1 /*
2 * Copyright (C) 2008 The Android Open Source Project
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * * Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * * Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in
12 * the documentation and/or other materials provided with the
13 * distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 #include "libc_init_common.h"
30
31 #include <asm/page.h>
32 #include <bionic_tls.h>
33 #include <elf.h>
34 #include <errno.h>
35 #include <stddef.h>
36 #include <stdint.h>
37 #include <stdio.h>
38 #include <stdlib.h>
39 #include <sys/auxv.h>
40 #include <unistd.h>
41
42 #include "atexit.h"
43 #include "private/bionic_auxv.h"
44 #include "private/bionic_ssp.h"
45 #include "private/KernelArgumentBlock.h"
46 #include "pthread_internal.h"
47
48 extern "C" abort_msg_t** __abort_message_ptr;
49 extern "C" unsigned __get_sp(void);
50 extern "C" int __system_properties_init(void);
51
52 // Not public, but well-known in the BSDs.
53 const char* __progname;
54
55 // Declared in <unistd.h>.
56 char** environ;
57
58 // Declared in <private/bionic_ssp.h>.
59 uintptr_t __stack_chk_guard = 0;
60
61 // Declared in <asm/page.h>.
62 unsigned int __page_size = PAGE_SIZE;
63 unsigned int __page_shift = PAGE_SHIFT;
64
65 /* Init TLS for the initial thread. Called by the linker _before_ libc is mapped
66 * in memory. Beware: all writes to libc globals from this function will
67 * apply to linker-private copies and will not be visible from libc later on.
68 *
69 * Note: this function creates a pthread_internal_t for the initial thread and
70 * stores the pointer in TLS, but does not add it to pthread's gThreadList. This
71 * has to be done later from libc itself (see __libc_init_common).
72 *
73 * This function also stores a pointer to the kernel argument block in a TLS slot to be
74 * picked up by the libc constructor.
75 */
__libc_init_tls(KernelArgumentBlock & args)76 void __libc_init_tls(KernelArgumentBlock& args) {
77 __libc_auxv = args.auxv;
78
79 unsigned stack_top = (__get_sp() & ~(PAGE_SIZE - 1)) + PAGE_SIZE;
80 unsigned stack_size = 128 * 1024;
81 unsigned stack_bottom = stack_top - stack_size;
82
83 static void* tls[BIONIC_TLS_SLOTS];
84 static pthread_internal_t thread;
85 thread.tid = gettid();
86 thread.tls = tls;
87 pthread_attr_init(&thread.attr);
88 pthread_attr_setstack(&thread.attr, (void*) stack_bottom, stack_size);
89 _init_thread(&thread, false);
90 __init_tls(&thread);
91 tls[TLS_SLOT_BIONIC_PREINIT] = &args;
92 }
93
__libc_init_common(KernelArgumentBlock & args)94 void __libc_init_common(KernelArgumentBlock& args) {
95 // Initialize various globals.
96 environ = args.envp;
97 errno = 0;
98 __libc_auxv = args.auxv;
99 __progname = args.argv[0] ? args.argv[0] : "<unknown>";
100 __abort_message_ptr = args.abort_message_ptr;
101
102 // AT_RANDOM is a pointer to 16 bytes of randomness on the stack.
103 __stack_chk_guard = *reinterpret_cast<uintptr_t*>(getauxval(AT_RANDOM));
104
105 // Get the main thread from TLS and add it to the thread list.
106 pthread_internal_t* main_thread = __get_thread();
107 main_thread->allocated_on_heap = false;
108 _pthread_internal_add(main_thread);
109
110 __system_properties_init(); // Requires 'environ'.
111 }
112
113 /* This function will be called during normal program termination
114 * to run the destructors that are listed in the .fini_array section
115 * of the executable, if any.
116 *
117 * 'fini_array' points to a list of function addresses. The first
118 * entry in the list has value -1, the last one has value 0.
119 */
__libc_fini(void * array)120 void __libc_fini(void* array) {
121 void** fini_array = reinterpret_cast<void**>(array);
122 const size_t minus1 = ~(size_t)0; /* ensure proper sign extension */
123
124 /* Sanity check - first entry must be -1 */
125 if (array == NULL || (size_t)fini_array[0] != minus1) {
126 return;
127 }
128
129 /* skip over it */
130 fini_array += 1;
131
132 /* Count the number of destructors. */
133 int count = 0;
134 while (fini_array[count] != NULL) {
135 ++count;
136 }
137
138 /* Now call each destructor in reverse order. */
139 while (count > 0) {
140 void (*func)() = (void (*)()) fini_array[--count];
141
142 /* Sanity check, any -1 in the list is ignored */
143 if ((size_t)func == minus1) {
144 continue;
145 }
146
147 func();
148 }
149
150 #ifndef LIBC_STATIC
151 {
152 extern void __libc_postfini(void) __attribute__((weak));
153 if (__libc_postfini) {
154 __libc_postfini();
155 }
156 }
157 #endif
158 }
159