1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _ASM_IA64_SPINLOCK_H
3 #define _ASM_IA64_SPINLOCK_H
4
5 /*
6 * Copyright (C) 1998-2003 Hewlett-Packard Co
7 * David Mosberger-Tang <davidm@hpl.hp.com>
8 * Copyright (C) 1999 Walt Drummond <drummond@valinux.com>
9 *
10 * This file is used for SMP configurations only.
11 */
12
13 #include <linux/compiler.h>
14 #include <linux/kernel.h>
15 #include <linux/bitops.h>
16
17 #include <linux/atomic.h>
18 #include <asm/intrinsics.h>
19 #include <asm/barrier.h>
20 #include <asm/processor.h>
21
22 #define arch_spin_lock_init(x) ((x)->lock = 0)
23
24 /*
25 * Ticket locks are conceptually two parts, one indicating the current head of
26 * the queue, and the other indicating the current tail. The lock is acquired
27 * by atomically noting the tail and incrementing it by one (thus adding
28 * ourself to the queue and noting our position), then waiting until the head
29 * becomes equal to the the initial value of the tail.
30 * The pad bits in the middle are used to prevent the next_ticket number
31 * overflowing into the now_serving number.
32 *
33 * 31 17 16 15 14 0
34 * +----------------------------------------------------+
35 * | now_serving | padding | next_ticket |
36 * +----------------------------------------------------+
37 */
38
39 #define TICKET_SHIFT 17
40 #define TICKET_BITS 15
41 #define TICKET_MASK ((1 << TICKET_BITS) - 1)
42
__ticket_spin_lock(arch_spinlock_t * lock)43 static __always_inline void __ticket_spin_lock(arch_spinlock_t *lock)
44 {
45 int *p = (int *)&lock->lock, ticket, serve;
46
47 ticket = ia64_fetchadd(1, p, acq);
48
49 if (!(((ticket >> TICKET_SHIFT) ^ ticket) & TICKET_MASK))
50 return;
51
52 ia64_invala();
53
54 for (;;) {
55 asm volatile ("ld4.c.nc %0=[%1]" : "=r"(serve) : "r"(p) : "memory");
56
57 if (!(((serve >> TICKET_SHIFT) ^ ticket) & TICKET_MASK))
58 return;
59 cpu_relax();
60 }
61 }
62
__ticket_spin_trylock(arch_spinlock_t * lock)63 static __always_inline int __ticket_spin_trylock(arch_spinlock_t *lock)
64 {
65 int tmp = READ_ONCE(lock->lock);
66
67 if (!(((tmp >> TICKET_SHIFT) ^ tmp) & TICKET_MASK))
68 return ia64_cmpxchg(acq, &lock->lock, tmp, tmp + 1, sizeof (tmp)) == tmp;
69 return 0;
70 }
71
__ticket_spin_unlock(arch_spinlock_t * lock)72 static __always_inline void __ticket_spin_unlock(arch_spinlock_t *lock)
73 {
74 unsigned short *p = (unsigned short *)&lock->lock + 1, tmp;
75
76 /* This could be optimised with ARCH_HAS_MMIOWB */
77 mmiowb();
78 asm volatile ("ld2.bias %0=[%1]" : "=r"(tmp) : "r"(p));
79 WRITE_ONCE(*p, (tmp + 2) & ~1);
80 }
81
__ticket_spin_is_locked(arch_spinlock_t * lock)82 static inline int __ticket_spin_is_locked(arch_spinlock_t *lock)
83 {
84 long tmp = READ_ONCE(lock->lock);
85
86 return !!(((tmp >> TICKET_SHIFT) ^ tmp) & TICKET_MASK);
87 }
88
__ticket_spin_is_contended(arch_spinlock_t * lock)89 static inline int __ticket_spin_is_contended(arch_spinlock_t *lock)
90 {
91 long tmp = READ_ONCE(lock->lock);
92
93 return ((tmp - (tmp >> TICKET_SHIFT)) & TICKET_MASK) > 1;
94 }
95
arch_spin_value_unlocked(arch_spinlock_t lock)96 static __always_inline int arch_spin_value_unlocked(arch_spinlock_t lock)
97 {
98 return !(((lock.lock >> TICKET_SHIFT) ^ lock.lock) & TICKET_MASK);
99 }
100
arch_spin_is_locked(arch_spinlock_t * lock)101 static inline int arch_spin_is_locked(arch_spinlock_t *lock)
102 {
103 return __ticket_spin_is_locked(lock);
104 }
105
arch_spin_is_contended(arch_spinlock_t * lock)106 static inline int arch_spin_is_contended(arch_spinlock_t *lock)
107 {
108 return __ticket_spin_is_contended(lock);
109 }
110 #define arch_spin_is_contended arch_spin_is_contended
111
arch_spin_lock(arch_spinlock_t * lock)112 static __always_inline void arch_spin_lock(arch_spinlock_t *lock)
113 {
114 __ticket_spin_lock(lock);
115 }
116
arch_spin_trylock(arch_spinlock_t * lock)117 static __always_inline int arch_spin_trylock(arch_spinlock_t *lock)
118 {
119 return __ticket_spin_trylock(lock);
120 }
121
arch_spin_unlock(arch_spinlock_t * lock)122 static __always_inline void arch_spin_unlock(arch_spinlock_t *lock)
123 {
124 __ticket_spin_unlock(lock);
125 }
126
arch_spin_lock_flags(arch_spinlock_t * lock,unsigned long flags)127 static __always_inline void arch_spin_lock_flags(arch_spinlock_t *lock,
128 unsigned long flags)
129 {
130 arch_spin_lock(lock);
131 }
132 #define arch_spin_lock_flags arch_spin_lock_flags
133
134 #ifdef ASM_SUPPORTED
135
136 static __always_inline void
arch_read_lock_flags(arch_rwlock_t * lock,unsigned long flags)137 arch_read_lock_flags(arch_rwlock_t *lock, unsigned long flags)
138 {
139 __asm__ __volatile__ (
140 "tbit.nz p6, p0 = %1,%2\n"
141 "br.few 3f\n"
142 "1:\n"
143 "fetchadd4.rel r2 = [%0], -1;;\n"
144 "(p6) ssm psr.i\n"
145 "2:\n"
146 "hint @pause\n"
147 "ld4 r2 = [%0];;\n"
148 "cmp4.lt p7,p0 = r2, r0\n"
149 "(p7) br.cond.spnt.few 2b\n"
150 "(p6) rsm psr.i\n"
151 ";;\n"
152 "3:\n"
153 "fetchadd4.acq r2 = [%0], 1;;\n"
154 "cmp4.lt p7,p0 = r2, r0\n"
155 "(p7) br.cond.spnt.few 1b\n"
156 : : "r"(lock), "r"(flags), "i"(IA64_PSR_I_BIT)
157 : "p6", "p7", "r2", "memory");
158 }
159
160 #define arch_read_lock_flags arch_read_lock_flags
161 #define arch_read_lock(lock) arch_read_lock_flags(lock, 0)
162
163 #else /* !ASM_SUPPORTED */
164
165 #define arch_read_lock_flags(rw, flags) arch_read_lock(rw)
166
167 #define arch_read_lock(rw) \
168 do { \
169 arch_rwlock_t *__read_lock_ptr = (rw); \
170 \
171 while (unlikely(ia64_fetchadd(1, (int *) __read_lock_ptr, acq) < 0)) { \
172 ia64_fetchadd(-1, (int *) __read_lock_ptr, rel); \
173 while (*(volatile int *)__read_lock_ptr < 0) \
174 cpu_relax(); \
175 } \
176 } while (0)
177
178 #endif /* !ASM_SUPPORTED */
179
180 #define arch_read_unlock(rw) \
181 do { \
182 arch_rwlock_t *__read_lock_ptr = (rw); \
183 ia64_fetchadd(-1, (int *) __read_lock_ptr, rel); \
184 } while (0)
185
186 #ifdef ASM_SUPPORTED
187
188 static __always_inline void
arch_write_lock_flags(arch_rwlock_t * lock,unsigned long flags)189 arch_write_lock_flags(arch_rwlock_t *lock, unsigned long flags)
190 {
191 __asm__ __volatile__ (
192 "tbit.nz p6, p0 = %1, %2\n"
193 "mov ar.ccv = r0\n"
194 "dep r29 = -1, r0, 31, 1\n"
195 "br.few 3f;;\n"
196 "1:\n"
197 "(p6) ssm psr.i\n"
198 "2:\n"
199 "hint @pause\n"
200 "ld4 r2 = [%0];;\n"
201 "cmp4.eq p0,p7 = r0, r2\n"
202 "(p7) br.cond.spnt.few 2b\n"
203 "(p6) rsm psr.i\n"
204 ";;\n"
205 "3:\n"
206 "cmpxchg4.acq r2 = [%0], r29, ar.ccv;;\n"
207 "cmp4.eq p0,p7 = r0, r2\n"
208 "(p7) br.cond.spnt.few 1b;;\n"
209 : : "r"(lock), "r"(flags), "i"(IA64_PSR_I_BIT)
210 : "ar.ccv", "p6", "p7", "r2", "r29", "memory");
211 }
212
213 #define arch_write_lock_flags arch_write_lock_flags
214 #define arch_write_lock(rw) arch_write_lock_flags(rw, 0)
215
216 #define arch_write_trylock(rw) \
217 ({ \
218 register long result; \
219 \
220 __asm__ __volatile__ ( \
221 "mov ar.ccv = r0\n" \
222 "dep r29 = -1, r0, 31, 1;;\n" \
223 "cmpxchg4.acq %0 = [%1], r29, ar.ccv\n" \
224 : "=r"(result) : "r"(rw) : "ar.ccv", "r29", "memory"); \
225 (result == 0); \
226 })
227
arch_write_unlock(arch_rwlock_t * x)228 static inline void arch_write_unlock(arch_rwlock_t *x)
229 {
230 u8 *y = (u8 *)x;
231 barrier();
232 asm volatile ("st1.rel.nta [%0] = r0\n\t" :: "r"(y+3) : "memory" );
233 }
234
235 #else /* !ASM_SUPPORTED */
236
237 #define arch_write_lock(l) \
238 ({ \
239 __u64 ia64_val, ia64_set_val = ia64_dep_mi(-1, 0, 31, 1); \
240 __u32 *ia64_write_lock_ptr = (__u32 *) (l); \
241 do { \
242 while (*ia64_write_lock_ptr) \
243 ia64_barrier(); \
244 ia64_val = ia64_cmpxchg4_acq(ia64_write_lock_ptr, ia64_set_val, 0); \
245 } while (ia64_val); \
246 })
247
248 #define arch_write_trylock(rw) \
249 ({ \
250 __u64 ia64_val; \
251 __u64 ia64_set_val = ia64_dep_mi(-1, 0, 31,1); \
252 ia64_val = ia64_cmpxchg4_acq((__u32 *)(rw), ia64_set_val, 0); \
253 (ia64_val == 0); \
254 })
255
arch_write_unlock(arch_rwlock_t * x)256 static inline void arch_write_unlock(arch_rwlock_t *x)
257 {
258 barrier();
259 x->write_lock = 0;
260 }
261
262 #endif /* !ASM_SUPPORTED */
263
arch_read_trylock(arch_rwlock_t * x)264 static inline int arch_read_trylock(arch_rwlock_t *x)
265 {
266 union {
267 arch_rwlock_t lock;
268 __u32 word;
269 } old, new;
270 old.lock = new.lock = *x;
271 old.lock.write_lock = new.lock.write_lock = 0;
272 ++new.lock.read_counter;
273 return (u32)ia64_cmpxchg4_acq((__u32 *)(x), new.word, old.word) == old.word;
274 }
275
276 #endif /* _ASM_IA64_SPINLOCK_H */
277