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runtime: FreeBSD fast clock_gettime HPET timecounter support

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This is a followup for CL 93156.

Fixes #22942.

Change-Id: Ic6e2de44011d041b91454353a6f2e3b0cf590060
Reviewed-on: https://go-review.googlesource.com/108095
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
This commit is contained in:
Yuval Pavel Zholkover 2018-04-19 17:52:14 +03:00 committed by Ian Lance Taylor
parent 279b530d68
commit 58c231f244
6 changed files with 89 additions and 21 deletions
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1
src/runtime/defs_freebsd.go
View File

@ -53,6 +53,7 @@ const (
PROT_EXEC = C.PROT_EXEC
MAP_ANON = C.MAP_ANON
MAP_SHARED = C.MAP_SHARED
MAP_PRIVATE = C.MAP_PRIVATE
MAP_FIXED = C.MAP_FIXED

1
src/runtime/defs_freebsd_386.go
View File

@ -22,6 +22,7 @@ const (
_PROT_EXEC = 0x4
_MAP_ANON = 0x1000
_MAP_SHARED = 0x1
_MAP_PRIVATE = 0x2
_MAP_FIXED = 0x10

1
src/runtime/defs_freebsd_amd64.go
View File

@ -22,6 +22,7 @@ const (
_PROT_EXEC = 0x4
_MAP_ANON = 0x1000
_MAP_SHARED = 0x1
_MAP_PRIVATE = 0x2
_MAP_FIXED = 0x10

1
src/runtime/defs_freebsd_arm.go
View File

@ -22,6 +22,7 @@ const (
_PROT_EXEC = 0x4
_MAP_ANON = 0x1000
_MAP_SHARED = 0x1
_MAP_PRIVATE = 0x2
_MAP_FIXED = 0x10

43
src/runtime/vdso_freebsd.go
View File

@ -16,37 +16,41 @@ const _VDSO_TH_NUM = 4 // defined in <sys/vdso.h> #ifdef _KERNEL
var timekeepSharedPage *vdsoTimekeep
//go:nosplit
func (bt bintime) Add(bt2 bintime) bintime {
func (bt *bintime) Add(bt2 *bintime) {
u := bt.frac
bt.frac += bt2.frac
if u > bt.frac {
bt.sec++
}
bt.sec += bt2.sec
return bt
}
//go:nosplit
func (bt bintime) AddX(x uint64) bintime {
func (bt *bintime) AddX(x uint64) {
u := bt.frac
bt.frac += x
if u > bt.frac {
bt.sec++
}
return bt
}
var binuptimeDummy uint32
var (
// binuptimeDummy is used in binuptime as the address of an atomic.Load, to simulate
// an atomic_thread_fence_acq() call which behaves as an instruction reordering and
// memory barrier.
binuptimeDummy uint32
zeroBintime bintime
)
// based on /usr/src/lib/libc/sys/__vdso_gettimeofday.c
//
//go:nosplit
func binuptime(abs bool) (bintime, bool) {
var bt bintime
func binuptime(abs bool) (bt bintime) {
timehands := (*[_VDSO_TH_NUM]vdsoTimehands)(add(unsafe.Pointer(timekeepSharedPage), vdsoTimekeepSize))
for {
if timekeepSharedPage.enabled == 0 {
return bt, false
return zeroBintime
}
curr := atomic.Load(&timekeepSharedPage.current) // atomic_load_acq_32
@ -55,13 +59,13 @@ func binuptime(abs bool) (bintime, bool) {
bt = th.offset
if tc, ok := th.getTimecounter(); !ok {
return bt, false
return zeroBintime
} else {
delta := (tc - th.offset_count) & th.counter_mask
bt = bt.AddX(th.scale * uint64(delta))
bt.AddX(th.scale * uint64(delta))
}
if abs {
bt = bt.Add(th.boottime)
bt.Add(&th.boottime)
}
atomic.Load(&binuptimeDummy) // atomic_thread_fence_acq()
@ -69,13 +73,13 @@ func binuptime(abs bool) (bintime, bool) {
break
}
}
return bt, true
return bt
}
//go:nosplit
func vdsoClockGettime(clockID int32) (bintime, bool) {
func vdsoClockGettime(clockID int32) bintime {
if timekeepSharedPage == nil || timekeepSharedPage.ver != _VDSO_TK_VER_CURR {
return bintime{}, false
return zeroBintime
}
abs := false
switch clockID {
@ -84,9 +88,8 @@ func vdsoClockGettime(clockID int32) (bintime, bool) {
case _CLOCK_REALTIME:
abs = true
default:
return bintime{}, false
return zeroBintime
}
return binuptime(abs)
}
@ -95,16 +98,16 @@ func fallback_walltime() (sec int64, nsec int32)
//go:nosplit
func nanotime() int64 {
bt, ok := vdsoClockGettime(_CLOCK_MONOTONIC)
if !ok {
bt := vdsoClockGettime(_CLOCK_MONOTONIC)
if bt == zeroBintime {
return fallback_nanotime()
}
return int64((1e9 * uint64(bt.sec)) + ((1e9 * uint64(bt.frac>>32)) >> 32))
}
func walltime() (sec int64, nsec int32) {
bt, ok := vdsoClockGettime(_CLOCK_REALTIME)
if !ok {
bt := vdsoClockGettime(_CLOCK_REALTIME)
if bt == zeroBintime {
return fallback_walltime()
}
return int64(bt.sec), int32((1e9 * uint64(bt.frac>>32)) >> 32)

63
src/runtime/vdso_freebsd_x86.go
View File

@ -7,8 +7,35 @@
package runtime
import (
"runtime/internal/atomic"
"unsafe"
)
const (
_VDSO_TH_ALGO_X86_TSC = 1
_VDSO_TH_ALGO_X86_TSC = 1
_VDSO_TH_ALGO_X86_HPET = 2
)
const (
_HPET_DEV_MAP_MAX = 10
_HPET_MAIN_COUNTER = 0xf0 /* Main counter register */
)
var (
hpetDevMap [_HPET_DEV_MAP_MAX]uintptr
hpetDevPath = [_HPET_DEV_MAP_MAX][11]byte{
{'/', 'd', 'e', 'v', '/', 'h', 'p', 'e', 't', '0', 0},
{'/', 'd', 'e', 'v', '/', 'h', 'p', 'e', 't', '1', 0},
{'/', 'd', 'e', 'v', '/', 'h', 'p', 'e', 't', '2', 0},
{'/', 'd', 'e', 'v', '/', 'h', 'p', 'e', 't', '3', 0},
{'/', 'd', 'e', 'v', '/', 'h', 'p', 'e', 't', '4', 0},
{'/', 'd', 'e', 'v', '/', 'h', 'p', 'e', 't', '5', 0},
{'/', 'd', 'e', 'v', '/', 'h', 'p', 'e', 't', '6', 0},
{'/', 'd', 'e', 'v', '/', 'h', 'p', 'e', 't', '7', 0},
{'/', 'd', 'e', 'v', '/', 'h', 'p', 'e', 't', '8', 0},
{'/', 'd', 'e', 'v', '/', 'h', 'p', 'e', 't', '9', 0},
}
)
//go:nosplit
@ -20,11 +47,45 @@ func (th *vdsoTimehands) getTSCTimecounter() uint32 {
return uint32(tsc)
}
//go:nosplit
func (th *vdsoTimehands) getHPETTimecounter() (uint32, bool) {
idx := int(th.x86_hpet_idx)
if idx >= len(hpetDevMap) {
return 0, false
}
p := atomic.Loaduintptr(&hpetDevMap[idx])
if p == 0 {
fd := open(&hpetDevPath[idx][0], 0 /* O_RDONLY */, 0)
if fd < 0 {
atomic.Casuintptr(&hpetDevMap[idx], 0, ^uintptr(0))
return 0, false
}
addr, mmapErr := mmap(nil, physPageSize, _PROT_READ, _MAP_SHARED, fd, 0)
closefd(fd)
newP := uintptr(addr)
if mmapErr != 0 {
newP = ^uintptr(0)
}
if !atomic.Casuintptr(&hpetDevMap[idx], 0, newP) && mmapErr == 0 {
munmap(addr, physPageSize)
}
p = atomic.Loaduintptr(&hpetDevMap[idx])
}
if p == ^uintptr(0) {
return 0, false
}
return *(*uint32)(unsafe.Pointer(p + _HPET_MAIN_COUNTER)), true
}
//go:nosplit
func (th *vdsoTimehands) getTimecounter() (uint32, bool) {
switch th.algo {
case _VDSO_TH_ALGO_X86_TSC:
return th.getTSCTimecounter(), true
case _VDSO_TH_ALGO_X86_HPET:
return th.getHPETTimecounter()
default:
return 0, false
}