github.com/MerlinKodo/gvisor@v0.0.0-20231110090155-957f62ecf90e/pkg/sentry/hostcpu/getcpu_amd64.s (about)

     1  // Copyright 2018 The gVisor Authors.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  #include "textflag.h"
    16  
    17  // func GetCPU() uint32
    18  TEXT ·GetCPU(SB),NOSPLIT|NOFRAME,$0-4
    19  	BYTE $0x0f; BYTE $0x01; BYTE $0xf9; // RDTSCP
    20  	// On Linux, the bottom 12 bits of IA32_TSC_AUX are CPU and the upper 20
    21  	// are node. See arch/x86/entry/vdso/vma.c:vgetcpu_cpu_init().
    22  	ANDL	$0xfff, CX
    23  	MOVL	CX, ret+0(FP)
    24  	RET