import getisar0(), getisar1(), getpfr0() from https://github.com/MikaelUrankar/go/commit/b46aa4ee007eedd2b7be40ac46dce507a39225b3#diff-ea01e2d7a6eb362c2114bdfca93fdaf2R42, see golang#31746.

Author: bsd-hacker

src/runtime/asm_arm64.s

@@ -1312,3 +1312,28 @@ TEXT runtime·panicSlice3CU(SB),NOSPLIT,$0-16
 	MOVD	R0, x+0(FP)
 	MOVD	R1, y+8(FP)
 	JMP	runtime·goPanicSlice3CU(SB)
+
+// func getisar0() uint64
+TEXT runtime·getisar0(SB),NOSPLIT,$0
+	// get Instruction Set Attributes 0 into x0
+	// mrs x0, ID_AA64ISAR0_EL1 = d5380600
+	WORD	$0xd5380600
+	MOVD	R0, ret+0(FP)
+	RET
+
+// func getisar1() uint64
+TEXT runtime·getisar1(SB),NOSPLIT,$0
+	// get Instruction Set Attributes 1 into x0
+	// mrs x0, ID_AA64ISAR1_EL1 = d5380620
+	WORD	$0xd5380620
+	MOVD	R0, ret+0(FP)
+	RET
+
+// func getpfr0() uint64
+TEXT runtime·getpfr0(SB),NOSPLIT,$0
+	// get Processor Feature Register 0 into x0
+	// mrs x0, ID_AA64PFR0_EL1 = d5380400
+	WORD	$0xd5380400
+	MOVD	R0, ret+0(FP)
+	RET
+

src/runtime/os_freebsd.go

@@ -394,6 +394,7 @@ const (
 )
 
 func sysauxv(auxv []uintptr) {
+	archauxv(_AT_HWCAP, 0)
 	for i := 0; auxv[i] != _AT_NULL; i += 2 {
 		tag, val := auxv[i], auxv[i+1]
 		switch tag {

src/runtime/os_freebsd_arm64.go

@@ -8,17 +8,154 @@ package runtime
 
 import "internal/cpu"
 
+func getisar0() uint64
+func getisar1() uint64
+func getpfr0() uint64
+
+const (
+	hwcap_FP       = 1 << 0
+	hwcap_ASIMD    = 1 << 1
+	hwcap_EVTSTRM  = 1 << 2
+	hwcap_AES      = 1 << 3
+	hwcap_PMULL    = 1 << 4
+	hwcap_SHA1     = 1 << 5
+	hwcap_SHA2     = 1 << 6
+	hwcap_CRC32    = 1 << 7
+	hwcap_ATOMICS  = 1 << 8
+	hwcap_FPHP     = 1 << 9
+	hwcap_ASIMDHP  = 1 << 10
+	hwcap_CPUID    = 1 << 11
+	hwcap_ASIMDRDM = 1 << 12
+	hwcap_JSCVT    = 1 << 13
+	hwcap_FCMA     = 1 << 14
+	hwcap_LRCPC    = 1 << 15
+	hwcap_DCPOP    = 1 << 16
+	hwcap_SHA3     = 1 << 17
+	hwcap_SM3      = 1 << 18
+	hwcap_SM4      = 1 << 19
+	hwcap_ASIMDDP  = 1 << 20
+	hwcap_SHA512   = 1 << 21
+	hwcap_SVE      = 1 << 22
+	hwcap_ASIMDFHM = 1 << 23
+)
+
 func archauxv(tag, val uintptr) {
 	switch tag {
 	case _AT_HWCAP:
 		// arm64 doesn't have a 'cpuid' instruction equivalent and relies on
 		// HWCAP/HWCAP2 bits for hardware capabilities.
-		cpu.HWCap = uint(val)
+		// detection. See issue #31746.
+		var isar0, isar1, pfr0 uint64
+
+		isar0 = getisar0()
+		isar1 = getisar1()
+		pfr0 = getpfr0()
+
+		// ID_AA64ISAR0_EL1
+		switch extract_bits(isar0, 4, 7) {
+		case 1:
+			cpu.HWCap |= hwcap_AES
+		case 2:
+			cpu.HWCap |= hwcap_PMULL | hwcap_AES
+		}
+
+		switch extract_bits(isar0, 8, 11) {
+		case 1:
+			cpu.HWCap |= hwcap_SHA1
+		}
+
+		switch extract_bits(isar0, 12, 15) {
+		case 1:
+			cpu.HWCap |= hwcap_SHA2
+		case 2:
+			cpu.HWCap |= hwcap_SHA2 | hwcap_SHA512
+		}
+
+		switch extract_bits(isar0, 16, 19) {
+		case 1:
+			cpu.HWCap |= hwcap_CRC32
+		}
+
+		switch extract_bits(isar0, 20, 23) {
+		case 2:
+			cpu.HWCap |= hwcap_ATOMICS
+		}
+
+		switch extract_bits(isar0, 28, 31) {
+		case 1:
+			cpu.HWCap |= hwcap_ASIMDRDM
+		}
+
+		switch extract_bits(isar0, 32, 35) {
+		case 1:
+			cpu.HWCap |= hwcap_SHA3
+		}
+
+		switch extract_bits(isar0, 36, 39) {
+		case 1:
+			cpu.HWCap |= hwcap_SM3
+		}
+
+		switch extract_bits(isar0, 40, 43) {
+		case 1:
+			cpu.HWCap |= hwcap_SM4
+		}
+
+		switch extract_bits(isar0, 44, 47) {
+		case 1:
+			cpu.HWCap |= hwcap_ASIMDDP
+		}
+
+		// ID_AA64ISAR1_EL1
+		switch extract_bits(isar1, 0, 3) {
+		case 1:
+			cpu.HWCap |= hwcap_DCPOP
+		}
+
+		switch extract_bits(isar1, 12, 15) {
+		case 1:
+			cpu.HWCap |= hwcap_JSCVT
+		}
+
+		switch extract_bits(isar1, 16, 19) {
+		case 1:
+			cpu.HWCap |= hwcap_FCMA
+		}
+
+		switch extract_bits(isar1, 20, 23) {
+		case 1:
+			cpu.HWCap |= hwcap_LRCPC
+		}
+
+		// ID_AA64PFR0_EL1
+		switch extract_bits(pfr0, 16, 19) {
+		case 0:
+			cpu.HWCap |= hwcap_FP
+		case 1:
+			cpu.HWCap |= hwcap_FP | hwcap_FPHP
+		}
+
+		switch extract_bits(pfr0, 20, 23) {
+		case 0:
+			cpu.HWCap |= hwcap_ASIMD
+		case 1:
+			cpu.HWCap |= hwcap_ASIMD | hwcap_ASIMDHP
+		}
+
+		switch extract_bits(pfr0, 32, 35) {
+		case 1:
+			cpu.HWCap |= hwcap_SVE
+		}
+
 	case _AT_HWCAP2:
 		cpu.HWCap2 = uint(val)
 	}
 }
 
+func extract_bits(data uint64, start, end uint) uint {
+	return (uint)(data >> start) & ((1 << (end - start + 1)) - 1)
+}
+
 //go:nosplit
 func cputicks() int64 {
 	// Currently cputicks() is used in blocking profiler and to seed runtime·fastrand().