1 /* TLS emulation. 2 Copyright (C) 2006-2020 Free Software Foundation, Inc. 3 Contributed by Jakub Jelinek <jakub@redhat.com>. 4 5 This file is part of GCC. 6 7 GCC is free software; you can redistribute it and/or modify it under 8 the terms of the GNU General Public License as published by the Free 9 Software Foundation; either version 3, or (at your option) any later 10 version. 11 12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY 13 WARRANTY; without even the implied warranty of MERCHANTABILITY or 14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 15 for more details. 16 17 Under Section 7 of GPL version 3, you are granted additional 18 permissions described in the GCC Runtime Library Exception, version 19 3.1, as published by the Free Software Foundation. 20 21 You should have received a copy of the GNU General Public License and 22 a copy of the GCC Runtime Library Exception along with this program; 23 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 24 <http://www.gnu.org/licenses/>. */ 25 26 #include "tconfig.h" 27 #include "tsystem.h" 28 #include "coretypes.h" 29 #include "tm.h" 30 #include "libgcc_tm.h" 31 #include "gthr.h" 32 33 typedef unsigned int word __attribute__((mode(word))); 34 typedef unsigned int pointer __attribute__((mode(pointer))); 35 36 struct __emutls_object 37 { 38 word size; 39 word align; 40 union { 41 pointer offset; 42 void *ptr; 43 } loc; 44 void *templ; 45 }; 46 47 struct __emutls_array 48 { 49 pointer size; 50 void **data[]; 51 }; 52 53 /* EMUTLS_ATTR is provided to allow targets to build the emulated tls 54 routines as weak definitions, for example. 55 If there is no definition, fall back to the default. */ 56 #ifndef EMUTLS_ATTR 57 # define EMUTLS_ATTR 58 #endif 59 60 EMUTLS_ATTR 61 void *__emutls_get_address (void *); 62 EMUTLS_ATTR 63 void __emutls_register_common (void *, word, word, void *); 64 65 #ifdef __GTHREADS 66 #ifdef __GTHREAD_MUTEX_INIT 67 static __gthread_mutex_t emutls_mutex = __GTHREAD_MUTEX_INIT; 68 #else 69 static __gthread_mutex_t emutls_mutex; 70 #endif 71 static __gthread_key_t emutls_key; 72 static pointer emutls_size; 73 74 static void 75 emutls_destroy (void *ptr) 76 { 77 struct __emutls_array *arr = ptr; 78 pointer size = arr->size; 79 pointer i; 80 81 for (i = 0; i < size; ++i) 82 { 83 if (arr->data[i]) 84 free (arr->data[i][-1]); 85 } 86 87 free (ptr); 88 } 89 90 static void 91 emutls_init (void) 92 { 93 #ifndef __GTHREAD_MUTEX_INIT 94 __GTHREAD_MUTEX_INIT_FUNCTION (&emutls_mutex); 95 #endif 96 if (__gthread_key_create (&emutls_key, emutls_destroy) != 0) 97 abort (); 98 } 99 #endif 100 101 static void * 102 emutls_alloc (struct __emutls_object *obj) 103 { 104 void *ptr; 105 void *ret; 106 107 /* We could use here posix_memalign if available and adjust 108 emutls_destroy accordingly. */ 109 if (obj->align <= sizeof (void *)) 110 { 111 ptr = malloc (obj->size + sizeof (void *)); 112 if (ptr == NULL) 113 abort (); 114 ((void **) ptr)[0] = ptr; 115 ret = ptr + sizeof (void *); 116 } 117 else 118 { 119 ptr = malloc (obj->size + sizeof (void *) + obj->align - 1); 120 if (ptr == NULL) 121 abort (); 122 ret = (void *) (((pointer) (ptr + sizeof (void *) + obj->align - 1)) 123 & ~(pointer)(obj->align - 1)); 124 ((void **) ret)[-1] = ptr; 125 } 126 127 if (obj->templ) 128 memcpy (ret, obj->templ, obj->size); 129 else 130 memset (ret, 0, obj->size); 131 132 return ret; 133 } 134 135 /* Despite applying the attribute to the declaration, in this case the mis- 136 match between the builtin's declaration [void * (*)(void *)] and the 137 implementation here, causes the decl. attributes to be discarded. */ 138 139 EMUTLS_ATTR void * 140 __emutls_get_address (void *vobj) 141 { 142 struct __emutls_object *obj = vobj; 143 144 if (! __gthread_active_p ()) 145 { 146 if (__builtin_expect (obj->loc.ptr == NULL, 0)) 147 obj->loc.ptr = emutls_alloc (obj); 148 return obj->loc.ptr; 149 } 150 151 #ifndef __GTHREADS 152 abort (); 153 #else 154 pointer offset = __atomic_load_n (&obj->loc.offset, __ATOMIC_ACQUIRE); 155 156 if (__builtin_expect (offset == 0, 0)) 157 { 158 static __gthread_once_t once = __GTHREAD_ONCE_INIT; 159 __gthread_once (&once, emutls_init); 160 __gthread_mutex_lock (&emutls_mutex); 161 offset = obj->loc.offset; 162 if (offset == 0) 163 { 164 offset = ++emutls_size; 165 __atomic_store_n (&obj->loc.offset, offset, __ATOMIC_RELEASE); 166 } 167 __gthread_mutex_unlock (&emutls_mutex); 168 } 169 170 struct __emutls_array *arr = __gthread_getspecific (emutls_key); 171 if (__builtin_expect (arr == NULL, 0)) 172 { 173 pointer size = offset + 32; 174 arr = calloc (size + 1, sizeof (void *)); 175 if (arr == NULL) 176 abort (); 177 arr->size = size; 178 __gthread_setspecific (emutls_key, (void *) arr); 179 } 180 else if (__builtin_expect (offset > arr->size, 0)) 181 { 182 pointer orig_size = arr->size; 183 pointer size = orig_size * 2; 184 if (offset > size) 185 size = offset + 32; 186 arr = realloc (arr, (size + 1) * sizeof (void *)); 187 if (arr == NULL) 188 abort (); 189 arr->size = size; 190 memset (arr->data + orig_size, 0, 191 (size - orig_size) * sizeof (void *)); 192 __gthread_setspecific (emutls_key, (void *) arr); 193 } 194 195 void *ret = arr->data[offset - 1]; 196 if (__builtin_expect (ret == NULL, 0)) 197 { 198 ret = emutls_alloc (obj); 199 arr->data[offset - 1] = ret; 200 } 201 return ret; 202 #endif 203 } 204 205 EMUTLS_ATTR void 206 __emutls_register_common (void *vobj, 207 word size, word align, void *templ) 208 { 209 struct __emutls_object *obj = vobj; 210 211 if (obj->size < size) 212 { 213 obj->size = size; 214 obj->templ = NULL; 215 } 216 if (obj->align < align) 217 obj->align = align; 218 if (templ && size == obj->size) 219 obj->templ = templ; 220 } 221