Commit 5aad0368 authored by Hengqi Chen's avatar Hengqi Chen Committed by Andrii Nakryiko
Browse files

tools/resolve_btfids: Emit warnings and patch zero id for missing symbols 



Kernel functions referenced by .BTF_ids may be changed from global to static
and get inlined or get renamed/removed, and thus disappears from BTF.
This causes kernel build failure when resolve_btfids do id patch for symbols
in .BTF_ids in vmlinux. Update resolve_btfids to emit warning messages and
patch zero id for missing symbols instead of aborting kernel build process.

Suggested-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Signed-off-by: default avatarHengqi Chen <hengqi.chen@gmail.com>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Acked-by: default avatarYonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210727132532.2473636-2-hengqi.chen@gmail.com
parent 33b57e0c

tools/bpf/resolve_btfids/main.c

+7 −6
Original line number Diff line number Diff line
@@ -291,7 +291,7 @@ static int compressed_section_fix(Elf *elf, Elf_Scn *scn, GElf_Shdr *sh) 
	sh->sh_addralign = expected;



	if (gelf_update_shdr(scn, sh) == 0) {

		printf("FAILED cannot update section header: %s\n",

		pr_err("FAILED cannot update section header: %s\n",

			elf_errmsg(-1));

		return -1;

	}
@@ -317,6 +317,7 @@ static int elf_collect(struct object *obj) 


	elf = elf_begin(fd, ELF_C_RDWR_MMAP, NULL);

	if (!elf) {

		close(fd);

		pr_err("FAILED cannot create ELF descriptor: %s\n",

			elf_errmsg(-1));

		return -1;
@@ -484,7 +485,7 @@ static int symbols_resolve(struct object *obj) 
	err = libbpf_get_error(btf);

	if (err) {

		pr_err("FAILED: load BTF from %s: %s\n",

			obj->path, strerror(-err));

			obj->btf ?: obj->path, strerror(-err));

		return -1;

	}
@@ -555,8 +556,7 @@ static int id_patch(struct object *obj, struct btf_id *id) 
	int i;



	if (!id->id) {

		pr_err("FAILED unresolved symbol %s\n", id->name);

		return -EINVAL;

		pr_err("WARN: resolve_btfids: unresolved symbol %s\n", id->name);

	}



	for (i = 0; i < id->addr_cnt; i++) {
@@ -734,8 +734,9 @@ int main(int argc, const char **argv) 


	err = 0;

out:

	if (obj.efile.elf)

	if (obj.efile.elf) {

		elf_end(obj.efile.elf);

		close(obj.efile.fd);

	}

	return err;

}