Commit 157a1a27 authored by Hendrik Brueckner's avatar Hendrik Brueckner Committed by Martin Schwidefsky
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[S390] vdso: use ntp adjusted clock multiplier 



Commit "timekeeping: Fix clock_gettime vsyscall time warp" (0696b711)
introduced the new parameter "mult" to update_vsyscall(). This parameter
contains the internal NTP adjusted clock multiplier.

The s390x vdso did not use this adjusted multiplier.  Instead, it used
the constant clock multiplier for gettimeofday() and clock_gettime()
variants.  This may result in observable time warps as explained in
commit 0696b711.

Make the NTP adjusted clock multiplier available to the s390x vdso
implementation and use it for time calculations.

Cc: <stable@kernel.org>
Signed-off-by: default avatarHendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 8821d24c

arch/s390/include/asm/vdso.h

+1 −0
Original line number Original line Diff line number Diff line
@@ -29,6 +29,7 @@ struct vdso_data { 
	__u32 tz_minuteswest;		/* Minutes west of Greenwich	0x30 */

	__u32 tz_minuteswest;		/* Minutes west of Greenwich	0x30 */

	__u32 tz_dsttime;		/* Type of dst correction	0x34 */

	__u32 tz_dsttime;		/* Type of dst correction	0x34 */

	__u32 ectg_available;

	__u32 ectg_available;

	__u32 ntp_mult;			/* NTP adjusted multiplier	0x3C */

};

};





struct vdso_per_cpu_data {

struct vdso_per_cpu_data {

arch/s390/kernel/asm-offsets.c

+1 −0
Original line number Original line Diff line number Diff line
@@ -61,6 +61,7 @@ int main(void) 
	DEFINE(__VDSO_WTOM_NSEC, offsetof(struct vdso_data, wtom_clock_nsec));

	DEFINE(__VDSO_WTOM_NSEC, offsetof(struct vdso_data, wtom_clock_nsec));

	DEFINE(__VDSO_TIMEZONE, offsetof(struct vdso_data, tz_minuteswest));

	DEFINE(__VDSO_TIMEZONE, offsetof(struct vdso_data, tz_minuteswest));

	DEFINE(__VDSO_ECTG_OK, offsetof(struct vdso_data, ectg_available));

	DEFINE(__VDSO_ECTG_OK, offsetof(struct vdso_data, ectg_available));

	DEFINE(__VDSO_NTP_MULT, offsetof(struct vdso_data, ntp_mult));

	DEFINE(__VDSO_ECTG_BASE, offsetof(struct vdso_per_cpu_data, ectg_timer_base));

	DEFINE(__VDSO_ECTG_BASE, offsetof(struct vdso_per_cpu_data, ectg_timer_base));

	DEFINE(__VDSO_ECTG_USER, offsetof(struct vdso_per_cpu_data, ectg_user_time));

	DEFINE(__VDSO_ECTG_USER, offsetof(struct vdso_per_cpu_data, ectg_user_time));

	/* constants used by the vdso */

	/* constants used by the vdso */

arch/s390/kernel/time.c

+1 −0
Original line number Original line Diff line number Diff line
@@ -221,6 +221,7 @@ void update_vsyscall(struct timespec *wall_time, struct clocksource *clock, 
	vdso_data->xtime_clock_nsec = wall_time->tv_nsec;

	vdso_data->xtime_clock_nsec = wall_time->tv_nsec;

	vdso_data->wtom_clock_sec = wall_to_monotonic.tv_sec;

	vdso_data->wtom_clock_sec = wall_to_monotonic.tv_sec;

	vdso_data->wtom_clock_nsec = wall_to_monotonic.tv_nsec;

	vdso_data->wtom_clock_nsec = wall_to_monotonic.tv_nsec;

	vdso_data->ntp_mult = mult;

	smp_wmb();

	smp_wmb();

	++vdso_data->tb_update_count;

	++vdso_data->tb_update_count;

}

}

arch/s390/kernel/vdso32/clock_gettime.S

+6 −6
Original line number Original line Diff line number Diff line
@@ -38,13 +38,13 @@ __kernel_clock_gettime: 
	sl	%r1,__VDSO_XTIME_STAMP+4(%r5)

	sl	%r1,__VDSO_XTIME_STAMP+4(%r5)

	brc	3,2f

	brc	3,2f

	ahi	%r0,-1

	ahi	%r0,-1

2:	mhi	%r0,1000			/* cyc2ns(clock,cycle_delta) */

2:	ms	%r0,__VDSO_NTP_MULT(%r5)	/* cyc2ns(clock,cycle_delta) */

	lr	%r2,%r0

	lr	%r2,%r0

	lhi	%r0,1000

	l	%r0,__VDSO_NTP_MULT(%r5)

	ltr	%r1,%r1

	ltr	%r1,%r1

	mr	%r0,%r0

	mr	%r0,%r0

	jnm	3f

	jnm	3f

	ahi	%r0,1000

	a	%r0,__VDSO_NTP_MULT(%r5)

3:	alr	%r0,%r2

3:	alr	%r0,%r2

	srdl	%r0,12

	srdl	%r0,12

	al	%r0,__VDSO_XTIME_NSEC(%r5)	/*  + xtime */

	al	%r0,__VDSO_XTIME_NSEC(%r5)	/*  + xtime */
@@ -86,13 +86,13 @@ __kernel_clock_gettime: 
	sl	%r1,__VDSO_XTIME_STAMP+4(%r5)

	sl	%r1,__VDSO_XTIME_STAMP+4(%r5)

	brc	3,12f

	brc	3,12f

	ahi	%r0,-1

	ahi	%r0,-1

12:	mhi	%r0,1000			/* cyc2ns(clock,cycle_delta) */

12:	ms	%r0,__VDSO_NTP_MULT(%r5)	/* cyc2ns(clock,cycle_delta) */

	lr	%r2,%r0

	lr	%r2,%r0

	lhi	%r0,1000

	l	%r0,__VDSO_NTP_MULT(%r5)

	ltr	%r1,%r1

	ltr	%r1,%r1

	mr	%r0,%r0

	mr	%r0,%r0

	jnm	13f

	jnm	13f

	ahi	%r0,1000

	a	%r0,__VDSO_NTP_MULT(%r5)

13:	alr	%r0,%r2

13:	alr	%r0,%r2

	srdl	%r0,12

	srdl	%r0,12

	al	%r0,__VDSO_XTIME_NSEC(%r5)	/*  + xtime */

	al	%r0,__VDSO_XTIME_NSEC(%r5)	/*  + xtime */

arch/s390/kernel/vdso32/gettimeofday.S

+3 −3
Original line number Original line Diff line number Diff line
@@ -35,13 +35,13 @@ __kernel_gettimeofday: 
	sl	%r1,__VDSO_XTIME_STAMP+4(%r5)

	sl	%r1,__VDSO_XTIME_STAMP+4(%r5)

	brc	3,3f

	brc	3,3f

	ahi	%r0,-1

	ahi	%r0,-1

3:	mhi	%r0,1000			/* cyc2ns(clock,cycle_delta) */

3:	ms	%r0,__VDSO_NTP_MULT(%r5)	/* cyc2ns(clock,cycle_delta) */

	st	%r0,24(%r15)

	st	%r0,24(%r15)

	lhi	%r0,1000

	l	%r0,__VDSO_NTP_MULT(%r5)

	ltr	%r1,%r1

	ltr	%r1,%r1

	mr	%r0,%r0

	mr	%r0,%r0

	jnm	4f

	jnm	4f

	ahi	%r0,1000

	a	%r0,__VDSO_NTP_MULT(%r5)

4:	al	%r0,24(%r15)

4:	al	%r0,24(%r15)

	srdl	%r0,12

	srdl	%r0,12

	al	%r0,__VDSO_XTIME_NSEC(%r5)	/*  + xtime */

	al	%r0,__VDSO_XTIME_NSEC(%r5)	/*  + xtime */

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