cpu: support ARM feature detection on Linux

Updates golang/go#33508

Change-Id: I9ea01090f5b4ac95c1a14881c305461bd4a7b5dd
Reviewed-on: https://go-review.googlesource.com/c/sys/+/190525
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>
Reviewed-by: Martin Möhrmann <moehrmann@google.com>

cpu/cpu.go

@@ -78,6 +78,42 @@ var ARM64 struct {
  _ CacheLinePad
 }
 
+// ARM contains the supported CPU features of the current ARM (32-bit) platform.
+// All feature flags are false if:
+// 1. the current platform is not arm, or
+// 2. the current operating system is not Linux.
+var ARM struct {
+ _ CacheLinePad
+ HasSWP bool // SWP instruction support
+ HasHALF bool // Half-word load and store support
+ HasTHUMB bool // ARM Thumb instruction set
+ Has26BIT bool // Address space limited to 26-bits
+ HasFASTMUL bool // 32-bit operand, 64-bit result multiplication support
+ HasFPA bool // Floating point arithmetic support
+ HasVFP bool // Vector floating point support
+ HasEDSP bool // DSP Extensions support
+ HasJAVA bool // Java instruction set
+ HasIWMMXT bool // Intel Wireless MMX technology support
+ HasCRUNCH bool // MaverickCrunch context switching and handling
+ HasTHUMBEE bool // Thumb EE instruction set
+ HasNEON bool // NEON instruction set
+ HasVFPv3 bool // Vector floating point version 3 support
+ HasVFPv3D16 bool // Vector floating point version 3 D8-D15
+ HasTLS bool // Thread local storage support
+ HasVFPv4 bool // Vector floating point version 4 support
+ HasIDIVA bool // Integer divide instruction support in ARM mode
+ HasIDIVT bool // Integer divide instruction support in Thumb mode
+ HasVFPD32 bool // Vector floating point version 3 D15-D31
+ HasLPAE bool // Large Physical Address Extensions
+ HasEVTSTRM bool // Event stream support
+ HasAES bool // AES hardware implementation
+ HasPMULL bool // Polynomial multiplication instruction set
+ HasSHA1 bool // SHA1 hardware implementation
+ HasSHA2 bool // SHA2 hardware implementation
+ HasCRC32 bool // CRC32 hardware implementation
+ _ CacheLinePad
+}
+
 // PPC64 contains the supported CPU features of the current ppc64/ppc64le platforms.
 // If the current platform is not ppc64/ppc64le then all feature flags are false.
 //

cpu/cpu_arm.go

@@ -6,4 +6,35 @@ package cpu
 
 const cacheLineSize = 32
 
-func doinit() {}
+// HWCAP/HWCAP2 bits.
+// These are specific to Linux.
+const (
+ hwcap_SWP = 1 << 0
+ hwcap_HALF = 1 << 1
+ hwcap_THUMB = 1 << 2
+ hwcap_26BIT = 1 << 3
+ hwcap_FAST_MULT = 1 << 4
+ hwcap_FPA = 1 << 5
+ hwcap_VFP = 1 << 6
+ hwcap_EDSP = 1 << 7
+ hwcap_JAVA = 1 << 8
+ hwcap_IWMMXT = 1 << 9
+ hwcap_CRUNCH = 1 << 10
+ hwcap_THUMBEE = 1 << 11
+ hwcap_NEON = 1 << 12
+ hwcap_VFPv3 = 1 << 13
+ hwcap_VFPv3D16 = 1 << 14
+ hwcap_TLS = 1 << 15
+ hwcap_VFPv4 = 1 << 16
+ hwcap_IDIVA = 1 << 17
+ hwcap_IDIVT = 1 << 18
+ hwcap_VFPD32 = 1 << 19
+ hwcap_LPAE = 1 << 20
+ hwcap_EVTSTRM = 1 << 21
+
+ hwcap2_AES = 1 << 0
+ hwcap2_PMULL = 1 << 1
+ hwcap2_SHA1 = 1 << 2
+ hwcap2_SHA2 = 1 << 3
+ hwcap2_CRC32 = 1 << 4
+)

cpu/cpu_linux_arm.go

@@ -0,0 +1,39 @@
+// Copyright 2019 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 cpu
+
+func doinit() {
+ ARM.HasSWP = isSet(hwCap, hwcap_SWP)
+ ARM.HasHALF = isSet(hwCap, hwcap_HALF)
+ ARM.HasTHUMB = isSet(hwCap, hwcap_THUMB)
+ ARM.Has26BIT = isSet(hwCap, hwcap_26BIT)
+ ARM.HasFASTMUL = isSet(hwCap, hwcap_FAST_MULT)
+ ARM.HasFPA = isSet(hwCap, hwcap_FPA)
+ ARM.HasVFP = isSet(hwCap, hwcap_VFP)
+ ARM.HasEDSP = isSet(hwCap, hwcap_EDSP)
+ ARM.HasJAVA = isSet(hwCap, hwcap_JAVA)
+ ARM.HasIWMMXT = isSet(hwCap, hwcap_IWMMXT)
+ ARM.HasCRUNCH = isSet(hwCap, hwcap_CRUNCH)
+ ARM.HasTHUMBEE = isSet(hwCap, hwcap_THUMBEE)
+ ARM.HasNEON = isSet(hwCap, hwcap_NEON)
+ ARM.HasVFPv3 = isSet(hwCap, hwcap_VFPv3)
+ ARM.HasVFPv3D16 = isSet(hwCap, hwcap_VFPv3D16)
+ ARM.HasTLS = isSet(hwCap, hwcap_TLS)
+ ARM.HasVFPv4 = isSet(hwCap, hwcap_VFPv4)
+ ARM.HasIDIVA = isSet(hwCap, hwcap_IDIVA)
+ ARM.HasIDIVT = isSet(hwCap, hwcap_IDIVT)
+ ARM.HasVFPD32 = isSet(hwCap, hwcap_VFPD32)
+ ARM.HasLPAE = isSet(hwCap, hwcap_LPAE)
+ ARM.HasEVTSTRM = isSet(hwCap, hwcap_EVTSTRM)
+ ARM.HasAES = isSet(hwCap2, hwcap2_AES)
+ ARM.HasPMULL = isSet(hwCap2, hwcap2_PMULL)
+ ARM.HasSHA1 = isSet(hwCap2, hwcap2_SHA1)
+ ARM.HasSHA2 = isSet(hwCap2, hwcap2_SHA2)
+ ARM.HasCRC32 = isSet(hwCap2, hwcap2_CRC32)
+}
+
+func isSet(hwc uint, value uint) bool {
+ return hwc&value != 0
+}