1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause 3 * 4 * Copyright (c) 2004 Doug Rabson 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29 /* 30 * Semi-public interface from thread libraries to rtld for managing 31 * TLS. 32 */ 33 34 #ifndef _RTLD_TLS_H_ 35 #define _RTLD_TLS_H_ 36 37 /* 38 * Allocate a TLS block for a new thread. The memory allocated will 39 * include 'tcbsize' bytes aligned to a 'tcbalign' boundary (in bytes) 40 * for the thread library's private purposes. The location of the TCB 41 * block is returned by this function. For architectures using 42 * 'Variant I' TLS, the thread local storage follows the TCB, and for 43 * 'Variant II', the thread local storage precedes it. For 44 * architectures using the 'Variant II' model (e.g. i386, amd64) the 45 * TCB must begin with two pointer fields which are used by rtld for 46 * its TLS implementation. For the 'Variant I' model, the TCB must 47 * begin with a single pointer field for rtld's implementation. 48 * 49 * If the value of 'oldtls' is non-NULL, the new TLS block will be 50 * initialised using the values contained in 'oldtls' and 'oldtls' 51 * will be freed. This is typically used when initialising a thread 52 * library to migrate from using the initial bootstrap TLS block 53 * created by rtld to one which contains suitable thread library 54 * private data. 55 * 56 * The value returned from this function is suitable for installing 57 * directly into the thread pointer register. 58 */ 59 void *_rtld_allocate_tls(void *oldtls, size_t tcbsize, size_t tcbalign) 60 __exported; 61 62 /* 63 * Free a TLS block allocated using _rtld_allocate_tls(). The tcbsize 64 * and tcbalign parameters must be the same as those used to allocate 65 * the block. 66 */ 67 void _rtld_free_tls(void *tcb, size_t tcbsize, size_t tcbalign) __exported; 68 69 #endif 70