tls.c revision 133754 
1/*-
2 * Copyright (c) 2004 Doug Rabson
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 * 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.
13 *
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
24 * SUCH DAMAGE.
25 *
26 *	$FreeBSD: head/lib/libc/gen/tls.c 133754 2004-08-15 16:18:52Z dfr $
27 */
28
29/*
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.
33 */
34
35#include <stdlib.h>
36#include <string.h>
37#include <elf.h>
38#include <assert.h>
39#include "libc_private.h"
40
41/* XXX not sure what variants to use for arm. */
42
43#if defined(__ia64__) || defined(__alpha__) || defined(__powerpc__)
44#define TLS_VARIANT_I
45#endif
46#if defined(__i386__) || defined(__amd64__) || defined(__sparc64__)
47#define TLS_VARIANT_II
48#endif
49
50#ifndef PIC
51
52#define round(size, align) \
53	(((size) + (align) - 1) & ~((align) - 1))
54
55static size_t tls_static_space;
56static size_t tls_init_size;
57#ifdef TLS_VARIANT_I
58static size_t tls_init_offset;
59#endif
60static void *tls_init;
61
62void _rtld_free_tls(void *tcb, size_t tcbsize, size_t tcbalign);
63#endif
64
65#ifdef __i386__
66
67extern void *___tls_get_addr(void *ti) __attribute__((__regparm__(1)));
68
69#pragma weak ___tls_get_addr
70__attribute__((__regparm__(1)))
71void *
72___tls_get_addr(void *ti)
73{
74	return (0);
75}
76
77#endif
78
79#pragma weak __tls_get_addr
80void *
81__tls_get_addr()
82{
83	return (0);
84}
85
86#ifdef TLS_VARIANT_I
87
88void
89_rtld_free_tls(void *tls, size_t tcbsize, size_t tcbalign)
90{
91#ifndef PIC
92	Elf_Addr* dtv;
93
94	dtv = ((Elf_Addr**)tls)[0];
95	free(tls);
96	free(dtv);
97#endif
98}
99
100/*
101 * Allocate Static TLS using the Variant I method.
102 */
103void *
104_rtld_allocate_tls(void *oldtls, size_t tcbsize, size_t tcbalign)
105{
106#ifndef PIC
107	size_t size;
108	char *tls;
109	Elf_Addr *dtv;
110
111	size = tls_static_space;
112
113	tls = malloc(size);
114	dtv = malloc(3 * sizeof(Elf_Addr));
115
116	*(Elf_Addr**) tls = dtv;
117
118	dtv[0] = 1;
119	dtv[1] = 1;
120	dtv[2] = (Elf_Addr)(tls + tls_init_offset);
121	if (oldtls) {
122		/*
123		 * Copy the static TLS block over whole.
124		 */
125		memcpy(tls + tls_init_offset,
126		    (char*) oldtls + tls_init_offset,
127		    tls_static_space - tls_init_offset);
128
129		/*
130		 * We assume that this block was the one we created with
131		 * allocate_initial_tls().
132		 */
133		_rtld_free_tls(oldtls, 2*sizeof(Elf_Addr), sizeof(Elf_Addr));
134	} else {
135		memcpy(tls + tls_init_offset, tls_init, tls_init_size);
136		memset(tls + tls_init_offset + tls_init_size,
137		    0, tls_static_space - tls_init_size);
138	}
139
140	return tls;
141#else
142	return (0);
143#endif
144}
145
146#endif
147
148#ifdef TLS_VARIANT_II
149
150/*
151 * Free Static TLS using the Variant II method.
152 */
153#pragma weak _rtld_free_tls
154void
155_rtld_free_tls(void *tcb, size_t tcbsize, size_t tcbalign)
156{
157#ifndef PIC
158	size_t size;
159	Elf_Addr* dtv;
160	Elf_Addr tlsstart, tlsend;
161
162	/*
163	 * Figure out the size of the initial TLS block so that we can
164	 * find stuff which ___tls_get_addr() allocated dynamically.
165	 */
166	size = round(tls_static_space, tcbalign);
167
168	dtv = ((Elf_Addr**)tcb)[1];
169	tlsend = (Elf_Addr) tcb;
170	tlsstart = tlsend - size;
171	free((void*) tlsstart);
172	free(dtv);
173#endif
174}
175
176#pragma weak _rtld_allocate_tls
177/*
178 * Allocate Static TLS using the Variant II method.
179 */
180void *
181_rtld_allocate_tls(void *oldtls, size_t tcbsize, size_t tcbalign)
182{
183#ifndef PIC
184	size_t size;
185	char *tls;
186	Elf_Addr *dtv;
187	Elf_Addr segbase, oldsegbase;
188
189	size = round(tls_static_space, tcbalign);
190
191	assert(tcbsize >= 2*sizeof(Elf_Addr));
192	tls = malloc(size + tcbsize);
193	dtv = malloc(3 * sizeof(Elf_Addr));
194
195	segbase = (Elf_Addr)(tls + size);
196	((Elf_Addr*)segbase)[0] = segbase;
197	((Elf_Addr*)segbase)[1] = (Elf_Addr) dtv;
198
199	dtv[0] = 1;
200	dtv[1] = 1;
201	dtv[2] = segbase - tls_static_space;
202
203	if (oldtls) {
204		/*
205		 * Copy the static TLS block over whole.
206		 */
207		oldsegbase = (Elf_Addr) oldtls;
208		memcpy((void *)(segbase - tls_static_space),
209		    (const void *)(oldsegbase - tls_static_space),
210		    tls_static_space);
211
212		/*
213		 * We assume that this block was the one we created with
214		 * allocate_initial_tls().
215		 */
216		_rtld_free_tls(oldtls, 2*sizeof(Elf_Addr), sizeof(Elf_Addr));
217	} else {
218		memcpy((void *)(segbase - tls_static_space),
219		    tls_init, tls_init_size);
220		memset((void *)(segbase - tls_static_space + tls_init_size),
221		    0, tls_static_space - tls_init_size);
222	}
223
224	return (void*) segbase;
225#else
226	return (0);
227#endif
228}
229
230#endif
231
232void
233_init_tls()
234{
235#ifndef PIC
236	extern char **environ;
237	Elf_Addr *sp;
238	Elf_Auxinfo *aux, *auxp;
239	Elf_Phdr *phdr;
240	size_t phent, phnum;
241	int i;
242
243	sp = (Elf_Addr *) environ;
244	while (*sp++ != 0)
245		;
246	aux = (Elf_Auxinfo *) sp;
247	phdr = 0;
248	phent = phnum = 0;
249	for (auxp = aux; auxp->a_type != AT_NULL; auxp++) {
250		switch (auxp->a_type) {
251		case AT_PHDR:
252			phdr = auxp->a_un.a_ptr;
253			break;
254
255		case AT_PHENT:
256			phent = auxp->a_un.a_val;
257			break;
258
259		case AT_PHNUM:
260			phnum = auxp->a_un.a_val;
261			break;
262		}
263	}
264	if (phdr == 0 || phent != sizeof(Elf_Phdr) || phnum == 0)
265		return;
266
267	for (i = 0; i < phnum; i++) {
268		if (phdr[i].p_type == PT_TLS) {
269#ifdef TLS_VARIANT_I
270			tls_static_space = round(2*sizeof(Elf_Addr),
271			    phdr[i].p_align) + phdr[i].p_memsz;
272			tls_init_offset = round(2*sizeof(Elf_Addr),
273			    phdr[i].p_align);
274#else
275			tls_static_space = round(phdr[i].p_memsz,
276			    phdr[i].p_align);
277#endif
278			tls_init_size = phdr[i].p_filesz;
279			tls_init = (void*) phdr[i].p_vaddr;
280		}
281	}
282
283	if (tls_static_space > 0) {
284		void* tls;
285
286		tls = _rtld_allocate_tls(NULL, 2*sizeof(Elf_Addr),
287		    sizeof(Elf_Addr));
288
289		_set_tp(tls);
290	}
291#endif
292}
293