1 /* $OpenBSD: tib.h,v 1.3 2016/05/07 19:05:21 guenther Exp $ */ 2 /* 3 * Copyright (c) 2011,2014 Philip Guenther <guenther@openbsd.org> 4 * 5 * Permission to use, copy, modify, and distribute this software for any 6 * purpose with or without fee is hereby granted, provided that the above 7 * copyright notice and this permission notice appear in all copies. 8 * 9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 16 */ 17 18 /* 19 * Thread Information Block (TIB) and Thread Local Storage (TLS) handling 20 * (the TCB, Thread Control Block, is part of the TIB) 21 */ 22 23 #ifndef _TIB_H_ 24 #define _TIB_H_ 25 26 #include <sys/types.h> 27 #include <machine/tcb.h> 28 29 #include <stddef.h> 30 31 32 /* 33 * This header defines struct tib and at least eight macros: 34 * TLS_VARIANT 35 * Either 1 or 2 (Actually defined by <machine/tcb.h>) 36 * 37 * TCB_SET(tcb) 38 * Set the TCB pointer for this thread to 'tcb' 39 * 40 * TCB_GET() 41 * Return the TCB pointer for this thread 42 * 43 * TCB_TO_TIB(tcb) 44 * Given a TCB pointer, return the matching TIB pointer 45 * 46 * TIB_TO_TCB(tib) 47 * Given a TIB pointer, return the matching TCB pointer 48 * 49 * TIB_INIT(tib, dtv, thread) 50 * Initializes a TIB for a new thread, using the supplied 51 * values for its dtv and thread pointers 52 * 53 * TIB_GET() 54 * Short-hand for TCB_TO_TIB(TCB_GET()) 55 * 56 * TIB_EXTRA_ALIGN 57 * On TLS varaint 2 archs, what alignment is sufficient 58 * for the extra space that will be used for struct pthread? 59 * 60 * The following functions are provided by either ld.so (dynamic) or 61 * libc (static) for allocating and freeing a common memory block that 62 * will hold both the TIB and the pthread structure: 63 * _dl_allocate_tib(sizeof(struct pthread)) 64 * Allocates a combined TIB and pthread memory region. 65 * The argument is the amount of space to reserve 66 * for the pthread structure. Returns a pointer to 67 * the TIB inside the allocated block. 68 * 69 * _dl_free_tib(tib, sizeof(struct pthread)) 70 * Frees a TIB and pthread block previously allocated 71 * with _dl_allocate_tib(). Must be passed the return 72 * value of that previous call. 73 */ 74 75 /* 76 * Regarding <machine/tcb.h>: 77 * - it must define the TLS_VARIANT macro 78 * - it may define TCB_OFFSET if the TCB address in the kernel and/or 79 * register is offset from the actual TCB address. TCB_OFFSET > 0 80 * means the kernel/register points to *after* the real data. 81 * - if there's a faster way to get or set the TCB pointer for the thread 82 * than the __{get,set}_tcb() syscalls, it should define either or both 83 * the TCB_{GET,SET} macros to do so. 84 */ 85 86 87 /* If <machine/tcb.h> doesn't provide a better way, then use the default */ 88 #ifdef TCB_GET 89 # define TCB_HAVE_MD_GET 1 90 #else 91 # define TCB_GET() __get_tcb() 92 #endif 93 #ifdef TCB_SET 94 # define TCB_HAVE_MD_SET 1 95 #else 96 # define TCB_SET(tcb) __set_tcb(tcb) 97 #endif 98 #ifndef TCB_OFFSET 99 # define TCB_OFFSET 0 100 #endif 101 102 /* 103 * tib_cantcancel values is non-zero is the thread should skip all 104 * cancellation processing 105 */ 106 #define CANCEL_DISABLED 1 107 #define CANCEL_DYING 2 108 109 /* 110 * tib_cancel_point is non-zero if we're in a cancel point; its modified 111 * by the cancel point code and read by the cancellation signal handler 112 */ 113 #define CANCEL_POINT 1 114 #define CANCEL_POINT_DELAYED 2 115 116 117 #if TLS_VARIANT == 1 118 /* 119 * ABI specifies that the static TLS data starts two words after the 120 * (notional) thread pointer, with the first of those two words being 121 * the TLS dtv pointer. The other (second) word is reserved for the 122 * implementation, so we place the pointer to the thread structure there, 123 * but we place our actual thread bits before the TCB, at negative offsets 124 * from the TCB pointer. Ergo, memory is laid out, low to high, as: 125 * 126 * [pthread structure] 127 * TIB { 128 * ...cancelation and other int-sized info... 129 * int errno 130 * void *locale 131 * TCB (- TCB_OFFSET) { 132 * void *dtv 133 * struct pthread *thread 134 * } 135 * } 136 * static TLS data 137 */ 138 139 struct tib { 140 int tib_thread_flags; /* internal to libpthread */ 141 pid_t tib_tid; 142 int tib_cantcancel; 143 int tib_cancel_point; 144 int tib_canceled; 145 int tib_errno; 146 void *tib_locale; 147 void *tib_dtv; /* internal to the runtime linker */ 148 void *tib_thread; 149 }; 150 151 152 #elif TLS_VARIANT == 2 153 /* 154 * ABI specifies that the static TLS data occupies the memory before 155 * the TCB pointer, at negative offsets, and that on i386 and amd64 156 * the word the TCB points to contains a pointer to itself. So, 157 * we place errno and our thread bits after that. Memory is laid 158 * out, low to high, as: 159 * static TLS data 160 * TIB { 161 * TCB (- TCB_OFFSET) { 162 * self pointer [i386/amd64 only] 163 * void *dtv 164 * } 165 * struct pthread *thread 166 * void *locale 167 * int errno 168 * ...cancelation and other int-sized info... 169 * } 170 * [pthread structure] 171 */ 172 173 struct tib { 174 #if defined(__i386) || defined(__amd64) 175 struct tib *__tib_self; 176 # define __tib_tcb __tib_self 177 #endif 178 void *tib_dtv; /* internal to the runtime linker */ 179 void *tib_thread; 180 void *tib_locale; 181 int tib_errno; 182 int tib_canceled; 183 int tib_cancel_point; 184 int tib_cantcancel; 185 pid_t tib_tid; 186 int tib_thread_flags; /* internal to libpthread */ 187 #if !defined(__LP64__) && !defined(__i386) 188 int __tib_padding; /* padding for 8byte alignment */ 189 #endif 190 }; 191 192 #if defined(__i386) || defined(__amd64) 193 # define _TIB_PREP(tib) \ 194 ((void)((tib)->__tib_self = (tib))) 195 #elif !defined(__LP64__) && !defined(__i386) 196 # define _TIB_PREP(tib) ((void)((tib)->__tib_padding = 0)) 197 #endif 198 199 #define TIB_EXTRA_ALIGN sizeof(void *) 200 201 #else 202 # error "unknown TLS variant" 203 #endif 204 205 /* nothing to do by default */ 206 #ifndef _TIB_PREP 207 # define _TIB_PREP(tib) ((void)0) 208 #endif 209 210 #define TIB_INIT(tib, dtv, thread) do { \ 211 (tib)->tib_thread = (thread); \ 212 (tib)->tib_locale = NULL; \ 213 (tib)->tib_cantcancel = 0; \ 214 (tib)->tib_cancel_point = 0; \ 215 (tib)->tib_canceled = 0; \ 216 (tib)->tib_dtv = (dtv); \ 217 (tib)->tib_errno = 0; \ 218 _TIB_PREP(tib); \ 219 } while (0) 220 221 #ifndef __tib_tcb 222 # define __tib_tcb tib_dtv 223 #endif 224 #define _TIBO_TCB (offsetof(struct tib, __tib_tcb) + TCB_OFFSET) 225 226 #define TCB_TO_TIB(tcb) ((struct tib *)((char *)(tcb) - _TIBO_TCB)) 227 #define TIB_TO_TCB(tib) ((char *)(tib) + _TIBO_TCB) 228 #define TIB_GET() TCB_TO_TIB(TCB_GET()) 229 230 231 __BEGIN_DECLS 232 void *_dl_allocate_tib(size_t _extra) __dso_public; 233 void _dl_free_tib(void *_tib, size_t _extra) __dso_public; 234 235 /* The actual syscalls */ 236 void *__get_tcb(void); 237 void __set_tcb(void *_tcb); 238 __END_DECLS 239 240 #endif /* _TIB_H_ */ 241