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38 #pragma weak pthread_key_create
39 #pragma weak pthread_setspecific
40 #pragma weak pthread_getspecific
41 #pragma weak pthread_once
43 using namespace ABI_NAMESPACE;
46 * Saves the result of the landing pad that we have found. For ARM, this is
47 * stored in the generic unwind structure, while on other platforms it is
48 * stored in the C++ exception.
50 static void saveLandingPad(struct _Unwind_Context *context,
51 struct _Unwind_Exception *ucb,
52 struct __cxa_exception *ex,
54 dw_eh_ptr_t landingPad)
57 // On ARM, we store the saved exception in the generic part of the structure
58 ucb->barrier_cache.sp = _Unwind_GetGR(context, 13);
59 ucb->barrier_cache.bitpattern[1] = (uint32_t)selector;
60 ucb->barrier_cache.bitpattern[3] = (uint32_t)landingPad;
62 // Cache the results for the phase 2 unwind, if we found a handler
63 // and this is not a foreign exception.
66 ex->handlerSwitchValue = selector;
67 ex->catchTemp = landingPad;
72 * Loads the saved landing pad. Returns 1 on success, 0 on failure.
74 static int loadLandingPad(struct _Unwind_Context *context,
75 struct _Unwind_Exception *ucb,
76 struct __cxa_exception *ex,
77 unsigned long *selector,
78 dw_eh_ptr_t *landingPad)
81 *selector = ucb->barrier_cache.bitpattern[1];
82 *landingPad = (dw_eh_ptr_t)ucb->barrier_cache.bitpattern[3];
87 *selector = ex->handlerSwitchValue;
88 *landingPad = (dw_eh_ptr_t)ex->catchTemp;
95 static inline _Unwind_Reason_Code continueUnwinding(struct _Unwind_Exception *ex,
96 struct _Unwind_Context *context)
99 if (__gnu_unwind_frame(ex, context) != _URC_OK) { return _URC_FAILURE; }
101 return _URC_CONTINUE_UNWIND;
105 extern "C" void __cxa_free_exception(void *thrown_exception);
106 extern "C" void __cxa_free_dependent_exception(void *thrown_exception);
107 extern "C" void* __dynamic_cast(const void *sub,
108 const __class_type_info *src,
109 const __class_type_info *dst,
110 ptrdiff_t src2dst_offset);
113 * The type of a handler that has been found.
120 * A cleanup - the exception will propagate through this frame, but code
121 * must be run when this happens.
125 * A catch statement. The exception will not propagate past this frame
126 * (without an explicit rethrow).
132 * Per-thread info required by the runtime. We store a single structure
133 * pointer in thread-local storage, because this tends to be a scarce resource
134 * and it's impolite to steal all of it and not leave any for the rest of the
137 * Instances of this structure are allocated lazily - at most one per thread -
138 * and are destroyed on thread termination.
140 struct __cxa_thread_info
142 /** The termination handler for this thread. */
143 terminate_handler terminateHandler;
144 /** The unexpected exception handler for this thread. */
145 unexpected_handler unexpectedHandler;
147 * The number of emergency buffers held by this thread. This is 0 in
148 * normal operation - the emergency buffers are only used when malloc()
149 * fails to return memory for allocating an exception. Threads are not
150 * permitted to hold more than 4 emergency buffers (as per recommendation
151 * in ABI spec [3.3.1]).
153 int emergencyBuffersHeld;
155 * The exception currently running in a cleanup.
157 _Unwind_Exception *currentCleanup;
159 * Our state with respect to foreign exceptions. Usually none, set to
160 * caught if we have just caught an exception and rethrown if we are
168 } foreign_exception_state;
170 * The public part of this structure, accessible from outside of this
173 __cxa_eh_globals globals;
176 * Dependent exception. This
178 struct __cxa_dependent_exception
181 void *primaryException;
183 std::type_info *exceptionType;
184 void (*exceptionDestructor) (void *);
185 unexpected_handler unexpectedHandler;
186 terminate_handler terminateHandler;
187 __cxa_exception *nextException;
190 _Unwind_Exception *nextCleanup;
193 int handlerSwitchValue;
194 const char *actionRecord;
195 const char *languageSpecificData;
199 void *primaryException;
201 _Unwind_Exception unwindHeader;
211 virtual ~exception() throw();
212 virtual const char* what() const throw();
217 extern "C" std::type_info *__cxa_current_exception_type();
220 * Class of exceptions to distinguish between this and other exception types.
222 * The first four characters are the vendor ID. Currently, we use GNUC,
223 * because we aim for ABI-compatibility with the GNU implementation, and
224 * various checks may test for equality of the class, which is incorrect.
226 static const uint64_t exception_class =
227 EXCEPTION_CLASS('G', 'N', 'U', 'C', 'C', '+', '+', '\0');
229 * Class used for dependent exceptions.
231 static const uint64_t dependent_exception_class =
232 EXCEPTION_CLASS('G', 'N', 'U', 'C', 'C', '+', '+', '\x01');
234 * The low four bytes of the exception class, indicating that we conform to the
235 * Itanium C++ ABI. This is currently unused, but should be used in the future
236 * if we change our exception class, to allow this library and libsupc++ to be
237 * linked to the same executable and both to interoperate.
239 static const uint32_t abi_exception_class =
240 GENERIC_EXCEPTION_CLASS('C', '+', '+', '\0');
242 static bool isCXXException(uint64_t cls)
244 return (cls == exception_class) || (cls == dependent_exception_class);
247 static bool isDependentException(uint64_t cls)
249 return cls == dependent_exception_class;
252 static __cxa_exception *exceptionFromPointer(void *ex)
254 return (__cxa_exception*)((char*)ex -
255 offsetof(struct __cxa_exception, unwindHeader));
257 static __cxa_exception *realExceptionFromException(__cxa_exception *ex)
259 if (!isDependentException(ex->unwindHeader.exception_class)) { return ex; }
260 return ((__cxa_exception*)(((__cxa_dependent_exception*)ex)->primaryException))-1;
266 // Forward declaration of standard library terminate() function used to
268 void terminate(void);
271 using namespace ABI_NAMESPACE;
275 /** The global termination handler. */
276 static terminate_handler terminateHandler = abort;
277 /** The global unexpected exception handler. */
278 static unexpected_handler unexpectedHandler = std::terminate;
280 /** Key used for thread-local data. */
281 static pthread_key_t eh_key;
285 * Cleanup function, allowing foreign exception handlers to correctly destroy
286 * this exception if they catch it.
288 static void exception_cleanup(_Unwind_Reason_Code reason,
289 struct _Unwind_Exception *ex)
291 __cxa_free_exception((void*)ex);
293 static void dependent_exception_cleanup(_Unwind_Reason_Code reason,
294 struct _Unwind_Exception *ex)
297 __cxa_free_dependent_exception((void*)ex);
301 * Recursively walk a list of exceptions and delete them all in post-order.
303 static void free_exception_list(__cxa_exception *ex)
305 if (0 != ex->nextException)
307 free_exception_list(ex->nextException);
309 // __cxa_free_exception() expects to be passed the thrown object, which
310 // immediately follows the exception, not the exception itself
311 __cxa_free_exception(ex+1);
315 * Cleanup function called when a thread exists to make certain that all of the
316 * per-thread data is deleted.
318 static void thread_cleanup(void* thread_info)
320 __cxa_thread_info *info = (__cxa_thread_info*)thread_info;
321 if (info->globals.caughtExceptions)
323 // If this is a foreign exception, ask it to clean itself up.
324 if (info->foreign_exception_state != __cxa_thread_info::none)
326 _Unwind_Exception *e = (_Unwind_Exception*)info->globals.caughtExceptions;
327 e->exception_cleanup(_URC_FOREIGN_EXCEPTION_CAUGHT, e);
331 free_exception_list(info->globals.caughtExceptions);
339 * Once control used to protect the key creation.
341 static pthread_once_t once_control = PTHREAD_ONCE_INIT;
344 * We may not be linked against a full pthread implementation. If we're not,
345 * then we need to fake the thread-local storage by storing 'thread-local'
346 * things in a global.
350 * Thread-local storage for a single-threaded program.
352 static __cxa_thread_info singleThreadInfo;
356 static void init_key(void)
358 if ((0 == pthread_key_create) ||
359 (0 == pthread_setspecific) ||
360 (0 == pthread_getspecific))
365 pthread_key_create(&eh_key, thread_cleanup);
366 pthread_setspecific(eh_key, (void*)0x42);
367 fakeTLS = (pthread_getspecific(eh_key) != (void*)0x42);
368 pthread_setspecific(eh_key, 0);
372 * Returns the thread info structure, creating it if it is not already created.
374 static __cxa_thread_info *thread_info()
376 if ((0 == pthread_once) || pthread_once(&once_control, init_key))
380 if (fakeTLS) { return &singleThreadInfo; }
381 __cxa_thread_info *info = (__cxa_thread_info*)pthread_getspecific(eh_key);
384 info = (__cxa_thread_info*)calloc(1, sizeof(__cxa_thread_info));
385 pthread_setspecific(eh_key, info);
390 * Fast version of thread_info(). May fail if thread_info() is not called on
391 * this thread at least once already.
393 static __cxa_thread_info *thread_info_fast()
395 if (fakeTLS) { return &singleThreadInfo; }
396 return (__cxa_thread_info*)pthread_getspecific(eh_key);
399 * ABI function returning the __cxa_eh_globals structure.
401 extern "C" __cxa_eh_globals *ABI_NAMESPACE::__cxa_get_globals(void)
403 return &(thread_info()->globals);
406 * Version of __cxa_get_globals() assuming that __cxa_get_globals() has already
407 * been called at least once by this thread.
409 extern "C" __cxa_eh_globals *ABI_NAMESPACE::__cxa_get_globals_fast(void)
411 return &(thread_info_fast()->globals);
415 * An emergency allocation reserved for when malloc fails. This is treated as
416 * 16 buffers of 1KB each.
418 static char emergency_buffer[16384];
420 * Flag indicating whether each buffer is allocated.
422 static bool buffer_allocated[16];
424 * Lock used to protect emergency allocation.
426 static pthread_mutex_t emergency_malloc_lock = PTHREAD_MUTEX_INITIALIZER;
428 * Condition variable used to wait when two threads are both trying to use the
429 * emergency malloc() buffer at once.
431 static pthread_cond_t emergency_malloc_wait = PTHREAD_COND_INITIALIZER;
434 * Allocates size bytes from the emergency allocation mechanism, if possible.
435 * This function will fail if size is over 1KB or if this thread already has 4
436 * emergency buffers. If all emergency buffers are allocated, it will sleep
437 * until one becomes available.
439 static char *emergency_malloc(size_t size)
441 if (size > 1024) { return 0; }
443 __cxa_thread_info *info = thread_info();
444 // Only 4 emergency buffers allowed per thread!
445 if (info->emergencyBuffersHeld > 3) { return 0; }
447 pthread_mutex_lock(&emergency_malloc_lock);
451 // While we were sleeping on the lock, another thread might have free'd
452 // enough memory for us to use, so try the allocation again - no point
453 // using the emergency buffer if there is some real memory that we can
455 void *m = calloc(1, size);
458 pthread_mutex_unlock(&emergency_malloc_lock);
461 for (int i=0 ; i<16 ; i++)
463 if (!buffer_allocated[i])
466 buffer_allocated[i] = true;
470 // If there still isn't a buffer available, then sleep on the condition
471 // variable. This will be signalled when another thread releases one
472 // of the emergency buffers.
475 pthread_cond_wait(&emergency_malloc_wait, &emergency_malloc_lock);
478 pthread_mutex_unlock(&emergency_malloc_lock);
479 info->emergencyBuffersHeld++;
480 return emergency_buffer + (1024 * buffer);
484 * Frees a buffer returned by emergency_malloc().
486 * Note: Neither this nor emergency_malloc() is particularly efficient. This
487 * should not matter, because neither will be called in normal operation - they
488 * are only used when the program runs out of memory, which should not happen
491 static void emergency_malloc_free(char *ptr)
494 // Find the buffer corresponding to this pointer.
495 for (int i=0 ; i<16 ; i++)
497 if (ptr == (void*)(emergency_buffer + (1024 * i)))
504 "Trying to free something that is not an emergency buffer!");
505 // emergency_malloc() is expected to return 0-initialized data. We don't
506 // zero the buffer when allocating it, because the static buffers will
507 // begin life containing 0 values.
508 memset((void*)ptr, 0, 1024);
509 // Signal the condition variable to wake up any threads that are blocking
510 // waiting for some space in the emergency buffer
511 pthread_mutex_lock(&emergency_malloc_lock);
512 // In theory, we don't need to do this with the lock held. In practice,
513 // our array of bools will probably be updated using 32-bit or 64-bit
514 // memory operations, so this update may clobber adjacent values.
515 buffer_allocated[buffer] = false;
516 pthread_cond_signal(&emergency_malloc_wait);
517 pthread_mutex_unlock(&emergency_malloc_lock);
520 static char *alloc_or_die(size_t size)
522 char *buffer = (char*)calloc(1, size);
524 // If calloc() doesn't want to give us any memory, try using an emergency
528 buffer = emergency_malloc(size);
529 // This is only reached if the allocation is greater than 1KB, and
530 // anyone throwing objects that big really should know better.
533 fprintf(stderr, "Out of memory attempting to allocate exception\n");
539 static void free_exception(char *e)
541 // If this allocation is within the address range of the emergency buffer,
542 // don't call free() because it was not allocated with malloc()
543 if ((e > emergency_buffer) &&
544 (e < (emergency_buffer + sizeof(emergency_buffer))))
546 emergency_malloc_free(e);
555 * Allocates an exception structure. Returns a pointer to the space that can
556 * be used to store an object of thrown_size bytes. This function will use an
557 * emergency buffer if malloc() fails, and may block if there are no such
560 extern "C" void *__cxa_allocate_exception(size_t thrown_size)
562 size_t size = thrown_size + sizeof(__cxa_exception);
563 char *buffer = alloc_or_die(size);
564 return buffer+sizeof(__cxa_exception);
567 extern "C" void *__cxa_allocate_dependent_exception(void)
569 size_t size = sizeof(__cxa_dependent_exception);
570 char *buffer = alloc_or_die(size);
571 return buffer+sizeof(__cxa_dependent_exception);
575 * __cxa_free_exception() is called when an exception was thrown in between
576 * calling __cxa_allocate_exception() and actually throwing the exception.
577 * This happens when the object's copy constructor throws an exception.
579 * In this implementation, it is also called by __cxa_end_catch() and during
582 extern "C" void __cxa_free_exception(void *thrown_exception)
584 __cxa_exception *ex = ((__cxa_exception*)thrown_exception) - 1;
585 // Free the object that was thrown, calling its destructor
586 if (0 != ex->exceptionDestructor)
590 ex->exceptionDestructor(thrown_exception);
594 // FIXME: Check that this is really what the spec says to do.
599 free_exception((char*)ex);
602 static void releaseException(__cxa_exception *exception)
604 if (isDependentException(exception->unwindHeader.exception_class))
606 __cxa_free_dependent_exception(exception+1);
609 if (__sync_sub_and_fetch(&exception->referenceCount, 1) == 0)
611 // __cxa_free_exception() expects to be passed the thrown object,
612 // which immediately follows the exception, not the exception
614 __cxa_free_exception(exception+1);
618 void __cxa_free_dependent_exception(void *thrown_exception)
620 __cxa_dependent_exception *ex = ((__cxa_dependent_exception*)thrown_exception) - 1;
621 assert(isDependentException(ex->unwindHeader.exception_class));
622 if (ex->primaryException)
624 releaseException(realExceptionFromException((__cxa_exception*)ex));
626 free_exception((char*)ex);
630 * Callback function used with _Unwind_Backtrace().
632 * Prints a stack trace. Used only for debugging help.
634 * Note: As of FreeBSD 8.1, dladd() still doesn't work properly, so this only
635 * correctly prints function names from public, relocatable, symbols.
637 static _Unwind_Reason_Code trace(struct _Unwind_Context *context, void *c)
641 dladdr((void*)(uintptr_t)__cxa_current_exception_type, &myinfo);
642 void *ip = (void*)_Unwind_GetIP(context);
644 if (dladdr(ip, &info) != 0)
646 if (mylookup == 0 || strcmp(info.dli_fname, myinfo.dli_fname) != 0)
648 printf("%p:%s() in %s\n", ip, info.dli_sname, info.dli_fname);
651 return _URC_CONTINUE_UNWIND;
655 * Report a failure that occurred when attempting to throw an exception.
657 * If the failure happened by falling off the end of the stack without finding
658 * a handler, prints a back trace before aborting.
660 static void report_failure(_Unwind_Reason_Code err, __cxa_exception *thrown_exception)
665 case _URC_FATAL_PHASE1_ERROR:
666 fprintf(stderr, "Fatal error during phase 1 unwinding\n");
669 case _URC_FATAL_PHASE2_ERROR:
670 fprintf(stderr, "Fatal error during phase 2 unwinding\n");
673 case _URC_END_OF_STACK:
674 fprintf(stderr, "Terminating due to uncaught exception %p",
675 (void*)thrown_exception);
676 thrown_exception = realExceptionFromException(thrown_exception);
677 static const __class_type_info *e_ti =
678 static_cast<const __class_type_info*>(&typeid(std::exception));
679 const __class_type_info *throw_ti =
680 dynamic_cast<const __class_type_info*>(thrown_exception->exceptionType);
684 (std::exception*)e_ti->cast_to((void*)(thrown_exception+1),
688 fprintf(stderr, " '%s'", e->what());
692 size_t bufferSize = 128;
693 char *demangled = (char*)malloc(bufferSize);
694 const char *mangled = thrown_exception->exceptionType->name();
696 demangled = __cxa_demangle(mangled, demangled, &bufferSize, &status);
697 fprintf(stderr, " of type %s\n",
698 status == 0 ? (const char*)demangled : mangled);
699 if (status == 0) { free(demangled); }
700 // Print a back trace if no handler is found.
701 // TODO: Make this optional
702 _Unwind_Backtrace(trace, 0);
708 static void throw_exception(__cxa_exception *ex)
710 __cxa_thread_info *info = thread_info();
711 ex->unexpectedHandler = info->unexpectedHandler;
712 if (0 == ex->unexpectedHandler)
714 ex->unexpectedHandler = unexpectedHandler;
716 ex->terminateHandler = info->terminateHandler;
717 if (0 == ex->terminateHandler)
719 ex->terminateHandler = terminateHandler;
721 info->globals.uncaughtExceptions++;
723 _Unwind_Reason_Code err = _Unwind_RaiseException(&ex->unwindHeader);
724 // The _Unwind_RaiseException() function should not return, it should
725 // unwind the stack past this function. If it does return, then something
727 report_failure(err, ex);
732 * ABI function for throwing an exception. Takes the object to be thrown (the
733 * pointer returned by __cxa_allocate_exception()), the type info for the
734 * pointee, and the destructor (if there is one) as arguments.
736 extern "C" void __cxa_throw(void *thrown_exception,
737 std::type_info *tinfo,
740 __cxa_exception *ex = ((__cxa_exception*)thrown_exception) - 1;
742 ex->referenceCount = 1;
743 ex->exceptionType = tinfo;
745 ex->exceptionDestructor = dest;
747 ex->unwindHeader.exception_class = exception_class;
748 ex->unwindHeader.exception_cleanup = exception_cleanup;
753 extern "C" void __cxa_rethrow_primary_exception(void* thrown_exception)
755 if (NULL == thrown_exception) { return; }
757 __cxa_exception *original = exceptionFromPointer(thrown_exception);
758 __cxa_dependent_exception *ex = ((__cxa_dependent_exception*)__cxa_allocate_dependent_exception())-1;
760 ex->primaryException = thrown_exception;
761 __cxa_increment_exception_refcount(thrown_exception);
763 ex->exceptionType = original->exceptionType;
764 ex->unwindHeader.exception_class = dependent_exception_class;
765 ex->unwindHeader.exception_cleanup = dependent_exception_cleanup;
767 throw_exception((__cxa_exception*)ex);
770 extern "C" void *__cxa_current_primary_exception(void)
772 __cxa_eh_globals* globals = __cxa_get_globals();
773 __cxa_exception *ex = globals->caughtExceptions;
775 if (0 == ex) { return NULL; }
776 ex = realExceptionFromException(ex);
777 __sync_fetch_and_add(&ex->referenceCount, 1);
781 extern "C" void __cxa_increment_exception_refcount(void* thrown_exception)
783 if (NULL == thrown_exception) { return; }
784 __cxa_exception *ex = ((__cxa_exception*)thrown_exception) - 1;
785 if (isDependentException(ex->unwindHeader.exception_class)) { return; }
786 __sync_fetch_and_add(&ex->referenceCount, 1);
788 extern "C" void __cxa_decrement_exception_refcount(void* thrown_exception)
790 if (NULL == thrown_exception) { return; }
791 __cxa_exception *ex = ((__cxa_exception*)thrown_exception) - 1;
792 releaseException(ex);
796 * ABI function. Rethrows the current exception. Does not remove the
797 * exception from the stack or decrement its handler count - the compiler is
798 * expected to set the landing pad for this function to the end of the catch
799 * block, and then call _Unwind_Resume() to continue unwinding once
800 * __cxa_end_catch() has been called and any cleanup code has been run.
802 extern "C" void __cxa_rethrow()
804 __cxa_thread_info *ti = thread_info();
805 __cxa_eh_globals *globals = &ti->globals;
806 // Note: We don't remove this from the caught list here, because
807 // __cxa_end_catch will be called when we unwind out of the try block. We
808 // could probably make this faster by providing an alternative rethrow
809 // function and ensuring that all cleanup code is run before calling it, so
810 // we can skip the top stack frame when unwinding.
811 __cxa_exception *ex = globals->caughtExceptions;
816 "Attempting to rethrow an exception that doesn't exist!\n");
820 if (ti->foreign_exception_state != __cxa_thread_info::none)
822 ti->foreign_exception_state = __cxa_thread_info::rethrown;
823 _Unwind_Exception *e = (_Unwind_Exception*)ex;
824 _Unwind_Reason_Code err = _Unwind_Resume_or_Rethrow(e);
825 report_failure(err, ex);
829 assert(ex->handlerCount > 0 && "Rethrowing uncaught exception!");
831 // ex->handlerCount will be decremented in __cxa_end_catch in enclosing
834 // Make handler count negative. This will tell __cxa_end_catch that
835 // exception was rethrown and exception object should not be destroyed
836 // when handler count become zero
837 ex->handlerCount = -ex->handlerCount;
839 // Continue unwinding the stack with this exception. This should unwind to
840 // the place in the caller where __cxa_end_catch() is called. The caller
841 // will then run cleanup code and bounce the exception back with
843 _Unwind_Reason_Code err = _Unwind_Resume_or_Rethrow(&ex->unwindHeader);
844 report_failure(err, ex);
848 * Returns the type_info object corresponding to the filter.
850 static std::type_info *get_type_info_entry(_Unwind_Context *context,
854 // Get the address of the record in the table.
855 dw_eh_ptr_t record = lsda->type_table -
856 dwarf_size_of_fixed_size_field(lsda->type_table_encoding)*filter;
858 dw_eh_ptr_t start = record;
859 // Read the value, but it's probably an indirect reference...
860 int64_t offset = read_value(lsda->type_table_encoding, &record);
862 // (If the entry is 0, don't try to dereference it. That would be bad.)
863 if (offset == 0) { return 0; }
865 // ...so we need to resolve it
866 return (std::type_info*)resolve_indirect_value(context,
867 lsda->type_table_encoding, offset, start);
873 * Checks the type signature found in a handler against the type of the thrown
874 * object. If ex is 0 then it is assumed to be a foreign exception and only
877 static bool check_type_signature(__cxa_exception *ex,
878 const std::type_info *type,
881 void *exception_ptr = (void*)(ex+1);
882 const std::type_info *ex_type = ex ? ex->exceptionType : 0;
884 bool is_ptr = ex ? ex_type->__is_pointer_p() : false;
887 exception_ptr = *(void**)exception_ptr;
889 // Always match a catchall, even with a foreign exception
891 // Note: A 0 here is a catchall, not a cleanup, so we return true to
892 // indicate that we found a catch.
897 adjustedPtr = exception_ptr;
902 if (0 == ex) { return false; }
904 // If the types are the same, no casting is needed.
905 if (*type == *ex_type)
907 adjustedPtr = exception_ptr;
912 if (type->__do_catch(ex_type, &exception_ptr, 1))
914 adjustedPtr = exception_ptr;
921 * Checks whether the exception matches the type specifiers in this action
922 * record. If the exception only matches cleanups, then this returns false.
923 * If it matches a catch (including a catchall) then it returns true.
925 * The selector argument is used to return the selector that is passed in the
926 * second exception register when installing the context.
928 static handler_type check_action_record(_Unwind_Context *context,
930 dw_eh_ptr_t action_record,
932 unsigned long *selector,
935 if (!action_record) { return handler_cleanup; }
936 handler_type found = handler_none;
937 while (action_record)
939 int filter = read_sleb128(&action_record);
940 dw_eh_ptr_t action_record_offset_base = action_record;
941 int displacement = read_sleb128(&action_record);
942 action_record = displacement ?
943 action_record_offset_base + displacement : 0;
944 // We only check handler types for C++ exceptions - foreign exceptions
945 // are only allowed for cleanups and catchalls.
948 std::type_info *handler_type = get_type_info_entry(context, lsda, filter);
949 if (check_type_signature(ex, handler_type, adjustedPtr))
952 return handler_catch;
955 else if (filter < 0 && 0 != ex)
957 bool matched = false;
961 std::type_info *handler_type = get_type_info_entry(context, lsda, filter--);
964 if (check_type_signature(ex, handler_type, adjustedPtr))
969 handler_type = get_type_info_entry(context, lsda, filter--);
972 unsigned char *type_index = ((unsigned char*)lsda->type_table - filter - 1);
975 std::type_info *handler_type = get_type_info_entry(context, lsda, *(type_index++));
976 // If the exception spec matches a permitted throw type for
977 // this function, don't report a handler - we are allowed to
978 // propagate this exception out.
979 if (check_type_signature(ex, handler_type, adjustedPtr))
986 if (matched) { continue; }
987 // If we don't find an allowed exception spec, we need to install
988 // the context for this action. The landing pad will then call the
989 // unexpected exception function. Treat this as a catch
990 return handler_catch;
992 else if (filter == 0)
995 found = handler_cleanup;
1001 static void pushCleanupException(_Unwind_Exception *exceptionObject,
1002 __cxa_exception *ex)
1005 __cxa_thread_info *info = thread_info_fast();
1009 if (ex->cleanupCount > 1)
1011 assert(exceptionObject == info->currentCleanup);
1014 ex->nextCleanup = info->currentCleanup;
1016 info->currentCleanup = exceptionObject;
1021 * The exception personality function. This is referenced in the unwinding
1022 * DWARF metadata and is called by the unwind library for each C++ stack frame
1023 * containing catch or cleanup code.
1026 BEGIN_PERSONALITY_FUNCTION(__gxx_personality_v0)
1027 // This personality function is for version 1 of the ABI. If you use it
1028 // with a future version of the ABI, it won't know what to do, so it
1029 // reports a fatal error and give up before it breaks anything.
1032 return _URC_FATAL_PHASE1_ERROR;
1034 __cxa_exception *ex = 0;
1035 __cxa_exception *realEx = 0;
1037 // If this exception is throw by something else then we can't make any
1038 // assumptions about its layout beyond the fields declared in
1039 // _Unwind_Exception.
1040 bool foreignException = !isCXXException(exceptionClass);
1042 // If this isn't a foreign exception, then we have a C++ exception structure
1043 if (!foreignException)
1045 ex = exceptionFromPointer(exceptionObject);
1046 realEx = realExceptionFromException(ex);
1049 unsigned char *lsda_addr =
1050 (unsigned char*)_Unwind_GetLanguageSpecificData(context);
1052 // No LSDA implies no landing pads - try the next frame
1053 if (0 == lsda_addr) { return continueUnwinding(exceptionObject, context); }
1055 // These two variables define how the exception will be handled.
1056 dwarf_eh_action action = {0};
1057 unsigned long selector = 0;
1059 // During the search phase, we do a complete lookup. If we return
1060 // _URC_HANDLER_FOUND, then the phase 2 unwind will call this function with
1061 // a _UA_HANDLER_FRAME action, telling us to install the handler frame. If
1062 // we return _URC_CONTINUE_UNWIND, we may be called again later with a
1063 // _UA_CLEANUP_PHASE action for this frame.
1065 // The point of the two-stage unwind allows us to entirely avoid any stack
1066 // unwinding if there is no handler. If there are just cleanups found,
1067 // then we can just panic call an abort function.
1069 // Matching a handler is much more expensive than matching a cleanup,
1070 // because we don't need to bother doing type comparisons (or looking at
1071 // the type table at all) for a cleanup. This means that there is no need
1072 // to cache the result of finding a cleanup, because it's (quite) quick to
1073 // look it up again from the action table.
1074 if (actions & _UA_SEARCH_PHASE)
1076 struct dwarf_eh_lsda lsda = parse_lsda(context, lsda_addr);
1078 if (!dwarf_eh_find_callsite(context, &lsda, &action))
1080 // EH range not found. This happens if exception is thrown and not
1081 // caught inside a cleanup (destructor). We should call
1082 // terminate() in this case. The catchTemp (landing pad) field of
1083 // exception object will contain null when personality function is
1084 // called with _UA_HANDLER_FRAME action for phase 2 unwinding.
1085 return _URC_HANDLER_FOUND;
1088 handler_type found_handler = check_action_record(context, &lsda,
1089 action.action_record, realEx, &selector, ex->adjustedPtr);
1090 // If there's no action record, we've only found a cleanup, so keep
1091 // searching for something real
1092 if (found_handler == handler_catch)
1094 // Cache the results for the phase 2 unwind, if we found a handler
1095 // and this is not a foreign exception.
1098 saveLandingPad(context, exceptionObject, ex, selector, action.landing_pad);
1099 ex->languageSpecificData = (const char*)lsda_addr;
1100 ex->actionRecord = (const char*)action.action_record;
1101 // ex->adjustedPtr is set when finding the action record.
1103 return _URC_HANDLER_FOUND;
1105 return continueUnwinding(exceptionObject, context);
1109 // If this is a foreign exception, we didn't have anywhere to cache the
1110 // lookup stuff, so we need to do it again. If this is either a forced
1111 // unwind, a foreign exception, or a cleanup, then we just install the
1112 // context for a cleanup.
1113 if (!(actions & _UA_HANDLER_FRAME))
1116 struct dwarf_eh_lsda lsda = parse_lsda(context, lsda_addr);
1117 dwarf_eh_find_callsite(context, &lsda, &action);
1118 if (0 == action.landing_pad) { return continueUnwinding(exceptionObject, context); }
1119 handler_type found_handler = check_action_record(context, &lsda,
1120 action.action_record, realEx, &selector, ex->adjustedPtr);
1121 // Ignore handlers this time.
1122 if (found_handler != handler_cleanup) { return continueUnwinding(exceptionObject, context); }
1123 pushCleanupException(exceptionObject, ex);
1125 else if (foreignException)
1127 struct dwarf_eh_lsda lsda = parse_lsda(context, lsda_addr);
1128 dwarf_eh_find_callsite(context, &lsda, &action);
1129 check_action_record(context, &lsda, action.action_record, realEx,
1130 &selector, ex->adjustedPtr);
1132 else if (ex->catchTemp == 0)
1134 // Uncaught exception in cleanup, calling terminate
1139 // Restore the saved info if we saved some last time.
1140 loadLandingPad(context, exceptionObject, ex, &selector, &action.landing_pad);
1142 ex->handlerSwitchValue = 0;
1146 _Unwind_SetIP(context, (unsigned long)action.landing_pad);
1147 _Unwind_SetGR(context, __builtin_eh_return_data_regno(0),
1148 (unsigned long)exceptionObject);
1149 _Unwind_SetGR(context, __builtin_eh_return_data_regno(1), selector);
1151 return _URC_INSTALL_CONTEXT;
1155 * ABI function called when entering a catch statement. The argument is the
1156 * pointer passed out of the personality function. This is always the start of
1157 * the _Unwind_Exception object. The return value for this function is the
1158 * pointer to the caught exception, which is either the adjusted pointer (for
1159 * C++ exceptions) of the unadjusted pointer (for foreign exceptions).
1161 #if __GNUC__ > 3 && __GNUC_MINOR__ > 2
1162 extern "C" void *__cxa_begin_catch(void *e) throw()
1164 extern "C" void *__cxa_begin_catch(void *e)
1167 // We can't call the fast version here, because if the first exception that
1168 // we see is a foreign exception then we won't have called it yet.
1169 __cxa_thread_info *ti = thread_info();
1170 __cxa_eh_globals *globals = &ti->globals;
1171 globals->uncaughtExceptions--;
1172 _Unwind_Exception *exceptionObject = (_Unwind_Exception*)e;
1174 if (isCXXException(exceptionObject->exception_class))
1176 __cxa_exception *ex = exceptionFromPointer(exceptionObject);
1178 if (ex->handlerCount == 0)
1180 // Add this to the front of the list of exceptions being handled
1181 // and increment its handler count so that it won't be deleted
1183 ex->nextException = globals->caughtExceptions;
1184 globals->caughtExceptions = ex;
1187 if (ex->handlerCount < 0)
1189 // Rethrown exception is catched before end of catch block.
1190 // Clear the rethrow flag (make value positive) - we are allowed
1191 // to delete this exception at the end of the catch block, as long
1192 // as it isn't thrown again later.
1204 // __cxa_begin_catch() <- we are here
1207 ex->handlerCount = -ex->handlerCount + 1;
1213 ti->foreign_exception_state = __cxa_thread_info::none;
1215 return ex->adjustedPtr;
1219 // If this is a foreign exception, then we need to be able to
1220 // store it. We can't chain foreign exceptions, so we give up
1221 // if there are already some outstanding ones.
1222 if (globals->caughtExceptions != 0)
1226 globals->caughtExceptions = (__cxa_exception*)exceptionObject;
1227 ti->foreign_exception_state = __cxa_thread_info::caught;
1229 // exceptionObject is the pointer to the _Unwind_Exception within the
1230 // __cxa_exception. The throw object is after this
1231 return ((char*)exceptionObject + sizeof(_Unwind_Exception));
1237 * ABI function called when exiting a catch block. This will free the current
1238 * exception if it is no longer referenced in other catch blocks.
1240 extern "C" void __cxa_end_catch()
1242 // We can call the fast version here because the slow version is called in
1243 // __cxa_throw(), which must have been called before we end a catch block
1244 __cxa_thread_info *ti = thread_info_fast();
1245 __cxa_eh_globals *globals = &ti->globals;
1246 __cxa_exception *ex = globals->caughtExceptions;
1248 assert(0 != ex && "Ending catch when no exception is on the stack!");
1250 if (ti->foreign_exception_state != __cxa_thread_info::none)
1252 globals->caughtExceptions = 0;
1253 if (ti->foreign_exception_state != __cxa_thread_info::rethrown)
1255 _Unwind_Exception *e = (_Unwind_Exception*)ti->globals.caughtExceptions;
1256 e->exception_cleanup(_URC_FOREIGN_EXCEPTION_CAUGHT, e);
1258 ti->foreign_exception_state = __cxa_thread_info::none;
1262 bool deleteException = true;
1264 if (ex->handlerCount < 0)
1266 // exception was rethrown. Exception should not be deleted even if
1267 // handlerCount become zero.
1277 // __cxa_end_catch(); <- we are here
1283 deleteException = false;
1290 if (ex->handlerCount == 0)
1292 globals->caughtExceptions = ex->nextException;
1293 if (deleteException)
1295 releaseException(ex);
1301 * ABI function. Returns the type of the current exception.
1303 extern "C" std::type_info *__cxa_current_exception_type()
1305 __cxa_eh_globals *globals = __cxa_get_globals();
1306 __cxa_exception *ex = globals->caughtExceptions;
1307 return ex ? ex->exceptionType : 0;
1311 * ABI function, called when an exception specification is violated.
1313 * This function does not return.
1315 extern "C" void __cxa_call_unexpected(void*exception)
1317 _Unwind_Exception *exceptionObject = (_Unwind_Exception*)exception;
1318 if (exceptionObject->exception_class == exception_class)
1320 __cxa_exception *ex = exceptionFromPointer(exceptionObject);
1321 if (ex->unexpectedHandler)
1323 ex->unexpectedHandler();
1324 // Should not be reached.
1329 // Should not be reached.
1334 * ABI function, returns the adjusted pointer to the exception object.
1336 extern "C" void *__cxa_get_exception_ptr(void *exceptionObject)
1338 return exceptionFromPointer(exceptionObject)->adjustedPtr;
1342 * As an extension, we provide the ability for the unexpected and terminate
1343 * handlers to be thread-local. We default to the standards-compliant
1344 * behaviour where they are global.
1346 static bool thread_local_handlers = false;
1352 * Sets whether unexpected and terminate handlers should be thread-local.
1354 void set_use_thread_local_handlers(bool flag) throw()
1356 thread_local_handlers = flag;
1359 * Sets a thread-local unexpected handler.
1361 unexpected_handler set_unexpected(unexpected_handler f) throw()
1363 static __cxa_thread_info *info = thread_info();
1364 unexpected_handler old = info->unexpectedHandler;
1365 info->unexpectedHandler = f;
1369 * Sets a thread-local terminate handler.
1371 terminate_handler set_terminate(terminate_handler f) throw()
1373 static __cxa_thread_info *info = thread_info();
1374 terminate_handler old = info->terminateHandler;
1375 info->terminateHandler = f;
1383 * Sets the function that will be called when an exception specification is
1386 unexpected_handler set_unexpected(unexpected_handler f) throw()
1388 if (thread_local_handlers) { return pathscale::set_unexpected(f); }
1390 return ATOMIC_SWAP(&unexpectedHandler, f);
1393 * Sets the function that is called to terminate the program.
1395 terminate_handler set_terminate(terminate_handler f) throw()
1397 if (thread_local_handlers) { return pathscale::set_terminate(f); }
1399 return ATOMIC_SWAP(&terminateHandler, f);
1402 * Terminates the program, calling a custom terminate implementation if
1407 static __cxa_thread_info *info = thread_info();
1408 if (0 != info && 0 != info->terminateHandler)
1410 info->terminateHandler();
1411 // Should not be reached - a terminate handler is not expected to
1418 * Called when an unexpected exception is encountered (i.e. an exception
1419 * violates an exception specification). This calls abort() unless a
1420 * custom handler has been set..
1424 static __cxa_thread_info *info = thread_info();
1425 if (0 != info && 0 != info->unexpectedHandler)
1427 info->unexpectedHandler();
1428 // Should not be reached - a terminate handler is not expected to
1432 unexpectedHandler();
1435 * Returns whether there are any exceptions currently being thrown that
1436 * have not been caught. This can occur inside a nested catch statement.
1438 bool uncaught_exception() throw()
1440 __cxa_thread_info *info = thread_info();
1441 return info->globals.uncaughtExceptions != 0;
1444 * Returns the current unexpected handler.
1446 unexpected_handler get_unexpected() throw()
1448 __cxa_thread_info *info = thread_info();
1449 if (info->unexpectedHandler)
1451 return info->unexpectedHandler;
1453 return ATOMIC_LOAD(&unexpectedHandler);
1456 * Returns the current terminate handler.
1458 terminate_handler get_terminate() throw()
1460 __cxa_thread_info *info = thread_info();
1461 if (info->terminateHandler)
1463 return info->terminateHandler;
1465 return ATOMIC_LOAD(&terminateHandler);
1469 extern "C" _Unwind_Exception *__cxa_get_cleanup(void)
1471 __cxa_thread_info *info = thread_info_fast();
1472 _Unwind_Exception *exceptionObject = info->currentCleanup;
1473 if (isCXXException(exceptionObject->exception_class))
1475 __cxa_exception *ex = exceptionFromPointer(exceptionObject);
1477 if (ex->cleanupCount == 0)
1479 info->currentCleanup = ex->nextCleanup;
1480 ex->nextCleanup = 0;
1485 info->currentCleanup = 0;
1487 return exceptionObject;
1491 ".pushsection .text.__cxa_end_cleanup \n"
1492 ".global __cxa_end_cleanup \n"
1493 ".type __cxa_end_cleanup, \"function\" \n"
1494 "__cxa_end_cleanup: \n"
1495 " push {r1, r2, r3, r4} \n"
1496 " bl __cxa_get_cleanup \n"
1497 " push {r1, r2, r3, r4} \n"
1498 " b _Unwind_Resume \n"