mirror of
https://github.com/golang/go
synced 2024-11-19 15:54:46 -07:00
76 lines
2.1 KiB
Go
76 lines
2.1 KiB
Go
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// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package runtime
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import "unsafe"
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const (
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_AT_NULL = 0
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_AT_PLATFORM = 15 // introduced in at least 2.6.11
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_AT_HWCAP = 16 // introduced in at least 2.6.11
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_AT_RANDOM = 25 // introduced in 2.6.29
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_HWCAP_VFP = 1 << 6 // introduced in at least 2.6.11
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_HWCAP_VFPv3 = 1 << 13 // introduced in 2.6.30
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)
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var randomNumber uint32
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var armArch uint8 = 6 // we default to ARMv6
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var hwcap uint32 // set by setup_auxv
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var goarm uint8 // set by 5l
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func checkgoarm() {
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if goarm > 5 && hwcap&_HWCAP_VFP == 0 {
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print("runtime: this CPU has no floating point hardware, so it cannot run\n")
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print("this GOARM=", goarm, " binary. Recompile using GOARM=5.\n")
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exit(1)
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}
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if goarm > 6 && hwcap&_HWCAP_VFPv3 == 0 {
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print("runtime: this CPU has no VFPv3 floating point hardware, so it cannot run\n")
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print("this GOARM=", goarm, " binary. Recompile using GOARM=5.\n")
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exit(1)
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}
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}
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//go:nosplit
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func setup_auxv(argc int32, argv **byte) {
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// skip over argv, envv to get to auxv
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n := argc + 1
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for argv_index(argv, n) != nil {
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n++
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}
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n++
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auxv := (*[1 << 28]uint32)(add(unsafe.Pointer(argv), uintptr(n)*ptrSize))
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for i := 0; auxv[i] != _AT_NULL; i += 2 {
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switch auxv[i] {
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case _AT_RANDOM: // kernel provided 16-byte worth of random data
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if auxv[i+1] != 0 {
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randomNumber = *(*uint32)(unsafe.Pointer(uintptr(auxv[i+1])))
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}
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case _AT_PLATFORM: // v5l, v6l, v7l
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t := *(*uint8)(unsafe.Pointer(uintptr(auxv[i+1] + 1)))
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if '5' <= t && t <= '7' {
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armArch = t - '0'
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}
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case _AT_HWCAP: // CPU capability bit flags
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hwcap = auxv[i+1]
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}
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}
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}
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func cputicks() int64 {
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// Currently cputicks() is used in blocking profiler and to seed fastrand1().
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// nanotime() is a poor approximation of CPU ticks that is enough for the profiler.
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// randomNumber provides better seeding of fastrand1.
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return nanotime() + int64(randomNumber)
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}
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