1 /* SPDX-License-Identifier: GPL-2.0 */ 1
2 #ifndef __VDSO_HELPERS_H
3 #define __VDSO_HELPERS_H
4
5 #ifndef __ASSEMBLY__
6
7 #include <asm/barrier.h>
8 #include <vdso/datapage.h>
9
10 static __always_inline u32 vdso_read_begin(con
11 {
12 u32 seq;
13
14 while (unlikely((seq = READ_ONCE(vd->s
15 cpu_relax();
16
17 smp_rmb();
18 return seq;
19 }
20
21 static __always_inline u32 vdso_read_retry(con
22 u32
23 {
24 u32 seq;
25
26 smp_rmb();
27 seq = READ_ONCE(vd->seq);
28 return seq != start;
29 }
30
31 static __always_inline void vdso_write_begin(s
32 {
33 /*
34 * WRITE_ONCE() is required otherwise
35 * updates to vd[x].seq and it is poss
36 * reader is inconsistent.
37 */
38 WRITE_ONCE(vd[CS_HRES_COARSE].seq, vd[
39 WRITE_ONCE(vd[CS_RAW].seq, vd[CS_RAW].
40 smp_wmb();
41 }
42
43 static __always_inline void vdso_write_end(str
44 {
45 smp_wmb();
46 /*
47 * WRITE_ONCE() is required otherwise
48 * updates to vd[x].seq and it is poss
49 * reader is inconsistent.
50 */
51 WRITE_ONCE(vd[CS_HRES_COARSE].seq, vd[
52 WRITE_ONCE(vd[CS_RAW].seq, vd[CS_RAW].
53 }
54
55 #endif /* !__ASSEMBLY__ */
56
57 #endif /* __VDSO_HELPERS_H */
58
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