diff options
Diffstat (limited to 'src/runtime/os_linux_arm.go')
-rw-r--r-- | src/runtime/os_linux_arm.go | 78 |
1 files changed, 78 insertions, 0 deletions
diff --git a/src/runtime/os_linux_arm.go b/src/runtime/os_linux_arm.go new file mode 100644 index 000000000..d5b37d6ab --- /dev/null +++ b/src/runtime/os_linux_arm.go @@ -0,0 +1,78 @@ +// 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) +} |