1 /* TLS emulation.
2 Copyright (C) 2006-2023 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 (struct __emutls_object *);
62 EMUTLS_ATTR
63 void __emutls_register_common (struct __emutls_object *, 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 (struct __emutls_object *obj)
141 {
142 if (! __gthread_active_p ())
143 {
144 if (__builtin_expect (obj->loc.ptr == NULL, 0))
145 obj->loc.ptr = emutls_alloc (obj);
146 return obj->loc.ptr;
147 }
148
149 #ifndef __GTHREADS
150 abort ();
151 #else
152 pointer offset = __atomic_load_n (&obj->loc.offset, __ATOMIC_ACQUIRE);
153
154 if (__builtin_expect (offset == 0, 0))
155 {
156 static __gthread_once_t once = __GTHREAD_ONCE_INIT;
157 __gthread_once (&once, emutls_init);
158 __gthread_mutex_lock (&emutls_mutex);
159 offset = obj->loc.offset;
160 if (offset == 0)
161 {
162 offset = ++emutls_size;
163 __atomic_store_n (&obj->loc.offset, offset, __ATOMIC_RELEASE);
164 }
165 __gthread_mutex_unlock (&emutls_mutex);
166 }
167
168 struct __emutls_array *arr = __gthread_getspecific (emutls_key);
169 if (__builtin_expect (arr == NULL, 0))
170 {
171 pointer size = offset + 32;
172 arr = calloc (size + 1, sizeof (void *));
173 if (arr == NULL)
174 abort ();
175 arr->size = size;
176 __gthread_setspecific (emutls_key, (void *) arr);
177 }
178 else if (__builtin_expect (offset > arr->size, 0))
179 {
180 pointer orig_size = arr->size;
181 pointer size = orig_size * 2;
182 if (offset > size)
183 size = offset + 32;
184 arr = realloc (arr, (size + 1) * sizeof (void *));
185 if (arr == NULL)
186 abort ();
187 arr->size = size;
188 memset (arr->data + orig_size, 0,
189 (size - orig_size) * sizeof (void *));
190 __gthread_setspecific (emutls_key, (void *) arr);
191 }
192
193 void *ret = arr->data[offset - 1];
194 if (__builtin_expect (ret == NULL, 0))
195 {
196 ret = emutls_alloc (obj);
197 arr->data[offset - 1] = ret;
198 }
199 return ret;
200 #endif
201 }
202
203 EMUTLS_ATTR void
204 __emutls_register_common (struct __emutls_object *obj,
205 word size, word align, void *templ)
206 {
207 if (obj->size < size)
208 {
209 obj->size = size;
210 obj->templ = NULL;
211 }
212 if (obj->align < align)
213 obj->align = align;
214 if (templ && size == obj->size)
215 obj->templ = templ;
216 }