| // Copyright 2015 The Go Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| package runtime |
| |
| var randomNumber uint32 |
| |
| func archauxv(tag, val uintptr) { |
| switch tag { |
| case _AT_RANDOM: |
| // sysargs filled in startupRandomData, but that |
| // pointer may not be word aligned, so we must treat |
| // it as a byte array. |
| randomNumber = uint32(startupRandomData[4]) | uint32(startupRandomData[5])<<8 | |
| uint32(startupRandomData[6])<<16 | uint32(startupRandomData[7])<<24 |
| } |
| } |
| |
| //go:nosplit |
| func cputicks() int64 { |
| // Currently cputicks() is used in blocking profiler and to seed fastrand1(). |
| // nanotime() is a poor approximation of CPU ticks that is enough for the profiler. |
| // randomNumber provides better seeding of fastrand1. |
| return nanotime() + int64(randomNumber) |
| } |