internal/cpu: add detection for the new ECDSA and EDDSA capabilities on s390x

This CL will check for the Message-Security-Assist Extension 9 facility
which enables the KDSA instruction.

Change-Id: I659aac09726e0999ec652ef1f5983072c8131a48
Reviewed-on: https://go-review.googlesource.com/c/go/+/174529
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/cmd/vet/all/whitelist/s390x.txt

@@ -10,6 +10,7 @@ internal/cpu/cpu_s390x.s: [s390x] kmctrQuery: invalid MOVD of ret+0(FP); interna
 internal/cpu/cpu_s390x.s: [s390x] kmaQuery: invalid MOVD of ret+0(FP); internal/cpu.queryResult is 16-byte value
 internal/cpu/cpu_s390x.s: [s390x] kimdQuery: invalid MOVD of ret+0(FP); internal/cpu.queryResult is 16-byte value
 internal/cpu/cpu_s390x.s: [s390x] klmdQuery: invalid MOVD of ret+0(FP); internal/cpu.queryResult is 16-byte value
+internal/cpu/cpu_s390x.s: [s390x] kdsaQuery: invalid MOVD of ret+0(FP); internal/cpu.queryResult is 16-byte value
 vendor/golang.org/x/sys/cpu/cpu_s390x.s: [s390x] stfle: invalid MOVD of ret+0(FP); vendor/golang.org/x/sys/cpu.facilityList is 32-byte value
 vendor/golang.org/x/sys/cpu/cpu_s390x.s: [s390x] kmQuery: invalid MOVD of ret+0(FP); vendor/golang.org/x/sys/cpu.queryResult is 16-byte value
 vendor/golang.org/x/sys/cpu/cpu_s390x.s: [s390x] kmcQuery: invalid MOVD of ret+0(FP); vendor/golang.org/x/sys/cpu.queryResult is 16-byte value

src/internal/cpu/cpu.go

@@ -128,6 +128,9 @@ type s390x struct {
 	HasSHA3   bool // K{I,L}MD-SHA3-{224,256,384,512} and K{I,L}MD-SHAKE-{128,256} functions
 	HasVX     bool // vector facility. Note: the runtime sets this when it processes auxv records.
 	HasVXE    bool // vector-enhancements facility 1
+	HasKDSA   bool // elliptic curve functions
+	HasECDSA  bool // NIST curves
+	HasEDDSA  bool // Edwards curves
 	_         CacheLinePad
 }
 

src/internal/cpu/cpu_s390x.go

@@ -36,6 +36,20 @@ const (
 	ghash function = 65 // GHASH
 )
 
+const (
+	// KDSA function codes
+	ecdsaVerifyP256    function = 1  // NIST P256
+	ecdsaVerifyP384    function = 2  // NIST P384
+	ecdsaVerifyP521    function = 3  // NIST P521
+	ecdsaSignP256      function = 9  // NIST P256
+	ecdsaSignP384      function = 10 // NIST P384
+	ecdsaSignP521      function = 11 // NIST P521
+	eddsaVerifyEd25519 function = 32 // Curve25519
+	eddsaVerifyEd448   function = 36 // Curve448
+	eddsaSignEd25519   function = 40 // Curve25519
+	eddsaSignEd448     function = 44 // Curve448
+)
+
 // queryResult contains the result of a Query function
 // call. Bits are numbered in big endian order so the
 // leftmost bit (the MSB) is at index 0.
@@ -76,6 +90,7 @@ const (
 	msa4 facility = 77  // message-security-assist extension 4
 	msa5 facility = 57  // message-security-assist extension 5
 	msa8 facility = 146 // message-security-assist extension 8
+	msa9 facility = 155 // message-security-assist extension 9
 
 	// vector facilities
 	vxe facility = 135 // vector-enhancements 1
@@ -113,6 +128,7 @@ func kmctrQuery() queryResult
 func kmaQuery() queryResult
 func kimdQuery() queryResult
 func klmdQuery() queryResult
+func kdsaQuery() queryResult
 
 func doinit() {
 	options = []option{
@@ -125,6 +141,7 @@ func doinit() {
 		{Name: "etf3eh", Feature: &S390X.HasETF3EH},
 		{Name: "vx", Feature: &S390X.HasVX},
 		{Name: "vxe", Feature: &S390X.HasVXE},
+		{Name: "kdsa", Feature: &S390X.HasKDSA},
 	}
 
 	aes := []function{aes128, aes192, aes256}
@@ -164,6 +181,12 @@ func doinit() {
 			shake128, shake256,
 		}
 		S390X.HasSHA3 = kimd.Has(sha3...) && klmd.Has(sha3...)
+		S390X.HasKDSA = facilities.Has(msa9) // elliptic curves
+		if S390X.HasKDSA {
+			kdsa := kdsaQuery()
+			S390X.HasECDSA = kdsa.Has(ecdsaVerifyP256, ecdsaSignP256, ecdsaVerifyP384, ecdsaSignP384, ecdsaVerifyP521, ecdsaSignP521)
+			S390X.HasEDDSA = kdsa.Has(eddsaVerifyEd25519, eddsaSignEd25519, eddsaVerifyEd448, eddsaSignEd448)
+		}
 	}
 	if S390X.HasVX {
 		S390X.HasVXE = facilities.Has(vxe)

src/internal/cpu/cpu_s390x.s

@@ -53,3 +53,11 @@ TEXT ·klmdQuery(SB), NOSPLIT|NOFRAME, $0-16
 	MOVD $ret+0(FP), R1 // address of 16-byte return value
 	WORD $0xB93F0024    // compute last message digest (KLMD)
 	RET
+
+// func kdsaQuery() queryResult
+TEXT ·kdsaQuery(SB), NOSPLIT|NOFRAME, $0-16
+	MOVD $0, R0         // set function code to 0 (KLMD-Query)
+	MOVD $ret+0(FP), R1 // address of 16-byte return value
+	WORD $0xB93A0008    // compute digital signature authentication
+	RET
+