bionic_tls.h revision 2f68866f371faa8ef727fc91e59e1e93326a3949
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 "__get_tls.h" 35 36__BEGIN_DECLS 37 38/** WARNING WARNING WARNING 39 ** 40 ** This header file is *NOT* part of the public Bionic ABI/API 41 ** and should not be used/included by user-serviceable parts of 42 ** the system (e.g. applications). 43 ** 44 ** It is only provided here for the benefit of the system dynamic 45 ** linker and the OpenGL sub-system (which needs to access the 46 ** pre-allocated slot directly for performance reason). 47 **/ 48 49/* Well-known TLS slots. What data goes in which slot is arbitrary unless otherwise noted. */ 50enum { 51 TLS_SLOT_SELF = 0, /* The kernel requires this specific slot for x86. */ 52 TLS_SLOT_THREAD_ID, 53 TLS_SLOT_ERRNO, 54 55 /* This slot in the child's TLS is used to synchronize the parent and child 56 * during thread initialization. The child finishes with this mutex before 57 * running any code that can set errno, so we can reuse the errno slot. */ 58 TLS_SLOT_START_MUTEX = TLS_SLOT_ERRNO, 59 60 /* These two aren't used by bionic itself, but allow the graphics code to 61 * access TLS directly rather than using the pthread API. */ 62 TLS_SLOT_OPENGL_API = 3, 63 TLS_SLOT_OPENGL = 4, 64 65 /* This slot is only used to pass information from the dynamic linker to 66 * libc.so when the C library is loaded in to memory. The C runtime init 67 * function will then clear it. Since its use is extremely temporary, 68 * we reuse an existing location that isn't needed during libc startup. */ 69 TLS_SLOT_BIONIC_PREINIT = TLS_SLOT_OPENGL_API, 70 71 TLS_SLOT_STACK_GUARD = 5, /* GCC requires this specific slot for x86. */ 72 TLS_SLOT_DLERROR, 73 74 TLS_SLOT_FIRST_USER_SLOT /* Must come last! */ 75}; 76 77/* 78 * There are two kinds of slot used internally by bionic --- there are the well-known slots 79 * enumerated above, and then there are those that are allocated during startup by calls to 80 * pthread_key_create; grep for GLOBAL_INIT_THREAD_LOCAL_BUFFER to find those. We need to manually 81 * maintain that second number, but pthread_test will fail if we forget. 82 */ 83#define GLOBAL_INIT_THREAD_LOCAL_BUFFER_COUNT 5 84 85#define BIONIC_ALIGN(x, a) (((x) + (a - 1)) & ~(a - 1)) 86 87/* 88 * Maximum number of elements in the TLS array. 89 * This includes space for pthread keys and our own internal slots. 90 * We need to round up to maintain stack alignment. 91 */ 92#define BIONIC_TLS_SLOTS BIONIC_ALIGN(PTHREAD_KEYS_MAX + TLS_SLOT_FIRST_USER_SLOT + GLOBAL_INIT_THREAD_LOCAL_BUFFER_COUNT, 4) 93 94__END_DECLS 95 96#if defined(__cplusplus) 97class KernelArgumentBlock; 98extern __LIBC_HIDDEN__ void __libc_init_tls(KernelArgumentBlock& args); 99#endif 100 101#endif /* __BIONIC_PRIVATE_BIONIC_TLS_H_ */ 102