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s390/vdso: add vdso support for coarse clocks
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Add CLOCK_REALTIME_COARSE and CLOCK_MONOTONIC_COARSE optimization to
the 64-bit and 31-bit vdso.

Signed-off-by: Martin Schwidefsky <[email protected]>
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Martin Schwidefsky committed Sep 9, 2014
1 parent 070b7be commit b7eacb5
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Showing 7 changed files with 95 additions and 10 deletions.
18 changes: 11 additions & 7 deletions arch/s390/include/asm/vdso.h
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Original file line number Diff line number Diff line change
Expand Up @@ -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 {
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7 changes: 7 additions & 0 deletions arch/s390/kernel/asm-offsets.c
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Expand Up @@ -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));
Expand All @@ -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));
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13 changes: 13 additions & 0 deletions arch/s390/kernel/time.c
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Expand Up @@ -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();
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11 changes: 9 additions & 2 deletions arch/s390/kernel/vdso32/clock_getres.S
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Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand All @@ -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
24 changes: 24 additions & 0 deletions arch/s390/kernel/vdso32/clock_gettime.S
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Original file line number Diff line number Diff line change
Expand Up @@ -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

Expand Down Expand Up @@ -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 */
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8 changes: 7 additions & 1 deletion arch/s390/kernel/vdso64/clock_getres.S
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Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand All @@ -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 */
Expand All @@ -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
24 changes: 24 additions & 0 deletions arch/s390/kernel/vdso64/clock_gettime.S
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Original file line number Diff line number Diff line change
Expand Up @@ -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

Expand Down Expand Up @@ -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 */
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