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-rw-r--r--arch/arm/include/asm/cmpxchg.h295
1 files changed, 295 insertions, 0 deletions
diff --git a/arch/arm/include/asm/cmpxchg.h b/arch/arm/include/asm/cmpxchg.h
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1#ifndef __ASM_ARM_CMPXCHG_H
2#define __ASM_ARM_CMPXCHG_H
3
4#include <linux/irqflags.h>
5#include <asm/barrier.h>
6
7#if defined(CONFIG_CPU_SA1100) || defined(CONFIG_CPU_SA110)
8/*
9 * On the StrongARM, "swp" is terminally broken since it bypasses the
10 * cache totally. This means that the cache becomes inconsistent, and,
11 * since we use normal loads/stores as well, this is really bad.
12 * Typically, this causes oopsen in filp_close, but could have other,
13 * more disastrous effects. There are two work-arounds:
14 * 1. Disable interrupts and emulate the atomic swap
15 * 2. Clean the cache, perform atomic swap, flush the cache
16 *
17 * We choose (1) since its the "easiest" to achieve here and is not
18 * dependent on the processor type.
19 *
20 * NOTE that this solution won't work on an SMP system, so explcitly
21 * forbid it here.
22 */
23#define swp_is_buggy
24#endif
25
26static inline unsigned long __xchg(unsigned long x, volatile void *ptr, int size)
27{
28 extern void __bad_xchg(volatile void *, int);
29 unsigned long ret;
30#ifdef swp_is_buggy
31 unsigned long flags;
32#endif
33#if __LINUX_ARM_ARCH__ >= 6
34 unsigned int tmp;
35#endif
36
37 smp_mb();
38
39 switch (size) {
40#if __LINUX_ARM_ARCH__ >= 6
41 case 1:
42 asm volatile("@ __xchg1\n"
43 "1: ldrexb %0, [%3]\n"
44 " strexb %1, %2, [%3]\n"
45 " teq %1, #0\n"
46 " bne 1b"
47 : "=&r" (ret), "=&r" (tmp)
48 : "r" (x), "r" (ptr)
49 : "memory", "cc");
50 break;
51 case 4:
52 asm volatile("@ __xchg4\n"
53 "1: ldrex %0, [%3]\n"
54 " strex %1, %2, [%3]\n"
55 " teq %1, #0\n"
56 " bne 1b"
57 : "=&r" (ret), "=&r" (tmp)
58 : "r" (x), "r" (ptr)
59 : "memory", "cc");
60 break;
61#elif defined(swp_is_buggy)
62#ifdef CONFIG_SMP
63#error SMP is not supported on this platform
64#endif
65 case 1:
66 raw_local_irq_save(flags);
67 ret = *(volatile unsigned char *)ptr;
68 *(volatile unsigned char *)ptr = x;
69 raw_local_irq_restore(flags);
70 break;
71
72 case 4:
73 raw_local_irq_save(flags);
74 ret = *(volatile unsigned long *)ptr;
75 *(volatile unsigned long *)ptr = x;
76 raw_local_irq_restore(flags);
77 break;
78#else
79 case 1:
80 asm volatile("@ __xchg1\n"
81 " swpb %0, %1, [%2]"
82 : "=&r" (ret)
83 : "r" (x), "r" (ptr)
84 : "memory", "cc");
85 break;
86 case 4:
87 asm volatile("@ __xchg4\n"
88 " swp %0, %1, [%2]"
89 : "=&r" (ret)
90 : "r" (x), "r" (ptr)
91 : "memory", "cc");
92 break;
93#endif
94 default:
95 __bad_xchg(ptr, size), ret = 0;
96 break;
97 }
98 smp_mb();
99
100 return ret;
101}
102
103#define xchg(ptr,x) \
104 ((__typeof__(*(ptr)))__xchg((unsigned long)(x),(ptr),sizeof(*(ptr))))
105
106#include <asm-generic/cmpxchg-local.h>
107
108#if __LINUX_ARM_ARCH__ < 6
109/* min ARCH < ARMv6 */
110
111#ifdef CONFIG_SMP
112#error "SMP is not supported on this platform"
113#endif
114
115/*
116 * cmpxchg_local and cmpxchg64_local are atomic wrt current CPU. Always make
117 * them available.
118 */
119#define cmpxchg_local(ptr, o, n) \
120 ((__typeof__(*(ptr)))__cmpxchg_local_generic((ptr), (unsigned long)(o),\
121 (unsigned long)(n), sizeof(*(ptr))))
122#define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n))
123
124#ifndef CONFIG_SMP
125#include <asm-generic/cmpxchg.h>
126#endif
127
128#else /* min ARCH >= ARMv6 */
129
130extern void __bad_cmpxchg(volatile void *ptr, int size);
131
132/*
133 * cmpxchg only support 32-bits operands on ARMv6.
134 */
135
136static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
137 unsigned long new, int size)
138{
139 unsigned long oldval, res;
140
141 switch (size) {
142#ifndef CONFIG_CPU_V6 /* min ARCH >= ARMv6K */
143 case 1:
144 do {
145 asm volatile("@ __cmpxchg1\n"
146 " ldrexb %1, [%2]\n"
147 " mov %0, #0\n"
148 " teq %1, %3\n"
149 " strexbeq %0, %4, [%2]\n"
150 : "=&r" (res), "=&r" (oldval)
151 : "r" (ptr), "Ir" (old), "r" (new)
152 : "memory", "cc");
153 } while (res);
154 break;
155 case 2:
156 do {
157 asm volatile("@ __cmpxchg1\n"
158 " ldrexh %1, [%2]\n"
159 " mov %0, #0\n"
160 " teq %1, %3\n"
161 " strexheq %0, %4, [%2]\n"
162 : "=&r" (res), "=&r" (oldval)
163 : "r" (ptr), "Ir" (old), "r" (new)
164 : "memory", "cc");
165 } while (res);
166 break;
167#endif
168 case 4:
169 do {
170 asm volatile("@ __cmpxchg4\n"
171 " ldrex %1, [%2]\n"
172 " mov %0, #0\n"
173 " teq %1, %3\n"
174 " strexeq %0, %4, [%2]\n"
175 : "=&r" (res), "=&r" (oldval)
176 : "r" (ptr), "Ir" (old), "r" (new)
177 : "memory", "cc");
178 } while (res);
179 break;
180 default:
181 __bad_cmpxchg(ptr, size);
182 oldval = 0;
183 }
184
185 return oldval;
186}
187
188static inline unsigned long __cmpxchg_mb(volatile void *ptr, unsigned long old,
189 unsigned long new, int size)
190{
191 unsigned long ret;
192
193 smp_mb();
194 ret = __cmpxchg(ptr, old, new, size);
195 smp_mb();
196
197 return ret;
198}
199
200#define cmpxchg(ptr,o,n) \
201 ((__typeof__(*(ptr)))__cmpxchg_mb((ptr), \
202 (unsigned long)(o), \
203 (unsigned long)(n), \
204 sizeof(*(ptr))))
205
206static inline unsigned long __cmpxchg_local(volatile void *ptr,
207 unsigned long old,
208 unsigned long new, int size)
209{
210 unsigned long ret;
211
212 switch (size) {
213#ifdef CONFIG_CPU_V6 /* min ARCH == ARMv6 */
214 case 1:
215 case 2:
216 ret = __cmpxchg_local_generic(ptr, old, new, size);
217 break;
218#endif
219 default:
220 ret = __cmpxchg(ptr, old, new, size);
221 }
222
223 return ret;
224}
225
226#define cmpxchg_local(ptr,o,n) \
227 ((__typeof__(*(ptr)))__cmpxchg_local((ptr), \
228 (unsigned long)(o), \
229 (unsigned long)(n), \
230 sizeof(*(ptr))))
231
232#ifndef CONFIG_CPU_V6 /* min ARCH >= ARMv6K */
233
234/*
235 * Note : ARMv7-M (currently unsupported by Linux) does not support
236 * ldrexd/strexd. If ARMv7-M is ever supported by the Linux kernel, it should
237 * not be allowed to use __cmpxchg64.
238 */
239static inline unsigned long long __cmpxchg64(volatile void *ptr,
240 unsigned long long old,
241 unsigned long long new)
242{
243 register unsigned long long oldval asm("r0");
244 register unsigned long long __old asm("r2") = old;
245 register unsigned long long __new asm("r4") = new;
246 unsigned long res;
247
248 do {
249 asm volatile(
250 " @ __cmpxchg8\n"
251 " ldrexd %1, %H1, [%2]\n"
252 " mov %0, #0\n"
253 " teq %1, %3\n"
254 " teqeq %H1, %H3\n"
255 " strexdeq %0, %4, %H4, [%2]\n"
256 : "=&r" (res), "=&r" (oldval)
257 : "r" (ptr), "Ir" (__old), "r" (__new)
258 : "memory", "cc");
259 } while (res);
260
261 return oldval;
262}
263
264static inline unsigned long long __cmpxchg64_mb(volatile void *ptr,
265 unsigned long long old,
266 unsigned long long new)
267{
268 unsigned long long ret;
269
270 smp_mb();
271 ret = __cmpxchg64(ptr, old, new);
272 smp_mb();
273
274 return ret;
275}
276
277#define cmpxchg64(ptr,o,n) \
278 ((__typeof__(*(ptr)))__cmpxchg64_mb((ptr), \
279 (unsigned long long)(o), \
280 (unsigned long long)(n)))
281
282#define cmpxchg64_local(ptr,o,n) \
283 ((__typeof__(*(ptr)))__cmpxchg64((ptr), \
284 (unsigned long long)(o), \
285 (unsigned long long)(n)))
286
287#else /* min ARCH = ARMv6 */
288
289#define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n))
290
291#endif
292
293#endif /* __LINUX_ARM_ARCH__ >= 6 */
294
295#endif /* __ASM_ARM_CMPXCHG_H */
generated by cgit v1.2.2 (git 2.25.0) at 2024-12-28 00:17:52 -0500