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