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runtime: common handling of _AT_RANDOM auxv

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The Linux kernel provides 16 bytes of random data via the auxv vector
at startup. Currently we consume this separately on 386, amd64, arm,
and arm64. Now that we have a common auxv parser, handle _AT_RANDOM in
the common path.

Change-Id: Ib69549a1d37e2d07a351cf0f44007bcd24f0d20d
Reviewed-on: https://go-review.googlesource.com/22062
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
This commit is contained in:
Austin Clements 2016-04-14 12:32:28 -04:00
parent c955bb2040
commit 90addd3d41
5 changed files with 16 additions and 27 deletions
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9
src/runtime/os_linux.go
View File

@ -177,7 +177,8 @@ var failallocatestack = []byte("runtime: failed to allocate stack for the new OS
var failthreadcreate = []byte("runtime: failed to create new OS thread\n")
const (
_AT_NULL = 0 // End of vector
_AT_NULL = 0 // End of vector
_AT_RANDOM = 25 // introduced in 2.6.29
)
func sysargs(argc int32, argv **byte) {
@ -195,6 +196,12 @@ func sysargs(argc int32, argv **byte) {
auxv := (*[1 << 28]uintptr)(add(unsafe.Pointer(argv), uintptr(n)*sys.PtrSize))
for i := 0; auxv[i] != _AT_NULL; i += 2 {
tag, val := auxv[i], auxv[i+1]
switch tag {
case _AT_RANDOM:
// The kernel provides a pointer to 16-bytes
// worth of random data.
startupRandomData = (*[16]byte)(unsafe.Pointer(val))[:]
}
archauxv(tag, val)
}
}

7
src/runtime/os_linux_386.go
View File

@ -4,16 +4,9 @@
package runtime
import "unsafe"
const (
_AT_RANDOM = 25
_AT_SYSINFO = 32
)
func archauxv(tag, val uintptr) {
switch tag {
case _AT_RANDOM:
startupRandomData = (*[16]byte)(unsafe.Pointer(val))[:]
}
}

9
src/runtime/os_linux_arm.go
View File

@ -9,7 +9,6 @@ import "unsafe"
const (
_AT_PLATFORM = 15 // introduced in at least 2.6.11
_AT_HWCAP = 16 // introduced in at least 2.6.11
_AT_RANDOM = 25 // introduced in 2.6.29
_HWCAP_VFP = 1 << 6 // introduced in at least 2.6.11
_HWCAP_VFPv3 = 1 << 13 // introduced in 2.6.30
@ -34,10 +33,10 @@ func checkgoarm() {
func archauxv(tag, val uintptr) {
switch tag {
case _AT_RANDOM: // kernel provides a pointer to 16-bytes worth of random data
startupRandomData = (*[16]byte)(unsafe.Pointer(val))[:]
// the pointer provided may not be word aligned, so we must treat it
// as a byte array.
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

14
src/runtime/os_linux_arm64.go
View File

@ -4,20 +4,14 @@
package runtime
import "unsafe"
const (
_AT_RANDOM = 25 // introduced in 2.6.29
)
var randomNumber uint32
func archauxv(tag, val uintptr) {
switch tag {
case _AT_RANDOM: // kernel provides a pointer to 16-bytes worth of random data
startupRandomData = (*[16]byte)(unsafe.Pointer(val))[:]
// the pointer provided may not be word aligned, so we must treat it
// as a byte array.
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
}

4
src/runtime/vdso_linux_amd64.go
View File

@ -18,7 +18,6 @@ import "unsafe"
// http://refspecs.linuxfoundation.org/LSB_3.2.0/LSB-Core-generic/LSB-Core-generic/symversion.html
const (
_AT_RANDOM = 25
_AT_SYSINFO_EHDR = 33
_PT_LOAD = 1 /* Loadable program segment */
@ -303,8 +302,5 @@ func archauxv(tag, val uintptr) {
info1 := (*vdso_info)(noescape(unsafe.Pointer(&info)))
vdso_init_from_sysinfo_ehdr(info1, (*elf64Ehdr)(unsafe.Pointer(val)))
vdso_parse_symbols(info1, vdso_find_version(info1, &linux26))
case _AT_RANDOM:
startupRandomData = (*[16]byte)(unsafe.Pointer(val))[:]
}
}