libc_init_common.cpp revision 322e7bce235ec6e3f82f65669423a1d9e997b51e 
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 <sys/time.h>
41#include <sys/resource.h>
42#include <unistd.h>
43
44#include "atexit.h"
45#include "private/bionic_auxv.h"
46#include "private/bionic_ssp.h"
47#include "private/KernelArgumentBlock.h"
48#include "pthread_internal.h"
49
50extern "C" abort_msg_t** __abort_message_ptr;
51extern "C" unsigned __get_sp(void);
52extern "C" int __system_properties_init(void);
53
54// Not public, but well-known in the BSDs.
55const char* __progname;
56
57// Declared in <unistd.h>.
58char** environ;
59
60// Declared in <private/bionic_ssp.h>.
61uintptr_t __stack_chk_guard = 0;
62
63// Declared in <asm/page.h>.
64unsigned int __page_size = PAGE_SIZE;
65unsigned int __page_shift = PAGE_SHIFT;
66
67static size_t get_stack_size() {
68  const size_t minimal_stack_size = 128 * 1024;
69  size_t stack_size = minimal_stack_size;
70  struct rlimit stack_limit;
71  int rlimit_result = getrlimit(RLIMIT_STACK, &stack_limit);
72  if ((rlimit_result == 0) && (stack_limit.rlim_cur != RLIM_INFINITY)) {
73    stack_size = stack_limit.rlim_cur;
74    stack_size = (stack_size & ~(PAGE_SIZE - 1));
75    if (stack_size < minimal_stack_size) {
76      stack_size = minimal_stack_size;
77    }
78  }
79  return stack_size;
80}
81
82/* Init TLS for the initial thread. Called by the linker _before_ libc is mapped
83 * in memory. Beware: all writes to libc globals from this function will
84 * apply to linker-private copies and will not be visible from libc later on.
85 *
86 * Note: this function creates a pthread_internal_t for the initial thread and
87 * stores the pointer in TLS, but does not add it to pthread's gThreadList. This
88 * has to be done later from libc itself (see __libc_init_common).
89 *
90 * This function also stores a pointer to the kernel argument block in a TLS slot to be
91 * picked up by the libc constructor.
92 */
93void __libc_init_tls(KernelArgumentBlock& args) {
94  __libc_auxv = args.auxv;
95
96  uintptr_t stack_top = (__get_sp() & ~(PAGE_SIZE - 1)) + PAGE_SIZE;
97  size_t stack_size = get_stack_size();
98  uintptr_t stack_bottom = stack_top - stack_size;
99
100  static void* tls[BIONIC_TLS_SLOTS];
101  static pthread_internal_t thread;
102  thread.tid = gettid();
103  thread.tls = tls;
104  pthread_attr_init(&thread.attr);
105  pthread_attr_setstack(&thread.attr, (void*) stack_bottom, stack_size);
106  _init_thread(&thread, false);
107  __init_tls(&thread);
108  tls[TLS_SLOT_BIONIC_PREINIT] = &args;
109}
110
111void __libc_init_common(KernelArgumentBlock& args) {
112  // Initialize various globals.
113  environ = args.envp;
114  errno = 0;
115  __libc_auxv = args.auxv;
116  __progname = args.argv[0] ? args.argv[0] : "<unknown>";
117  __abort_message_ptr = args.abort_message_ptr;
118
119  // AT_RANDOM is a pointer to 16 bytes of randomness on the stack.
120  __stack_chk_guard = *reinterpret_cast<uintptr_t*>(getauxval(AT_RANDOM));
121
122  // Get the main thread from TLS and add it to the thread list.
123  pthread_internal_t* main_thread = __get_thread();
124  main_thread->allocated_on_heap = false;
125  _pthread_internal_add(main_thread);
126
127  __system_properties_init(); // Requires 'environ'.
128}
129
130/* This function will be called during normal program termination
131 * to run the destructors that are listed in the .fini_array section
132 * of the executable, if any.
133 *
134 * 'fini_array' points to a list of function addresses. The first
135 * entry in the list has value -1, the last one has value 0.
136 */
137void __libc_fini(void* array) {
138  void** fini_array = reinterpret_cast<void**>(array);
139  const size_t minus1 = ~(size_t)0; /* ensure proper sign extension */
140
141  /* Sanity check - first entry must be -1 */
142  if (array == NULL || (size_t)fini_array[0] != minus1) {
143    return;
144  }
145
146  /* skip over it */
147  fini_array += 1;
148
149  /* Count the number of destructors. */
150  int count = 0;
151  while (fini_array[count] != NULL) {
152    ++count;
153  }
154
155  /* Now call each destructor in reverse order. */
156  while (count > 0) {
157    void (*func)() = (void (*)()) fini_array[--count];
158
159    /* Sanity check, any -1 in the list is ignored */
160    if ((size_t)func == minus1) {
161      continue;
162    }
163
164    func();
165  }
166
167#ifndef LIBC_STATIC
168  {
169    extern void __libc_postfini(void) __attribute__((weak));
170    if (__libc_postfini) {
171      __libc_postfini();
172    }
173  }
174#endif
175}
176