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1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef __VDSO_HELPERS_H
3 #define __VDSO_HELPERS_H
7 #include <vdso/datapage.h>
9 static __always_inline u32
vdso_read_begin(const struct vdso_data
*vd
)
13 while ((seq
= READ_ONCE(vd
->seq
)) & 1)
20 static __always_inline u32
vdso_read_retry(const struct vdso_data
*vd
,
26 seq
= READ_ONCE(vd
->seq
);
30 static __always_inline
void vdso_write_begin(struct vdso_data
*vd
)
33 * WRITE_ONCE it is required otherwise the compiler can validly tear
34 * updates to vd[x].seq and it is possible that the value seen by the
35 * reader it is inconsistent.
37 WRITE_ONCE(vd
[CS_HRES_COARSE
].seq
, vd
[CS_HRES_COARSE
].seq
+ 1);
38 WRITE_ONCE(vd
[CS_RAW
].seq
, vd
[CS_RAW
].seq
+ 1);
42 static __always_inline
void vdso_write_end(struct vdso_data
*vd
)
46 * WRITE_ONCE it is required otherwise the compiler can validly tear
47 * updates to vd[x].seq and it is possible that the value seen by the
48 * reader it is inconsistent.
50 WRITE_ONCE(vd
[CS_HRES_COARSE
].seq
, vd
[CS_HRES_COARSE
].seq
+ 1);
51 WRITE_ONCE(vd
[CS_RAW
].seq
, vd
[CS_RAW
].seq
+ 1);
54 #endif /* !__ASSEMBLY__ */
56 #endif /* __VDSO_HELPERS_H */