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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 #ifndef __BIONIC_PRIVATE_BIONIC_TLS_H_
     30 #define __BIONIC_PRIVATE_BIONIC_TLS_H_
     31 
     32 #include <sys/cdefs.h>
     33 #include <sys/limits.h>
     34 #include "bionic_macros.h"
     35 #include "__get_tls.h"
     36 
     37 __BEGIN_DECLS
     38 
     39 /** WARNING WARNING WARNING
     40  **
     41  ** This header file is *NOT* part of the public Bionic ABI/API
     42  ** and should not be used/included by user-serviceable parts of
     43  ** the system (e.g. applications).
     44  **
     45  ** It is only provided here for the benefit of the system dynamic
     46  ** linker and the OpenGL sub-system (which needs to access the
     47  ** pre-allocated slot directly for performance reason).
     48  **/
     49 
     50 // Well-known TLS slots. What data goes in which slot is arbitrary unless otherwise noted.
     51 enum {
     52   TLS_SLOT_SELF = 0, // The kernel requires this specific slot for x86.
     53   TLS_SLOT_THREAD_ID,
     54   TLS_SLOT_ERRNO,
     55 
     56   // These two aren't used by bionic itself, but allow the graphics code to
     57   // access TLS directly rather than using the pthread API.
     58   TLS_SLOT_OPENGL_API = 3,
     59   TLS_SLOT_OPENGL = 4,
     60 
     61   // This slot is only used to pass information from the dynamic linker to
     62   // libc.so when the C library is loaded in to memory. The C runtime init
     63   // function will then clear it. Since its use is extremely temporary,
     64   // we reuse an existing location that isn't needed during libc startup.
     65   TLS_SLOT_BIONIC_PREINIT = TLS_SLOT_OPENGL_API,
     66 
     67   TLS_SLOT_STACK_GUARD = 5, // GCC requires this specific slot for x86.
     68   TLS_SLOT_DLERROR,
     69 
     70   BIONIC_TLS_SLOTS // Must come last!
     71 };
     72 
     73 /*
     74  * Bionic uses some pthread keys internally. All pthread keys used internally
     75  * should be created in constructors, except for keys that may be used in or
     76  * before constructors.
     77  *
     78  * We need to manually maintain the count of pthread keys used internally, but
     79  * pthread_test should fail if we forget.
     80  *
     81  * These are the pthread keys currently used internally by libc:
     82  *
     83  *  basename               libc (ThreadLocalBuffer)
     84  *  dirname                libc (ThreadLocalBuffer)
     85  *  uselocale              libc (can be used in constructors)
     86  *  getmntent_mntent       libc (ThreadLocalBuffer)
     87  *  getmntent_strings      libc (ThreadLocalBuffer)
     88  *  ptsname                libc (ThreadLocalBuffer)
     89  *  ttyname                libc (ThreadLocalBuffer)
     90  *  strerror               libc (ThreadLocalBuffer)
     91  *  strsignal              libc (ThreadLocalBuffer)
     92  *  passwd                 libc (ThreadLocalBuffer)
     93  *  group                  libc (ThreadLocalBuffer)
     94  *  _res_key               libc (constructor in BSD code)
     95  */
     96 
     97 #define LIBC_PTHREAD_KEY_RESERVED_COUNT 12
     98 
     99 #if defined(USE_JEMALLOC)
    100 /* Internally, jemalloc uses a single key for per thread data. */
    101 #define JEMALLOC_PTHREAD_KEY_RESERVED_COUNT 1
    102 #define BIONIC_PTHREAD_KEY_RESERVED_COUNT (LIBC_PTHREAD_KEY_RESERVED_COUNT + JEMALLOC_PTHREAD_KEY_RESERVED_COUNT)
    103 #else
    104 #define BIONIC_PTHREAD_KEY_RESERVED_COUNT LIBC_PTHREAD_KEY_RESERVED_COUNT
    105 #endif
    106 
    107 /*
    108  * Maximum number of pthread keys allocated.
    109  * This includes pthread keys used internally and externally.
    110  */
    111 #define BIONIC_PTHREAD_KEY_COUNT (BIONIC_PTHREAD_KEY_RESERVED_COUNT + PTHREAD_KEYS_MAX)
    112 
    113 __END_DECLS
    114 
    115 #if defined(__cplusplus)
    116 class KernelArgumentBlock;
    117 extern __LIBC_HIDDEN__ void __libc_init_tls(KernelArgumentBlock& args);
    118 #endif
    119 
    120 #endif /* __BIONIC_PRIVATE_BIONIC_TLS_H_ */
    121