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 package runtime 6 7 var randomNumber uint32 8 9 func archauxv(tag, val uintptr) { 10 switch tag { 11 case _AT_RANDOM: 12 // sysargs filled in startupRandomData, but that 13 // pointer may not be word aligned, so we must treat 14 // it as a byte array. 15 randomNumber = uint32(startupRandomData[4]) | uint32(startupRandomData[5])<<8 | 16 uint32(startupRandomData[6])<<16 | uint32(startupRandomData[7])<<24 17 } 18 } 19 20 //go:nosplit 21 func cputicks() int64 { 22 // Currently cputicks() is used in blocking profiler and to seed fastrand(). 23 // nanotime() is a poor approximation of CPU ticks that is enough for the profiler. 24 // randomNumber provides better seeding of fastrand. 25 return nanotime() + int64(randomNumber) 26 } 27
