hybris/common/gingerbread/bionic_tls.h

   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 #ifndef _SYS_TLS_H
  29 #define _SYS_TLS_H
  30
  31 #include <sys/cdefs.h>
  32
  33 __BEGIN_DECLS
  34
  35 /** WARNING WARNING WARNING
  36  **
  37  ** This header file is *NOT* part of the public Bionic ABI/API
  38  ** and should not be used/included by user-serviceable parts of
  39  ** the system (e.g. applications).
  40  **
  41  ** It is only provided here for the benefit of the system dynamic
  42  ** linker and the OpenGL sub-system (which needs to access the
  43  ** pre-allocated slot directly for performance reason).
  44  **/
  45
  46 /* maximum number of elements in the TLS array */
  47 #define BIONIC_TLS_SLOTS            64
  48
  49 /* note that slot 0, called TLS_SLOT_SELF must point to itself.
  50  * this is required to implement thread-local storage with the x86
  51  * Linux kernel, that reads the TLS from fs:[0], where 'fs' is a
  52  * thread-specific segment descriptor...
  53  */
  54
  55 /* Well known TLS slots */
  56 #define TLS_SLOT_SELF               0
  57 #define TLS_SLOT_THREAD_ID          1
  58 #define TLS_SLOT_ERRNO              2
  59
  60 #define TLS_SLOT_OPENGL_API         3
  61 #define TLS_SLOT_OPENGL             4
  62
  63 /* this slot is only used to pass information from the dynamic linker to
  64  * libc.so when the C library is loaded in to memory. The C runtime init
  65  * function will then clear it. Since its use is extremely temporary,
  66  * we reuse an existing location.
  67  */
  68 #define  TLS_SLOT_BIONIC_PREINIT    (TLS_SLOT_ERRNO+1)
  69
  70 /* small technical note: it is not possible to call pthread_setspecific
  71  * on keys that are <= TLS_SLOT_MAX_WELL_KNOWN, which is why it is set to
  72  * TLS_SLOT_ERRNO.
  73  *
  74  * later slots like TLS_SLOT_OPENGL are pre-allocated through the use of
  75  * TLS_DEFAULT_ALLOC_MAP. this means that there is no need to use
  76  * pthread_key_create() to initialize them. on the other hand, there is
  77  * no destructor associated to them (we might need to implement this later)
  78  */
  79 #define TLS_SLOT_MAX_WELL_KNOWN     TLS_SLOT_ERRNO
  80
  81 #define TLS_DEFAULT_ALLOC_MAP       0x0000001F
  82
  83 /* set the Thread Local Storage, must contain at least BIONIC_TLS_SLOTS pointers */
  84 extern void __init_tls(void**  tls, void*  thread_info);
  85
  86 /* syscall only, do not call directly */
  87 extern int __set_tls(void *ptr);
  88
  89 /* get the TLS */
  90 #ifdef __arm__
  91 /* The standard way to get the TLS is to call a kernel helper
  92  * function (i.e. a function provided at a fixed address in a
  93  * "magic page" mapped in all user-space address spaces ), which
  94  * contains the most appropriate code path for the target device.
  95  *
  96  * However, for performance reasons, we're going to use our own
  97  * machine code for the system's C shared library.
  98  *
  99  * We cannot use this optimization in the static version of the
 100  * C library, because we don't know where the corresponding code
 101  * is going to run.
 102  */
 103 #  ifdef LIBC_STATIC
 104
 105 /* Use the kernel helper in static C library. */
 106   typedef volatile void* (__kernel_get_tls_t)(void);
 107 #    define __get_tls() (*(__kernel_get_tls_t *)0xffff0fe0)()
 108
 109 #  else /* !LIBC_STATIC */
 110 /* Use optimized code path.
 111  * Note that HAVE_ARM_TLS_REGISTER is build-specific
 112  * (it must match your kernel configuration)
 113  */
 114 #    ifdef HAVE_ARM_TLS_REGISTER
 115  /* We can read the address directly from a coprocessor
 116   * register, which avoids touching the data cache
 117   * completely.
 118   */
 119 #      define __get_tls() \
 120     ({ register unsigned int __val asm("r0"); \
 121        asm ("mrc p15, 0, r0, c13, c0, 3" : "=r"(__val) ); \
 122        (volatile void*)__val; })
 123 #    else /* !HAVE_ARM_TLS_REGISTER */
 124  /* The kernel provides the address of the TLS at a fixed
 125   * address of the magic page too.
 126   */
 127 #      define __get_tls() ( *((volatile void **) 0xffff0ff0) )
 128 #    endif
 129 #  endif /* !LIBC_STATIC */
 130 #else /* !ARM */
 131 extern void*  __get_tls( void );
 132 #endif /* !ARM */
 133
 134 /* return the stack base and size, used by our malloc debugger */
 135 extern void*  __get_stack_base(int  *p_stack_size);
 136
 137 __END_DECLS
 138
 139 #endif /* _SYS_TLS_H */