Update

vendor/golang.org/x/sys/cpu/cpu_riscv64.s

@@ -0,0 +1,17 @@
+// 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 gc
+
+#include "textflag.h"
+
+// Read the vector register length in bytes from the vlenb CSR.
+// May only be called when the vector extension is present.
+// func readVLENB() uint
+TEXT ·readVLENB(SB), NOSPLIT|NOFRAME, $0-8
+	// Go 1.25's assembler does not recognize VLENB, so use its raw CSRR encoding.
+	// Replace WORD with CSRR VLENB, X10 once go.mod requires Go 1.27.
+	WORD	$0xc2202573
+	MOV	X10, ret+0(FP)
+	RET