1 // Copyright 2020 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 //go:build arm64 && darwin && !ios
6 7 package cpu
8 9 import _ "unsafe" // for linkname
10 11 func osInit() {
12 // macOS 12 moved these to the hw.optional.arm tree, but as of Go 1.24 we
13 // still support macOS 11. See [Determine Encryption Capabilities].
14 //
15 // [Determine Encryption Capabilities]: https://developer.apple.com/documentation/kernel/1387446-sysctlbyname/determining_instruction_set_characteristics#3918855
16 ARM64.HasATOMICS = sysctlEnabled([]byte("hw.optional.armv8_1_atomics\x00"))
17 ARM64.HasCRC32 = sysctlEnabled([]byte("hw.optional.armv8_crc32\x00"))
18 ARM64.HasSHA512 = sysctlEnabled([]byte("hw.optional.armv8_2_sha512\x00"))
19 ARM64.HasSHA3 = sysctlEnabled([]byte("hw.optional.armv8_2_sha3\x00"))
20 21 ARM64.HasDIT = sysctlEnabled([]byte("hw.optional.arm.FEAT_DIT\x00"))
22 23 // There are no hw.optional sysctl values for the below features on macOS 11
24 // to detect their supported state dynamically (although they are available
25 // in the hw.optional.arm tree on macOS 12). Assume the CPU features that
26 // Apple Silicon M1 supports to be available on all future iterations.
27 ARM64.HasAES = true
28 ARM64.HasPMULL = true
29 ARM64.HasSHA1 = true
30 ARM64.HasSHA2 = true
31 }
32 33 //go:noescape
34 func getsysctlbyname(name []byte) (int32, int32)
35 36 // sysctlEnabled should be an internal detail,
37 // but widely used packages access it using linkname.
38 // Notable members of the hall of shame include:
39 // - github.com/bytedance/gopkg
40 // - github.com/songzhibin97/gkit
41 //
42 // Do not remove or change the type signature.
43 // See go.dev/issue/67401.
44 //
45 //go:linkname sysctlEnabled
46 func sysctlEnabled(name []byte) bool {
47 ret, value := getsysctlbyname(name)
48 if ret < 0 {
49 return false
50 }
51 return value > 0
52 }
53