Commit e15bf9e3 authored by Anna-Maria Behnsen's avatar Anna-Maria Behnsen Committed by Thomas Gleixner
Browse files

vdso/helpers: Prepare introduction of struct vdso_clock 



To support multiple PTP clocks, the VDSO data structure needs to be
reworked. All clock specific data will end up in struct vdso_clock and in
struct vdso_time_data there will be an array of VDSO clocks. For now,
vdso_clock is simply a define which maps vdso_clock to vdso_time_data.

Prepare all functions which need the pointer to the vdso_clock array to
work well after the structures get reworked. Replace the struct vdso_time_data
pointer with a struct vdso_clock pointer where applicable.

No functional change.

Signed-off-by: default avatarAnna-Maria Behnsen <anna-maria@linutronix.de>
Signed-off-by: default avatarNam Cao <namcao@linutronix.de>
Signed-off-by: default avatarThomas Weißschuh <thomas.weissschuh@linutronix.de>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20250303-vdso-clock-v1-5-c1b5c69a166f@linutronix.de
parent a05f14de

include/vdso/helpers.h

+12 −8
Original line number Diff line number Diff line
@@ -7,49 +7,53 @@ 
#include <asm/barrier.h>

#include <vdso/datapage.h>



static __always_inline u32 vdso_read_begin(const struct vdso_time_data *vd)

static __always_inline u32 vdso_read_begin(const struct vdso_clock *vc)

{

	u32 seq;



	while (unlikely((seq = READ_ONCE(vd->seq)) & 1))

	while (unlikely((seq = READ_ONCE(vc->seq)) & 1))

		cpu_relax();



	smp_rmb();

	return seq;

}



static __always_inline u32 vdso_read_retry(const struct vdso_time_data *vd,

static __always_inline u32 vdso_read_retry(const struct vdso_clock *vc,

					   u32 start)

{

	u32 seq;



	smp_rmb();

	seq = READ_ONCE(vd->seq);

	seq = READ_ONCE(vc->seq);

	return seq != start;

}



static __always_inline void vdso_write_begin(struct vdso_time_data *vd)

{

	struct vdso_clock *vc = vd;



	/*

	 * WRITE_ONCE() is required otherwise the compiler can validly tear

	 * updates to vd[x].seq and it is possible that the value seen by the

	 * reader is inconsistent.

	 */

	WRITE_ONCE(vd[CS_HRES_COARSE].seq, vd[CS_HRES_COARSE].seq + 1);

	WRITE_ONCE(vd[CS_RAW].seq, vd[CS_RAW].seq + 1);

	WRITE_ONCE(vc[CS_HRES_COARSE].seq, vc[CS_HRES_COARSE].seq + 1);

	WRITE_ONCE(vc[CS_RAW].seq, vc[CS_RAW].seq + 1);

	smp_wmb();

}



static __always_inline void vdso_write_end(struct vdso_time_data *vd)

{

	struct vdso_clock *vc = vd;



	smp_wmb();

	/*

	 * WRITE_ONCE() is required otherwise the compiler can validly tear

	 * updates to vd[x].seq and it is possible that the value seen by the

	 * reader is inconsistent.

	 */

	WRITE_ONCE(vd[CS_HRES_COARSE].seq, vd[CS_HRES_COARSE].seq + 1);

	WRITE_ONCE(vd[CS_RAW].seq, vd[CS_RAW].seq + 1);

	WRITE_ONCE(vc[CS_HRES_COARSE].seq, vc[CS_HRES_COARSE].seq + 1);

	WRITE_ONCE(vc[CS_RAW].seq, vc[CS_RAW].seq + 1);

}



#endif /* !__ASSEMBLY__ */