On 2021/7/27 4:16 AM, Andrii Nakryiko wrote:
> On Sun, Jul 25, 2021 at 7:18 AM Hengqi Chen <hengqi.chen@xxxxxxxxx> wrote:
>>
>> Kernel functions referenced by .BTF_ids may changed from global to static
>> and get inlined 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.
>>
>> Signed-off-by: Hengqi Chen <hengqi.chen@xxxxxxxxx>
>> ---
>> tools/bpf/resolve_btfids/main.c | 13 +++++++------
>> 1 file changed, 7 insertions(+), 6 deletions(-)
>>
>> diff --git a/tools/bpf/resolve_btfids/main.c b/tools/bpf/resolve_btfids/main.c
>> index 3ad9301b0f00..3ea19e33250d 100644
>> --- a/tools/bpf/resolve_btfids/main.c
>> +++ b/tools/bpf/resolve_btfids/main.c
>> @@ -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: unresolved symbol %s\n", id->name);
>
> we should probably give a bit more information for people to get back
> to us for this. For starters, maybe prefix the message with
> "resolve_btfids:" so that people at least can grep something relevant?
>
OK, will do.
>> }
>>
>> 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);
>> + close(obj.efile.fd);
>> + }
>> return err;
>> }
>> --
>> 2.25.1
