2 * Copyright (c) 2004 Doug Rabson
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * $FreeBSD: src/lib/libc/gen/tls.c,v 1.7 2005/03/01 23:42:00 davidxu Exp $
27 * $DragonFly: src/lib/libc/gen/tls.c,v 1.9 2005/05/11 19:46:52 dillon Exp $
31 * Define stubs for TLS internals so that programs and libraries can
32 * link. These functions will be replaced by functional versions at
33 * runtime from ld-elf.so.1.
36 #include <sys/cdefs.h>
39 #include <machine/tls.h>
48 #include "libc_private.h"
50 __weak_reference(__libc_allocate_tls, _rtld_allocate_tls);
51 __weak_reference(__libc_free_tls, _rtld_free_tls);
52 __weak_reference(__libc_call_init, _rtld_call_init);
54 __weak_reference(___libc_tls_get_addr, ___tls_get_addr);
56 __weak_reference(__libc_tls_get_addr, __tls_get_addr);
57 __weak_reference(__libc_tls_get_addr_tcb, __tls_get_addr_tcb);
58 __weak_reference(_libc_init_tls, _init_tls);
60 struct tls_tcb *__libc_allocate_tls(void);
61 void __libc_free_tls(struct tls_tcb *tcb);
63 #if !defined(RTLD_STATIC_TLS_VARIANT_II)
64 #error "Unsupported TLS layout"
69 #define round(size, align) \
70 (((size) + (align) - 1) & ~((align) - 1))
72 static size_t tls_static_space;
73 static size_t tls_init_size;
74 static void *tls_init;
75 static struct tls_tcb *initial_tcb;
82 void *___libc_tls_get_addr(void *ti) __attribute__((__regparm__(1)));
84 __attribute__((__regparm__(1)))
86 ___libc_tls_get_addr(void *ti __unused)
93 void *__libc_tls_get_addr(void *ti);
94 void *__libc_tls_get_addr_tcb(struct tls_tcb *, void *);
97 __libc_tls_get_addr(void *ti __unused)
103 __libc_tls_get_addr_tcb(struct tls_tcb *tcb __unused, void *got_ptr __unused)
111 * Free Static TLS, weakly bound to _rtld_free_tls()
114 __libc_free_tls(struct tls_tcb *tcb)
118 data_size = (tls_static_space + RTLD_STATIC_TLS_ALIGN_MASK) &
119 ~RTLD_STATIC_TLS_ALIGN_MASK;
121 if (tcb == initial_tcb) {
122 /* initial_tcb was allocated with sbrk(), cannot call free() */
124 free((char *)tcb - data_size);
129 * Allocate Static TLS, weakly bound to _rtld_allocate_tls()
131 * NOTE! There is a chicken-and-egg problem here because no TLS exists
132 * on the first call into this function.
135 __libc_allocate_tls(void)
141 data_size = (tls_static_space + RTLD_STATIC_TLS_ALIGN_MASK) &
142 ~RTLD_STATIC_TLS_ALIGN_MASK;
145 * Allocate space. malloc() may require a working TLS segment
146 * so we use sbrk() for main's TLS.
148 if (initial_tcb == NULL)
149 tcb = sbrk(data_size + sizeof(*tcb) + 3 * sizeof(Elf_Addr));
151 tcb = malloc(data_size + sizeof(*tcb));
153 tcb = (struct tls_tcb *)((char *)tcb + data_size);
154 dtv = (Elf_Addr *)(tcb + 1);
156 memset(tcb, 0, sizeof(*tcb));
157 #ifdef RTLD_TCB_HAS_SELF_POINTER
163 * Dummy-up the module array. A static binary has only one. This
164 * allows us to support the generic __tls_get_addr compiler ABI
165 * function. However, if there is no RTLD linked in, nothing in
166 * the program should ever call __tls_get_addr (and our version
167 * of it doesn't do anything).
171 dtv[2] = (Elf_Addr)((char *)tcb - tls_static_space);
173 memcpy((char *)tcb - tls_static_space,
174 tls_init, tls_init_size);
175 memset((char *)tcb - tls_static_space + tls_init_size,
176 0, tls_static_space - tls_init_size);
179 * Activate the initial TCB
181 if (initial_tcb == NULL) {
191 __libc_allocate_tls(void)
197 __libc_free_tls(struct tls_tcb *tcb __unused)
204 __libc_call_init(void)
208 extern char **environ;
217 * If this is a static binary there is no RTLD and so we have not
218 * yet calculated the static space requirement. Do so now.
221 Elf_Auxinfo *aux, *auxp;
226 sp = (Elf_Addr *) environ;
229 aux = (Elf_Auxinfo *) sp;
232 for (auxp = aux; auxp->a_type != AT_NULL; auxp++) {
233 switch (auxp->a_type) {
235 phdr = auxp->a_un.a_ptr;
239 phent = auxp->a_un.a_val;
243 phnum = auxp->a_un.a_val;
247 if (phdr == 0 || phent != sizeof(Elf_Phdr) || phnum == 0)
250 for (i = 0; (unsigned)i < phnum; i++) {
251 if (phdr[i].p_type == PT_TLS) {
252 tls_static_space = round(phdr[i].p_memsz,
254 tls_init_size = phdr[i].p_filesz;
255 tls_init = (void*) phdr[i].p_vaddr;
261 * Allocate the initial TLS segment. The TLS has not been set up
262 * yet for either the static or dynamic linked case (RTLD no longer
263 * sets up an initial TLS segment for us).
265 tcb = _libc_allocate_tls();
271 * Allocate a standard TLS. This function is called by libc and by
272 * thread libraries to create a new TCB with libc-related fields properly
273 * initialized (whereas _rtld_allocate_tls() is unable to completely set
276 * Note that this is different from __libc_allocate_tls which is the
277 * weakly bound symbol that handles the case where _rtld_allocate_tls
281 _libc_allocate_tls(void)
285 tcb = _rtld_allocate_tls();
288 #if defined(__thread)
290 tcb->tcb_errno_p = &errno;
292 /* TLS libc dynamically linked */
293 tcb->tcb_errno_p = __tls_get_addr_tcb(tcb, __get_errno_GOT_ptr());
295 /* TLS libc (threaded or unthreaded) */
296 tcb->tcb_errno_p = (void *)((char *)tcb + __get_errno_GS_offset());