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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   TLS_SLOT_FIRST_USER_SLOT // Must come last!
     71 };
     72 
     73 /*
     74  * There are two kinds of slot used internally by bionic --- there are the well-known slots
     75  * enumerated above, and then there are those that are allocated during startup by calls to
     76  * pthread_key_create; grep for GLOBAL_INIT_THREAD_LOCAL_BUFFER to find those. We need to manually
     77  * maintain that second number, but pthread_test will fail if we forget.
     78  */
     79 #define GLOBAL_INIT_THREAD_LOCAL_BUFFER_COUNT 5
     80 
     81 #if defined(USE_JEMALLOC)
     82 /* jemalloc uses 5 keys for itself. */
     83 #define BIONIC_TLS_RESERVED_SLOTS (GLOBAL_INIT_THREAD_LOCAL_BUFFER_COUNT + 5)
     84 #else
     85 #define BIONIC_TLS_RESERVED_SLOTS GLOBAL_INIT_THREAD_LOCAL_BUFFER_COUNT
     86 #endif
     87 
     88 /*
     89  * Maximum number of elements in the TLS array.
     90  * This includes space for pthread keys and our own internal slots.
     91  * We need to round up to maintain stack alignment.
     92  */
     93 #define BIONIC_TLS_SLOTS BIONIC_ALIGN(PTHREAD_KEYS_MAX + TLS_SLOT_FIRST_USER_SLOT + BIONIC_TLS_RESERVED_SLOTS, 4)
     94 
     95 __END_DECLS
     96 
     97 #if defined(__cplusplus)
     98 class KernelArgumentBlock;
     99 extern __LIBC_HIDDEN__ void __libc_init_tls(KernelArgumentBlock& args);
    100 #endif
    101 
    102 #endif /* __BIONIC_PRIVATE_BIONIC_TLS_H_ */
    103