x86/mce: Convert to insn_decode()

Simplify code, no functional changes.
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210304174237.31945-11-bp@alien8.de

arch/x86/kernel/cpu/mce/severity.c

@@ -218,15 +218,15 @@ static struct severity {
 static bool is_copy_from_user(struct pt_regs *regs)
 {
 	u8 insn_buf[MAX_INSN_SIZE];
-	struct insn insn;
 	unsigned long addr;
+	struct insn insn;
+	int ret;
 
 	if (copy_from_kernel_nofault(insn_buf, (void *)regs->ip, MAX_INSN_SIZE))
 		return false;
 
-	kernel_insn_init(&insn, insn_buf, MAX_INSN_SIZE);
-	insn_get_opcode(&insn);
-	if (!insn.opcode.got)
+	ret = insn_decode(&insn, insn_buf, MAX_INSN_SIZE, INSN_MODE_KERN);
+	if (ret < 0)
 		return false;
 
 	switch (insn.opcode.value) {
@@ -234,10 +234,6 @@ static bool is_copy_from_user(struct pt_regs *regs)
 	case 0x8A: case 0x8B:
 	/* MOVZ mem,reg */
 	case 0xB60F: case 0xB70F:
-		insn_get_modrm(&insn);
-		insn_get_sib(&insn);
-		if (!insn.modrm.got || !insn.sib.got)
-			return false;
 		addr = (unsigned long)insn_get_addr_ref(&insn, regs);
 		break;
 	/* REP MOVS */