // because we don't need to bother doing type comparisons (or looking at 1127 // the type table at all) for a cleanup. This means that there is no need 1128 // to cache the result of finding a cleanup, because it's (quite) quick to 1129 // look it up again from the action table. 1130 if (actions & _UA_SEARCH_PHASE) 1131 { 1132 struct dwarf_eh_lsda lsda = parse_lsda(context, lsda_addr); 1133 1134 if (!dwarf_eh_find_callsite(context, &lsda, &action)) 1135 { 1136 // EH range not found. This happens if exception is thrown and not 1137 // caught inside a cleanup (destructor). We should call 1138 // terminate() in this case. The catchTemp (landing pad) field of 1139 // exception object will contain null when personality function is 1140 // called with _UA_HANDLER_FRAME action for phase 2 unwinding. 1141 return _URC_HANDLER_FOUND; 1142 } 1143 1144 handler_type found_handler = check_action_record(context, &lsda, 1145 action.action_record, realEx, &selector, ex->adjustedPtr); 1146 // If there's no action record, we've only found a cleanup, so keep 1147 // searching for something real 1148 if (found_handler == handler_catch) 1149 { 1150 // Cache the results for the phase 2 unwind, if we found a handler 1151 // and this is not a foreign exception. 1152 if (ex) 1153 { 1154 saveLandingPad(context, exceptionObject, ex, selector, action.landing_pad); 1155 ex->languageSpecificData = reinterpret_cast<const char*>(lsda_addr); 1156 ex->actionRecord = reinterpret_cast<const char*>(action.action_record); 1157 // ex->adjustedPtr is set when finding the action record. 1158 } 1159 return _URC_HANDLER_FOUND; 1160 } 1161 return continueUnwinding(exceptionObject, context); 1162 } 1163 1164 1165 // If this is a foreign exception, we didn't have anywhere to cache the 1166 // lookup stuff, so we need to do it again. If this is either a forced 1167 // unwind, a foreign exception, or a cleanup, then we just install the 1168 // context for a cleanup. 1169 if (!(actions & _UA_HANDLER_FRAME)) 1170 { 1171 // cleanup 1172 struct dwarf_eh_lsda lsda = parse_lsda(context, lsda_addr); 1173 dwarf_eh_find_callsite(context, &lsda, &action); 1174 if (0 == action.landing_pad) { return continueUnwinding(exceptionObject, context); } 1175 handler_type found_handler = check_action_record(context, &lsda, 1176 action.action_record, realEx, &selector, ex->adjustedPtr); 1177 // Ignore handlers this time. 1178 if (found_handler != handler_cleanup) { return continueUnwinding(exceptionObject, context); } 1179 pushCleanupException(exceptionObject, ex); 1180 } 1181 else if (foreignException) 1182 { 1183 struct dwarf_eh_lsda lsda = parse_lsda(context, lsda_addr); 1184 dwarf_eh_find_callsite(context, &lsda, &action); 1185 check_action_record(context, &lsda, action.action_record, realEx, 1186 &selector, ex->adjustedPtr); 1187 } 1188 else if (ex->catchTemp == 0) 1189 { 1190 // Uncaught exception in cleanup, calling terminate 1191 std::terminate(); 1192 } 1193 else 1194 { 1195 // Restore the saved info if we saved some last time. 1196 loadLandingPad(context, exceptionObject, ex, &selector, &action.landing_pad); 1197 ex->catchTemp = 0; 1198 ex->handlerSwitchValue = 0; 1199 } 1200 1201 1202 _Unwind_SetIP(context, reinterpret_cast<unsigned long>(action.landing_pad)); 1203 _Unwind_SetGR(context, __builtin_eh_return_data_regno(0), 1204 reinterpret_cast<unsigned long>(exceptionObject)); 1205 _Unwind_SetGR(context, __builtin_eh_return_data_regno(1), selector); 1206 1207 return _URC_INSTALL_CONTEXT; 1208 } 1209 1210 /** 1211 * ABI function called when entering a catch statement. The argument is the 1212 * pointer passed out of the personality function. This is always the start of 1213 * the _Unwind_Exception object. The return value for this function is the 1214 * pointer to the caught exception, which is either the adjusted pointer (for 1215 * C++ exceptions) of the unadjusted pointer (for foreign exceptions). 1216 */ 1217 #if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 4) 1218 extern "C" void *__cxa_begin_catch(void *e) throw() 1219 #else 1220 extern "C" void *__cxa_begin_catch(void *e) 1221 #endif 1222 { 1223 // We can't call the fast version here, because if the first exception that 1224 // we see is a foreign exception then we won't have called it yet. 1225 __cxa_thread_info *ti = thread_info(); 1226 __cxa_eh_globals *globals = &ti->globals; 1227 globals->uncaughtExceptions--; 1228 _Unwind_Exception *exceptionObject = static_cast<_Unwind_Exception*>(e); 1229 1230 if (isCXXException(exceptionObject->exception_class)) 1231 { 1232 __cxa_exception *ex = exceptionFromPointer(exceptionObject); 1233 1234 if (ex->handlerCount == 0) 1235 { 1236 // Add this to the front of the list of exceptions being handled 1237 // and increment its handler count so that it won't be deleted 1238 // prematurely. 1239 ex->nextException = globals->caughtExceptions; 1240 globals->caughtExceptions = ex; 1241 } 1242 1243 if (ex->handlerCount < 0) 1244 { 1245 // Rethrown exception is catched before end of catch block. 1246 // Clear the rethrow flag (make value positive) - we are allowed 1247 // to delete this exception at the end of the catch block, as long 1248 // as it isn't thrown again later. 1249 1250 // Code pattern: 1251 // 1252 // try { 1253 // throw x; 1254 // } 1255 // catch() { 1256 // try { 1257 // throw; 1258 // } 1259 // catch() { 1260 // __cxa_begin_catch() <- we are here 1261 // } 1262 // } 1263 ex->handlerCount = -ex->handlerCount + 1; 1264 } 1265 else 1266 { 1267 ex->handlerCount++; 1268 } 1269 ti->foreign_exception_state = __cxa_thread_info::none; 1270 1271 return ex->adjustedPtr; 1272 } 1273 else 1274 { 1275 // If this is a foreign exception, then we need to be able to 1276 // store it. We can't chain foreign exceptions, so we give up 1277 // if there are already some outstanding ones. 1278 if (globals->caughtExceptions != 0) 1279 { 1280 std::terminate(); 1281 } 1282 globals->caughtExceptions = reinterpret_cast<__cxa_exception*>(exceptionObject); 1283 ti->foreign_exception_state = __cxa_thread_info::caught; 1284 } 1285 // exceptionObject is the pointer to the _Unwind_Exception within the 1286 // __cxa_exception. The throw object is after this 1287 return (reinterpret_cast<char*>(exceptionObject) + sizeof(_Unwind_Exception)); 1288 } 1289 1290 1291 1292 /** 1293 * ABI function called when exiting a catch block. This will free the current 1294 * exception if it is no longer referenced in other catch blocks. 1295 */ 1296 extern "C" void __cxa_end_catch() 1297 { 1298 // We can call the fast version here because the slow version is called in 1299 // __cxa_throw(), which must have been called before we end a catch block 1300 __cxa_thread_info *ti = thread_info_fast(); 1301 __cxa_eh_globals *globals = &ti->globals; 1302 __cxa_exception *ex = globals->caughtExceptions; 1303 1304 assert(0 != ex && "Ending catch when no exception is on the stack!"); 1305 1306 if (ti->foreign_exception_state != __cxa_thread_info::none) 1307 { 1308 if (ti->foreign_exception_state != __cxa_thread_info::rethrown) 1309 { 1310 _Unwind_Exception *e = reinterpret_cast<_Unwind_Exception*>(ti->globals.caughtExceptions); 1311 if (e->exception_cleanup) 1312 e->exception_cleanup(_URC_FOREIGN_EXCEPTION_CAUGHT, e); 1313 } 1314 globals->caughtExceptions = 0; 1315 ti->foreign_exception_state = __cxa_thread_info::none; 1316 return; 1317 } 1318 1319 bool deleteException = true; 1320 1321 if (ex->handlerCount < 0) 1322 { 1323 // exception was rethrown. Exception should not be deleted even if 1324 // handlerCount become zero. 1325 // Code pattern: 1326 // try { 1327 // throw x; 1328 // } 1329 // catch() { 1330 // { 1331 // throw; 1332 // } 1333 // cleanup { 1334 // __cxa_end_catch(); <- we are here 1335 // } 1336 // } 1337 // 1338 1339 ex->handlerCount++; 1340 deleteException = false; 1341 } 1342 else 1343 { 1344 ex->handlerCount--; 1345 } 1346 1347 if (ex->handlerCount == 0) 1348 { 1349 globals->caughtExceptions = ex->nextException; 1350 if (deleteException) 1351 { 1352 releaseException(ex); 1353 } 1354 } 1355 } 1356 1357 /** 1358 * ABI function. Returns the type of the current exception. 1359 */ 1360 extern "C" std::type_info *__cxa_current_exception_type() 1361 { 1362 __cxa_eh_globals *globals = __cxa_get_globals(); 1363 __cxa_exception *ex = globals->caughtExceptions; 1364 return ex ? ex->exceptionType : 0; 1365 } 1366 1367 /** 1368 * ABI function, called when an exception specification is violated. 1369 * 1370 * This function does not return. 1371 */ 1372 extern "C" void __cxa_call_unexpected(void*exception) 1373 { 1374 _Unwind_Exception *exceptionObject = static_cast<_Unwind_Exception*>(exception); 1375 if (exceptionObject->exception_class == exception_class) 1376 { 1377 __cxa_exception *ex = exceptionFromPointer(exceptionObject); 1378 if (ex->unexpectedHandler) 1379 { 1380 ex->unexpectedHandler(); 1381 // Should not be reached. 1382 abort(); 1383 } 1384 } 1385 std::unexpected(); 1386 // Should not be reached. 1387 abort(); 1388 } 1389 1390 /** 1391 * ABI function, returns the adjusted pointer to the exception object. 1392 */ 1393 extern "C" void *__cxa_get_exception_ptr(void *exceptionObject) 1394 { 1395 return exceptionFromPointer(exceptionObject)->adjustedPtr; 1396 } 1397 1398 /** 1399 * As an extension, we provide the ability for the unexpected and terminate 1400 * handlers to be thread-local. We default to the standards-compliant 1401 * behaviour where they are global. 1402 */ 1403 static bool thread_local_handlers = false; 1404 1405 1406 namespace pathscale 1407 { 1408 /** 1409 * Sets whether unexpected and terminate handlers should be thread-local. 1410 */ 1411 void set_use_thread_local_handlers(bool flag) throw() 1412 { 1413 thread_local_handlers = flag; 1414 } 1415 /** 1416 * Sets a thread-local unexpected handler. 1417 */ 1418 unexpected_handler set_unexpected(unexpected_handler f) throw() 1419 { 1420 static __cxa_thread_info *info = thread_info(); 1421 unexpected_handler old = info->unexpectedHandler; 1422 info->unexpectedHandler = f; 1423 return old; 1424 } 1425 /** 1426 * Sets a thread-local terminate handler. 1427 */ 1428 terminate_handler set_terminate(terminate_handler f) throw() 1429 { 1430 static __cxa_thread_info *info = thread_info(); 1431 terminate_handler old = info->terminateHandler; 1432 info->terminateHandler = f; 1433 return old; 1434 } 1435 } 1436 1437 namespace std 1438 { 1439 /** 1440 * Sets the function that will be called when an exception specification is 1441 * violated. 1442 */ 1443 unexpected_handler set_unexpected(unexpected_handler f) throw() 1444 { 1445 if (thread_local_handlers) { return pathscale::set_unexpected(f); } 1446 1447 return ATOMIC_SWAP(&unexpectedHandler, f); 1448 } 1449 /** 1450 * Sets the function that is called to terminate the program. 1451 */ 1452 terminate_handler set_terminate(terminate_handler f) throw() 1453 { 1454 if (thread_local_handlers) { return pathscale::set_terminate(f); } 1455 1456 return ATOMIC_SWAP(&terminateHandler, f); 1457 } 1458 /** 1459 * Terminates the program, calling a custom terminate implementation if 1460 * required. 1461 */ 1462 void terminate() 1463 { 1464 static __cxa_thread_info *info = thread_info(); 1465 if (0 != info && 0 != info->terminateHandler) 1466 { 1467 info->terminateHandler(); 1468 // Should not be reached - a terminate handler is not expected to 1469 // return. 1470 abort(); 1471 } 1472 terminateHandler(); 1473 } 1474 /** 1475 * Called when an unexpected exception is encountered (i.e. an exception 1476 * violates an exception specification). This calls abort() unless a 1477 * custom handler has been set.. 1478 */ 1479 void unexpected() 1480 { 1481 static __cxa_thread_info *info = thread_info(); 1482 if (0 != info && 0 != info->unexpectedHandler) 1483 { 1484 info->unexpectedHandler(); 1485 // Should not be reached - a terminate handler is not expected to 1486 // return. 1487 abort(); 1488 } 1489 unexpectedHandler(); 1490 } 1491 /** 1492 * Returns whether there are any exceptions currently being thrown that 1493 * have not been caught. This can occur inside a nested catch statement. 1494 */ 1495 bool uncaught_exception() throw() 1496 { 1497 __cxa_thread_info *info = thread_info(); 1498 return info->globals.uncaughtExceptions != 0; 1499 } 1500 /** 1501 * Returns the number of exceptions currently being thrown that have not 1502 * been caught. This can occur inside a nested catch statement. 1503 */ 1504 int uncaught_exceptions() throw() 1505 { 1506 __cxa_thread_info *info = thread_info(); 1507 return info->globals.uncaughtExceptions; 1508 } 1509 /** 1510 * Returns the current unexpected handler. 1511 */ 1512 unexpected_handler get_unexpected() throw() 1513 { 1514 __cxa_thread_info *info = thread_info(); 1515 if (info->unexpectedHandler) 1516 { 1517 return info->unexpectedHandler; 1518 } 1519 return ATOMIC_LOAD(&unexpectedHandler); 1520 } 1521 /** 1522 * Returns the current terminate handler. 1523 */ 1524 terminate_handler get_terminate() throw() 1525 { 1526 __cxa_thread_info *info = thread_info(); 1527 if (info->terminateHandler) 1528 { 1529 return info->terminateHandler; 1530 } 1531 return ATOMIC_LOAD(&terminateHandler); 1532 } 1533 } 1534 #if defined(__arm__) && !defined(__ARM_DWARF_EH__) 1535 extern "C" _Unwind_Exception *__cxa_get_cleanup(void) 1536 { 1537 __cxa_thread_info *info = thread_info_fast(); 1538 _Unwind_Exception *exceptionObject = info->currentCleanup; 1539 if (isCXXException(exceptionObject->exception_class)) 1540 { 1541 __cxa_exception *ex = exceptionFromPointer(exceptionObject); 1542 ex->cleanupCount--; 1543 if (ex->cleanupCount == 0) 1544 { 1545 info->currentCleanup = ex->nextCleanup; 1546 ex->nextCleanup = 0; 1547 } 1548 } 1549 else 1550 { 1551 info->currentCleanup = 0; 1552 } 1553 return exceptionObject; 1554 } 1555 1556 asm ( 1557 ".pushsection .text.__cxa_end_cleanup \n" 1558 ".global __cxa_end_cleanup \n" 1559 ".type __cxa_end_cleanup, \"function\" \n" 1560 "__cxa_end_cleanup: \n" 1561 " push {r1, r2, r3, r4} \n" 1562 " bl __cxa_get_cleanup \n" 1563 " push {r1, r2, r3, r4} \n" 1564 " b _Unwind_Resume \n" 1565 " bl abort \n" 1566 ".popsection \n" 1567 ); 1568 #endif 1569