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 #include <pthread.h> 29 30 31 struct user_desc { 32 unsigned int entry_number; 33 unsigned long base_addr; 34 unsigned int limit; 35 unsigned int seg_32bit:1; 36 unsigned int contents:2; 37 unsigned int read_exec_only:1; 38 unsigned int limit_in_pages:1; 39 unsigned int seg_not_present:1; 40 unsigned int useable:1; 41 unsigned int empty:25; 42 }; 43 44 extern int __set_thread_area(struct user_desc *u_info); 45 46 /* the following can't be const, since the first call will 47 * update the 'entry_number' field 48 */ 49 static struct user_desc _tls_desc = 50 { 51 -1, 52 0, 53 0x1000, 54 1, 55 0, 56 0, 57 1, 58 0, 59 1, 60 0 61 }; 62 63 static pthread_mutex_t _tls_desc_lock = PTHREAD_MUTEX_INITIALIZER; 64 65 struct _thread_area_head { 66 void *self; 67 }; 68 69 /* we implement thread local storage through the gs: segment descriptor 70 * we create a segment descriptor for the tls 71 */ 72 int __set_tls(void *ptr) 73 { 74 int rc, segment; 75 76 pthread_mutex_lock(&_tls_desc_lock); 77 _tls_desc.base_addr = (unsigned long)ptr; 78 79 /* We also need to write the location of the tls to ptr[0] */ 80 ((struct _thread_area_head *)ptr)->self = ptr; 81 82 rc = __set_thread_area( &_tls_desc ); 83 if (rc != 0) 84 { 85 /* could not set thread local area */ 86 pthread_mutex_unlock(&_tls_desc_lock); 87 return -1; 88 } 89 90 /* this weird computation comes from GLibc */ 91 segment = _tls_desc.entry_number*8 + 3; 92 asm __volatile__ ( 93 " movw %w0, %%gs" :: "q"(segment) 94 ); 95 pthread_mutex_unlock(&_tls_desc_lock); 96 97 return 0; 98 } 99 100 101 102
