src/dyldExceptions.c

   1 /* -*- mode: C++; c-basic-offset: 4; tab-width: 4 -*-
   2  *
   3  * Copyright (c) 2004-2011 Apple Inc. All rights reserved.
   4  *
   5  * @APPLE_LICENSE_HEADER_START@
   6  *
   7  * This file contains Original Code and/or Modifications of Original Code
   8  * as defined in and that are subject to the Apple Public Source License
   9  * Version 2.0 (the 'License'). You may not use this file except in
  10  * compliance with the License. Please obtain a copy of the License at
  11  * http://www.opensource.apple.com/apsl/ and read it before using this
  12  * file.
  13  *
  14  * The Original Code and all software distributed under the License are
  15  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  16  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  17  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  19  * Please see the License for the specific language governing rights and
  20  * limitations under the License.
  21  *
  22  * @APPLE_LICENSE_HEADER_END@
  23  */
  24
  25 #include <stdlib.h>
  26 #include <string.h>
  27 #include <mach-o/loader.h>
  28 #include <unistd.h>
  29 #include <stdio.h>
  30 #include <stdbool.h>
  31 #include <stdarg.h>
  32 #include <pthread.h>
  33 #include <Availability.h>
  34
  35 #include "mach-o/dyld_priv.h"
  36 #include "dyldLibSystemInterface.h"
  37
  38 extern void _ZN4dyld3logEPKcz(const char*, ...);
  39 extern struct LibSystemHelpers* _ZN4dyld17gLibSystemHelpersE;
  40
  41
  42 #if __LP64__
  43         #define LC_SEGMENT_COMMAND              LC_SEGMENT_64
  44         #define macho_header                    mach_header_64
  45         #define macho_segment_command   segment_command_64
  46         #define macho_section                   section_64
  47         #define getsectdatafromheader   getsectdatafromheader_64
  48 #else
  49         #define LC_SEGMENT_COMMAND              LC_SEGMENT
  50         #define macho_header                    mach_header
  51         #define macho_segment_command   segment_command
  52         #define macho_section                   section
  53 #endif
  54
  55
  56 //
  57 //  The standard versions of __cxa_get_globals*() from libstdc++-static.a cannot be used.
  58 //  On Mac OS X, they use keymgr which dyld does not implement.
  59 //  On iPhoneOS, they use pthread_key_create which dyld cannot use.
  60 //
  61 //   Implement these ourselves to make upcalls into libSystem to malloc and create a pthread key
  62 //
  63 static pthread_key_t                            sCxaKey = 0;
  64 static char                                                     sPreMainCxaGlobals[2*sizeof(long)];
  65
  66 // called by libstdc++.a
  67 char* __cxa_get_globals()
  68 {
  69         // if libSystem.dylib not yet initialized, or is old libSystem, use shared global
  70         if ( (_ZN4dyld17gLibSystemHelpersE == NULL) || (_ZN4dyld17gLibSystemHelpersE->version < 7) )
  71                 return sPreMainCxaGlobals;
  72
  73         if ( sCxaKey == 0 ) {
  74                 // create key
  75                 // we don't need a lock because only one thread can be in dyld at a time
  76                 _ZN4dyld17gLibSystemHelpersE->pthread_key_create(&sCxaKey, &free);
  77         }
  78         char* data = (char*)_ZN4dyld17gLibSystemHelpersE->pthread_getspecific(sCxaKey);
  79         if ( data == NULL ) {
  80                 data = calloc(2,sizeof(void*));
  81                 _ZN4dyld17gLibSystemHelpersE->pthread_setspecific(sCxaKey, data);
  82         }
  83         return data;
  84 }
  85
  86 // called by libstdc++.a
  87 char* __cxa_get_globals_fast()
  88 {
  89         // if libSystem.dylib not yet initialized, or is old libSystem, use shared global
  90         if ( (_ZN4dyld17gLibSystemHelpersE == NULL) || (_ZN4dyld17gLibSystemHelpersE->version < 7) )
  91                 return sPreMainCxaGlobals;
  92
  93         return _ZN4dyld17gLibSystemHelpersE->pthread_getspecific(sCxaKey);
  94 }
  95
  96
  97
  98
  99 #if !__arm__
 100 //
 101 //  The intel versions of dyld uses zero-cost exceptions which are handled by
 102 //  linking with a special copy of libunwind.a
 103 //
 104
 105 extern void*  ehStart  __asm("section$start$__TEXT$__eh_frame");
 106 extern void*  ehEnd    __asm("section$end$__TEXT$__eh_frame");
 107 extern void*  uwStart  __asm("section$start$__TEXT$__unwind_info");
 108 extern void*  uwEnd    __asm("section$end$__TEXT$__unwind_info");
 109
 110 extern void*  textStart __asm("section$start$__TEXT$__text");
 111 extern void*  textEnd   __asm("section$end$__TEXT$__text");
 112
 113 extern void* __dso_handle;
 114
 115 // called by libuwind code to find unwind information sections in dyld
 116 bool _dyld_find_unwind_sections(void* addr, struct dyld_unwind_sections* info)
 117 {
 118         if ( ((void*)&textStart < addr) && (addr < (void*)&textEnd) ) {
 119         info->mh = (struct mach_header*)&__dso_handle;
 120         info->dwarf_section = &ehStart;
 121         info->dwarf_section_length = ((char*)&ehEnd - (char*)&ehStart);
 122         info->compact_unwind_section = &uwStart;
 123         info->compact_unwind_section_length = ((char*)&uwEnd - (char*)&uwStart);
 124                 return true;
 125         }
 126         else {
 127                 return false;
 128         }
 129 }
 130
 131 #endif // !__arm__
 132
 133
 134 #if __arm__
 135
 136 struct _Unwind_FunctionContext
 137 {
 138         // next function in stack of handlers
 139         struct _Unwind_FunctionContext*         prev;
 140
 141 };
 142
 143
 144 static pthread_key_t                                            sThreadChainKey = 0;
 145 static struct _Unwind_FunctionContext*          sStaticThreadChain = NULL;
 146
 147 //
 148 // When libSystem's initializers are run, they call back into dyld's
 149 // registerThreadHelpers which creates a pthread key and calls
 150 //  __Unwind_SjLj_SetThreadKey().
 151 //
 152 void __Unwind_SjLj_SetThreadKey(pthread_key_t key)
 153 {
 154         sThreadChainKey = key;
 155         //_ZN4dyld3logEPKcz("__Unwind_SjLj_SetThreadKey(key=%d), sStaticThreadChain=%p\n", key, sStaticThreadChain);
 156         // switch static chain to be per thread
 157         _ZN4dyld17gLibSystemHelpersE->pthread_setspecific(sThreadChainKey, sStaticThreadChain);
 158         sStaticThreadChain = NULL;
 159         //_ZN4dyld3logEPKcz("__Unwind_SjLj_SetThreadKey(key=%d), result=%d, new top=%p\n", key, result, pthread_getspecific(sThreadChainKey));
 160 }
 161
 162
 163 //static void printChain()
 164 //{
 165 //      _ZN4dyld3logEPKcz("chain: ");
 166 //      struct _Unwind_FunctionContext* start = sStaticThreadChain;
 167 //      if ( sThreadChainKey != 0 ) {
 168 //              start = (struct _Unwind_FunctionContext*)pthread_getspecific(sThreadChainKey);
 169 //      }
 170 //      for (struct _Unwind_FunctionContext* p = start; p != NULL; p = p->prev) {
 171 //              _ZN4dyld3logEPKcz("%p -> ", p);
 172 //      }
 173 //      _ZN4dyld3logEPKcz("\n");
 174 //}
 175
 176
 177 struct _Unwind_FunctionContext* __Unwind_SjLj_GetTopOfFunctionStack()
 178 {
 179         //_ZN4dyld3logEPKcz("__Unwind_SjLj_GetTopOfFunctionStack(),           key=%d, ", sThreadChainKey);
 180         //printChain();
 181         if ( sThreadChainKey != 0 ) {
 182                 return (struct _Unwind_FunctionContext*)pthread_getspecific(sThreadChainKey);
 183         }
 184         else {
 185                 return sStaticThreadChain;
 186         }
 187 }
 188
 189 void __Unwind_SjLj_SetTopOfFunctionStack(struct _Unwind_FunctionContext* fc)
 190 {
 191         //_ZN4dyld3logEPKcz("__Unwind_SjLj_SetTopOfFunctionStack(%p), key=%d, prev=%p\n",
 192         //      fc, sThreadChainKey, (fc != NULL) ? fc->prev : NULL);
 193         if ( sThreadChainKey != 0 )
 194                 _ZN4dyld17gLibSystemHelpersE->pthread_setspecific(sThreadChainKey, fc);
 195         else
 196                 sStaticThreadChain = fc;
 197         //_ZN4dyld3logEPKcz("__Unwind_SjLj_SetTopOfFunctionStack(%p), key=%d, ", fc, sThreadChainKey);
 198         //printChain();
 199 }
 200
 201 #endif
 202
 203
 204