Enable pkg/cpuid support on arm64.

Fixes #1255

Signed-off-by: Haibo Xu <haibo.xu@arm.com>
Change-Id: I8614e6f3ee321c2989567e4e712aa8f28cc9db14

1 files changed, 461 insertions, 0 deletions

diff --git a/pkg/cpuid/cpuid_arm64.go b/pkg/cpuid/cpuid_arm64.go
new file mode 100644
index 000000000..6d71290c9
--- /dev/null
+++ b/pkg/cpuid/cpuid_arm64.go
@@ -0,0 +1,461 @@
+// Copyright 2020 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// +build arm64
+
+package cpuid
+
+import (
+	"bytes"
+	"encoding/binary"
+	"fmt"
+	"io/ioutil"
+	"strconv"
+	"strings"
+
+	"gvisor.dev/gvisor/pkg/log"
+)
+
+// ARM64 doesn't have a 'cpuid' equivalent, which means it have no architected
+// discovery mechanism for hardware features available to userspace code at EL0.
+// The kernel exposes the presence of these features to userspace through a set
+// of flags(HWCAP/HWCAP2) bits, exposed in the auxilliary vector.
+// Ref Documentation/arm64/elf_hwcaps.rst for more info.
+//
+// Currently, only the HWCAP bits are supported.
+
+const (
+	// Single and double precision float point types.
+	ARM64FeatureFP Feature = iota
+
+	// Advanced SIMD with single and double precision
+	// float point arithmetic.
+	ARM64FeatureASIMD
+
+	// The generic timer is configured to generate
+	// events at a frequency of approximately 100KHz.
+	ARM64FeatureEVTSTRM
+
+	// AES instructions(AESE/AESD/AESMC/AESIMC).
+	ARM64FeatureAES
+
+	// AES instructions(PMULL/PMULL2).
+	ARM64FeaturePMULL
+
+	// SHA1 instructions(SHA1C/SHA1P/SHA1M etc).
+	ARM64FeatureSHA1
+
+	// SHA2 instructions(SHA256H/SHA256H2/SHA256SU0 etc).
+	ARM64FeatureSHA2
+
+	// CRC32 instructions(CRC32B/CRC32H/CRC32W etc).
+	ARM64FeatureCRC32
+
+	// Atomic instructions(LDADD/LDCLR/LDEOR/LDSET etc).
+	ARM64FeatureATOMICS
+
+	// Half precision float point arithmetic.
+	ARM64FeatureFPHP
+
+	// ASIMD with half precision float point arithmetic.
+	ARM64FeatureASIMDHP
+
+	// EL0 access to certain ID registers is available.
+	ARM64FeatureCPUID
+
+	// SQRDMLAH and SQRDMLSH instructions implemented.
+	ARM64FeatureASIMDRDM
+
+	// The FJCVTZS instruction is implemented.
+	ARM64FeatureJSCVT
+
+	// The FCMLA and FCADD instructions are implemented.
+	ARM64FeatureFCMA
+
+	// The LDAPRB/LDAPRH/LDAPR instructions are implemented.
+	ARM64FeatureLRCPC
+
+	// DC instruction(DC CVAP) supported.
+	ARM64FeatureDCPOP
+
+	// SHA3 instructions(EOR3/RAX1/XAR/BCAX) implemented.
+	ARM64FeatureSHA3
+
+	// SM3 instructions(SM3SS1/SM3TT1A/SM3TT1B) implemented.
+	ARM64FeatureSM3
+
+	// SM4 instructions(SM4E/SM4EKEY) implemented.
+	ARM64FeatureSM4
+
+	// Dot Product instructions(UDOT/SDOT) implemented.
+	ARM64FeatureASIMDDP
+
+	// SHA2 instructions(SHA512H/SHA512H2/SHA512SU0) implemented.
+	ARM64FeatureSHA512
+
+	// Scalable Vector Extension implemented.
+	ARM64FeatureSVE
+
+	// FMLAL and FMLSL instructions are implemented.
+	ARM64FeatureASIMDFHM
+)
+
+// ELF auxiliary vector tags
+const (
+	_AT_NULL   = 0  // End of vector
+	_AT_HWCAP  = 16 // hardware capability bit vector
+	_AT_HWCAP2 = 26 // hardware capability bit vector 2
+)
+
+// These should not be changed after they are initialized.
+var hwCap uint
+
+// To make emulation of /proc/cpuinfo easy, these names match the names of the
+// basic features in Linux defined in arch/arm64/kernel/cpuinfo.c.
+var arm64FeatureStrings = map[Feature]string{
+	ARM64FeatureFP:       "fp",
+	ARM64FeatureASIMD:    "asimd",
+	ARM64FeatureEVTSTRM:  "evtstrm",
+	ARM64FeatureAES:      "aes",
+	ARM64FeaturePMULL:    "pmull",
+	ARM64FeatureSHA1:     "sha1",
+	ARM64FeatureSHA2:     "sha2",
+	ARM64FeatureCRC32:    "crc32",
+	ARM64FeatureATOMICS:  "atomics",
+	ARM64FeatureFPHP:     "fphp",
+	ARM64FeatureASIMDHP:  "asimdhp",
+	ARM64FeatureCPUID:    "cpuid",
+	ARM64FeatureASIMDRDM: "asimdrdm",
+	ARM64FeatureJSCVT:    "jscvt",
+	ARM64FeatureFCMA:     "fcma",
+	ARM64FeatureLRCPC:    "lrcpc",
+	ARM64FeatureDCPOP:    "dcpop",
+	ARM64FeatureSHA3:     "sha3",
+	ARM64FeatureSM3:      "sm3",
+	ARM64FeatureSM4:      "sm4",
+	ARM64FeatureASIMDDP:  "asimddp",
+	ARM64FeatureSHA512:   "sha512",
+	ARM64FeatureSVE:      "sve",
+	ARM64FeatureASIMDFHM: "asimdfhm",
+}
+
+var (
+	cpuFreqMHz float64
+	cpuImplHex uint64
+	cpuArchDec uint64
+	cpuVarHex  uint64
+	cpuPartHex uint64
+	cpuRevDec  uint64
+)
+
+// arm64FeaturesFromString includes features from arm64FeatureStrings.
+var arm64FeaturesFromString = make(map[string]Feature)
+
+// FeatureFromString returns the Feature associated with the given feature
+// string plus a bool to indicate if it could find the feature.
+func FeatureFromString(s string) (Feature, bool) {
+	f, b := arm64FeaturesFromString[s]
+	return f, b
+}
+
+// String implements fmt.Stringer.
+func (f Feature) String() string {
+	if s := f.flagString(); s != "" {
+		return s
+	}
+
+	return fmt.Sprintf("<cpuflag %d>", f)
+}
+
+func (f Feature) flagString() string {
+	if s, ok := arm64FeatureStrings[f]; ok {
+		return s
+	}
+
+	return ""
+}
+
+// FeatureSet is a set of Features for a CPU.
+//
+// +stateify savable
+type FeatureSet struct {
+	// Set is the set of features that are enabled in this FeatureSet.
+	Set map[Feature]bool
+
+	// CPUImplementer is part of the processor signature.
+	CPUImplementer uint8
+
+	// CPUArchitecture is part of the processor signature.
+	CPUArchitecture uint8
+
+	// CPUVariant is part of the processor signature.
+	CPUVariant uint8
+
+	// CPUPartnum is part of the processor signature.
+	CPUPartnum uint16
+
+	// CPURevision is part of the processor signature.
+	CPURevision uint8
+}
+
+// CheckHostCompatible returns nil if fs is a subset of the host feature set.
+// Noop on arm64.
+func (fs *FeatureSet) CheckHostCompatible() error {
+	return nil
+}
+
+// ExtendedStateSize returns the number of bytes needed to save the "extended
+// state" for this processor and the boundary it must be aligned to. Extended
+// state includes floating point(NEON) registers, and other cpu state that's not
+// associated with the normal task context.
+func (fs *FeatureSet) ExtendedStateSize() (size, align uint) {
+	// ARMv8 provide 32x128bits NEON registers.
+	//
+	// Ref arch/arm64/include/uapi/asm/ptrace.h
+	// struct user_fpsimd_state {
+	//        __uint128_t     vregs[32];
+	//        __u32           fpsr;
+	//	  __u32           fpcr;
+	//	  __u32           __reserved[2];
+	// };
+	return 528, 16
+}
+
+// HasFeature tests whether or not a feature is in the given feature set.
+func (fs *FeatureSet) HasFeature(feature Feature) bool {
+	return fs.Set[feature]
+}
+
+// UseXsaveopt returns true if 'fs' supports the "xsaveopt" instruction.
+// Noop on arm64.
+func (fs *FeatureSet) UseXsave() bool {
+	return false
+}
+
+// FlagsString prints out supported CPU "flags" field in /proc/cpuinfo.
+func (fs *FeatureSet) FlagsString() string {
+	var s []string
+	for f, _ := range arm64FeatureStrings {
+		if fs.Set[f] {
+			if fstr := f.flagString(); fstr != "" {
+				s = append(s, fstr)
+			}
+		}
+	}
+	return strings.Join(s, " ")
+}
+
+// WriteCPUInfoTo is to generate a section of one cpu in /proc/cpuinfo. This is
+// a minimal /proc/cpuinfo, and the bogomips field is simply made up.
+func (fs FeatureSet) WriteCPUInfoTo(cpu uint, b *bytes.Buffer) {
+	fmt.Fprintf(b, "processor\t: %d\n", cpu)
+	fmt.Fprintf(b, "BogoMIPS\t: %.02f\n", cpuFreqMHz) // It's bogus anyway.
+	fmt.Fprintf(b, "Features\t\t: %s\n", fs.FlagsString())
+	fmt.Fprintf(b, "CPU implementer\t: 0x%x\n", cpuImplHex)
+	fmt.Fprintf(b, "CPU architecture\t: %d\n", cpuArchDec)
+	fmt.Fprintf(b, "CPU variant\t: 0x%x\n", cpuVarHex)
+	fmt.Fprintf(b, "CPU part\t: 0x%x\n", cpuPartHex)
+	fmt.Fprintf(b, "CPU revision\t: %d\n", cpuRevDec)
+	fmt.Fprintln(b, "") // The /proc/cpuinfo file ends with an extra newline.
+}
+
+// HostFeatureSet uses hwCap to get host values and construct a feature set
+// that matches that of the host machine.
+func HostFeatureSet() *FeatureSet {
+	s := make(map[Feature]bool)
+
+	for f, _ := range arm64FeatureStrings {
+		if hwCap&(1<<f) != 0 {
+			s[f] = true
+		}
+	}
+
+	return &FeatureSet{
+		Set:             s,
+		CPUImplementer:  uint8(cpuImplHex),
+		CPUArchitecture: uint8(cpuArchDec),
+		CPUVariant:      uint8(cpuVarHex),
+		CPUPartnum:      uint16(cpuPartHex),
+		CPURevision:     uint8(cpuRevDec),
+	}
+}
+
+// Reads bogomips from host /proc/cpuinfo. Must run before whitelisting.
+// This value is used to create the fake /proc/cpuinfo from a FeatureSet.
+func initCPUInfo() {
+	cpuinfob, err := ioutil.ReadFile("/proc/cpuinfo")
+	if err != nil {
+		// Leave it as 0. The standalone VDSO bails out in the same way.
+		log.Warningf("Could not read /proc/cpuinfo: %v", err)
+		return
+	}
+	cpuinfo := string(cpuinfob)
+
+	// We get the value straight from host /proc/cpuinfo.
+	for _, line := range strings.Split(cpuinfo, "\n") {
+		switch {
+		case strings.Contains(line, "BogoMIPS"):
+			{
+				splitMHz := strings.Split(line, ":")
+				if len(splitMHz) < 2 {
+					log.Warningf("Could not read /proc/cpuinfo: malformed BogoMIPS")
+					break
+				}
+
+				// If there was a problem, leave cpuFreqMHz as 0.
+				var err error
+				cpuFreqMHz, err = strconv.ParseFloat(strings.TrimSpace(splitMHz[1]), 64)
+				if err != nil {
+					log.Warningf("Could not parse BogoMIPS value %v: %v", splitMHz[1], err)
+					cpuFreqMHz = 0
+				}
+			}
+		case strings.Contains(line, "CPU implementer"):
+			{
+				splitImpl := strings.Split(line, ":")
+				if len(splitImpl) < 2 {
+					log.Warningf("Could not read /proc/cpuinfo: malformed CPU implementer")
+					break
+				}
+
+				// If there was a problem, leave cpuImplHex as 0.
+				var err error
+				cpuImplHex, err = strconv.ParseUint(strings.TrimSpace(splitImpl[1]), 0, 64)
+				if err != nil {
+					log.Warningf("Could not parse CPU implementer value %v: %v", splitImpl[1], err)
+					cpuImplHex = 0
+				}
+			}
+		case strings.Contains(line, "CPU architecture"):
+			{
+				splitArch := strings.Split(line, ":")
+				if len(splitArch) < 2 {
+					log.Warningf("Could not read /proc/cpuinfo: malformed CPU architecture")
+					break
+				}
+
+				// If there was a problem, leave cpuArchDec as 0.
+				var err error
+				cpuArchDec, err = strconv.ParseUint(strings.TrimSpace(splitArch[1]), 0, 64)
+				if err != nil {
+					log.Warningf("Could not parse CPU architecture value %v: %v", splitArch[1], err)
+					cpuArchDec = 0
+				}
+			}
+		case strings.Contains(line, "CPU variant"):
+			{
+				splitVar := strings.Split(line, ":")
+				if len(splitVar) < 2 {
+					log.Warningf("Could not read /proc/cpuinfo: malformed CPU variant")
+					break
+				}
+
+				// If there was a problem, leave cpuVarHex as 0.
+				var err error
+				cpuVarHex, err = strconv.ParseUint(strings.TrimSpace(splitVar[1]), 0, 64)
+				if err != nil {
+					log.Warningf("Could not parse CPU variant value %v: %v", splitVar[1], err)
+					cpuVarHex = 0
+				}
+			}
+		case strings.Contains(line, "CPU part"):
+			{
+				splitPart := strings.Split(line, ":")
+				if len(splitPart) < 2 {
+					log.Warningf("Could not read /proc/cpuinfo: malformed CPU part")
+					break
+				}
+
+				// If there was a problem, leave cpuPartHex as 0.
+				var err error
+				cpuPartHex, err = strconv.ParseUint(strings.TrimSpace(splitPart[1]), 0, 64)
+				if err != nil {
+					log.Warningf("Could not parse CPU part value %v: %v", splitPart[1], err)
+					cpuPartHex = 0
+				}
+			}
+		case strings.Contains(line, "CPU revision"):
+			{
+				splitRev := strings.Split(line, ":")
+				if len(splitRev) < 2 {
+					log.Warningf("Could not read /proc/cpuinfo: malformed CPU revision")
+					break
+				}
+
+				// If there was a problem, leave cpuRevDec as 0.
+				var err error
+				cpuRevDec, err = strconv.ParseUint(strings.TrimSpace(splitRev[1]), 0, 64)
+				if err != nil {
+					log.Warningf("Could not parse CPU revision value %v: %v", splitRev[1], err)
+					cpuRevDec = 0
+				}
+			}
+		}
+	}
+}
+
+// The auxiliary vector of a process on the Linux system can be read
+// from /proc/self/auxv, and tags and values are stored as 8-bytes
+// decimal key-value pairs on the 64-bit system.
+//
+// $ od -t d8 /proc/self/auxv
+//  0000000                   33      140734615224320
+//  0000020                   16           3219913727
+//  0000040                    6                 4096
+//  0000060                   17                  100
+//  0000100                    3       94665627353152
+//  0000120                    4                   56
+//  0000140                    5                    9
+//  0000160                    7      140425502162944
+//  0000200                    8                    0
+//  0000220                    9       94665627365760
+//  0000240                   11                 1000
+//  0000260                   12                 1000
+//  0000300                   13                 1000
+//  0000320                   14                 1000
+//  0000340                   23                    0
+//  0000360                   25      140734614619513
+//  0000400                   26                    0
+//  0000420                   31      140734614626284
+//  0000440                   15      140734614619529
+//  0000460                    0                    0
+func initHwCap() {
+	auxv, err := ioutil.ReadFile("/proc/self/auxv")
+	if err != nil {
+		log.Warningf("Could not read /proc/self/auxv: %v", err)
+		return
+	}
+
+	l := len(auxv) / 16
+	for i := 0; i < l; i++ {
+		tag := binary.LittleEndian.Uint64(auxv[i*16:])
+		val := binary.LittleEndian.Uint64(auxv[(i*16 + 8):])
+		if tag == _AT_HWCAP {
+			hwCap = uint(val)
+			break
+		}
+	}
+}
+
+func initFeaturesFromString() {
+	for f, s := range arm64FeatureStrings {
+		arm64FeaturesFromString[s] = f
+	}
+}
+
+func init() {
+	initCPUInfo()
+	initHwCap()
+	initFeaturesFromString()
+}