1/* $OpenBSD: tib.h,v 1.10 2023/12/08 19:14:36 miod 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 variant 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/* All archs but mips64 have fast TCB_GET() and don't need caching */
88#ifndef __mips64__
89# define TCB_HAVE_MD_GET 1
90#endif
91#ifdef TCB_SET
92# define TCB_HAVE_MD_SET 1
93#else
94# define TCB_SET(tcb) __set_tcb(tcb)
95#endif
96#ifndef TCB_OFFSET
97# define TCB_OFFSET 0
98#endif
99
100/*
101 * tib_cantcancel values is non-zero if the thread should skip all
102 * cancellation processing
103 */
104#define CANCEL_DISABLED 1
105#define CANCEL_DYING 2
106
107/*
108 * tib_cancel_point is non-zero if we're in a cancel point; its modified
109 * by the cancel point code and read by the cancellation signal handler
110 */
111#define CANCEL_POINT 1
112#define CANCEL_POINT_DELAYED 2
113
114
115#if TLS_VARIANT == 1
116/*
117 * ABI specifies that the static TLS data starts two words after the
118 * (notional) thread pointer, with the first of those two words being
119 * the TLS dtv pointer. The other (second) word is reserved for the
120 * implementation, so we place the pointer to the thread structure there,
121 * but we place our actual thread bits before the TCB, at negative offsets
122 * from the TCB pointer. Ergo, memory is laid out, low to high, as:
123 *
124 * [pthread structure]
125 * TIB {
126 * ...cancelation and other int-sized info...
127 * int errno
128 * void *locale
129 * TCB (- TCB_OFFSET) {
130 * void *dtv
131 * struct pthread *thread
132 * }
133 * }
134 * static TLS data
135 */
136
137struct tib {
138 void *tib_atexit;
139 int tib_thread_flags; /* internal to libpthread */
140 pid_t tib_tid;
141 int tib_cantcancel;
142 int tib_cancel_point;
143 int tib_canceled;
144 int tib_errno;
145 void *tib_locale;
146#ifdef __powerpc64__
147 void *tib_thread;
148 void *tib_dtv; /* internal to the runtime linker */
149#else
150 void *tib_dtv; /* internal to the runtime linker */
151 void *tib_thread;
152#endif
153};
154
155
156#elif TLS_VARIANT == 2
157/*
158 * ABI specifies that the static TLS data occupies the memory before
159 * the TCB pointer, at negative offsets, and that on i386 and amd64
160 * the word the TCB points to contains a pointer to itself. So,
161 * we place errno and our thread bits after that. Memory is laid
162 * out, low to high, as:
163 * static TLS data
164 * TIB {
165 * TCB (- TCB_OFFSET) {
166 * self pointer [i386/amd64 only]
167 * void *dtv
168 * }
169 * struct pthread *thread
170 * void *locale
171 * int errno
172 * ...cancelation and other int-sized info...
173 * }
174 * [pthread structure]
175 */
176
177struct tib {
178#if defined(__i386) || defined(__amd64)
179 struct tib *__tib_self;
180# define __tib_tcb __tib_self
181#endif
182 void *tib_dtv; /* internal to the runtime linker */
183 void *tib_thread;
184 void *tib_locale;
185 int tib_errno;
186 int tib_canceled;
187 int tib_cancel_point;
188 int tib_cantcancel;
189 pid_t tib_tid;
190 int tib_thread_flags; /* internal to libpthread */
191 void *tib_atexit;
192};
193
194#if defined(__i386) || defined(__amd64)
195# define _TIB_PREP(tib) \
196 ((void)((tib)->__tib_self = (tib)))
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_atexit = NULL; \
213 (tib)->tib_locale = NULL; \
214 (tib)->tib_cantcancel = 0; \
215 (tib)->tib_cancel_point = 0; \
216 (tib)->tib_canceled = 0; \
217 (tib)->tib_dtv = (dtv); \
218 (tib)->tib_errno = 0; \
219 (tib)->tib_thread_flags = 0; \
220 _TIB_PREP(tib); \
221 } while (0)
222
223#ifndef __tib_tcb
224# define __tib_tcb tib_dtv
225#endif
226#define _TIBO_TCB (offsetof(struct tib, __tib_tcb) + TCB_OFFSET)
227
228#define TCB_TO_TIB(tcb) ((struct tib *)((char *)(tcb) - _TIBO_TCB))
229#define TIB_TO_TCB(tib) ((char *)(tib) + _TIBO_TCB)
230#define TIB_GET() TCB_TO_TIB(TCB_GET())
231
232
233__BEGIN_DECLS
234struct dl_info;
235struct dl_phdr_info;
236struct dl_cb_0 {
237 void *(*dl_allocate_tib)(size_t);
238 void (*dl_free_tib)(void *, size_t);
239 void (*dl_clean_boot)(void);
240 void *(*dlopen)(const char *, int);
241 int (*dlclose)(void *);
242 void *(*dlsym)(void *, const char *);
243 int (*dladdr)(const void *, struct dl_info *);
244 int (*dlctl)(void *, int, void *);
245 char *(*dlerror)(void);
246 int (*dl_iterate_phdr)(int (*)(struct dl_phdr_info *,
247 size_t, void *), void *);
248};
249
250#define DL_CB_CUR 0
251typedef struct dl_cb_0 dl_cb;
252
253/* type of function passed to init functions that returns a dl_cb */
254typedef const void *dl_cb_cb(int _version);
255
256void *_dl_allocate_tib(size_t _extra) __dso_public;
257void _dl_free_tib(void *_tib, size_t _extra) __dso_public;
258
259/* The actual syscalls */
260void *__get_tcb(void);
261void __set_tcb(void *_tcb);
262__END_DECLS
263
264#endif /* _TIB_H_ */