diff options
Diffstat (limited to 'pkg/sentry/time/sampler_unsafe.go')
-rw-r--r-- | pkg/sentry/time/sampler_unsafe.go | 56 |
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 +} |