Commit | Line | Data |
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d45599f4 MD |
1 | /* |
2 | * compat_arch_x86.c | |
3 | * | |
4 | * Userspace RCU library - x86 compatibility checks | |
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 | ||
23 | #include <stdio.h> | |
24 | #include <pthread.h> | |
25 | #include <signal.h> | |
26 | #include <assert.h> | |
a2e7bf9c | 27 | #include <urcu/uatomic.h> |
d45599f4 | 28 | |
976720e4 MD |
29 | /* |
30 | * Using attribute "weak" for __rcu_cas_avail and | |
31 | * __urcu_x86_compat_mutex. Those are globally visible by the entire | |
32 | * program, even though many shared objects may have their own version. | |
33 | * The first version that gets loaded will be used by the entire | |
34 | * program (executable and all shared objects). | |
35 | */ | |
36 | ||
d45599f4 MD |
37 | /* |
38 | * It does not really matter if the constructor is called before using | |
02be5561 | 39 | * the library, as long as the caller checks if __rcu_cas_avail < 0 and calls |
d45599f4 MD |
40 | * compat_arch_init() explicitely if needed. |
41 | */ | |
02be5561 | 42 | int __attribute__((constructor)) __rcu_cas_init(void); |
d45599f4 | 43 | |
d45599f4 MD |
44 | /* |
45 | * -1: unknown | |
46 | * 1: available | |
47 | * 0: unavailable | |
48 | */ | |
976720e4 | 49 | __attribute__((weak)) |
02be5561 | 50 | int __rcu_cas_avail = -1; |
d45599f4 | 51 | |
976720e4 MD |
52 | __attribute__((weak)) |
53 | pthread_mutex_t __urcu_x86_compat_mutex = PTHREAD_MUTEX_INITIALIZER; | |
bf9de1b7 | 54 | |
d45599f4 | 55 | /* |
bf9de1b7 MD |
56 | * get_eflags/set_eflags/compare_and_swap_is_available imported from glibc |
57 | * 2.3.5. linuxthreads/sysdeps/i386/pt-machine.h. | |
d45599f4 MD |
58 | */ |
59 | ||
bf9de1b7 | 60 | static int get_eflags (void) |
d45599f4 MD |
61 | { |
62 | int res; | |
63 | __asm__ __volatile__ ("pushfl; popl %0" : "=r" (res) : ); | |
64 | return res; | |
65 | } | |
66 | ||
bf9de1b7 | 67 | static void set_eflags (int newflags) |
d45599f4 MD |
68 | { |
69 | __asm__ __volatile__ ("pushl %0; popfl" : : "r" (newflags) : "cc"); | |
70 | } | |
71 | ||
bf9de1b7 | 72 | static int compare_and_swap_is_available (void) |
d45599f4 MD |
73 | { |
74 | int oldflags = get_eflags (); | |
75 | int changed; | |
76 | /* Flip AC bit in EFLAGS. */ | |
77 | set_eflags (oldflags ^ 0x40000); | |
78 | /* See if bit changed. */ | |
79 | changed = (get_eflags () ^ oldflags) & 0x40000; | |
80 | /* Restore EFLAGS. */ | |
81 | set_eflags (oldflags); | |
82 | /* If the AC flag did not change, it's a 386 and it lacks cmpxchg. | |
83 | Otherwise, it's a 486 or above and it has cmpxchg. */ | |
84 | return changed != 0; | |
85 | } | |
86 | ||
bf9de1b7 | 87 | static void mutex_lock_signal_save(pthread_mutex_t *mutex, sigset_t *oldmask) |
d45599f4 | 88 | { |
bf9de1b7 | 89 | sigset_t newmask; |
d45599f4 MD |
90 | int ret; |
91 | ||
92 | /* Disable signals */ | |
6ed4b2e6 | 93 | ret = sigfillset(&newmask); |
d45599f4 | 94 | assert(!ret); |
6ed4b2e6 | 95 | ret = pthread_sigmask(SIG_BLOCK, &newmask, oldmask); |
d45599f4 | 96 | assert(!ret); |
976720e4 | 97 | ret = pthread_mutex_lock(&__urcu_x86_compat_mutex); |
d45599f4 | 98 | assert(!ret); |
bf9de1b7 MD |
99 | } |
100 | ||
101 | static void mutex_lock_signal_restore(pthread_mutex_t *mutex, sigset_t *oldmask) | |
102 | { | |
103 | int ret; | |
104 | ||
976720e4 | 105 | ret = pthread_mutex_unlock(&__urcu_x86_compat_mutex); |
bf9de1b7 MD |
106 | assert(!ret); |
107 | ret = pthread_sigmask(SIG_SETMASK, oldmask, NULL); | |
108 | assert(!ret); | |
109 | } | |
110 | ||
111 | unsigned long _compat_uatomic_set(void *addr, unsigned long _new, int len) | |
112 | { | |
113 | sigset_t mask; | |
114 | unsigned long result; | |
115 | ||
976720e4 | 116 | mutex_lock_signal_save(&__urcu_x86_compat_mutex, &mask); |
bf9de1b7 MD |
117 | switch (len) { |
118 | case 1: | |
119 | *(unsigned char *)addr = (unsigned char)_new; | |
120 | result = *(unsigned char *)addr; | |
121 | break; | |
122 | case 2: | |
123 | *(unsigned short *)addr = (unsigned short)_new; | |
124 | result = *(unsigned short *)addr; | |
125 | break; | |
126 | case 4: | |
127 | *(unsigned int *)addr = (unsigned int)_new; | |
128 | result = *(unsigned int *)addr; | |
129 | break; | |
130 | default: | |
131 | /* | |
132 | * generate an illegal instruction. Cannot catch this with | |
133 | * linker tricks when optimizations are disabled. | |
134 | */ | |
c94627b5 | 135 | result = 0; |
bf9de1b7 MD |
136 | __asm__ __volatile__("ud2"); |
137 | } | |
976720e4 | 138 | mutex_lock_signal_restore(&__urcu_x86_compat_mutex, &mask); |
c94627b5 | 139 | return result; |
bf9de1b7 | 140 | } |
d45599f4 | 141 | |
bf9de1b7 MD |
142 | unsigned long _compat_uatomic_xchg(void *addr, unsigned long _new, int len) |
143 | { | |
144 | sigset_t mask; | |
145 | unsigned long retval; | |
146 | ||
976720e4 | 147 | mutex_lock_signal_save(&__urcu_x86_compat_mutex, &mask); |
bf9de1b7 MD |
148 | switch (len) { |
149 | case 1: | |
150 | retval = *(unsigned char *)addr; | |
151 | *(unsigned char *)addr = (unsigned char)_new; | |
152 | break; | |
153 | case 2: | |
154 | retval = *(unsigned short *)addr; | |
155 | *(unsigned short *)addr = (unsigned short)_new; | |
156 | break; | |
157 | case 4: | |
158 | retval = *(unsigned int *)addr; | |
159 | *(unsigned int *)addr = (unsigned int)_new; | |
160 | break; | |
161 | default: | |
162 | /* | |
163 | * generate an illegal instruction. Cannot catch this with | |
164 | * linker tricks when optimizations are disabled. | |
165 | */ | |
8c43fe72 | 166 | retval = 0; /* silence gcc warnings */ |
bf9de1b7 MD |
167 | __asm__ __volatile__("ud2"); |
168 | } | |
976720e4 | 169 | mutex_lock_signal_restore(&__urcu_x86_compat_mutex, &mask); |
bf9de1b7 MD |
170 | return retval; |
171 | } | |
172 | ||
173 | unsigned long _compat_uatomic_cmpxchg(void *addr, unsigned long old, | |
174 | unsigned long _new, int len) | |
175 | { | |
176 | unsigned long retval; | |
177 | sigset_t mask; | |
178 | ||
976720e4 | 179 | mutex_lock_signal_save(&__urcu_x86_compat_mutex, &mask); |
d45599f4 MD |
180 | switch (len) { |
181 | case 1: | |
182 | { | |
183 | unsigned char result = *(unsigned char *)addr; | |
bf9de1b7 | 184 | if (result == (unsigned char)old) |
d45599f4 | 185 | *(unsigned char *)addr = (unsigned char)_new; |
bf9de1b7 MD |
186 | retval = result; |
187 | break; | |
d45599f4 MD |
188 | } |
189 | case 2: | |
190 | { | |
191 | unsigned short result = *(unsigned short *)addr; | |
bf9de1b7 | 192 | if (result == (unsigned short)old) |
d45599f4 | 193 | *(unsigned short *)addr = (unsigned short)_new; |
bf9de1b7 MD |
194 | retval = result; |
195 | break; | |
d45599f4 MD |
196 | } |
197 | case 4: | |
198 | { | |
199 | unsigned int result = *(unsigned int *)addr; | |
bf9de1b7 | 200 | if (result == (unsigned int)old) |
d45599f4 | 201 | *(unsigned int *)addr = (unsigned int)_new; |
bf9de1b7 MD |
202 | retval = result; |
203 | break; | |
d45599f4 | 204 | } |
bf9de1b7 MD |
205 | default: |
206 | /* | |
207 | * generate an illegal instruction. Cannot catch this with | |
208 | * linker tricks when optimizations are disabled. | |
209 | */ | |
8c43fe72 | 210 | retval = 0; /* silence gcc warnings */ |
bf9de1b7 | 211 | __asm__ __volatile__("ud2"); |
d45599f4 | 212 | } |
976720e4 | 213 | mutex_lock_signal_restore(&__urcu_x86_compat_mutex, &mask); |
bf9de1b7 MD |
214 | return retval; |
215 | } | |
d45599f4 | 216 | |
985b35b1 PB |
217 | void _compat_uatomic_or(void *addr, unsigned long v, int len) |
218 | { | |
219 | sigset_t mask; | |
220 | ||
976720e4 | 221 | mutex_lock_signal_save(&__urcu_x86_compat_mutex, &mask); |
985b35b1 PB |
222 | switch (len) { |
223 | case 1: | |
224 | *(unsigned char *)addr |= (unsigned char)v; | |
225 | break; | |
226 | case 2: | |
227 | *(unsigned short *)addr |= (unsigned short)v; | |
228 | break; | |
229 | case 4: | |
230 | *(unsigned int *)addr |= (unsigned int)v; | |
231 | break; | |
232 | default: | |
233 | /* | |
234 | * generate an illegal instruction. Cannot catch this with | |
bf33aaea PB |
235 | * linker tricks when optimizations are disabled. |
236 | */ | |
237 | __asm__ __volatile__("ud2"); | |
238 | } | |
976720e4 | 239 | mutex_lock_signal_restore(&__urcu_x86_compat_mutex, &mask); |
bf33aaea PB |
240 | } |
241 | ||
242 | void _compat_uatomic_and(void *addr, unsigned long v, int len) | |
243 | { | |
244 | sigset_t mask; | |
245 | ||
976720e4 | 246 | mutex_lock_signal_save(&__urcu_x86_compat_mutex, &mask); |
bf33aaea PB |
247 | switch (len) { |
248 | case 1: | |
249 | *(unsigned char *)addr &= (unsigned char)v; | |
250 | break; | |
251 | case 2: | |
252 | *(unsigned short *)addr &= (unsigned short)v; | |
253 | break; | |
254 | case 4: | |
255 | *(unsigned int *)addr &= (unsigned int)v; | |
256 | break; | |
257 | default: | |
258 | /* | |
259 | * generate an illegal instruction. Cannot catch this with | |
985b35b1 PB |
260 | * linker tricks when optimizations are disabled. |
261 | */ | |
262 | __asm__ __volatile__("ud2"); | |
263 | } | |
976720e4 | 264 | mutex_lock_signal_restore(&__urcu_x86_compat_mutex, &mask); |
985b35b1 PB |
265 | } |
266 | ||
bf9de1b7 MD |
267 | unsigned long _compat_uatomic_add_return(void *addr, unsigned long v, int len) |
268 | { | |
269 | sigset_t mask; | |
270 | unsigned long result; | |
271 | ||
976720e4 | 272 | mutex_lock_signal_save(&__urcu_x86_compat_mutex, &mask); |
bf9de1b7 MD |
273 | switch (len) { |
274 | case 1: | |
275 | *(unsigned char *)addr += (unsigned char)v; | |
276 | result = *(unsigned char *)addr; | |
277 | break; | |
278 | case 2: | |
279 | *(unsigned short *)addr += (unsigned short)v; | |
280 | result = *(unsigned short *)addr; | |
281 | break; | |
282 | case 4: | |
283 | *(unsigned int *)addr += (unsigned int)v; | |
284 | result = *(unsigned int *)addr; | |
285 | break; | |
286 | default: | |
287 | /* | |
288 | * generate an illegal instruction. Cannot catch this with | |
289 | * linker tricks when optimizations are disabled. | |
290 | */ | |
8c43fe72 | 291 | result = 0; /* silence gcc warnings */ |
bf9de1b7 MD |
292 | __asm__ __volatile__("ud2"); |
293 | } | |
976720e4 | 294 | mutex_lock_signal_restore(&__urcu_x86_compat_mutex, &mask); |
bf9de1b7 | 295 | return result; |
d45599f4 MD |
296 | } |
297 | ||
02be5561 | 298 | int __rcu_cas_init(void) |
d45599f4 | 299 | { |
02be5561 MD |
300 | if (__rcu_cas_avail < 0) |
301 | __rcu_cas_avail = compare_and_swap_is_available(); | |
302 | return __rcu_cas_avail; | |
d45599f4 | 303 | } |