cpu: darwin/arm64 feature detection The ARM64 flags were not being correctly set for Mac M series laptops. Fixes golang/go#43046 Change-Id: I1d884dccd3f3a0a010ad7babbab26b73731ab583 Reviewed-on: https://go-review.googlesource.com/c/sys/+/737260 Auto-Submit: Keith Randall <khr@golang.org> Reviewed-by: Keith Randall <khr@google.com> Reviewed-by: Keith Randall <khr@golang.org> LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: David Chase <drchase@google.com>
diff --git a/cpu/asm_darwin_arm64_gc.s b/cpu/asm_darwin_arm64_gc.s new file mode 100644 index 0000000..e07fa75 --- /dev/null +++ b/cpu/asm_darwin_arm64_gc.s
@@ -0,0 +1,12 @@ +// Copyright 2024 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. + +//go:build darwin && arm64 && gc + +#include "textflag.h" + +TEXT libc_sysctlbyname_trampoline<>(SB),NOSPLIT,$0-0 + JMP libc_sysctlbyname(SB) +GLOBL ·libc_sysctlbyname_trampoline_addr(SB), RODATA, $8 +DATA ·libc_sysctlbyname_trampoline_addr(SB)/8, $libc_sysctlbyname_trampoline<>(SB)
diff --git a/cpu/cpu_darwin_arm64.go b/cpu/cpu_darwin_arm64.go index 30ee0f2..0b47074 100644 --- a/cpu/cpu_darwin_arm64.go +++ b/cpu/cpu_darwin_arm64.go
@@ -2,25 +2,66 @@ // Use of this source code is governed by a BSD-style // license that can be found in the LICENSE file. +//go:build darwin && arm64 && gc + package cpu -import "runtime" - func doinit() { - ARM64.HasASIMD = true - ARM64.HasFP = true + setMinimalFeatures() - if runtime.GOOS != "ios" { - // M-series SoCs are at least armv8.4-a - ARM64.HasCRC32 = true // armv8.1 - ARM64.HasATOMICS = true // armv8.2 - ARM64.HasJSCVT = true // armv8.3, if HasFP + // The feature flags are explained in [Instruction Set Detection]. + // There are some differences between MacOS versions: + // + // MacOS 11 and 12 do not have "hw.optional" sysctl values for some of the features. + // + // MacOS 13 changed some of the naming conventions to align with ARM Architecture Reference Manual. + // For example "hw.optional.armv8_2_sha512" became "hw.optional.arm.FEAT_SHA512". + // It currently checks both to stay compatible with MacOS 11 and 12. + // The old names also work with MacOS 13, however it's not clear whether + // they will continue working with future OS releases. + // + // Once MacOS 12 is no longer supported the old names can be removed. + // + // [Instruction Set Detection]: https://developer.apple.com/documentation/kernel/1387446-sysctlbyname/determining_instruction_set_characteristics - // Go already assumes these to be available - // because they were on the M1. - ARM64.HasAES = true - ARM64.HasPMULL = true - ARM64.HasSHA1 = true - ARM64.HasSHA2 = true - } + // Encryption, hashing and checksum capabilities + + // For the following flags there are no MacOS 11 sysctl flags. + ARM64.HasAES = true || darwinSysctlEnabled([]byte("hw.optional.arm.FEAT_AES\x00")) + ARM64.HasPMULL = true || darwinSysctlEnabled([]byte("hw.optional.arm.FEAT_PMULL\x00")) + ARM64.HasSHA1 = true || darwinSysctlEnabled([]byte("hw.optional.arm.FEAT_SHA1\x00")) + ARM64.HasSHA2 = true || darwinSysctlEnabled([]byte("hw.optional.arm.FEAT_SHA256\x00")) + + ARM64.HasSHA3 = darwinSysctlEnabled([]byte("hw.optional.armv8_2_sha3\x00")) || darwinSysctlEnabled([]byte("hw.optional.arm.FEAT_SHA3\x00")) + ARM64.HasSHA512 = darwinSysctlEnabled([]byte("hw.optional.armv8_2_sha512\x00")) || darwinSysctlEnabled([]byte("hw.optional.arm.FEAT_SHA512\x00")) + + ARM64.HasCRC32 = darwinSysctlEnabled([]byte("hw.optional.armv8_crc32\x00")) + + // Atomic and memory ordering + ARM64.HasATOMICS = darwinSysctlEnabled([]byte("hw.optional.armv8_1_atomics\x00")) || darwinSysctlEnabled([]byte("hw.optional.arm.FEAT_LSE\x00")) + ARM64.HasLRCPC = darwinSysctlEnabled([]byte("hw.optional.arm.FEAT_LRCPC\x00")) + + // SIMD and floating point capabilities + ARM64.HasFPHP = darwinSysctlEnabled([]byte("hw.optional.neon_fp16\x00")) || darwinSysctlEnabled([]byte("hw.optional.arm.FEAT_FP16\x00")) + ARM64.HasASIMDHP = darwinSysctlEnabled([]byte("hw.optional.neon_hpfp\x00")) || darwinSysctlEnabled([]byte("hw.optional.AdvSIMD_HPFPCvt\x00")) + ARM64.HasASIMDRDM = darwinSysctlEnabled([]byte("hw.optional.arm.FEAT_RDM\x00")) + ARM64.HasASIMDDP = darwinSysctlEnabled([]byte("hw.optional.arm.FEAT_DotProd\x00")) + ARM64.HasASIMDFHM = darwinSysctlEnabled([]byte("hw.optional.armv8_2_fhm\x00")) || darwinSysctlEnabled([]byte("hw.optional.arm.FEAT_FHM\x00")) + ARM64.HasI8MM = darwinSysctlEnabled([]byte("hw.optional.arm.FEAT_I8MM\x00")) + + ARM64.HasJSCVT = darwinSysctlEnabled([]byte("hw.optional.arm.FEAT_JSCVT\x00")) + ARM64.HasFCMA = darwinSysctlEnabled([]byte("hw.optional.armv8_3_compnum\x00")) || darwinSysctlEnabled([]byte("hw.optional.arm.FEAT_FCMA\x00")) + + // Miscellaneous + ARM64.HasDCPOP = darwinSysctlEnabled([]byte("hw.optional.arm.FEAT_DPB\x00")) + ARM64.HasEVTSTRM = darwinSysctlEnabled([]byte("hw.optional.arm.FEAT_ECV\x00")) + ARM64.HasDIT = darwinSysctlEnabled([]byte("hw.optional.arm.FEAT_DIT\x00")) + + // Not supported, but added for completeness + ARM64.HasCPUID = false + + ARM64.HasSM3 = false // darwinSysctlEnabled([]byte("hw.optional.arm.FEAT_SM3\x00")) + ARM64.HasSM4 = false // darwinSysctlEnabled([]byte("hw.optional.arm.FEAT_SM4\x00")) + ARM64.HasSVE = false // darwinSysctlEnabled([]byte("hw.optional.arm.FEAT_SVE\x00")) + ARM64.HasSVE2 = false // darwinSysctlEnabled([]byte("hw.optional.arm.FEAT_SVE2\x00")) }
diff --git a/cpu/cpu_darwin_arm64_other.go b/cpu/cpu_darwin_arm64_other.go new file mode 100644 index 0000000..4ee68e3 --- /dev/null +++ b/cpu/cpu_darwin_arm64_other.go
@@ -0,0 +1,29 @@ +// Copyright 2026 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. + +//go:build darwin && arm64 && !gc + +package cpu + +func doinit() { + setMinimalFeatures() + + ARM64.HasASIMD = true + ARM64.HasFP = true + + // Go already assumes these to be available because they were on the M1 + // and these are supported on all Apple arm64 chips. + ARM64.HasAES = true + ARM64.HasPMULL = true + ARM64.HasSHA1 = true + ARM64.HasSHA2 = true + + if runtime.GOOS != "ios" { + // Apple A7 processors do not support these, however + // M-series SoCs are at least armv8.4-a + ARM64.HasCRC32 = true // armv8.1 + ARM64.HasATOMICS = true // armv8.2 + ARM64.HasJSCVT = true // armv8.3, if HasFP + } +}
diff --git a/cpu/cpu_other_arm64.go b/cpu/cpu_other_arm64.go index c604824..6c7c5bf 100644 --- a/cpu/cpu_other_arm64.go +++ b/cpu/cpu_other_arm64.go
@@ -2,7 +2,7 @@ // Use of this source code is governed by a BSD-style // license that can be found in the LICENSE file. -//go:build !linux && !netbsd && !openbsd && !windows && !darwin && arm64 +//go:build !darwin && !linux && !netbsd && !openbsd && !windows && arm64 package cpu
diff --git a/cpu/syscall_darwin_arm64_gc.go b/cpu/syscall_darwin_arm64_gc.go new file mode 100644 index 0000000..7b4e67f --- /dev/null +++ b/cpu/syscall_darwin_arm64_gc.go
@@ -0,0 +1,54 @@ +// Copyright 2024 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. + +// Minimal copy from internal/cpu and runtime to make sysctl calls. + +//go:build darwin && arm64 && gc + +package cpu + +import ( + "syscall" + "unsafe" +) + +type Errno = syscall.Errno + +// adapted from internal/cpu/cpu_arm64_darwin.go +func darwinSysctlEnabled(name []byte) bool { + out := int32(0) + nout := unsafe.Sizeof(out) + if ret := sysctlbyname(&name[0], (*byte)(unsafe.Pointer(&out)), &nout, nil, 0); ret != nil { + return false + } + return out > 0 +} + +//go:cgo_import_dynamic libc_sysctl sysctl "/usr/lib/libSystem.B.dylib" + +var libc_sysctlbyname_trampoline_addr uintptr + +// adapted from runtime/sys_darwin.go in the pattern of sysctl() above, as defined in x/sys/unix +func sysctlbyname(name *byte, old *byte, oldlen *uintptr, new *byte, newlen uintptr) error { + if _, _, err := syscall_syscall6( + libc_sysctlbyname_trampoline_addr, + uintptr(unsafe.Pointer(name)), + uintptr(unsafe.Pointer(old)), + uintptr(unsafe.Pointer(oldlen)), + uintptr(unsafe.Pointer(new)), + uintptr(newlen), + 0, + ); err != 0 { + return err + } + + return nil +} + +//go:cgo_import_dynamic libc_sysctlbyname sysctlbyname "/usr/lib/libSystem.B.dylib" + +// Implemented in the runtime package (runtime/sys_darwin.go) +func syscall_syscall6(fn, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2 uintptr, err Errno) + +//go:linkname syscall_syscall6 syscall.syscall6