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tls.c revision 1.15 
      1 /*	$NetBSD: tls.c,v 1.15 2023/02/10 08:12:48 skrll 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 1.15 2023/02/10 08:12:48 skrll Exp $");
     33 
     34 #include <sys/param.h>
     35 #include <sys/ucontext.h>
     36 #include <lwp.h>
     37 #include <stdalign.h>
     38 #include <stddef.h>
     39 #include <string.h>
     40 #include "debug.h"
     41 #include "rtld.h"
     42 
     43 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II)
     44 
     45 static struct tls_tcb *_rtld_tls_allocate_locked(void);
     46 
     47 #ifndef TLS_DTV_OFFSET
     48 #define	TLS_DTV_OFFSET	0
     49 #endif
     50 
     51 static size_t _rtld_tls_static_space;	/* Static TLS space allocated */
     52 static size_t _rtld_tls_static_offset;	/* Next offset for static TLS to use */
     53 size_t _rtld_tls_dtv_generation = 1;
     54 size_t _rtld_tls_max_index = 1;
     55 
     56 #define	DTV_GENERATION(dtv)		((size_t)((dtv)[0]))
     57 #define	DTV_MAX_INDEX(dtv)		((size_t)((dtv)[-1]))
     58 #define	SET_DTV_GENERATION(dtv, val)	(dtv)[0] = (void *)(size_t)(val)
     59 #define	SET_DTV_MAX_INDEX(dtv, val)	(dtv)[-1] = (void *)(size_t)(val)
     60 
     61 void *
     62 _rtld_tls_get_addr(void *tls, size_t idx, size_t offset)
     63 {
     64 	struct tls_tcb *tcb = tls;
     65 	void **dtv, **new_dtv;
     66 	sigset_t mask;
     67 
     68 	_rtld_exclusive_enter(&mask);
     69 
     70 	dtv = tcb->tcb_dtv;
     71 
     72 	if (__predict_false(DTV_GENERATION(dtv) != _rtld_tls_dtv_generation)) {
     73 		size_t to_copy = DTV_MAX_INDEX(dtv);
     74 
     75 		new_dtv = xcalloc((2 + _rtld_tls_max_index) * sizeof(*dtv));
     76 		++new_dtv;
     77 		if (to_copy > _rtld_tls_max_index)
     78 			to_copy = _rtld_tls_max_index;
     79 		memcpy(new_dtv + 1, dtv + 1, to_copy * sizeof(*dtv));
     80 		xfree(dtv - 1);
     81 		dtv = tcb->tcb_dtv = new_dtv;
     82 		SET_DTV_MAX_INDEX(dtv, _rtld_tls_max_index);
     83 		SET_DTV_GENERATION(dtv, _rtld_tls_dtv_generation);
     84 	}
     85 
     86 	if (__predict_false(dtv[idx] == NULL))
     87 		dtv[idx] = _rtld_tls_module_allocate(idx);
     88 
     89 	_rtld_exclusive_exit(&mask);
     90 
     91 	return (uint8_t *)dtv[idx] + offset;
     92 }
     93 
     94 void
     95 _rtld_tls_initial_allocation(void)
     96 {
     97 	struct tls_tcb *tcb;
     98 
     99 	_rtld_tls_static_space = _rtld_tls_static_offset +
    100 	    RTLD_STATIC_TLS_RESERVATION;
    101 
    102 #ifndef __HAVE_TLS_VARIANT_I
    103 	_rtld_tls_static_space = roundup2(_rtld_tls_static_space,
    104 	    alignof(max_align_t));
    105 #endif
    106 	dbg(("_rtld_tls_static_space %zu", _rtld_tls_static_space));
    107 
    108 	tcb = _rtld_tls_allocate_locked();
    109 #ifdef __HAVE___LWP_SETTCB
    110 	__lwp_settcb(tcb);
    111 #else
    112 	_lwp_setprivate(tcb);
    113 #endif
    114 }
    115 
    116 static struct tls_tcb *
    117 _rtld_tls_allocate_locked(void)
    118 {
    119 	Obj_Entry *obj;
    120 	struct tls_tcb *tcb;
    121 	uint8_t *p, *q;
    122 
    123 	p = xcalloc(_rtld_tls_static_space + sizeof(struct tls_tcb));
    124 #ifdef __HAVE_TLS_VARIANT_I
    125 	tcb = (struct tls_tcb *)p;
    126 	p += sizeof(struct tls_tcb);
    127 #else
    128 	p += _rtld_tls_static_space;
    129 	tcb = (struct tls_tcb *)p;
    130 	tcb->tcb_self = tcb;
    131 #endif
    132 	dbg(("tcb %p", tcb));
    133 	tcb->tcb_dtv = xcalloc(sizeof(*tcb->tcb_dtv) * (2 + _rtld_tls_max_index));
    134 	++tcb->tcb_dtv;
    135 	SET_DTV_MAX_INDEX(tcb->tcb_dtv, _rtld_tls_max_index);
    136 	SET_DTV_GENERATION(tcb->tcb_dtv, _rtld_tls_dtv_generation);
    137 
    138 	for (obj = _rtld_objlist; obj != NULL; obj = obj->next) {
    139 		if (obj->tls_done) {
    140 #ifdef __HAVE_TLS_VARIANT_I
    141 			q = p + obj->tlsoffset;
    142 #else
    143 			q = p - obj->tlsoffset;
    144 #endif
    145 			dbg(("obj %p dtv %p tlsoffset %zu",
    146 			    obj, q, obj->tlsoffset));
    147 			if (obj->tlsinitsize)
    148 				memcpy(q, obj->tlsinit, obj->tlsinitsize);
    149 			tcb->tcb_dtv[obj->tlsindex] = q;
    150 		}
    151 	}
    152 
    153 	return tcb;
    154 }
    155 
    156 struct tls_tcb *
    157 _rtld_tls_allocate(void)
    158 {
    159 	struct tls_tcb *tcb;
    160 	sigset_t mask;
    161 
    162 	_rtld_exclusive_enter(&mask);
    163 	tcb = _rtld_tls_allocate_locked();
    164 	_rtld_exclusive_exit(&mask);
    165 
    166 	return tcb;
    167 }
    168 
    169 void
    170 _rtld_tls_free(struct tls_tcb *tcb)
    171 {
    172 	size_t i, max_index;
    173 	uint8_t *p, *p_end;
    174 	sigset_t mask;
    175 
    176 	_rtld_exclusive_enter(&mask);
    177 
    178 #ifdef __HAVE_TLS_VARIANT_I
    179 	p = (uint8_t *)tcb;
    180 #else
    181 	p = (uint8_t *)tcb - _rtld_tls_static_space;
    182 #endif
    183 	p_end = p + _rtld_tls_static_space;
    184 
    185 	max_index = DTV_MAX_INDEX(tcb->tcb_dtv);
    186 	for (i = 1; i <= max_index; ++i) {
    187 		if ((uint8_t *)tcb->tcb_dtv[i] < p ||
    188 		    (uint8_t *)tcb->tcb_dtv[i] >= p_end)
    189 			xfree(tcb->tcb_dtv[i]);
    190 	}
    191 	xfree(tcb->tcb_dtv - 1);
    192 	xfree(p);
    193 
    194 	_rtld_exclusive_exit(&mask);
    195 }
    196 
    197 void *
    198 _rtld_tls_module_allocate(size_t idx)
    199 {
    200 	Obj_Entry *obj;
    201 	uint8_t *p;
    202 
    203 	for (obj = _rtld_objlist; obj != NULL; obj = obj->next) {
    204 		if (obj->tlsindex == idx)
    205 			break;
    206 	}
    207 	if (obj == NULL) {
    208 		_rtld_error("Module for TLS index %zu missing", idx);
    209 		_rtld_die();
    210 	}
    211 
    212 	p = xmalloc(obj->tlssize);
    213 	memcpy(p, obj->tlsinit, obj->tlsinitsize);
    214 	memset(p + obj->tlsinitsize, 0, obj->tlssize - obj->tlsinitsize);
    215 
    216 	return p;
    217 }
    218 
    219 int
    220 _rtld_tls_offset_allocate(Obj_Entry *obj)
    221 {
    222 	size_t offset, next_offset;
    223 
    224 	if (obj->tls_done)
    225 		return 0;
    226 	if (obj->tlssize == 0) {
    227 		obj->tlsoffset = 0;
    228 		obj->tls_done = 1;
    229 		return 0;
    230 	}
    231 
    232 #ifdef __HAVE_TLS_VARIANT_I
    233 	offset = roundup2(_rtld_tls_static_offset, obj->tlsalign);
    234 	next_offset = offset + obj->tlssize;
    235 #else
    236 	offset = roundup2(_rtld_tls_static_offset + obj->tlssize,
    237 	    obj->tlsalign);
    238 	next_offset = offset;
    239 #endif
    240 
    241 	/*
    242 	 * Check if the static allocation was already done.
    243 	 * This happens if dynamically loaded modules want to use
    244 	 * static TLS space.
    245 	 *
    246 	 * XXX Keep an actual free list and callbacks for initialisation.
    247 	 */
    248 	if (_rtld_tls_static_space) {
    249 		if (obj->tlsinitsize) {
    250 			_rtld_error("%s: Use of initialized "
    251 			    "Thread Local Storage with model initial-exec "
    252 			    "and dlopen is not supported",
    253 			    obj->path);
    254 			return -1;
    255 		}
    256 		if (next_offset > _rtld_tls_static_space) {
    257 			_rtld_error("%s: No space available "
    258 			    "for static Thread Local Storage",
    259 			    obj->path);
    260 			return -1;
    261 		}
    262 	}
    263 	obj->tlsoffset = offset;
    264 	_rtld_tls_static_offset = next_offset;
    265 	obj->tls_done = 1;
    266 
    267 	return 0;
    268 }
    269 
    270 void
    271 _rtld_tls_offset_free(Obj_Entry *obj)
    272 {
    273 
    274 	/*
    275 	 * XXX See above.
    276 	 */
    277 	obj->tls_done = 0;
    278 	return;
    279 }
    280 
    281 #if defined(__HAVE_COMMON___TLS_GET_ADDR) && defined(RTLD_LOADER)
    282 /*
    283  * The fast path is access to an already allocated DTV entry.
    284  * This checks the current limit and the entry without needing any
    285  * locking. Entries are only freed on dlclose() and it is an application
    286  * bug if code of the module is still running at that point.
    287  */
    288 void *
    289 __tls_get_addr(void *arg_)
    290 {
    291 	size_t *arg = (size_t *)arg_;
    292 	void **dtv;
    293 #ifdef __HAVE___LWP_GETTCB_FAST
    294 	struct tls_tcb * const tcb = __lwp_gettcb_fast();
    295 #else
    296 	struct tls_tcb * const tcb = __lwp_getprivate_fast();
    297 #endif
    298 	size_t idx = arg[0], offset = arg[1] + TLS_DTV_OFFSET;
    299 
    300 	dtv = tcb->tcb_dtv;
    301 
    302 	if (__predict_true(idx < DTV_MAX_INDEX(dtv) && dtv[idx] != NULL))
    303 		return (uint8_t *)dtv[idx] + offset;
    304 
    305 	return _rtld_tls_get_addr(tcb, idx, offset);
    306 }
    307 #endif
    308 
    309 #endif /* __HAVE_TLS_VARIANT_I || __HAVE_TLS_VARIANT_II */
    310