s390/vdso: add vdso support for coarse clocks

Add CLOCK_REALTIME_COARSE and CLOCK_MONOTONIC_COARSE optimization to
the 64-bit and 31-bit vdso.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/include/asm/vdso.h

@@ -22,13 +22,17 @@ struct vdso_data {
 	__u64 xtime_tod_stamp;		/* TOD clock for xtime		0x08 */
 	__u64 xtime_clock_sec;		/* Kernel time			0x10 */
 	__u64 xtime_clock_nsec;		/*				0x18 */
-	__u64 wtom_clock_sec;		/* Wall to monotonic clock	0x20 */
-	__u64 wtom_clock_nsec;		/*				0x28 */
-	__u32 tz_minuteswest;		/* Minutes west of Greenwich	0x30 */
-	__u32 tz_dsttime;		/* Type of dst correction	0x34 */
-	__u32 ectg_available;		/* ECTG instruction present	0x38 */
-	__u32 tk_mult;			/* Mult. used for xtime_nsec	0x3c */
-	__u32 tk_shift;			/* Shift used for xtime_nsec	0x40 */
+	__u64 xtime_coarse_sec;		/* Coarse kernel time		0x20 */
+	__u64 xtime_coarse_nsec;	/*				0x28 */
+	__u64 wtom_clock_sec;		/* Wall to monotonic clock	0x30 */
+	__u64 wtom_clock_nsec;		/*				0x38 */
+	__u64 wtom_coarse_sec;		/* Coarse wall to monotonic	0x40 */
+	__u64 wtom_coarse_nsec;		/*				0x48 */
+	__u32 tz_minuteswest;		/* Minutes west of Greenwich	0x50 */
+	__u32 tz_dsttime;		/* Type of dst correction	0x54 */
+	__u32 ectg_available;		/* ECTG instruction present	0x58 */
+	__u32 tk_mult;			/* Mult. used for xtime_nsec	0x5c */
+	__u32 tk_shift;			/* Shift used for xtime_nsec	0x60 */
 };
 
 struct vdso_per_cpu_data {

arch/s390/kernel/asm-offsets.c

@@ -62,8 +62,12 @@ int main(void)
 	DEFINE(__VDSO_XTIME_STAMP, offsetof(struct vdso_data, xtime_tod_stamp));
 	DEFINE(__VDSO_XTIME_SEC, offsetof(struct vdso_data, xtime_clock_sec));
 	DEFINE(__VDSO_XTIME_NSEC, offsetof(struct vdso_data, xtime_clock_nsec));
+	DEFINE(__VDSO_XTIME_CRS_SEC, offsetof(struct vdso_data, xtime_coarse_sec));
+	DEFINE(__VDSO_XTIME_CRS_NSEC, offsetof(struct vdso_data, xtime_coarse_nsec));
 	DEFINE(__VDSO_WTOM_SEC, offsetof(struct vdso_data, wtom_clock_sec));
 	DEFINE(__VDSO_WTOM_NSEC, offsetof(struct vdso_data, wtom_clock_nsec));
+	DEFINE(__VDSO_WTOM_CRS_SEC, offsetof(struct vdso_data, wtom_coarse_sec));
+	DEFINE(__VDSO_WTOM_CRS_NSEC, offsetof(struct vdso_data, wtom_coarse_nsec));
 	DEFINE(__VDSO_TIMEZONE, offsetof(struct vdso_data, tz_minuteswest));
 	DEFINE(__VDSO_ECTG_OK, offsetof(struct vdso_data, ectg_available));
 	DEFINE(__VDSO_TK_MULT, offsetof(struct vdso_data, tk_mult));
@@ -73,8 +77,11 @@ int main(void)
 	/* constants used by the vdso */
 	DEFINE(__CLOCK_REALTIME, CLOCK_REALTIME);
 	DEFINE(__CLOCK_MONOTONIC, CLOCK_MONOTONIC);
+	DEFINE(__CLOCK_REALTIME_COARSE, CLOCK_REALTIME_COARSE);
+	DEFINE(__CLOCK_MONOTONIC_COARSE, CLOCK_MONOTONIC_COARSE);
 	DEFINE(__CLOCK_THREAD_CPUTIME_ID, CLOCK_THREAD_CPUTIME_ID);
 	DEFINE(__CLOCK_REALTIME_RES, MONOTONIC_RES_NSEC);
+	DEFINE(__CLOCK_COARSE_RES, LOW_RES_NSEC);
 	BLANK();
 	/* idle data offsets */
 	DEFINE(__CLOCK_IDLE_ENTER, offsetof(struct s390_idle_data, clock_idle_enter));

arch/s390/kernel/time.c

@@ -232,6 +232,19 @@ void update_vsyscall(struct timekeeper *tk)
 		vdso_data->wtom_clock_nsec -= nsecps;
 		vdso_data->wtom_clock_sec++;
 	}
+
+	vdso_data->xtime_coarse_sec = tk->xtime_sec;
+	vdso_data->xtime_coarse_nsec =
+		(long)(tk->tkr.xtime_nsec >> tk->tkr.shift);
+	vdso_data->wtom_coarse_sec =
+		vdso_data->xtime_coarse_sec + tk->wall_to_monotonic.tv_sec;
+	vdso_data->wtom_coarse_nsec =
+		vdso_data->xtime_coarse_nsec + tk->wall_to_monotonic.tv_nsec;
+	while (vdso_data->wtom_coarse_nsec >= NSEC_PER_SEC) {
+		vdso_data->wtom_coarse_nsec -= NSEC_PER_SEC;
+		vdso_data->wtom_coarse_sec++;
+	}
+
 	vdso_data->tk_mult = tk->tkr.mult;
 	vdso_data->tk_shift = tk->tkr.shift;
 	smp_wmb();

arch/s390/kernel/vdso32/clock_getres.S

@@ -19,14 +19,20 @@
 	.type  __kernel_clock_getres,@function
 __kernel_clock_getres:
 	.cfi_startproc
+	basr	%r1,0
+	la	%r1,4f-.(%r1)
 	chi	%r2,__CLOCK_REALTIME
 	je	0f
 	chi	%r2,__CLOCK_MONOTONIC
+	je	0f
+	la	%r1,5f-4f(%r1)
+	chi	%r2,__CLOCK_REALTIME_COARSE
+	je	0f
+	chi	%r2,__CLOCK_MONOTONIC_COARSE
 	jne	3f
 0:	ltr	%r3,%r3
 	jz	2f				/* res == NULL */
-	basr	%r1,0
-1:	l	%r0,4f-1b(%r1)
+1:	l	%r0,0(%r1)
 	xc	0(4,%r3),0(%r3)			/* set tp->tv_sec to zero */
 	st	%r0,4(%r3)			/* store tp->tv_usec */
 2:	lhi	%r2,0
@@ -35,5 +41,6 @@ __kernel_clock_getres:
 	svc	0
 	br	%r14
 4:	.long	__CLOCK_REALTIME_RES
+5:	.long	__CLOCK_COARSE_RES
 	.cfi_endproc
 	.size	__kernel_clock_getres,.-__kernel_clock_getres

arch/s390/kernel/vdso32/clock_gettime.S

@@ -21,8 +21,12 @@ __kernel_clock_gettime:
 	.cfi_startproc
 	basr	%r5,0
 0:	al	%r5,21f-0b(%r5)			/* get &_vdso_data */
+	chi	%r2,__CLOCK_REALTIME_COARSE
+	je	10f
 	chi	%r2,__CLOCK_REALTIME
 	je	11f
+	chi	%r2,__CLOCK_MONOTONIC_COARSE
+	je	9f
 	chi	%r2,__CLOCK_MONOTONIC
 	jne	19f
 
@@ -68,6 +72,26 @@ __kernel_clock_gettime:
 	lhi	%r2,0
 	br	%r14
 
+	/* CLOCK_MONOTONIC_COARSE */
+9:	l	%r4,__VDSO_UPD_COUNT+4(%r5)	/* load update counter */
+	tml	%r4,0x0001			/* pending update ? loop */
+	jnz	9b
+	l	%r2,__VDSO_WTOM_CRS_SEC+4(%r5)
+	l	%r1,__VDSO_WTOM_CRS_NSEC+4(%r5)
+	cl	%r4,__VDSO_UPD_COUNT+4(%r5)	/* check update counter */
+	jne	9b
+	j	8b
+
+	/* CLOCK_REALTIME_COARSE */
+10:	l	%r4,__VDSO_UPD_COUNT+4(%r5)	/* load update counter */
+	tml	%r4,0x0001			/* pending update ? loop */
+	jnz	10b
+	l	%r2,__VDSO_XTIME_CRS_SEC+4(%r5)
+	l	%r1,__VDSO_XTIME_CRS_NSEC+4(%r5)
+	cl	%r4,__VDSO_UPD_COUNT+4(%r5)	/* check update counter */
+	jne	10b
+	j	17f
+
 	/* CLOCK_REALTIME */
 11:	l	%r4,__VDSO_UPD_COUNT+4(%r5)	/* load update counter */
 	tml	%r4,0x0001			/* pending update ? loop */

arch/s390/kernel/vdso64/clock_getres.S

@@ -19,6 +19,12 @@
 	.type  __kernel_clock_getres,@function
 __kernel_clock_getres:
 	.cfi_startproc
+	larl	%r1,4f
+	cghi	%r2,__CLOCK_REALTIME_COARSE
+	je	0f
+	cghi	%r2,__CLOCK_MONOTONIC_COARSE
+	je	0f
+	larl	%r1,3f
 	cghi	%r2,__CLOCK_REALTIME
 	je	0f
 	cghi	%r2,__CLOCK_MONOTONIC
@@ -32,7 +38,6 @@ __kernel_clock_getres:
 	jz	2f
 0:	ltgr	%r3,%r3
 	jz	1f				/* res == NULL */
-	larl	%r1,3f
 	lg	%r0,0(%r1)
 	xc	0(8,%r3),0(%r3)			/* set tp->tv_sec to zero */
 	stg	%r0,8(%r3)			/* store tp->tv_usec */
@@ -42,5 +47,6 @@ __kernel_clock_getres:
 	svc	0
 	br	%r14
 3:	.quad	__CLOCK_REALTIME_RES
+4:	.quad	__CLOCK_COARSE_RES
 	.cfi_endproc
 	.size	__kernel_clock_getres,.-__kernel_clock_getres

arch/s390/kernel/vdso64/clock_gettime.S

@@ -20,12 +20,16 @@
 __kernel_clock_gettime:
 	.cfi_startproc
 	larl	%r5,_vdso_data
+	cghi	%r2,__CLOCK_REALTIME_COARSE
+	je	4f
 	cghi	%r2,__CLOCK_REALTIME
 	je	5f
 	cghi	%r2,__CLOCK_THREAD_CPUTIME_ID
 	je	9f
 	cghi	%r2,-2		/* Per-thread CPUCLOCK with PID=0, VIRT=1 */
 	je	9f
+	cghi	%r2,__CLOCK_MONOTONIC_COARSE
+	je	3f
 	cghi	%r2,__CLOCK_MONOTONIC
 	jne	12f
 
@@ -54,6 +58,26 @@ __kernel_clock_gettime:
 	lghi	%r2,0
 	br	%r14
 
+	/* CLOCK_MONOTONIC_COARSE */
+3:	lg	%r4,__VDSO_UPD_COUNT(%r5)	/* load update counter */
+	tmll	%r4,0x0001			/* pending update ? loop */
+	jnz	3b
+	lg	%r0,__VDSO_WTOM_CRS_SEC(%r5)
+	lg	%r1,__VDSO_WTOM_CRS_NSEC(%r5)
+	clg	%r4,__VDSO_UPD_COUNT(%r5)	/* check update counter */
+	jne	3b
+	j	2b
+
+	/* CLOCK_REALTIME_COARSE */
+4:	lg	%r4,__VDSO_UPD_COUNT(%r5)	/* load update counter */
+	tmll	%r4,0x0001			/* pending update ? loop */
+	jnz	4b
+	lg	%r0,__VDSO_XTIME_CRS_SEC(%r5)
+	lg	%r1,__VDSO_XTIME_CRS_NSEC(%r5)
+	clg	%r4,__VDSO_UPD_COUNT(%r5)	/* check update counter */
+	jne	4b
+	j	7f
+
 	/* CLOCK_REALTIME */
 5:	lg	%r4,__VDSO_UPD_COUNT(%r5)	/* load update counter */
 	tmll	%r4,0x0001			/* pending update ? loop */