diff options
Diffstat (limited to 'pkg/sentry/time/tsc_amd64.s')
| -rw-r--r-- | pkg/sentry/time/tsc_amd64.s | 27 |
1 files changed, 27 insertions, 0 deletions
diff --git a/pkg/sentry/time/tsc_amd64.s b/pkg/sentry/time/tsc_amd64.s new file mode 100644 index 000000000..4cc604392 --- /dev/null +++ b/pkg/sentry/time/tsc_amd64.s @@ -0,0 +1,27 @@ +// Copyright 2018 Google Inc. +// +// 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. + +#include "textflag.h" + +TEXT ·Rdtsc(SB),NOSPLIT,$0-8 + // N.B. We need LFENCE on Intel, AMD is more complicated. + // Modern AMD CPUs with modern kernels make LFENCE behave like it does + // on Intel with MSR_F10H_DECFG_LFENCE_SERIALIZE_BIT. MFENCE is + // otherwise needed on AMD. + LFENCE + RDTSC + SHLQ $32, DX + ADDQ DX, AX + MOVQ AX, ret+0(FP) + RET |