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
39extern void _ZN4dyld3logEPKcz(const char*, ...);
40extern 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//
64static pthread_key_t				sCxaKey = 0;
65static char							sPreMainCxaGlobals[2*sizeof(long)];
66
67// called by libstdc++.a
68char* __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
88char* __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
105extern void*  ehStart  __asm("section$start$__TEXT$__eh_frame");
106extern void*  ehEnd    __asm("section$end$__TEXT$__eh_frame");
107extern void*  uwStart  __asm("section$start$__TEXT$__unwind_info");
108extern void*  uwEnd    __asm("section$end$__TEXT$__unwind_info");
109
110extern void*  textStart __asm("section$start$__TEXT$__text");
111extern void*  textEnd   __asm("section$end$__TEXT$__text");
112
113extern void* __dso_handle;
114
115// called by libuwind code to find unwind information sections in dyld
116bool _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
137struct _Unwind_FunctionContext
138{
139	// next function in stack of handlers
140	struct _Unwind_FunctionContext*		prev;
141
142};
143
144
145static pthread_key_t						sThreadChainKey = 0;
146static 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//
153void __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
178struct _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
190void __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
206