libc_init_common.cpp revision 42b2c6a5eed5e4ef35315b8cd32d1355f12a69b6 
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 <stddef.h>
30#include <stdio.h>
31#include <stdlib.h>
32#include <stdint.h>
33#include <unistd.h>
34#include <elf.h>
35#include <asm/page.h>
36#include "pthread_internal.h"
37#include "atexit.h"
38#include "KernelArgumentBlock.h"
39#include "libc_init_common.h"
40
41#include <bionic_tls.h>
42#include <errno.h>
43#include <private/bionic_auxv.h>
44
45extern "C" unsigned __get_sp(void);
46extern "C" int __system_properties_init(void);
47
48// Not public, but well-known in the BSDs.
49char* __progname;
50
51// Declared in <unistd.h>
52char** environ;
53
54// Declared in <asm/page.h>.
55unsigned int __page_size = PAGE_SIZE;
56unsigned int __page_shift = PAGE_SHIFT;
57
58/* Init TLS for the initial thread. Called by the linker _before_ libc is mapped
59 * in memory. Beware: all writes to libc globals from this function will
60 * apply to linker-private copies and will not be visible from libc later on.
61 *
62 * Note: this function creates a pthread_internal_t for the initial thread and
63 * stores the pointer in TLS, but does not add it to pthread's gThreadList. This
64 * has to be done later from libc itself (see __libc_init_common).
65 *
66 * This function also stores a pointer to the kernel argument block in a TLS slot to be
67 * picked up by the libc constructor.
68 */
69extern "C" void __libc_init_tls(void* kernel_argument_block) {
70  unsigned stack_top = (__get_sp() & ~(PAGE_SIZE - 1)) + PAGE_SIZE;
71  unsigned stack_size = 128 * 1024;
72  unsigned stack_bottom = stack_top - stack_size;
73
74  pthread_attr_t thread_attr;
75  pthread_attr_init(&thread_attr);
76  pthread_attr_setstack(&thread_attr, (void*) stack_bottom, stack_size);
77
78  static pthread_internal_t thread;
79  _init_thread(&thread, gettid(), &thread_attr, (void*) stack_bottom, false);
80
81  static void* tls_area[BIONIC_TLS_SLOTS];
82  __init_tls(tls_area, &thread);
83  tls_area[TLS_SLOT_BIONIC_PREINIT] = kernel_argument_block;
84}
85
86void __libc_init_common(KernelArgumentBlock& args) {
87  // Initialize various globals.
88  environ = args.envp;
89  errno = 0;
90  __libc_auxv = args.auxv;
91  __progname = args.argv[0] ? args.argv[0] : const_cast<char*>("<unknown>");
92
93  // Get the main thread from TLS and add it to the thread list.
94  pthread_internal_t* main_thread = __get_thread();
95  main_thread->allocated_on_heap = false;
96  _pthread_internal_add(main_thread);
97
98  __system_properties_init(); // Requires 'environ'.
99}
100
101/* This function will be called during normal program termination
102 * to run the destructors that are listed in the .fini_array section
103 * of the executable, if any.
104 *
105 * 'fini_array' points to a list of function addresses. The first
106 * entry in the list has value -1, the last one has value 0.
107 */
108void __libc_fini(void* array) {
109  void** fini_array = reinterpret_cast<void**>(array);
110  const size_t minus1 = ~(size_t)0; /* ensure proper sign extension */
111
112  /* Sanity check - first entry must be -1 */
113  if (array == NULL || (size_t)fini_array[0] != minus1) {
114    return;
115  }
116
117  /* skip over it */
118  fini_array += 1;
119
120  /* Count the number of destructors. */
121  int count = 0;
122  while (fini_array[count] != NULL) {
123    ++count;
124  }
125
126  /* Now call each destructor in reverse order. */
127  while (count > 0) {
128    void (*func)() = (void (*)()) fini_array[--count];
129
130    /* Sanity check, any -1 in the list is ignored */
131    if ((size_t)func == minus1) {
132      continue;
133    }
134
135    func();
136  }
137
138#ifndef LIBC_STATIC
139  {
140    extern void __libc_postfini(void) __attribute__((weak));
141    if (__libc_postfini) {
142      __libc_postfini();
143    }
144  }
145#endif
146}
147