1 // -*- C++ -*- Helpers for calling unextected and terminate
2 // Copyright (C) 2001-2018 Free Software Foundation, Inc.
3 //
4 // This file is part of GCC.
5 //
6 // GCC is free software; you can redistribute it and/or modify
7 // it under the terms of the GNU General Public License as published by
8 // the Free Software Foundation; either version 3, or (at your option)
9 // any later version.
10 //
11 // GCC is distributed in the hope that it will be useful,
12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14 // GNU General Public License for more details.
15 //
16 // Under Section 7 of GPL version 3, you are granted additional
17 // permissions described in the GCC Runtime Library Exception, version
18 // 3.1, as published by the Free Software Foundation.
19 
20 // You should have received a copy of the GNU General Public License and
21 // a copy of the GCC Runtime Library Exception along with this program;
22 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
23 // <http://www.gnu.org/licenses/>.
24 
25 #include <bits/c++config.h>
26 #include <cstdlib>
27 #include <bits/exception_defines.h>
28 #include "unwind-cxx.h"
29 
30 using namespace __cxxabiv1;
31 
32 #include "unwind-pe.h"
33 
34 
35 // Helper routine for when the exception handling code needs to call
36 // terminate.
37 
38 extern "C" void
__cxa_call_terminate(_Unwind_Exception * ue_header)39 __cxa_call_terminate(_Unwind_Exception* ue_header) throw ()
40 {
41 
42   if (ue_header)
43     {
44       // terminate is classed as a catch handler.
45       __cxa_begin_catch(ue_header);
46 
47       // Call the terminate handler that was in effect when we threw this
48       // exception.  */
49       if (__is_gxx_exception_class(ue_header->exception_class))
50 	{
51 	  __cxa_exception* xh;
52 
53 	  xh = __get_exception_header_from_ue(ue_header);
54 	  __terminate(xh->terminateHandler);
55 	}
56     }
57   /* Call the global routine if we don't have anything better.  */
58   std::terminate();
59 }
60 
61 
62 #ifdef __ARM_EABI_UNWINDER__
63 // The ARM EABI __cxa_call_unexpected has the same semantics as the generic
64 // routine, but the exception specification has a different format.
65 extern "C" void
__cxa_call_unexpected(void * exc_obj_in)66 __cxa_call_unexpected(void* exc_obj_in)
67 {
68   _Unwind_Exception* exc_obj
69     = reinterpret_cast<_Unwind_Exception*>(exc_obj_in);
70 
71   int rtti_count = 0;
72   _Unwind_Word rtti_stride = 0;
73   _Unwind_Word* rtti_list = NULL;
74   _Unwind_Ptr rtti_base = 0;
75   bool foreign_exception;
76   std::unexpected_handler unexpectedHandler = NULL;
77   std::terminate_handler terminateHandler = NULL;
78   __cxa_exception* xh;
79   if (__is_gxx_exception_class(exc_obj->exception_class))
80     {
81       // Save data from the EO, which may be clobbered by _cxa_begin_catch.
82       xh = __get_exception_header_from_ue(exc_obj);
83       unexpectedHandler = xh->unexpectedHandler;
84       terminateHandler = xh->terminateHandler;
85       rtti_count = exc_obj->barrier_cache.bitpattern[1];
86       rtti_base = (_Unwind_Ptr) exc_obj->barrier_cache.bitpattern[2];
87       rtti_stride = exc_obj->barrier_cache.bitpattern[3];
88       rtti_list = (_Unwind_Word*) exc_obj->barrier_cache.bitpattern[4];
89       foreign_exception = false;
90     }
91   else
92     foreign_exception = true;
93 
94   /* This must be called after extracting data from the EO, but before
95      calling unexpected().   */
96   __cxa_begin_catch(exc_obj);
97 
98   // This function is a handler for our exception argument.  If we exit
99   // by throwing a different exception, we'll need the original cleaned up.
100   struct end_catch_protect
101   {
102     end_catch_protect() { }
103     ~end_catch_protect() { __cxa_end_catch(); }
104   } end_catch_protect_obj;
105 
106 
107   __try
108     {
109       if (foreign_exception)
110 	std::unexpected();
111       else
112 	__unexpected(unexpectedHandler);
113     }
114   __catch(...)
115     {
116       /* See if the new exception matches the rtti list.  */
117       if (foreign_exception)
118 	std::terminate();
119 
120       // Get the exception thrown from unexpected.
121 
122       __cxa_eh_globals* globals = __cxa_get_globals_fast();
123       __cxa_exception* new_xh = globals->caughtExceptions;
124       void* new_ptr = __get_object_from_ambiguous_exception (new_xh);
125       const std::type_info* catch_type;
126       int n;
127       bool bad_exception_allowed = false;
128       const std::type_info& bad_exc = typeid(std::bad_exception);
129 
130       // Check the new exception against the rtti list
131       for (n = 0; n < rtti_count; n++)
132 	{
133 	  _Unwind_Word offset;
134 
135 	  offset = (_Unwind_Word) &rtti_list[n * (rtti_stride >> 2)];
136 	  offset = _Unwind_decode_typeinfo_ptr(rtti_base, offset);
137 	  catch_type = (const std::type_info*) (offset);
138 
139 	  if (__cxa_type_match(&new_xh->unwindHeader, catch_type, false,
140 			       &new_ptr) != ctm_failed)
141 	    __throw_exception_again;
142 
143 	  // If the exception spec allows std::bad_exception, throw that.
144 	  // We don't have a thrown object to compare against, but since
145 	  // bad_exception doesn't have virtual bases, that's OK; just pass NULL.
146 	  void* obj = NULL;
147 	  if (catch_type->__do_catch(&bad_exc, &obj, 1))
148 	    bad_exception_allowed = true;
149 	}
150 
151       // If the exception spec allows std::bad_exception, throw that.
152 #if __cpp_exceptions
153       if (bad_exception_allowed)
154 	throw std::bad_exception();
155 #endif
156 
157       // Otherwise, die.
158       __terminate(terminateHandler);
159     }
160 }
161 #endif // __ARM_EABI_UNWINDER__
162