libc_init_common.cpp revision 40eabe24e4e3ae8ebe437f1f4e43cf39cbba2e9e 
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.
49const char* __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 */
69void __libc_init_tls(KernelArgumentBlock& args) {
70  __libc_auxv = args.auxv;
71
72  unsigned stack_top = (__get_sp() & ~(PAGE_SIZE - 1)) + PAGE_SIZE;
73  unsigned stack_size = 128 * 1024;
74  unsigned stack_bottom = stack_top - stack_size;
75
76  static void* tls[BIONIC_TLS_SLOTS];
77  static pthread_internal_t thread;
78  thread.tid = gettid();
79  thread.tls = tls;
80  pthread_attr_init(&thread.attr);
81  pthread_attr_setstack(&thread.attr, (void*) stack_bottom, stack_size);
82  _init_thread(&thread, false);
83  __init_tls(&thread);
84  tls[TLS_SLOT_BIONIC_PREINIT] = &args;
85}
86
87void __libc_init_common(KernelArgumentBlock& args) {
88  // Initialize various globals.
89  environ = args.envp;
90  errno = 0;
91  __libc_auxv = args.auxv;
92  __progname = args.argv[0] ? args.argv[0] : "<unknown>";
93
94  // Get the main thread from TLS and add it to the thread list.
95  pthread_internal_t* main_thread = __get_thread();
96  main_thread->allocated_on_heap = false;
97  _pthread_internal_add(main_thread);
98
99  __system_properties_init(); // Requires 'environ'.
100}
101
102/* This function will be called during normal program termination
103 * to run the destructors that are listed in the .fini_array section
104 * of the executable, if any.
105 *
106 * 'fini_array' points to a list of function addresses. The first
107 * entry in the list has value -1, the last one has value 0.
108 */
109void __libc_fini(void* array) {
110  void** fini_array = reinterpret_cast<void**>(array);
111  const size_t minus1 = ~(size_t)0; /* ensure proper sign extension */
112
113  /* Sanity check - first entry must be -1 */
114  if (array == NULL || (size_t)fini_array[0] != minus1) {
115    return;
116  }
117
118  /* skip over it */
119  fini_array += 1;
120
121  /* Count the number of destructors. */
122  int count = 0;
123  while (fini_array[count] != NULL) {
124    ++count;
125  }
126
127  /* Now call each destructor in reverse order. */
128  while (count > 0) {
129    void (*func)() = (void (*)()) fini_array[--count];
130
131    /* Sanity check, any -1 in the list is ignored */
132    if ((size_t)func == minus1) {
133      continue;
134    }
135
136    func();
137  }
138
139#ifndef LIBC_STATIC
140  {
141    extern void __libc_postfini(void) __attribute__((weak));
142    if (__libc_postfini) {
143      __libc_postfini();
144    }
145  }
146#endif
147}
148