Home | History | Annotate | Download | only in bionic 
      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 <pthread.h>
     32 #include <stdatomic.h>
     33 
     34 #include "private/bionic_lock.h"
     35 #include "private/bionic_tls.h"
     36 
     37 // Has the thread been detached by a pthread_join or pthread_detach call?
     38 #define PTHREAD_ATTR_FLAG_DETACHED 0x00000001
     39 
     40 // Has the thread been joined by another thread?
     41 #define PTHREAD_ATTR_FLAG_JOINED 0x00000002
     42 
     43 // Used for pthread_attr_setinheritsched. We need two flags for this apparent
     44 // boolean because our historical behavior matches neither of the POSIX choices.
     45 #define PTHREAD_ATTR_FLAG_INHERIT 0x00000004
     46 #define PTHREAD_ATTR_FLAG_EXPLICIT 0x00000008
     47 
     48 class pthread_key_data_t {
     49  public:
     50   uintptr_t seq; // Use uintptr_t just for alignment, as we use pointer below.
     51   void* data;
     52 };
     53 
     54 enum ThreadJoinState {
     55   THREAD_NOT_JOINED,
     56   THREAD_EXITED_NOT_JOINED,
     57   THREAD_JOINED,
     58   THREAD_DETACHED
     59 };
     60 
     61 class thread_local_dtor;
     62 
     63 class pthread_internal_t {
     64  public:
     65   class pthread_internal_t* next;
     66   class pthread_internal_t* prev;
     67 
     68   pid_t tid;
     69 
     70  private:
     71   pid_t cached_pid_;
     72 
     73  public:
     74   pid_t invalidate_cached_pid() {
     75     pid_t old_value;
     76     get_cached_pid(&old_value);
     77     set_cached_pid(0);
     78     return old_value;
     79   }
     80 
     81   void set_cached_pid(pid_t value) {
     82     cached_pid_ = value;
     83   }
     84 
     85   bool get_cached_pid(pid_t* cached_pid) {
     86     *cached_pid = cached_pid_;
     87     return (*cached_pid != 0);
     88   }
     89 
     90   pthread_attr_t attr;
     91 
     92   _Atomic(ThreadJoinState) join_state;
     93 
     94   __pthread_cleanup_t* cleanup_stack;
     95 
     96   void* (*start_routine)(void*);
     97   void* start_routine_arg;
     98   void* return_value;
     99 
    100   void* alternate_signal_stack;
    101 
    102   Lock startup_handshake_lock;
    103 
    104   size_t mmap_size;
    105 
    106   thread_local_dtor* thread_local_dtors;
    107 
    108   void* tls[BIONIC_TLS_SLOTS];
    109 
    110   pthread_key_data_t key_data[BIONIC_PTHREAD_KEY_COUNT];
    111 
    112   /*
    113    * The dynamic linker implements dlerror(3), which makes it hard for us to implement this
    114    * per-thread buffer by simply using malloc(3) and free(3).
    115    */
    116 #define __BIONIC_DLERROR_BUFFER_SIZE 512
    117   char dlerror_buffer[__BIONIC_DLERROR_BUFFER_SIZE];
    118 
    119   bionic_tls* bionic_tls;
    120 };
    121 
    122 __LIBC_HIDDEN__ int __init_thread(pthread_internal_t* thread);
    123 __LIBC_HIDDEN__ bool __init_tls(pthread_internal_t* thread);
    124 __LIBC_HIDDEN__ void __init_thread_stack_guard(pthread_internal_t* thread);
    125 __LIBC_HIDDEN__ void __init_alternate_signal_stack(pthread_internal_t*);
    126 
    127 __LIBC_HIDDEN__ pthread_t           __pthread_internal_add(pthread_internal_t* thread);
    128 __LIBC_HIDDEN__ pthread_internal_t* __pthread_internal_find(pthread_t pthread_id);
    129 __LIBC_HIDDEN__ void                __pthread_internal_remove(pthread_internal_t* thread);
    130 __LIBC_HIDDEN__ void                __pthread_internal_remove_and_free(pthread_internal_t* thread);
    131 
    132 // Make __get_thread() inlined for performance reason. See http://b/19825434.
    133 static inline __always_inline pthread_internal_t* __get_thread() {
    134   void** tls = __get_tls();
    135   if (__predict_true(tls)) {
    136     return reinterpret_cast<pthread_internal_t*>(tls[TLS_SLOT_THREAD_ID]);
    137   }
    138 
    139   // This happens when called during libc initialization before TLS has been initialized.
    140   return nullptr;
    141 }
    142 
    143 static inline __always_inline bionic_tls& __get_bionic_tls() {
    144   return *__get_thread()->bionic_tls;
    145 }
    146 
    147 __LIBC_HIDDEN__ void pthread_key_clean_all(void);
    148 
    149 // Address space is precious on LP32, so use the minimum unit: one page.
    150 // On LP64, we could use more but there's no obvious advantage to doing
    151 // so, and the various media processes use RLIMIT_AS as a way to limit
    152 // the amount of allocation they'll do.
    153 #define PTHREAD_GUARD_SIZE PAGE_SIZE
    154 
    155 // SIGSTKSZ (8KiB) is not big enough.
    156 // An snprintf to a stack buffer of size PATH_MAX consumes ~7KiB of stack.
    157 // Also, on 64-bit, logging uses more than 8KiB by itself:
    158 // https://code.google.com/p/android/issues/detail?id=187064
    159 #define SIGNAL_STACK_SIZE_WITHOUT_GUARD (16 * 1024)
    160 
    161 // Traditionally we gave threads a 1MiB stack. When we started
    162 // allocating per-thread alternate signal stacks to ease debugging of
    163 // stack overflows, we subtracted the same amount we were using there
    164 // from the default thread stack size. This should keep memory usage
    165 // roughly constant.
    166 #define PTHREAD_STACK_SIZE_DEFAULT ((1 * 1024 * 1024) - SIGNAL_STACK_SIZE_WITHOUT_GUARD)
    167 
    168 // Leave room for a guard page in the internally created signal stacks.
    169 #define SIGNAL_STACK_SIZE (SIGNAL_STACK_SIZE_WITHOUT_GUARD + PTHREAD_GUARD_SIZE)
    170 
    171 // Needed by fork.
    172 __LIBC_HIDDEN__ extern void __bionic_atfork_run_prepare();
    173 __LIBC_HIDDEN__ extern void __bionic_atfork_run_child();
    174 __LIBC_HIDDEN__ extern void __bionic_atfork_run_parent();
    175