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tls.c revision 1.12 
      1 /*	$NetBSD: tls.c,v 1.12 2019/11/07 22:25:21 joerg Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2011 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Joerg Sonnenberger.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     29  * POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 
     32 #include <sys/cdefs.h>
     33 __RCSID("$NetBSD: tls.c,v 1.12 2019/11/07 22:25:21 joerg Exp $");
     34 
     35 #include "namespace.h"
     36 
     37 #define	_rtld_tls_allocate	__libc_rtld_tls_allocate
     38 #define	_rtld_tls_free		__libc_rtld_tls_free
     39 
     40 #include <sys/tls.h>
     41 
     42 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II)
     43 
     44 #include <sys/param.h>
     45 #include <sys/mman.h>
     46 #include <link_elf.h>
     47 #include <lwp.h>
     48 #include <stdbool.h>
     49 #include <stdalign.h>
     50 #include <stddef.h>
     51 #include <stdlib.h>
     52 #include <string.h>
     53 #include <unistd.h>
     54 
     55 __dso_hidden void	__libc_static_tls_setup(void);
     56 
     57 static bool is_dynamic;
     58 static const void *tls_initaddr;
     59 static size_t tls_initsize;
     60 static size_t tls_size;
     61 static size_t tls_allocation;
     62 static void *initial_thread_tcb;
     63 
     64 void * __libc_tls_get_addr(void);
     65 
     66 __weak_alias(__tls_get_addr, __libc_tls_get_addr)
     67 #ifdef __i386__
     68 __weak_alias(___tls_get_addr, __libc_tls_get_addr)
     69 #endif
     70 
     71 void *
     72 __libc_tls_get_addr(void)
     73 {
     74 
     75 	abort();
     76 	/* NOTREACHED */
     77 }
     78 
     79 __weak_alias(_rtld_tls_allocate, __libc_rtld_tls_allocate)
     80 
     81 struct tls_tcb *
     82 _rtld_tls_allocate(void)
     83 {
     84 	struct tls_tcb *tcb;
     85 	uint8_t *p;
     86 
     87 	if (initial_thread_tcb == NULL) {
     88 #ifdef __HAVE_TLS_VARIANT_II
     89 		tls_allocation = roundup2(tls_size, alignof(max_align_t));
     90 #else
     91 		tls_allocation = tls_size;
     92 #endif
     93 
     94 		initial_thread_tcb = p = mmap(NULL,
     95 		    tls_allocation + sizeof(*tcb), PROT_READ | PROT_WRITE,
     96 		    MAP_ANON, -1, 0);
     97 	} else {
     98 		p = calloc(1, tls_allocation + sizeof(*tcb));
     99 	}
    100 	if (p == NULL) {
    101 		static const char msg[] =  "TLS allocation failed, terminating\n";
    102 		write(STDERR_FILENO, msg, sizeof(msg));
    103 		_exit(127);
    104 	}
    105 #ifdef __HAVE_TLS_VARIANT_I
    106 	/* LINTED */
    107 	tcb = (struct tls_tcb *)p;
    108 	p += sizeof(struct tls_tcb);
    109 #else
    110 	/* LINTED tls_size is rounded above */
    111 	tcb = (struct tls_tcb *)(p + tls_allocation);
    112 	p = (uint8_t *)tcb - tls_size;
    113 	tcb->tcb_self = tcb;
    114 #endif
    115 	memcpy(p, tls_initaddr, tls_initsize);
    116 
    117 	return tcb;
    118 }
    119 
    120 __weak_alias(_rtld_tls_free, __libc_rtld_tls_free)
    121 
    122 void
    123 _rtld_tls_free(struct tls_tcb *tcb)
    124 {
    125 	uint8_t *p;
    126 
    127 #ifdef __HAVE_TLS_VARIANT_I
    128 	/* LINTED */
    129 	p = (uint8_t *)tcb;
    130 #else
    131 	/* LINTED */
    132 	p = (uint8_t *)tcb - tls_allocation;
    133 #endif
    134 	if (p == initial_thread_tcb)
    135 		munmap(p, tls_allocation + sizeof(*tcb));
    136 	else
    137 		free(p);
    138 }
    139 
    140 static int __section(".text.startup")
    141 __libc_static_tls_setup_cb(struct dl_phdr_info *data, size_t len, void *cookie)
    142 {
    143 	const Elf_Phdr *phdr = data->dlpi_phdr;
    144 	const Elf_Phdr *phlimit = data->dlpi_phdr + data->dlpi_phnum;
    145 
    146 	for (; phdr < phlimit; ++phdr) {
    147 		if (phdr->p_type == PT_INTERP) {
    148 			is_dynamic = true;
    149 			return -1;
    150 		}
    151 		if (phdr->p_type != PT_TLS)
    152 			continue;
    153 		tls_initaddr = (void *)(phdr->p_vaddr + data->dlpi_addr);
    154 		tls_initsize = phdr->p_filesz;
    155 		tls_size = phdr->p_memsz;
    156 	}
    157 	return 0;
    158 }
    159 
    160 void
    161 __libc_static_tls_setup(void)
    162 {
    163 	struct tls_tcb *tcb;
    164 
    165 	dl_iterate_phdr(__libc_static_tls_setup_cb, NULL);
    166 	if (is_dynamic)
    167 		return;
    168 
    169 	tcb = _rtld_tls_allocate();
    170 #ifdef __HAVE___LWP_SETTCB
    171 	__lwp_settcb(tcb);
    172 #else
    173 	_lwp_setprivate(tcb);
    174 #endif
    175 }
    176 
    177 #endif /* __HAVE_TLS_VARIANT_I || __HAVE_TLS_VARIANT_II */
    178