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tls.c revision 1.6 
      1 /*	$NetBSD: tls.c,v 1.6 2011/04/07 02:19:28 matt 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 1.6 2011/04/07 02:19:28 matt 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 #ifdef __powerpc__
    108 	/*
    109 	 * Save the tcb pointer so that libc can retrieve it.  Older
    110 	 * crt0 will obliterate r2 so there is code in libc to restore it.
    111 	 */
    112 	_lwp_setprivate(tcb);
    113 #endif
    114 #else
    115 	_lwp_setprivate(tcb);
    116 #endif
    117 }
    118 
    119 static struct tls_tcb *
    120 _rtld_tls_allocate_locked(void)
    121 {
    122 	Obj_Entry *obj;
    123 	struct tls_tcb *tcb;
    124 	uint8_t *p, *q;
    125 
    126 	p = xcalloc(_rtld_tls_static_space + sizeof(struct tls_tcb));
    127 #ifdef __HAVE_TLS_VARIANT_I
    128 	tcb = (struct tls_tcb *)p;
    129 	p += sizeof(struct tls_tcb);
    130 #else
    131 	p += _rtld_tls_static_space;
    132 	tcb = (struct tls_tcb *)p;
    133 	tcb->tcb_self = tcb;
    134 #endif
    135 	tcb->tcb_dtv = xcalloc(sizeof(*tcb->tcb_dtv) * (2 + _rtld_tls_max_index));
    136 	++tcb->tcb_dtv;
    137 	SET_DTV_MAX_INDEX(tcb->tcb_dtv, _rtld_tls_max_index);
    138 	SET_DTV_GENERATION(tcb->tcb_dtv, _rtld_tls_dtv_generation);
    139 
    140 	for (obj = _rtld_objlist; obj != NULL; obj = obj->next) {
    141 		if (obj->tlssize) {
    142 #ifdef __HAVE_TLS_VARIANT_I
    143 			q = p + obj->tlsoffset;
    144 #else
    145 			q = p - obj->tlsoffset;
    146 #endif
    147 			memcpy(q, obj->tlsinit, obj->tlsinitsize);
    148 			tcb->tcb_dtv[obj->tlsindex] = q;
    149 		}
    150 	}
    151 
    152 	return tcb;
    153 }
    154 
    155 struct tls_tcb *
    156 _rtld_tls_allocate(void)
    157 {
    158 	struct tls_tcb *tcb;
    159 	sigset_t mask;
    160 
    161 	_rtld_exclusive_enter(&mask);
    162 	tcb = _rtld_tls_allocate_locked();
    163 	_rtld_exclusive_exit(&mask);
    164 
    165 	return tcb;
    166 }
    167 
    168 void
    169 _rtld_tls_free(struct tls_tcb *tcb)
    170 {
    171 	size_t i, max_index;
    172 	uint8_t *p;
    173 	sigset_t mask;
    174 
    175 	_rtld_exclusive_enter(&mask);
    176 
    177 	max_index = DTV_MAX_INDEX(tcb->tcb_dtv);
    178 	for (i = 1; i <= max_index; ++i)
    179 		xfree(tcb->tcb_dtv[i]);
    180 	xfree(tcb->tcb_dtv - 1);
    181 
    182 #ifdef __HAVE_TLS_VARIANT_I
    183 	p = (uint8_t *)tcb;
    184 #else
    185 	p = (uint8_t *)tcb - _rtld_tls_static_space;
    186 #endif
    187 	xfree(p);
    188 
    189 	_rtld_exclusive_exit(&mask);
    190 }
    191 
    192 void *
    193 _rtld_tls_module_allocate(size_t idx)
    194 {
    195 	Obj_Entry *obj;
    196 	uint8_t *p;
    197 
    198 	for (obj = _rtld_objlist; obj != NULL; obj = obj->next) {
    199 		if (obj->tlsindex == idx)
    200 			break;
    201 	}
    202 	if (obj == NULL) {
    203 		_rtld_error("Module for TLS index %zu missing", idx);
    204 		_rtld_die();
    205 	}
    206 
    207 	p = xmalloc(obj->tlssize);
    208 	memcpy(p, obj->tlsinit, obj->tlsinitsize);
    209 	memset(p + obj->tlsinitsize, 0, obj->tlssize - obj->tlsinitsize);
    210 
    211 	return p;
    212 }
    213 
    214 int
    215 _rtld_tls_offset_allocate(Obj_Entry *obj)
    216 {
    217 	size_t offset, next_offset;
    218 
    219 	if (obj->tls_done)
    220 		return 0;
    221 	if (obj->tlssize == 0) {
    222 		obj->tlsoffset = 0;
    223 		obj->tls_done = 1;
    224 		return 0;
    225 	}
    226 
    227 #ifdef __HAVE_TLS_VARIANT_I
    228 	offset = roundup2(_rtld_tls_static_offset, obj->tlsalign);
    229 	next_offset = offset + obj->tlssize;
    230 #else
    231 	offset = roundup2(_rtld_tls_static_offset + obj->tlssize,
    232 	    obj->tlsalign);
    233 	next_offset = offset;
    234 #endif
    235 
    236 	/*
    237 	 * Check if the static allocation was already done.
    238 	 * This happens if dynamically loaded modules want to use
    239 	 * static TLS space.
    240 	 *
    241 	 * XXX Keep an actual free list and callbacks for initialisation.
    242 	 */
    243 	if (_rtld_tls_static_space) {
    244 		if (obj->tlsinitsize) {
    245 			_rtld_error("%s: Use of initialized "
    246 			    "Thread Locale Storage with model initial-exec "
    247 			    "and dlopen is not supported",
    248 			    obj->path);
    249 			return -1;
    250 		}
    251 		if (next_offset > _rtld_tls_static_space) {
    252 			_rtld_error("%s: No space available "
    253 			    "for static Thread Local Storage",
    254 			    obj->path);
    255 			return -1;
    256 		}
    257 	}
    258 	obj->tlsoffset = offset;
    259 	_rtld_tls_static_offset = next_offset;
    260 	obj->tls_done = 1;
    261 
    262 	return 0;
    263 }
    264 
    265 void
    266 _rtld_tls_offset_free(Obj_Entry *obj)
    267 {
    268 
    269 	/*
    270 	 * XXX See above.
    271 	 */
    272 	obj->tls_done = 0;
    273 	return;
    274 }
    275 
    276 #ifdef __HAVE_COMMON___TLS_GET_ADDR
    277 /*
    278  * The fast path is access to an already allocated DTV entry.
    279  * This checks the current limit and the entry without needing any
    280  * locking. Entries are only freed on dlclose() and it is an application
    281  * bug if code of the module is still running at that point.
    282  */
    283 void *
    284 __tls_get_addr(void *arg_)
    285 {
    286 	size_t *arg = (size_t *)arg_;
    287 	void **dtv;
    288 #ifdef __HAVE___LWP_GETTCB_FAST
    289 	struct tls_tcb * const tcb = __lwp_gettcb_fast();
    290 #else
    291 	struct tls_tcb * const tcb = __lwp_getprivate_fast();
    292 #endif
    293 	size_t idx = arg[0], offset = arg[1] + TLS_DTV_OFFSET;
    294 
    295 	dtv = tcb->tcb_dtv;
    296 
    297 	if (__predict_true(idx < DTV_MAX_INDEX(dtv) && dtv[idx] != NULL))
    298 		return (uint8_t *)dtv[idx] + offset;
    299 
    300 	return _rtld_tls_get_addr(tcb, idx, offset);
    301 }
    302 #endif
    303 
    304 #endif /* __HAVE_TLS_VARIANT_I || __HAVE_TLS_VARIANT_II */
    305