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 $
30 * Define stubs for TLS internals so that programs and libraries can
31 * link. These functions will be replaced by functional versions at
32 * runtime from ld-elf.so.1.
35 #include <sys/param.h>
39 #include <machine/tls.h>
48 #include "libc_private.h"
50 struct tls_tcb
*__libc_allocate_tls(void);
51 void __libc_free_tls(struct tls_tcb
*tcb
);
53 #if !defined(RTLD_STATIC_TLS_VARIANT_II)
54 #error "Unsupported TLS layout"
59 static size_t tls_static_space
;
60 static size_t tls_init_size
;
61 static void *tls_init
;
62 static struct tls_tcb
*initial_tcb
;
65 void *__libc_tls_get_addr(void *ti
);
66 void *__libc_tls_get_addr_tcb(struct tls_tcb
*, void *);
69 __libc_tls_get_addr(void *ti __unused
)
75 __libc_tls_get_addr_tcb(struct tls_tcb
*tcb __unused
, void *got_ptr __unused
)
83 * Free Static TLS, weakly bound to _rtld_free_tls()
86 __libc_free_tls(struct tls_tcb
*tcb
)
90 data_size
= (tls_static_space
+ RTLD_STATIC_TLS_ALIGN_MASK
) &
91 ~RTLD_STATIC_TLS_ALIGN_MASK
;
93 if (tcb
== initial_tcb
) {
94 /* initial_tcb was allocated with mmap(), cannot call free() */
96 free((char *)tcb
- data_size
);
101 * Allocate Static TLS, weakly bound to _rtld_allocate_tls()
103 * NOTE! There is a chicken-and-egg problem here because no TLS exists
104 * on the first call into this function.
107 __libc_allocate_tls(void)
113 data_size
= (tls_static_space
+ RTLD_STATIC_TLS_ALIGN_MASK
) &
114 ~RTLD_STATIC_TLS_ALIGN_MASK
;
117 * Allocate space. malloc() may require a working TLS segment
118 * so we use sbrk() for main's TLS. Oops, but in order to be
119 * compatible with older kernels we cannot use sbrk() because it
120 * will generate an errno (which needs the TLS), so use mmap().
122 if (initial_tcb
== NULL
) {
125 bytes
= data_size
+ sizeof(*tcb
) + 3 * sizeof(*dtv
);
126 bytes
= (bytes
+ PAGE_MASK
) & ~(size_t)PAGE_MASK
;
127 tcb
= mmap((void *)1, bytes
,
128 PROT_READ
| PROT_WRITE
,
129 MAP_PRIVATE
| MAP_ANON
,
132 tcb
= malloc(data_size
+ sizeof(*tcb
) + 3 * sizeof(*dtv
));
135 tcb
= (struct tls_tcb
*)((char *)tcb
+ data_size
);
136 dtv
= (Elf_Addr
*)(tcb
+ 1);
138 memset(tcb
, 0, sizeof(*tcb
));
139 #ifdef RTLD_TCB_HAS_SELF_POINTER
145 * Dummy-up the module array. A static binary has only one. This
146 * allows us to support the generic __tls_get_addr compiler ABI
147 * function. However, if there is no RTLD linked in, nothing in
148 * the program should ever call __tls_get_addr (and our version
149 * of it doesn't do anything).
153 dtv
[2] = (Elf_Addr
)((char *)tcb
- tls_static_space
);
155 memcpy((char *)tcb
- tls_static_space
,
156 tls_init
, tls_init_size
);
157 memset((char *)tcb
- tls_static_space
+ tls_init_size
,
158 0, tls_static_space
- tls_init_size
);
161 * Activate the initial TCB
163 if (initial_tcb
== NULL
) {
173 __libc_allocate_tls(void)
179 __libc_free_tls(struct tls_tcb
*tcb __unused
)
186 __libc_call_init(void)
190 extern char **environ
;
199 * If this is a static binary there is no RTLD and so we have not
200 * yet calculated the static space requirement. Do so now.
203 Elf_Auxinfo
*aux
, *auxp
;
208 sp
= (Elf_Addr
*) environ
;
211 aux
= (Elf_Auxinfo
*) sp
;
214 for (auxp
= aux
; auxp
->a_type
!= AT_NULL
; auxp
++) {
215 switch (auxp
->a_type
) {
217 phdr
= auxp
->a_un
.a_ptr
;
221 phent
= auxp
->a_un
.a_val
;
225 phnum
= auxp
->a_un
.a_val
;
229 if (phdr
== NULL
|| phent
!= sizeof(Elf_Phdr
) || phnum
== 0)
232 for (i
= 0; (unsigned)i
< phnum
; i
++) {
233 if (phdr
[i
].p_type
== PT_TLS
) {
234 tls_static_space
= roundup2(phdr
[i
].p_memsz
,
236 tls_init_size
= phdr
[i
].p_filesz
;
237 tls_init
= (void*) phdr
[i
].p_vaddr
;
243 * Allocate the initial TLS segment. The TLS has not been set up
244 * yet for either the static or dynamic linked case (RTLD no longer
245 * sets up an initial TLS segment for us).
247 tcb
= _libc_allocate_tls();
253 * Allocate a standard TLS. This function is called by libc and by
254 * thread libraries to create a new TCB with libc-related fields properly
255 * initialized (whereas _rtld_allocate_tls() is unable to completely set
258 * Note that this is different from __libc_allocate_tls which is the
259 * weakly bound symbol that handles the case where _rtld_allocate_tls
263 _libc_allocate_tls(void)
267 tcb
= _rtld_allocate_tls();
270 #if defined(__thread)
272 tcb
->tcb_errno_p
= &errno
;
274 /* TLS libc dynamically linked */
275 tcb
->tcb_errno_p
= __tls_get_addr_tcb(tcb
, __get_errno_GOT_ptr());
277 /* TLS libc (threaded or unthreaded) */
278 tcb
->tcb_errno_p
= (void *)((char *)tcb
+ __get_errno_GS_offset());
284 __weak_reference(__libc_allocate_tls
, _rtld_allocate_tls
);
285 __weak_reference(__libc_free_tls
, _rtld_free_tls
);
286 __weak_reference(__libc_call_init
, _rtld_call_init
);
287 __weak_reference(__libc_tls_get_addr
, __tls_get_addr
);
288 __weak_reference(__libc_tls_get_addr_tcb
, __tls_get_addr_tcb
);
289 __weak_reference(_libc_init_tls
, _init_tls
);