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runtime: get randomness from AT_RANDOM AUXV on linux/arm64

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Fixes #15147.

Change-Id: Ibfe46c747dea987787a51eb0c95ccd8c5f24f366
Reviewed-on: https://go-review.googlesource.com/21580
Run-TryBot: Minux Ma <minux@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
This commit is contained in:
Shenghou Ma 2016-04-05 23:09:39 -04:00 committed by Minux Ma
parent db9348b866
commit a2eded3421
2 changed files with 27 additions and 0 deletions
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26
src/runtime/os_linux_arm64.go
View File

@ -4,6 +4,11 @@
package runtime
import (
"runtime/internal/sys"
"unsafe"
)
const (
_AT_NULL = 0
_AT_RANDOM = 25 // introduced in 2.6.29
@ -11,6 +16,27 @@ const (
var randomNumber uint32
func sysargs(argc int32, argv **byte) {
// skip over argv, envv to get to auxv
n := argc + 1
for argv_index(argv, n) != nil {
n++
}
n++
auxv := (*[1 << 29]uint64)(add(unsafe.Pointer(argv), uintptr(n)*sys.PtrSize))
for i := 0; auxv[i] != _AT_NULL; i += 2 {
switch auxv[i] {
case _AT_RANDOM: // kernel provides a pointer to 16-bytes worth of random data
startupRandomData = (*[16]byte)(unsafe.Pointer(uintptr(auxv[i+1])))[:]
// the pointer provided 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().

1
src/runtime/vdso_none.go
View File

@ -5,6 +5,7 @@
// +build !linux !amd64
// +build !linux !386
// +build !linux !arm
// +build !linux !arm64
package runtime