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tls.c revision 1.5 
      1 /*	$NetBSD: tls.c,v 1.5 2011/03/29 20:56:35 joerg Exp $	*/
      2 /*-
      3  * Copyright (c) 2011 The NetBSD Foundation, Inc.
      4  * All rights reserved.
      5  *
      6  * This code is derived from software contributed to The NetBSD Foundation
      7  * by Joerg Sonnenberger.
      8  *
      9  * Redistribution and use in source and binary forms, with or without
     10  * modification, are permitted provided that the following conditions
     11  * are met:
     12  * 1. Redistributions of source code must retain the above copyright
     13  *    notice, this list of conditions and the following disclaimer.
     14  * 2. Redistributions in binary form must reproduce the above copyright
     15  *    notice, this list of conditions and the following disclaimer in the
     16  *    documentation and/or other materials provided with the distribution.
     17  *
     18  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     19  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     20  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     21  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     22  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     23  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     24  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     25  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     26  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     27  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     28  * POSSIBILITY OF SUCH DAMAGE.
     29  */
     30 
     31 #include <sys/cdefs.h>
     32 __RCSID("$NetBSD: tls.c,v 1.5 2011/03/29 20:56:35 joerg Exp $");
     33 
     34 #include <sys/param.h>
     35 #include <sys/ucontext.h>
     36 #include <lwp.h>
     37 #include <string.h>
     38 #include "rtld.h"
     39 
     40 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II)
     41 
     42 static struct tls_tcb *_rtld_tls_allocate_locked(void);
     43 
     44 #ifndef TLS_DTV_OFFSET
     45 #define	TLS_DTV_OFFSET	0
     46 #endif
     47 
     48 static size_t _rtld_tls_static_space;	/* Static TLS space allocated */
     49 static size_t _rtld_tls_static_offset;	/* Next offset for static TLS to use */
     50 size_t _rtld_tls_dtv_generation = 1;
     51 size_t _rtld_tls_max_index = 1;
     52 
     53 #define	DTV_GENERATION(dtv)	((size_t)((dtv)[0]))
     54 #define	DTV_MAX_INDEX(dtv)	((size_t)((dtv)[-1]))
     55 #define	SET_DTV_GENERATION(dtv, val)	(dtv)[0] = (void *)(size_t)(val)
     56 #define	SET_DTV_MAX_INDEX(dtv, val)	(dtv)[-1] = (void *)(size_t)(val)
     57 
     58 void *
     59 _rtld_tls_get_addr(void *tls, size_t idx, size_t offset)
     60 {
     61 	struct tls_tcb *tcb = tls;
     62 	void **dtv, **new_dtv;
     63 	sigset_t mask;
     64 
     65 	_rtld_exclusive_enter(&mask);
     66 
     67 	dtv = tcb->tcb_dtv;
     68 
     69 	if (__predict_false(DTV_GENERATION(dtv) != _rtld_tls_dtv_generation)) {
     70 		size_t to_copy = DTV_MAX_INDEX(dtv);
     71 
     72 		new_dtv = xcalloc((2 + _rtld_tls_max_index) * sizeof(*dtv));
     73 		++new_dtv;
     74 		if (to_copy > _rtld_tls_max_index)
     75 			to_copy = _rtld_tls_max_index;
     76 		memcpy(new_dtv + 1, dtv + 1, to_copy * sizeof(*dtv));
     77 		xfree(dtv - 1);
     78 		dtv = tcb->tcb_dtv = new_dtv;
     79 		SET_DTV_MAX_INDEX(dtv, _rtld_tls_max_index);
     80 		SET_DTV_GENERATION(dtv, _rtld_tls_dtv_generation);
     81 	}
     82 
     83 	if (__predict_false(dtv[idx] == NULL))
     84 		dtv[idx] = _rtld_tls_module_allocate(idx);
     85 
     86 	_rtld_exclusive_exit(&mask);
     87 
     88 	return (uint8_t *)dtv[idx] + offset;
     89 }
     90 
     91 void
     92 _rtld_tls_initial_allocation(void)
     93 {
     94 	struct tls_tcb *tcb;
     95 
     96 	_rtld_tls_static_space = _rtld_tls_static_offset +
     97 	    RTLD_STATIC_TLS_RESERVATION;
     98 
     99 #ifndef __HAVE_TLS_VARIANT_I
    100 	_rtld_tls_static_space = roundup2(_rtld_tls_static_space,
    101 	    sizeof(void *));
    102 #endif
    103 
    104 	tcb = _rtld_tls_allocate_locked();
    105 #ifdef __HAVE___LWP_SETTCB
    106 	__lwp_settcb(tcb);
    107 #else
    108 	_lwp_setprivate(tcb);
    109 #endif
    110 }
    111 
    112 static struct tls_tcb *
    113 _rtld_tls_allocate_locked(void)
    114 {
    115 	Obj_Entry *obj;
    116 	struct tls_tcb *tcb;
    117 	uint8_t *p, *q;
    118 
    119 	p = xcalloc(_rtld_tls_static_space + sizeof(struct tls_tcb));
    120 #ifdef __HAVE_TLS_VARIANT_I
    121 	tcb = (struct tls_tcb *)p;
    122 	p += sizeof(struct tls_tcb);
    123 #else
    124 	p += _rtld_tls_static_space;
    125 	tcb = (struct tls_tcb *)p;
    126 	tcb->tcb_self = tcb;
    127 #endif
    128 	tcb->tcb_dtv = xcalloc(sizeof(*tcb->tcb_dtv) * (2 + _rtld_tls_max_index));
    129 	++tcb->tcb_dtv;
    130 	SET_DTV_MAX_INDEX(tcb->tcb_dtv, _rtld_tls_max_index);
    131 	SET_DTV_GENERATION(tcb->tcb_dtv, _rtld_tls_dtv_generation);
    132 
    133 	for (obj = _rtld_objlist; obj != NULL; obj = obj->next) {
    134 		if (obj->tlssize) {
    135 #ifdef __HAVE_TLS_VARIANT_I
    136 			q = p + obj->tlsoffset;
    137 #else
    138 			q = p - obj->tlsoffset;
    139 #endif
    140 			memcpy(q, obj->tlsinit, obj->tlsinitsize);
    141 			tcb->tcb_dtv[obj->tlsindex] = q;
    142 		}
    143 	}
    144 
    145 	return tcb;
    146 }
    147 
    148 struct tls_tcb *
    149 _rtld_tls_allocate(void)
    150 {
    151 	struct tls_tcb *tcb;
    152 	sigset_t mask;
    153 
    154 	_rtld_exclusive_enter(&mask);
    155 	tcb = _rtld_tls_allocate_locked();
    156 	_rtld_exclusive_exit(&mask);
    157 
    158 	return tcb;
    159 }
    160 
    161 void
    162 _rtld_tls_free(struct tls_tcb *tcb)
    163 {
    164 	size_t i, max_index;
    165 	uint8_t *p;
    166 	sigset_t mask;
    167 
    168 	_rtld_exclusive_enter(&mask);
    169 
    170 	max_index = DTV_MAX_INDEX(tcb->tcb_dtv);
    171 	for (i = 1; i <= max_index; ++i)
    172 		xfree(tcb->tcb_dtv[i]);
    173 	xfree(tcb->tcb_dtv - 1);
    174 
    175 #ifdef __HAVE_TLS_VARIANT_I
    176 	p = (uint8_t *)tcb;
    177 #else
    178 	p = (uint8_t *)tcb - _rtld_tls_static_space;
    179 #endif
    180 	xfree(p);
    181 
    182 	_rtld_exclusive_exit(&mask);
    183 }
    184 
    185 void *
    186 _rtld_tls_module_allocate(size_t idx)
    187 {
    188 	Obj_Entry *obj;
    189 	uint8_t *p;
    190 
    191 	for (obj = _rtld_objlist; obj != NULL; obj = obj->next) {
    192 		if (obj->tlsindex == idx)
    193 			break;
    194 	}
    195 	if (obj == NULL) {
    196 		_rtld_error("Module for TLS index %zu missing", idx);
    197 		_rtld_die();
    198 	}
    199 
    200 	p = xmalloc(obj->tlssize);
    201 	memcpy(p, obj->tlsinit, obj->tlsinitsize);
    202 	memset(p + obj->tlsinitsize, 0, obj->tlssize - obj->tlsinitsize);
    203 
    204 	return p;
    205 }
    206 
    207 int
    208 _rtld_tls_offset_allocate(Obj_Entry *obj)
    209 {
    210 	size_t offset, next_offset;
    211 
    212 	if (obj->tls_done)
    213 		return 0;
    214 	if (obj->tlssize == 0) {
    215 		obj->tlsoffset = 0;
    216 		obj->tls_done = 1;
    217 		return 0;
    218 	}
    219 
    220 #ifdef __HAVE_TLS_VARIANT_I
    221 	offset = roundup2(_rtld_tls_static_offset, obj->tlsalign);
    222 	next_offset = offset + obj->tlssize;
    223 #else
    224 	offset = roundup2(_rtld_tls_static_offset + obj->tlssize,
    225 	    obj->tlsalign);
    226 	next_offset = offset;
    227 #endif
    228 
    229 	/*
    230 	 * Check if the static allocation was already done.
    231 	 * This happens if dynamically loaded modules want to use
    232 	 * static TLS space.
    233 	 *
    234 	 * XXX Keep an actual free list and callbacks for initialisation.
    235 	 */
    236 	if (_rtld_tls_static_space) {
    237 		if (obj->tlsinitsize) {
    238 			_rtld_error("%s: Use of initialized "
    239 			    "Thread Locale Storage with model initial-exec "
    240 			    "and dlopen is not supported",
    241 			    obj->path);
    242 			return -1;
    243 		}
    244 		if (next_offset > _rtld_tls_static_space) {
    245 			_rtld_error("%s: No space available "
    246 			    "for static Thread Local Storage",
    247 			    obj->path);
    248 			return -1;
    249 		}
    250 	}
    251 	obj->tlsoffset = offset;
    252 	_rtld_tls_static_offset = next_offset;
    253 	obj->tls_done = 1;
    254 
    255 	return 0;
    256 }
    257 
    258 void
    259 _rtld_tls_offset_free(Obj_Entry *obj)
    260 {
    261 
    262 	/*
    263 	 * XXX See above.
    264 	 */
    265 	obj->tls_done = 0;
    266 	return;
    267 }
    268 
    269 #ifdef __HAVE_COMMON___TLS_GET_ADDR
    270 /*
    271  * The fast path is access to an already allocated DTV entry.
    272  * This checks the current limit and the entry without needing any
    273  * locking. Entries are only freed on dlclose() and it is an application
    274  * bug if code of the module is still running at that point.
    275  */
    276 void *
    277 __tls_get_addr(void *arg_)
    278 {
    279 	size_t *arg = (size_t *)arg_;
    280 	void **dtv;
    281 #ifdef __HAVE___LWP_GETTCB_FAST
    282 	struct tls_tcb * const tcb = __lwp_gettcb_fast();
    283 #else
    284 	struct tls_tcb * const tcb = __lwp_getprivate_fast();
    285 #endif
    286 	size_t idx = arg[0], offset = arg[1] + TLS_DTV_OFFSET;
    287 
    288 	dtv = tcb->tcb_dtv;
    289 
    290 	if (__predict_true(idx < DTV_MAX_INDEX(dtv) && dtv[idx] != NULL))
    291 		return (uint8_t *)dtv[idx] + offset;
    292 
    293 	return _rtld_tls_get_addr(tcb, idx, offset);
    294 }
    295 #endif
    296 
    297 #endif /* __HAVE_TLS_VARIANT_I || __HAVE_TLS_VARIANT_II */
    298