x86/tools/insn_decoder_test: Convert to insn_decode()

Simplify code, no functional changes.
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210304174237.31945-17-bp@alien8.de

arch/x86/tools/insn_decoder_test.c

@@ -120,7 +120,7 @@ int main(int argc, char **argv)
 
 	while (fgets(line, BUFSIZE, stdin)) {
 		char copy[BUFSIZE], *s, *tab1, *tab2;
-		int nb = 0;
+		int nb = 0, ret;
 		unsigned int b;
 
 		if (line[0] == '<') {
@@ -148,10 +148,12 @@ int main(int argc, char **argv)
 			} else
 				break;
 		}
+
 		/* Decode an instruction */
-		insn_init(&insn, insn_buff, sizeof(insn_buff), x86_64);
-		insn_get_length(&insn);
-		if (insn.length != nb) {
+		ret = insn_decode(&insn, insn_buff, sizeof(insn_buff),
+				  x86_64 ? INSN_MODE_64 : INSN_MODE_32);
+
+		if (ret < 0 || insn.length != nb) {
 			warnings++;
 			pr_warn("Found an x86 instruction decoder bug, "
 				"please report this.\n", sym);