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tls.c revision 1.11 
      1 /*	$NetBSD: tls.c,v 1.11 2017/07/13 14:10:38 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 1.11 2017/07/13 14:10:38 joerg Exp $");
     33 
     34 #include <sys/param.h>
     35 #include <sys/ucontext.h>
     36 #include <lwp.h>
     37 #include <string.h>
     38 #include "debug.h"
     39 #include "rtld.h"
     40 
     41 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II)
     42 
     43 static struct tls_tcb *_rtld_tls_allocate_locked(void);
     44 
     45 #ifndef TLS_DTV_OFFSET
     46 #define	TLS_DTV_OFFSET	0
     47 #endif
     48 
     49 static size_t _rtld_tls_static_space;	/* Static TLS space allocated */
     50 static size_t _rtld_tls_static_offset;	/* Next offset for static TLS to use */
     51 size_t _rtld_tls_dtv_generation = 1;
     52 size_t _rtld_tls_max_index = 1;
     53 
     54 #define	DTV_GENERATION(dtv)	((size_t)((dtv)[0]))
     55 #define	DTV_MAX_INDEX(dtv)	((size_t)((dtv)[-1]))
     56 #define	SET_DTV_GENERATION(dtv, val)	(dtv)[0] = (void *)(size_t)(val)
     57 #define	SET_DTV_MAX_INDEX(dtv, val)	(dtv)[-1] = (void *)(size_t)(val)
     58 
     59 void *
     60 _rtld_tls_get_addr(void *tls, size_t idx, size_t offset)
     61 {
     62 	struct tls_tcb *tcb = tls;
     63 	void **dtv, **new_dtv;
     64 	sigset_t mask;
     65 
     66 	_rtld_exclusive_enter(&mask);
     67 
     68 	dtv = tcb->tcb_dtv;
     69 
     70 	if (__predict_false(DTV_GENERATION(dtv) != _rtld_tls_dtv_generation)) {
     71 		size_t to_copy = DTV_MAX_INDEX(dtv);
     72 
     73 		new_dtv = xcalloc((2 + _rtld_tls_max_index) * sizeof(*dtv));
     74 		++new_dtv;
     75 		if (to_copy > _rtld_tls_max_index)
     76 			to_copy = _rtld_tls_max_index;
     77 		memcpy(new_dtv + 1, dtv + 1, to_copy * sizeof(*dtv));
     78 		xfree(dtv - 1);
     79 		dtv = tcb->tcb_dtv = new_dtv;
     80 		SET_DTV_MAX_INDEX(dtv, _rtld_tls_max_index);
     81 		SET_DTV_GENERATION(dtv, _rtld_tls_dtv_generation);
     82 	}
     83 
     84 	if (__predict_false(dtv[idx] == NULL))
     85 		dtv[idx] = _rtld_tls_module_allocate(idx);
     86 
     87 	_rtld_exclusive_exit(&mask);
     88 
     89 	return (uint8_t *)dtv[idx] + offset;
     90 }
     91 
     92 void
     93 _rtld_tls_initial_allocation(void)
     94 {
     95 	struct tls_tcb *tcb;
     96 
     97 	_rtld_tls_static_space = _rtld_tls_static_offset +
     98 	    RTLD_STATIC_TLS_RESERVATION;
     99 
    100 #ifndef __HAVE_TLS_VARIANT_I
    101 	_rtld_tls_static_space = roundup2(_rtld_tls_static_space,
    102 	    sizeof(void *));
    103 #endif
    104 	dbg(("_rtld_tls_static_space %zu", _rtld_tls_static_space));
    105 
    106 	tcb = _rtld_tls_allocate_locked();
    107 #ifdef __HAVE___LWP_SETTCB
    108 	__lwp_settcb(tcb);
    109 #else
    110 	_lwp_setprivate(tcb);
    111 #endif
    112 }
    113 
    114 static struct tls_tcb *
    115 _rtld_tls_allocate_locked(void)
    116 {
    117 	Obj_Entry *obj;
    118 	struct tls_tcb *tcb;
    119 	uint8_t *p, *q;
    120 
    121 	p = xcalloc(_rtld_tls_static_space + sizeof(struct tls_tcb));
    122 #ifdef __HAVE_TLS_VARIANT_I
    123 	tcb = (struct tls_tcb *)p;
    124 	p += sizeof(struct tls_tcb);
    125 #else
    126 	p += _rtld_tls_static_space;
    127 	tcb = (struct tls_tcb *)p;
    128 	tcb->tcb_self = tcb;
    129 #endif
    130 	dbg(("tcb %p", tcb));
    131 	tcb->tcb_dtv = xcalloc(sizeof(*tcb->tcb_dtv) * (2 + _rtld_tls_max_index));
    132 	++tcb->tcb_dtv;
    133 	SET_DTV_MAX_INDEX(tcb->tcb_dtv, _rtld_tls_max_index);
    134 	SET_DTV_GENERATION(tcb->tcb_dtv, _rtld_tls_dtv_generation);
    135 
    136 	for (obj = _rtld_objlist; obj != NULL; obj = obj->next) {
    137 		if (obj->tls_done) {
    138 #ifdef __HAVE_TLS_VARIANT_I
    139 			q = p + obj->tlsoffset;
    140 #else
    141 			q = p - obj->tlsoffset;
    142 #endif
    143 			dbg(("obj %p dtv %p tlsoffset %zu",
    144 			    obj, q, obj->tlsoffset));
    145 			if (obj->tlsinitsize)
    146 				memcpy(q, obj->tlsinit, obj->tlsinitsize);
    147 			tcb->tcb_dtv[obj->tlsindex] = q;
    148 		}
    149 	}
    150 
    151 	return tcb;
    152 }
    153 
    154 struct tls_tcb *
    155 _rtld_tls_allocate(void)
    156 {
    157 	struct tls_tcb *tcb;
    158 	sigset_t mask;
    159 
    160 	_rtld_exclusive_enter(&mask);
    161 	tcb = _rtld_tls_allocate_locked();
    162 	_rtld_exclusive_exit(&mask);
    163 
    164 	return tcb;
    165 }
    166 
    167 void
    168 _rtld_tls_free(struct tls_tcb *tcb)
    169 {
    170 	size_t i, max_index;
    171 	uint8_t *p, *p_end;
    172 	sigset_t mask;
    173 
    174 	_rtld_exclusive_enter(&mask);
    175 
    176 #ifdef __HAVE_TLS_VARIANT_I
    177 	p = (uint8_t *)tcb;
    178 #else
    179 	p = (uint8_t *)tcb - _rtld_tls_static_space;
    180 #endif
    181 	p_end = p + _rtld_tls_static_space;
    182 
    183 	max_index = DTV_MAX_INDEX(tcb->tcb_dtv);
    184 	for (i = 1; i <= max_index; ++i) {
    185 		if ((uint8_t *)tcb->tcb_dtv[i] < p ||
    186 		    (uint8_t *)tcb->tcb_dtv[i] >= p_end)
    187 			xfree(tcb->tcb_dtv[i]);
    188 	}
    189 	xfree(tcb->tcb_dtv - 1);
    190 	xfree(p);
    191 
    192 	_rtld_exclusive_exit(&mask);
    193 }
    194 
    195 void *
    196 _rtld_tls_module_allocate(size_t idx)
    197 {
    198 	Obj_Entry *obj;
    199 	uint8_t *p;
    200 
    201 	for (obj = _rtld_objlist; obj != NULL; obj = obj->next) {
    202 		if (obj->tlsindex == idx)
    203 			break;
    204 	}
    205 	if (obj == NULL) {
    206 		_rtld_error("Module for TLS index %zu missing", idx);
    207 		_rtld_die();
    208 	}
    209 
    210 	p = xmalloc(obj->tlssize);
    211 	memcpy(p, obj->tlsinit, obj->tlsinitsize);
    212 	memset(p + obj->tlsinitsize, 0, obj->tlssize - obj->tlsinitsize);
    213 
    214 	return p;
    215 }
    216 
    217 int
    218 _rtld_tls_offset_allocate(Obj_Entry *obj)
    219 {
    220 	size_t offset, next_offset;
    221 
    222 	if (obj->tls_done)
    223 		return 0;
    224 	if (obj->tlssize == 0) {
    225 		obj->tlsoffset = 0;
    226 		obj->tls_done = 1;
    227 		return 0;
    228 	}
    229 
    230 #ifdef __HAVE_TLS_VARIANT_I
    231 	offset = roundup2(_rtld_tls_static_offset, obj->tlsalign);
    232 	next_offset = offset + obj->tlssize;
    233 #else
    234 	offset = roundup2(_rtld_tls_static_offset + obj->tlssize,
    235 	    obj->tlsalign);
    236 	next_offset = offset;
    237 #endif
    238 
    239 	/*
    240 	 * Check if the static allocation was already done.
    241 	 * This happens if dynamically loaded modules want to use
    242 	 * static TLS space.
    243 	 *
    244 	 * XXX Keep an actual free list and callbacks for initialisation.
    245 	 */
    246 	if (_rtld_tls_static_space) {
    247 		if (obj->tlsinitsize) {
    248 			_rtld_error("%s: Use of initialized "
    249 			    "Thread Local Storage with model initial-exec "
    250 			    "and dlopen is not supported",
    251 			    obj->path);
    252 			return -1;
    253 		}
    254 		if (next_offset > _rtld_tls_static_space) {
    255 			_rtld_error("%s: No space available "
    256 			    "for static Thread Local Storage",
    257 			    obj->path);
    258 			return -1;
    259 		}
    260 	}
    261 	obj->tlsoffset = offset;
    262 	_rtld_tls_static_offset = next_offset;
    263 	obj->tls_done = 1;
    264 
    265 	return 0;
    266 }
    267 
    268 void
    269 _rtld_tls_offset_free(Obj_Entry *obj)
    270 {
    271 
    272 	/*
    273 	 * XXX See above.
    274 	 */
    275 	obj->tls_done = 0;
    276 	return;
    277 }
    278 
    279 #ifdef __HAVE_COMMON___TLS_GET_ADDR
    280 /*
    281  * The fast path is access to an already allocated DTV entry.
    282  * This checks the current limit and the entry without needing any
    283  * locking. Entries are only freed on dlclose() and it is an application
    284  * bug if code of the module is still running at that point.
    285  */
    286 void *
    287 __tls_get_addr(void *arg_)
    288 {
    289 	size_t *arg = (size_t *)arg_;
    290 	void **dtv;
    291 #ifdef __HAVE___LWP_GETTCB_FAST
    292 	struct tls_tcb * const tcb = __lwp_gettcb_fast();
    293 #else
    294 	struct tls_tcb * const tcb = __lwp_getprivate_fast();
    295 #endif
    296 	size_t idx = arg[0], offset = arg[1] + TLS_DTV_OFFSET;
    297 
    298 	dtv = tcb->tcb_dtv;
    299 
    300 	if (__predict_true(idx < DTV_MAX_INDEX(dtv) && dtv[idx] != NULL))
    301 		return (uint8_t *)dtv[idx] + offset;
    302 
    303 	return _rtld_tls_get_addr(tcb, idx, offset);
    304 }
    305 #endif
    306 
    307 #endif /* __HAVE_TLS_VARIANT_I || __HAVE_TLS_VARIANT_II */
    308