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// Copyright 2009 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.
// Copyright 2009 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
import "unsafe"
const (
_AT_NULL = 0
_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
)
var randomNumber uint32
var armArch uint8 = 6 // we default to ARMv6
var hwcap uint32 // set by setup_auxv
var goarm uint8 // set by 5l
func checkgoarm() {
if goarm > 5 && hwcap&_HWCAP_VFP == 0 {
print("runtime: this CPU has no floating point hardware, so it cannot run\n")
print("this GOARM=", goarm, " binary. Recompile using GOARM=5.\n")
exit(1)
}
if goarm > 6 && hwcap&_HWCAP_VFPv3 == 0 {
print("runtime: this CPU has no VFPv3 floating point hardware, so it cannot run\n")
print("this GOARM=", goarm, " binary. Recompile using GOARM=5.\n")
exit(1)
}
}
//go:nosplit
func setup_auxv(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 << 28]uint32)(add(unsafe.Pointer(argv), uintptr(n)*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
if auxv[i+1] != 0 {
// the pointer provided may not be word alined, so we must to treat it
// as a byte array.
rnd := (*[16]byte)(unsafe.Pointer(uintptr(auxv[i+1])))
randomNumber = uint32(rnd[0]) | uint32(rnd[1])<<8 | uint32(rnd[2])<<16 | uint32(rnd[3])<<24
}
case _AT_PLATFORM: // v5l, v6l, v7l
t := *(*uint8)(unsafe.Pointer(uintptr(auxv[i+1] + 1)))
if '5' <= t && t <= '7' {
armArch = t - '0'
}
case _AT_HWCAP: // CPU capability bit flags
hwcap = auxv[i+1]
}
}
}
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)
}
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