src/dyldExceptions.c

   1 /* -*- mode: C++; c-basic-offset: 4; tab-width: 4 -*-
   2  *
   3  * Copyright (c) 2004-2011 Apple Inc. All rights reserved.
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   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,
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  19  * Please see the License for the specific language governing rights and
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  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
  39 extern void _ZN4dyld3logEPKcz(const char*, ...);
  40 extern struct LibSystemHelpers* _ZN4dyld17gLibSystemHelpersE;
  41
  42
  43 #if __LP64__
  44         #define LC_SEGMENT_COMMAND              LC_SEGMENT_64
  45         #define macho_header                    mach_header_64
  46         #define macho_segment_command   segment_command_64
  47         #define macho_section                   section_64
  48         #define getsectdatafromheader   getsectdatafromheader_64
  49 #else
  50         #define LC_SEGMENT_COMMAND              LC_SEGMENT
  51         #define macho_header                    mach_header
  52         #define macho_segment_command   segment_command
  53         #define macho_section                   section
  54 #endif
  55
  56
  57 //
  58 //  The standard versions of __cxa_get_globals*() from libstdc++-static.a cannot be used.
  59 //  On Mac OS X, they use keymgr which dyld does not implement.
  60 //  On iPhoneOS, they use pthread_key_create which dyld cannot use.
  61 //
  62 //   Implement these ourselves to make upcalls into libSystem to malloc and create a pthread key
  63 //
  64 static pthread_key_t                            sCxaKey = 0;
  65 static char                                                     sPreMainCxaGlobals[2*sizeof(long)];
  66
  67 // called by libstdc++.a
  68 char* __cxa_get_globals()
  69 {
  70         // if libSystem.dylib not yet initialized, or is old libSystem, use shared global
  71         if ( (_ZN4dyld17gLibSystemHelpersE == NULL) || (_ZN4dyld17gLibSystemHelpersE->version < 7) )
  72                 return sPreMainCxaGlobals;
  73
  74         if ( sCxaKey == 0 ) {
  75                 // create key
  76                 // we don't need a lock because only one thread can be in dyld at a time
  77                 _ZN4dyld17gLibSystemHelpersE->pthread_key_create(&sCxaKey, &free);
  78         }
  79         char* data = (char*)_ZN4dyld17gLibSystemHelpersE->pthread_getspecific(sCxaKey);
  80         if ( data == NULL ) {
  81                 data = calloc(2,sizeof(void*));
  82                 _ZN4dyld17gLibSystemHelpersE->pthread_setspecific(sCxaKey, data);
  83         }
  84         return data;
  85 }
  86
  87 // called by libstdc++.a
  88 char* __cxa_get_globals_fast()
  89 {
  90         // if libSystem.dylib not yet initialized, or is old libSystem, use shared global
  91         if ( (_ZN4dyld17gLibSystemHelpersE == NULL) || (_ZN4dyld17gLibSystemHelpersE->version < 7) )
  92                 return sPreMainCxaGlobals;
  93
  94         return _ZN4dyld17gLibSystemHelpersE->pthread_getspecific(sCxaKey);
  95 }
  96
  97
  98
  99 #if !__USING_SJLJ_EXCEPTIONS__
 100 //
 101 //  When dyld uses zero-cost exceptions it just needs to implement
 102 //  _dyld_find_unwind_sections to return sections inside dyld proper.
 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 #else
 132 //
 133 //  When dyld uses setjump-longjump exceptions it needs to implement
 134 //  routines to push and pop a stack of _Unwind_FunctionContext.
 135 //
 136
 137 struct _Unwind_FunctionContext
 138 {
 139         // next function in stack of handlers
 140         struct _Unwind_FunctionContext*         prev;
 141
 142 };
 143
 144
 145 static pthread_key_t                                            sThreadChainKey = 0;
 146 static struct _Unwind_FunctionContext*          sStaticThreadChain = NULL;
 147
 148 //
 149 // When libSystem's initializers are run, they call back into dyld's
 150 // registerThreadHelpers which creates a pthread key and calls
 151 //  __Unwind_SjLj_SetThreadKey().
 152 //
 153 void __Unwind_SjLj_SetThreadKey(pthread_key_t key)
 154 {
 155         sThreadChainKey = key;
 156         //_ZN4dyld3logEPKcz("__Unwind_SjLj_SetThreadKey(key=%d), sStaticThreadChain=%p\n", key, sStaticThreadChain);
 157         // switch static chain to be per thread
 158         _ZN4dyld17gLibSystemHelpersE->pthread_setspecific(sThreadChainKey, sStaticThreadChain);
 159         sStaticThreadChain = NULL;
 160         //_ZN4dyld3logEPKcz("__Unwind_SjLj_SetThreadKey(key=%d), result=%d, new top=%p\n", key, result, pthread_getspecific(sThreadChainKey));
 161 }
 162
 163
 164 //static void printChain()
 165 //{
 166 //      _ZN4dyld3logEPKcz("chain: ");
 167 //      struct _Unwind_FunctionContext* start = sStaticThreadChain;
 168 //      if ( sThreadChainKey != 0 ) {
 169 //              start = (struct _Unwind_FunctionContext*)pthread_getspecific(sThreadChainKey);
 170 //      }
 171 //      for (struct _Unwind_FunctionContext* p = start; p != NULL; p = p->prev) {
 172 //              _ZN4dyld3logEPKcz("%p -> ", p);
 173 //      }
 174 //      _ZN4dyld3logEPKcz("\n");
 175 //}
 176
 177
 178 struct _Unwind_FunctionContext* __Unwind_SjLj_GetTopOfFunctionStack()
 179 {
 180         //_ZN4dyld3logEPKcz("__Unwind_SjLj_GetTopOfFunctionStack(),           key=%d, ", sThreadChainKey);
 181         //printChain();
 182         if ( sThreadChainKey != 0 ) {
 183                 return (struct _Unwind_FunctionContext*)pthread_getspecific(sThreadChainKey);
 184         }
 185         else {
 186                 return sStaticThreadChain;
 187         }
 188 }
 189
 190 void __Unwind_SjLj_SetTopOfFunctionStack(struct _Unwind_FunctionContext* fc)
 191 {
 192         //_ZN4dyld3logEPKcz("__Unwind_SjLj_SetTopOfFunctionStack(%p), key=%d, prev=%p\n",
 193         //      fc, sThreadChainKey, (fc != NULL) ? fc->prev : NULL);
 194         if ( sThreadChainKey != 0 )
 195                 _ZN4dyld17gLibSystemHelpersE->pthread_setspecific(sThreadChainKey, fc);
 196         else
 197                 sStaticThreadChain = fc;
 198         //_ZN4dyld3logEPKcz("__Unwind_SjLj_SetTopOfFunctionStack(%p), key=%d, ", fc, sThreadChainKey);
 199         //printChain();
 200 }
 201
 202 #endif
 203
 204
 205