libbpf: Move function is_ldimm64() earlier in libbpf.c

mainline inclusion
from mainline-5.13-rc1
commit b8f871fa
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5EUVD
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=b8f871fa32ad392759bc70090fa8c60d9f10625c

-------------------------------------------------

Move function is_ldimm64() close to the beginning of libbpf.c,
so it can be reused by later code and the next patch as well.
There is no functionality change.
Signed-off-by: NYonghong Song <yhs@fb.com>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Acked-by: NAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210226204929.3885295-1-yhs@fb.com
(cherry picked from commit b8f871fa)
Signed-off-by: NWang Yufen <wangyufen@huawei.com>

tools/lib/bpf/libbpf.c

@@ -574,6 +574,11 @@ static bool insn_is_subprog_call(const struct bpf_insn *insn)
 	       insn->off == 0;
 }
 
+static bool is_ldimm64(struct bpf_insn *insn)
+{
+	return insn->code == (BPF_LD | BPF_IMM | BPF_DW);
+}
+
 static int
 bpf_object__init_prog(struct bpf_object *obj, struct bpf_program *prog,
 		      const char *name, size_t sec_idx, const char *sec_name,
@@ -3397,7 +3402,7 @@ static int bpf_program__record_reloc(struct bpf_program *prog,
 		return 0;
 	}
 
-	if (insn->code != (BPF_LD | BPF_IMM | BPF_DW)) {
+	if (!is_ldimm64(insn)) {
 		pr_warn("prog '%s': invalid relo against '%s' for insns[%d].code 0x%x\n",
 			prog->name, sym_name, insn_idx, insn->code);
 		return -LIBBPF_ERRNO__RELOC;
@@ -5621,11 +5626,6 @@ static void bpf_core_poison_insn(struct bpf_program *prog, int relo_idx,
 	insn->imm = 195896080; /* => 0xbad2310 => "bad relo" */
 }
 
-static bool is_ldimm64(struct bpf_insn *insn)
-{
-	return insn->code == (BPF_LD | BPF_IMM | BPF_DW);
-}
-
 static int insn_bpf_size_to_bytes(struct bpf_insn *insn)
 {
 	switch (BPF_SIZE(insn->code)) {