Commit | Line | Data |
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d45599f4 | 1 | /* |
0b1e236d | 2 | * compat_arch.c |
d45599f4 | 3 | * |
0b1e236d | 4 | * Userspace RCU library - architecture compatibility checks |
d45599f4 | 5 | * |
6982d6d7 | 6 | * Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
d45599f4 MD |
7 | * |
8 | * This library is free software; you can redistribute it and/or | |
9 | * modify it under the terms of the GNU Lesser General Public | |
10 | * License as published by the Free Software Foundation; either | |
11 | * version 2.1 of the License, or (at your option) any later version. | |
12 | * | |
13 | * This library is distributed in the hope that it will be useful, | |
14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
16 | * Lesser General Public License for more details. | |
17 | * | |
18 | * You should have received a copy of the GNU Lesser General Public | |
19 | * License along with this library; if not, write to the Free Software | |
20 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | |
21 | */ | |
22 | ||
0b1e236d MJ |
23 | #include <urcu/arch.h> |
24 | ||
101389e4 | 25 | #ifdef URCU_ARCH_X86_NO_CAS |
0b1e236d | 26 | |
d45599f4 MD |
27 | #include <stdio.h> |
28 | #include <pthread.h> | |
29 | #include <signal.h> | |
01477510 | 30 | #include <urcu/assert.h> |
a2e7bf9c | 31 | #include <urcu/uatomic.h> |
d45599f4 | 32 | |
976720e4 MD |
33 | /* |
34 | * Using attribute "weak" for __rcu_cas_avail and | |
35 | * __urcu_x86_compat_mutex. Those are globally visible by the entire | |
36 | * program, even though many shared objects may have their own version. | |
37 | * The first version that gets loaded will be used by the entire | |
38 | * program (executable and all shared objects). | |
39 | */ | |
40 | ||
d45599f4 MD |
41 | /* |
42 | * It does not really matter if the constructor is called before using | |
02be5561 | 43 | * the library, as long as the caller checks if __rcu_cas_avail < 0 and calls |
f99c6e92 | 44 | * compat_arch_init() explicitly if needed. |
d45599f4 | 45 | */ |
02be5561 | 46 | int __attribute__((constructor)) __rcu_cas_init(void); |
d45599f4 | 47 | |
d45599f4 MD |
48 | /* |
49 | * -1: unknown | |
50 | * 1: available | |
51 | * 0: unavailable | |
52 | */ | |
976720e4 | 53 | __attribute__((weak)) |
02be5561 | 54 | int __rcu_cas_avail = -1; |
d45599f4 | 55 | |
976720e4 MD |
56 | __attribute__((weak)) |
57 | pthread_mutex_t __urcu_x86_compat_mutex = PTHREAD_MUTEX_INITIALIZER; | |
bf9de1b7 | 58 | |
d45599f4 | 59 | /* |
bf9de1b7 MD |
60 | * get_eflags/set_eflags/compare_and_swap_is_available imported from glibc |
61 | * 2.3.5. linuxthreads/sysdeps/i386/pt-machine.h. | |
d45599f4 MD |
62 | */ |
63 | ||
bf9de1b7 | 64 | static int get_eflags (void) |
d45599f4 MD |
65 | { |
66 | int res; | |
67 | __asm__ __volatile__ ("pushfl; popl %0" : "=r" (res) : ); | |
68 | return res; | |
69 | } | |
70 | ||
bf9de1b7 | 71 | static void set_eflags (int newflags) |
d45599f4 MD |
72 | { |
73 | __asm__ __volatile__ ("pushl %0; popfl" : : "r" (newflags) : "cc"); | |
74 | } | |
75 | ||
bf9de1b7 | 76 | static int compare_and_swap_is_available (void) |
d45599f4 MD |
77 | { |
78 | int oldflags = get_eflags (); | |
79 | int changed; | |
80 | /* Flip AC bit in EFLAGS. */ | |
81 | set_eflags (oldflags ^ 0x40000); | |
82 | /* See if bit changed. */ | |
83 | changed = (get_eflags () ^ oldflags) & 0x40000; | |
84 | /* Restore EFLAGS. */ | |
85 | set_eflags (oldflags); | |
86 | /* If the AC flag did not change, it's a 386 and it lacks cmpxchg. | |
87 | Otherwise, it's a 486 or above and it has cmpxchg. */ | |
88 | return changed != 0; | |
89 | } | |
90 | ||
bf9de1b7 | 91 | static void mutex_lock_signal_save(pthread_mutex_t *mutex, sigset_t *oldmask) |
d45599f4 | 92 | { |
bf9de1b7 | 93 | sigset_t newmask; |
d45599f4 MD |
94 | int ret; |
95 | ||
96 | /* Disable signals */ | |
6ed4b2e6 | 97 | ret = sigfillset(&newmask); |
01477510 | 98 | urcu_posix_assert(!ret); |
6ed4b2e6 | 99 | ret = pthread_sigmask(SIG_BLOCK, &newmask, oldmask); |
01477510 | 100 | urcu_posix_assert(!ret); |
976720e4 | 101 | ret = pthread_mutex_lock(&__urcu_x86_compat_mutex); |
01477510 | 102 | urcu_posix_assert(!ret); |
bf9de1b7 MD |
103 | } |
104 | ||
105 | static void mutex_lock_signal_restore(pthread_mutex_t *mutex, sigset_t *oldmask) | |
106 | { | |
107 | int ret; | |
108 | ||
976720e4 | 109 | ret = pthread_mutex_unlock(&__urcu_x86_compat_mutex); |
01477510 | 110 | urcu_posix_assert(!ret); |
bf9de1b7 | 111 | ret = pthread_sigmask(SIG_SETMASK, oldmask, NULL); |
01477510 | 112 | urcu_posix_assert(!ret); |
bf9de1b7 MD |
113 | } |
114 | ||
115 | unsigned long _compat_uatomic_set(void *addr, unsigned long _new, int len) | |
116 | { | |
117 | sigset_t mask; | |
118 | unsigned long result; | |
119 | ||
976720e4 | 120 | mutex_lock_signal_save(&__urcu_x86_compat_mutex, &mask); |
bf9de1b7 MD |
121 | switch (len) { |
122 | case 1: | |
123 | *(unsigned char *)addr = (unsigned char)_new; | |
124 | result = *(unsigned char *)addr; | |
125 | break; | |
126 | case 2: | |
127 | *(unsigned short *)addr = (unsigned short)_new; | |
128 | result = *(unsigned short *)addr; | |
129 | break; | |
130 | case 4: | |
131 | *(unsigned int *)addr = (unsigned int)_new; | |
132 | result = *(unsigned int *)addr; | |
133 | break; | |
134 | default: | |
135 | /* | |
136 | * generate an illegal instruction. Cannot catch this with | |
137 | * linker tricks when optimizations are disabled. | |
138 | */ | |
c94627b5 | 139 | result = 0; |
bf9de1b7 MD |
140 | __asm__ __volatile__("ud2"); |
141 | } | |
976720e4 | 142 | mutex_lock_signal_restore(&__urcu_x86_compat_mutex, &mask); |
c94627b5 | 143 | return result; |
bf9de1b7 | 144 | } |
d45599f4 | 145 | |
bf9de1b7 MD |
146 | unsigned long _compat_uatomic_xchg(void *addr, unsigned long _new, int len) |
147 | { | |
148 | sigset_t mask; | |
149 | unsigned long retval; | |
150 | ||
976720e4 | 151 | mutex_lock_signal_save(&__urcu_x86_compat_mutex, &mask); |
bf9de1b7 MD |
152 | switch (len) { |
153 | case 1: | |
154 | retval = *(unsigned char *)addr; | |
155 | *(unsigned char *)addr = (unsigned char)_new; | |
156 | break; | |
157 | case 2: | |
158 | retval = *(unsigned short *)addr; | |
159 | *(unsigned short *)addr = (unsigned short)_new; | |
160 | break; | |
161 | case 4: | |
162 | retval = *(unsigned int *)addr; | |
163 | *(unsigned int *)addr = (unsigned int)_new; | |
164 | break; | |
165 | default: | |
166 | /* | |
167 | * generate an illegal instruction. Cannot catch this with | |
168 | * linker tricks when optimizations are disabled. | |
169 | */ | |
8c43fe72 | 170 | retval = 0; /* silence gcc warnings */ |
bf9de1b7 MD |
171 | __asm__ __volatile__("ud2"); |
172 | } | |
976720e4 | 173 | mutex_lock_signal_restore(&__urcu_x86_compat_mutex, &mask); |
bf9de1b7 MD |
174 | return retval; |
175 | } | |
176 | ||
177 | unsigned long _compat_uatomic_cmpxchg(void *addr, unsigned long old, | |
178 | unsigned long _new, int len) | |
179 | { | |
180 | unsigned long retval; | |
181 | sigset_t mask; | |
182 | ||
976720e4 | 183 | mutex_lock_signal_save(&__urcu_x86_compat_mutex, &mask); |
d45599f4 MD |
184 | switch (len) { |
185 | case 1: | |
186 | { | |
187 | unsigned char result = *(unsigned char *)addr; | |
bf9de1b7 | 188 | if (result == (unsigned char)old) |
d45599f4 | 189 | *(unsigned char *)addr = (unsigned char)_new; |
bf9de1b7 MD |
190 | retval = result; |
191 | break; | |
d45599f4 MD |
192 | } |
193 | case 2: | |
194 | { | |
195 | unsigned short result = *(unsigned short *)addr; | |
bf9de1b7 | 196 | if (result == (unsigned short)old) |
d45599f4 | 197 | *(unsigned short *)addr = (unsigned short)_new; |
bf9de1b7 MD |
198 | retval = result; |
199 | break; | |
d45599f4 MD |
200 | } |
201 | case 4: | |
202 | { | |
203 | unsigned int result = *(unsigned int *)addr; | |
bf9de1b7 | 204 | if (result == (unsigned int)old) |
d45599f4 | 205 | *(unsigned int *)addr = (unsigned int)_new; |
bf9de1b7 MD |
206 | retval = result; |
207 | break; | |
d45599f4 | 208 | } |
bf9de1b7 MD |
209 | default: |
210 | /* | |
211 | * generate an illegal instruction. Cannot catch this with | |
212 | * linker tricks when optimizations are disabled. | |
213 | */ | |
8c43fe72 | 214 | retval = 0; /* silence gcc warnings */ |
bf9de1b7 | 215 | __asm__ __volatile__("ud2"); |
d45599f4 | 216 | } |
976720e4 | 217 | mutex_lock_signal_restore(&__urcu_x86_compat_mutex, &mask); |
bf9de1b7 MD |
218 | return retval; |
219 | } | |
d45599f4 | 220 | |
985b35b1 PB |
221 | void _compat_uatomic_or(void *addr, unsigned long v, int len) |
222 | { | |
223 | sigset_t mask; | |
224 | ||
976720e4 | 225 | mutex_lock_signal_save(&__urcu_x86_compat_mutex, &mask); |
985b35b1 PB |
226 | switch (len) { |
227 | case 1: | |
228 | *(unsigned char *)addr |= (unsigned char)v; | |
229 | break; | |
230 | case 2: | |
231 | *(unsigned short *)addr |= (unsigned short)v; | |
232 | break; | |
233 | case 4: | |
234 | *(unsigned int *)addr |= (unsigned int)v; | |
235 | break; | |
236 | default: | |
237 | /* | |
238 | * generate an illegal instruction. Cannot catch this with | |
bf33aaea PB |
239 | * linker tricks when optimizations are disabled. |
240 | */ | |
241 | __asm__ __volatile__("ud2"); | |
242 | } | |
976720e4 | 243 | mutex_lock_signal_restore(&__urcu_x86_compat_mutex, &mask); |
bf33aaea PB |
244 | } |
245 | ||
246 | void _compat_uatomic_and(void *addr, unsigned long v, int len) | |
247 | { | |
248 | sigset_t mask; | |
249 | ||
976720e4 | 250 | mutex_lock_signal_save(&__urcu_x86_compat_mutex, &mask); |
bf33aaea PB |
251 | switch (len) { |
252 | case 1: | |
253 | *(unsigned char *)addr &= (unsigned char)v; | |
254 | break; | |
255 | case 2: | |
256 | *(unsigned short *)addr &= (unsigned short)v; | |
257 | break; | |
258 | case 4: | |
259 | *(unsigned int *)addr &= (unsigned int)v; | |
260 | break; | |
261 | default: | |
262 | /* | |
263 | * generate an illegal instruction. Cannot catch this with | |
985b35b1 PB |
264 | * linker tricks when optimizations are disabled. |
265 | */ | |
266 | __asm__ __volatile__("ud2"); | |
267 | } | |
976720e4 | 268 | mutex_lock_signal_restore(&__urcu_x86_compat_mutex, &mask); |
985b35b1 PB |
269 | } |
270 | ||
bf9de1b7 MD |
271 | unsigned long _compat_uatomic_add_return(void *addr, unsigned long v, int len) |
272 | { | |
273 | sigset_t mask; | |
274 | unsigned long result; | |
275 | ||
976720e4 | 276 | mutex_lock_signal_save(&__urcu_x86_compat_mutex, &mask); |
bf9de1b7 MD |
277 | switch (len) { |
278 | case 1: | |
279 | *(unsigned char *)addr += (unsigned char)v; | |
280 | result = *(unsigned char *)addr; | |
281 | break; | |
282 | case 2: | |
283 | *(unsigned short *)addr += (unsigned short)v; | |
284 | result = *(unsigned short *)addr; | |
285 | break; | |
286 | case 4: | |
287 | *(unsigned int *)addr += (unsigned int)v; | |
288 | result = *(unsigned int *)addr; | |
289 | break; | |
290 | default: | |
291 | /* | |
292 | * generate an illegal instruction. Cannot catch this with | |
293 | * linker tricks when optimizations are disabled. | |
294 | */ | |
8c43fe72 | 295 | result = 0; /* silence gcc warnings */ |
bf9de1b7 MD |
296 | __asm__ __volatile__("ud2"); |
297 | } | |
976720e4 | 298 | mutex_lock_signal_restore(&__urcu_x86_compat_mutex, &mask); |
bf9de1b7 | 299 | return result; |
d45599f4 MD |
300 | } |
301 | ||
02be5561 | 302 | int __rcu_cas_init(void) |
d45599f4 | 303 | { |
02be5561 MD |
304 | if (__rcu_cas_avail < 0) |
305 | __rcu_cas_avail = compare_and_swap_is_available(); | |
306 | return __rcu_cas_avail; | |
d45599f4 | 307 | } |
0b1e236d | 308 | #endif |