x86/traps: Convert to insn_decode()

Simplify code, no functional changes.
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210304174237.31945-15-bp@alien8.de

arch/x86/kernel/traps.c

@@ -498,14 +498,15 @@ static enum kernel_gp_hint get_kernel_gp_address(struct pt_regs *regs,
 {
 	u8 insn_buf[MAX_INSN_SIZE];
 	struct insn insn;
+	int ret;
 
 	if (copy_from_kernel_nofault(insn_buf, (void *)regs->ip,
 			MAX_INSN_SIZE))
 		return GP_NO_HINT;
 
-	kernel_insn_init(&insn, insn_buf, MAX_INSN_SIZE);
-	insn_get_modrm(&insn);
-	insn_get_sib(&insn);
+	ret = insn_decode(&insn, insn_buf, MAX_INSN_SIZE, INSN_MODE_KERN);
+	if (ret < 0)
+		return GP_NO_HINT;
 
 	*addr = (unsigned long)insn_get_addr_ref(&insn, regs);
 	if (*addr == -1UL)