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tls.c revision 1.17 
      1 /*	$NetBSD: tls.c,v 1.17 2023/06/01 08:20:10 riastradh 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 1.17 2023/06/01 08:20:10 riastradh 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(("lwp %d tls tcb %p", _lwp_self(), 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(("%s: [lwp %d] tls dtv %p index %zu offset %zu",
    146 			    obj->path, _lwp_self(),
    147 			    q, obj->tlsindex, obj->tlsoffset));
    148 			if (obj->tlsinitsize)
    149 				memcpy(q, obj->tlsinit, obj->tlsinitsize);
    150 			tcb->tcb_dtv[obj->tlsindex] = q;
    151 		}
    152 	}
    153 
    154 	return tcb;
    155 }
    156 
    157 struct tls_tcb *
    158 _rtld_tls_allocate(void)
    159 {
    160 	struct tls_tcb *tcb;
    161 	sigset_t mask;
    162 
    163 	_rtld_exclusive_enter(&mask);
    164 	tcb = _rtld_tls_allocate_locked();
    165 	_rtld_exclusive_exit(&mask);
    166 
    167 	return tcb;
    168 }
    169 
    170 void
    171 _rtld_tls_free(struct tls_tcb *tcb)
    172 {
    173 	size_t i, max_index;
    174 	uint8_t *p, *p_end;
    175 	sigset_t mask;
    176 
    177 	_rtld_exclusive_enter(&mask);
    178 
    179 #ifdef __HAVE_TLS_VARIANT_I
    180 	p = (uint8_t *)tcb;
    181 #else
    182 	p = (uint8_t *)tcb - _rtld_tls_static_space;
    183 #endif
    184 	p_end = p + _rtld_tls_static_space;
    185 
    186 	max_index = DTV_MAX_INDEX(tcb->tcb_dtv);
    187 	for (i = 1; i <= max_index; ++i) {
    188 		if ((uint8_t *)tcb->tcb_dtv[i] < p ||
    189 		    (uint8_t *)tcb->tcb_dtv[i] >= p_end)
    190 			xfree(tcb->tcb_dtv[i]);
    191 	}
    192 	xfree(tcb->tcb_dtv - 1);
    193 	xfree(p);
    194 
    195 	_rtld_exclusive_exit(&mask);
    196 }
    197 
    198 void *
    199 _rtld_tls_module_allocate(size_t idx)
    200 {
    201 	Obj_Entry *obj;
    202 	uint8_t *p;
    203 
    204 	for (obj = _rtld_objlist; obj != NULL; obj = obj->next) {
    205 		if (obj->tlsindex == idx)
    206 			break;
    207 	}
    208 	if (obj == NULL) {
    209 		_rtld_error("Module for TLS index %zu missing", idx);
    210 		_rtld_die();
    211 	}
    212 
    213 	p = xmalloc(obj->tlssize);
    214 	memcpy(p, obj->tlsinit, obj->tlsinitsize);
    215 	memset(p + obj->tlsinitsize, 0, obj->tlssize - obj->tlsinitsize);
    216 
    217 	return p;
    218 }
    219 
    220 int
    221 _rtld_tls_offset_allocate(Obj_Entry *obj)
    222 {
    223 	size_t offset, next_offset;
    224 
    225 	if (obj->tls_done)
    226 		return 0;
    227 	if (obj->tlssize == 0) {
    228 		obj->tlsoffset = 0;
    229 		obj->tls_done = 1;
    230 		return 0;
    231 	}
    232 
    233 #ifdef __HAVE_TLS_VARIANT_I
    234 	offset = roundup2(_rtld_tls_static_offset, obj->tlsalign);
    235 	next_offset = offset + obj->tlssize;
    236 #else
    237 	offset = roundup2(_rtld_tls_static_offset + obj->tlssize,
    238 	    obj->tlsalign);
    239 	next_offset = offset;
    240 #endif
    241 
    242 	/*
    243 	 * Check if the static allocation was already done.
    244 	 * This happens if dynamically loaded modules want to use
    245 	 * static TLS space.
    246 	 *
    247 	 * XXX Keep an actual free list and callbacks for initialisation.
    248 	 */
    249 	if (_rtld_tls_static_space) {
    250 		if (obj->tlsinitsize) {
    251 			_rtld_error("%s: Use of initialized "
    252 			    "Thread Local Storage with model initial-exec "
    253 			    "and dlopen is not supported",
    254 			    obj->path);
    255 			return -1;
    256 		}
    257 		if (next_offset > _rtld_tls_static_space) {
    258 			_rtld_error("%s: No space available "
    259 			    "for static Thread Local Storage",
    260 			    obj->path);
    261 			return -1;
    262 		}
    263 	}
    264 	obj->tlsoffset = offset;
    265 	dbg(("%s: static tls offset 0x%zx size %zu\n",
    266 	    obj->path, obj->tlsoffset, obj->tlssize));
    267 	_rtld_tls_static_offset = next_offset;
    268 	obj->tls_done = 1;
    269 
    270 	return 0;
    271 }
    272 
    273 void
    274 _rtld_tls_offset_free(Obj_Entry *obj)
    275 {
    276 
    277 	/*
    278 	 * XXX See above.
    279 	 */
    280 	obj->tls_done = 0;
    281 	return;
    282 }
    283 
    284 #if defined(__HAVE_COMMON___TLS_GET_ADDR) && defined(RTLD_LOADER)
    285 /*
    286  * The fast path is access to an already allocated DTV entry.
    287  * This checks the current limit and the entry without needing any
    288  * locking. Entries are only freed on dlclose() and it is an application
    289  * bug if code of the module is still running at that point.
    290  */
    291 void *
    292 __tls_get_addr(void *arg_)
    293 {
    294 	size_t *arg = (size_t *)arg_;
    295 	void **dtv;
    296 #ifdef __HAVE___LWP_GETTCB_FAST
    297 	struct tls_tcb * const tcb = __lwp_gettcb_fast();
    298 #else
    299 	struct tls_tcb * const tcb = __lwp_getprivate_fast();
    300 #endif
    301 	size_t idx = arg[0], offset = arg[1] + TLS_DTV_OFFSET;
    302 
    303 	dtv = tcb->tcb_dtv;
    304 
    305 	if (__predict_true(idx < DTV_MAX_INDEX(dtv) && dtv[idx] != NULL))
    306 		return (uint8_t *)dtv[idx] + offset;
    307 
    308 	return _rtld_tls_get_addr(tcb, idx, offset);
    309 }
    310 #endif
    311 
    312 #endif /* __HAVE_TLS_VARIANT_I || __HAVE_TLS_VARIANT_II */
    313