1 /* TLS emulation.
2 Copyright (C) 2006-2022 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
emutls_destroy(void * ptr)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
emutls_init(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 *
emutls_alloc(struct __emutls_object * obj)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 *
__emutls_get_address(void * vobj)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
__emutls_register_common(void * vobj,word size,word align,void * templ)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