github.com/x04/go/src@v0.0.0-20200202162449-3d481ceb3525/runtime/os_linux_arm64.go (about)

     1  // Copyright 2015 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  // +build arm64
     6  
     7  package runtime
     8  
     9  import "github.com/x04/go/src/internal/cpu"
    10  
    11  func archauxv(tag, val uintptr) {
    12  	switch tag {
    13  	case _AT_HWCAP:
    14  		// arm64 doesn't have a 'cpuid' instruction equivalent and relies on
    15  		// HWCAP/HWCAP2 bits for hardware capabilities.
    16  		hwcap := uint(val)
    17  		if GOOS == "android" {
    18  			// The Samsung S9+ kernel reports support for atomics, but not all cores
    19  			// actually support them, resulting in SIGILL. See issue #28431.
    20  			// TODO(elias.naur): Only disable the optimization on bad chipsets.
    21  			const hwcap_ATOMICS = 1 << 8
    22  			hwcap &= ^uint(hwcap_ATOMICS)
    23  		}
    24  		cpu.HWCap = hwcap
    25  	case _AT_HWCAP2:
    26  		cpu.HWCap2 = uint(val)
    27  	}
    28  }
    29  
    30  func osArchInit()	{}
    31  
    32  //go:nosplit
    33  func cputicks() int64 {
    34  	// Currently cputicks() is used in blocking profiler and to seed fastrand().
    35  	// nanotime() is a poor approximation of CPU ticks that is enough for the profiler.
    36  	return nanotime()
    37  }