tools/objtool: Convert to insn_decode()

Simplify code, no functional changes.
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210304174237.31945-18-bp@alien8.de

tools/objtool/arch/x86/decode.c

@@ -90,7 +90,7 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec,
 			    struct list_head *ops_list)
 {
 	struct insn insn;
-	int x86_64, sign;
+	int x86_64, sign, ret;
 	unsigned char op1, op2, rex = 0, rex_b = 0, rex_r = 0, rex_w = 0,
 		      rex_x = 0, modrm = 0, modrm_mod = 0, modrm_rm = 0,
 		      modrm_reg = 0, sib = 0;
@@ -101,10 +101,9 @@ int arch_decode_instruction(const struct elf *elf, const struct section *sec,
 	if (x86_64 == -1)
 		return -1;
 
-	insn_init(&insn, sec->data->d_buf + offset, maxlen, x86_64);
-	insn_get_length(&insn);
-
-	if (!insn_complete(&insn)) {
+	ret = insn_decode(&insn, sec->data->d_buf + offset, maxlen,
+			  x86_64 ? INSN_MODE_64 : INSN_MODE_32);
+	if (ret < 0) {
 		WARN("can't decode instruction at %s:0x%lx", sec->name, offset);
 		return -1;
 	}