On 2021/7/26 11:32 AM, Yonghong Song wrote:
>
>
> On 7/25/21 7:18 AM, Hengqi Chen 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
>
> the function could be renamed or removed too.
>
>> 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>
>
> LGTM with one minor comment below.
>
> Acked-by: Yonghong Song <yhs@xxxxxx>
>
>> ---
>> 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));
>
> Why you change "obj->path" to "obj->btf ?: obj->path"?
> Note that obj->path cannot be NULL.
The diff didn't see the whole picture. Let me quote it here:
```
btf = btf__parse(obj->btf ?: obj->path, NULL);
err = libbpf_get_error(btf);
if (err) {
pr_err("FAILED: load BTF from %s: %s\n",
obj->path, strerror(-err));
return -1;
}
```
Because btf__parse parses either obj->btf or obj->path,
I think the error message should reveal this.
>
>> return -1;
>> }
>>
> [...]
