Merge 216da0b7 (automated)

1 files changed, 56 insertions, 0 deletions

diff --git a/pkg/sentry/time/sampler_unsafe.go b/pkg/sentry/time/sampler_unsafe.go
new file mode 100644
index 000000000..e76180217
--- /dev/null
+++ b/pkg/sentry/time/sampler_unsafe.go
@@ -0,0 +1,56 @@
+// Copyright 2018 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package time
+
+import (
+	"syscall"
+	"unsafe"
+)
+
+// syscallTSCReferenceClocks is the standard referenceClocks, collecting
+// samples using CLOCK_GETTIME and RDTSC.
+type syscallTSCReferenceClocks struct {
+	tscCycleClock
+}
+
+// Sample implements sampler.Sample.
+func (syscallTSCReferenceClocks) Sample(c ClockID) (sample, error) {
+	var s sample
+
+	s.before = Rdtsc()
+
+	// Don't call clockGettime to avoid a call which may call morestack.
+	var ts syscall.Timespec
+	_, _, e := syscall.RawSyscall(syscall.SYS_CLOCK_GETTIME, uintptr(c), uintptr(unsafe.Pointer(&ts)), 0)
+	if e != 0 {
+		return sample{}, e
+	}
+
+	s.after = Rdtsc()
+	s.ref = ReferenceNS(ts.Nano())
+
+	return s, nil
+}
+
+// clockGettime calls SYS_CLOCK_GETTIME, returning time in nanoseconds.
+func clockGettime(c ClockID) (ReferenceNS, error) {
+	var ts syscall.Timespec
+	_, _, e := syscall.RawSyscall(syscall.SYS_CLOCK_GETTIME, uintptr(c), uintptr(unsafe.Pointer(&ts)), 0)
+	if e != 0 {
+		return 0, e
+	}
+
+	return ReferenceNS(ts.Nano()), nil
+}