On Sun, Aug 9, 2020 at 8:05 AM Jiri Olsa <jolsa@xxxxxxxxxx> wrote:
>
> Adding btf_struct_ids_match function to check if given address provided
> by BTF object + offset is also address of another nested BTF object.
>
> This allows to pass an argument to helper, which is defined via parent
> BTF object + offset, like for bpf_d_path (added in following changes):
>
> SEC("fentry/filp_close")
> int BPF_PROG(prog_close, struct file *file, void *id)
> {
> ...
> ret = bpf_d_path(&file->f_path, ...
>
> The first bpf_d_path argument is hold by verifier as BTF file object
> plus offset of f_path member.
>
> The btf_struct_ids_match function will walk the struct file object and
> check if there's nested struct path object on the given offset.
>
> Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
> ---
LGTM.
Acked-by: Andrii Nakryiko <andriin@xxxxxx>
> include/linux/bpf.h | 2 ++
> kernel/bpf/btf.c | 31 +++++++++++++++++++++++++++++++
> kernel/bpf/verifier.c | 17 +++++++++++------
> 3 files changed, 44 insertions(+), 6 deletions(-)
>
[...]
