| The Android Open Source Project | 1dc9e47 | 2009-03-03 19:28:35 -0800 | [diff] [blame^] | 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 | struct _thread_area_head { |
| 64 | void *self; |
| 65 | }; |
| 66 | |
| 67 | /* we implement thread local storage through the gs: segment descriptor |
| 68 | * we create a segment descriptor for the tls |
| 69 | */ |
| 70 | int __set_tls(void *ptr) |
| 71 | { |
| 72 | int rc, segment; |
| 73 | |
| 74 | _tls_desc.base_addr = (unsigned long)ptr; |
| 75 | |
| 76 | /* We also need to write the location of the tls to ptr[0] */ |
| 77 | ((struct _thread_area_head *)ptr)->self = ptr; |
| 78 | |
| 79 | rc = __set_thread_area( &_tls_desc ); |
| 80 | if (rc != 0) |
| 81 | { |
| 82 | /* could not set thread local area */ |
| 83 | return -1; |
| 84 | } |
| 85 | |
| 86 | /* this weird computation comes from GLibc */ |
| 87 | segment = _tls_desc.entry_number*8 + 3; |
| 88 | asm __volatile__ ( |
| 89 | " movw %w0, %%gs" :: "q"(segment) |
| 90 | ); |
| 91 | return 0; |
| 92 | } |
| 93 | |
| 94 | |
| 95 | |