1 // Copyright 2009 The Go Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE file. 4 5 package runtime 6 7 import "unsafe" 8 9 const ( 10 _AT_NULL = 0 11 _AT_PLATFORM = 15 // introduced in at least 2.6.11 12 _AT_HWCAP = 16 // introduced in at least 2.6.11 13 _AT_RANDOM = 25 // introduced in 2.6.29 14 15 _HWCAP_VFP = 1 << 6 // introduced in at least 2.6.11 16 _HWCAP_VFPv3 = 1 << 13 // introduced in 2.6.30 17 ) 18 19 var randomNumber uint32 20 var armArch uint8 = 6 // we default to ARMv6 21 var hwcap uint32 // set by setup_auxv 22 23 func checkgoarm() { 24 if goarm > 5 && hwcap&_HWCAP_VFP == 0 { 25 print("runtime: this CPU has no floating point hardware, so it cannot run\n") 26 print("this GOARM=", goarm, " binary. Recompile using GOARM=5.\n") 27 exit(1) 28 } 29 if goarm > 6 && hwcap&_HWCAP_VFPv3 == 0 { 30 print("runtime: this CPU has no VFPv3 floating point hardware, so it cannot run\n") 31 print("this GOARM=", goarm, " binary. Recompile using GOARM=5.\n") 32 exit(1) 33 } 34 } 35 36 func sysargs(argc int32, argv **byte) { 37 // skip over argv, envv to get to auxv 38 n := argc + 1 39 for argv_index(argv, n) != nil { 40 n++ 41 } 42 n++ 43 auxv := (*[1 << 28]uint32)(add(unsafe.Pointer(argv), uintptr(n)*ptrSize)) 44 45 for i := 0; auxv[i] != _AT_NULL; i += 2 { 46 switch auxv[i] { 47 case _AT_RANDOM: // kernel provides a pointer to 16-bytes worth of random data 48 startupRandomData = (*[16]byte)(unsafe.Pointer(uintptr(auxv[i+1])))[:] 49 // the pointer provided may not be word aligned, so we must treat it 50 // as a byte array. 51 randomNumber = uint32(startupRandomData[4]) | uint32(startupRandomData[5])<<8 | 52 uint32(startupRandomData[6])<<16 | uint32(startupRandomData[7])<<24 53 54 case _AT_PLATFORM: // v5l, v6l, v7l 55 t := *(*uint8)(unsafe.Pointer(uintptr(auxv[i+1] + 1))) 56 if '5' <= t && t <= '7' { 57 armArch = t - '0' 58 } 59 60 case _AT_HWCAP: // CPU capability bit flags 61 hwcap = auxv[i+1] 62 } 63 } 64 } 65 66 //go:nosplit 67 func cputicks() int64 { 68 // Currently cputicks() is used in blocking profiler and to seed fastrand1(). 69 // nanotime() is a poor approximation of CPU ticks that is enough for the profiler. 70 // randomNumber provides better seeding of fastrand1. 71 return nanotime() + int64(randomNumber) 72 } 73
