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      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 #pragma once
     30 
     31 #include <locale.h>
     32 #include <mntent.h>
     33 #include <stdio.h>
     34 #include <sys/cdefs.h>
     35 #include <sys/param.h>
     36 
     37 #include "bionic_asm_tls.h"
     38 #include "bionic_macros.h"
     39 #include "__get_tls.h"
     40 #include "grp_pwd.h"
     41 
     42 /** WARNING WARNING WARNING
     43  **
     44  ** This header file is *NOT* part of the public Bionic ABI/API and should not
     45  ** be used/included by user-serviceable parts of the system (e.g.
     46  ** applications).
     47  **/
     48 
     49 class pthread_internal_t;
     50 
     51 // This struct is small, so the linker can allocate a temporary copy on its
     52 // stack. It can't be combined with pthread_internal_t because:
     53 //  - native bridge requires pthread_internal_t to have the same layout across
     54 //    architectures, and
     55 //  - On x86, this struct would have to be placed at the front of
     56 //    pthread_internal_t, moving fields like `tid`.
     57 //  - We'd like to avoid having a temporary pthread_internal_t object that
     58 //    needs to be transferred once the final size of static TLS is known.
     59 struct bionic_tcb {
     60   void* raw_slots_storage[BIONIC_TLS_SLOTS];
     61 
     62   // Return a reference to a slot given its TP-relative TLS_SLOT_xxx index.
     63   // The thread pointer (i.e. __get_tls()) points at &tls_slot(0).
     64   void*& tls_slot(size_t tpindex) {
     65     return raw_slots_storage[tpindex - MIN_TLS_SLOT];
     66   }
     67 
     68   // Initialize the main thread's final object using its bootstrap object.
     69   void copy_from_bootstrap(const bionic_tcb* boot) {
     70     // Copy everything. Problematic slots will be reinitialized.
     71     *this = *boot;
     72   }
     73 
     74   pthread_internal_t* thread() {
     75     return static_cast<pthread_internal_t*>(tls_slot(TLS_SLOT_THREAD_ID));
     76   }
     77 };
     78 
     79 /*
     80  * Bionic uses some pthread keys internally. All pthread keys used internally
     81  * should be created in constructors, except for keys that may be used in or
     82  * before constructors.
     83  *
     84  * We need to manually maintain the count of pthread keys used internally, but
     85  * pthread_test should fail if we forget.
     86  *
     87  * These are the pthread keys currently used internally by libc:
     88  *  _res_key               libc (constructor in BSD code)
     89  */
     90 
     91 #define LIBC_PTHREAD_KEY_RESERVED_COUNT 1
     92 
     93 /* Internally, jemalloc uses a single key for per thread data. */
     94 #define JEMALLOC_PTHREAD_KEY_RESERVED_COUNT 1
     95 #define BIONIC_PTHREAD_KEY_RESERVED_COUNT (LIBC_PTHREAD_KEY_RESERVED_COUNT + JEMALLOC_PTHREAD_KEY_RESERVED_COUNT)
     96 
     97 /*
     98  * Maximum number of pthread keys allocated.
     99  * This includes pthread keys used internally and externally.
    100  */
    101 #define BIONIC_PTHREAD_KEY_COUNT (BIONIC_PTHREAD_KEY_RESERVED_COUNT + PTHREAD_KEYS_MAX)
    102 
    103 class pthread_key_data_t {
    104  public:
    105   uintptr_t seq; // Use uintptr_t just for alignment, as we use pointer below.
    106   void* data;
    107 };
    108 
    109 // ~3 pages. This struct is allocated as static TLS memory (i.e. at a fixed
    110 // offset from the thread pointer).
    111 struct bionic_tls {
    112   pthread_key_data_t key_data[BIONIC_PTHREAD_KEY_COUNT];
    113 
    114   locale_t locale;
    115 
    116   char basename_buf[MAXPATHLEN];
    117   char dirname_buf[MAXPATHLEN];
    118 
    119   mntent mntent_buf;
    120   char mntent_strings[BUFSIZ];
    121 
    122   char ptsname_buf[32];
    123   char ttyname_buf[64];
    124 
    125   char strerror_buf[NL_TEXTMAX];
    126   char strsignal_buf[NL_TEXTMAX];
    127 
    128   group_state_t group;
    129   passwd_state_t passwd;
    130 
    131   // Initialize the main thread's final object using its bootstrap object.
    132   void copy_from_bootstrap(const bionic_tls* boot __attribute__((unused))) {
    133     // Nothing in bionic_tls needs to be preserved in the transition to the
    134     // final TLS objects, so don't copy anything.
    135   }
    136 };
    137 
    138 class KernelArgumentBlock;
    139 extern "C" void __libc_init_main_thread_early(const KernelArgumentBlock& args, bionic_tcb* temp_tcb);
    140 extern "C" void __libc_init_main_thread_late();
    141 extern "C" void __libc_init_main_thread_final();
    142