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 */ 140