libbpf: Use proper errno value in linker

Return values of the linker_append_sec_data() and the
linker_append_elf_relos() functions are propagated all the
way up to users of libbpf API. In some error cases these
functions return -1 which will be seen as -EPERM from user's
point of view. Instead, return a more reasonable -EINVAL.

Fixes: faf6ed3 ("libbpf: Add BPF static linker APIs")
Signed-off-by: Anton Protopopov <[email protected]>
Signed-off-by: Andrii Nakryiko <[email protected]>
Link: https://lore.kernel.org/bpf/[email protected]

Author: aspsk

tools/lib/bpf/linker.c

@@ -1376,7 +1376,7 @@ static int linker_append_sec_data(struct bpf_linker *linker, struct src_obj *obj
 		} else {
 			if (!secs_match(dst_sec, src_sec)) {
 				pr_warn("ELF sections %s are incompatible\n", src_sec->sec_name);
-				return -1;
+				return -EINVAL;
 			}
 
 			/* "license" and "version" sections are deduped */
@@ -2223,7 +2223,7 @@ static int linker_append_elf_relos(struct bpf_linker *linker, struct src_obj *ob
 			}
 		} else if (!secs_match(dst_sec, src_sec)) {
 			pr_warn("sections %s are not compatible\n", src_sec->sec_name);
-			return -1;
+			return -EINVAL;
 		}
 
 		/* shdr->sh_link points to SYMTAB */