Re: [RFC PATCH v11 bpf-next 08/14] bpf: Add btf_struct_ids_match function

[Andrii Nakryiko <andrii.nakryiko@gmail.com>]

On Sun, Aug 9, 2020 at 8:05 AM Jiri Olsa <jolsa@kernel.org> 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@kernel.org>
> ---

LGTM.

Acked-by: Andrii Nakryiko <andriin@fb.com>

>  include/linux/bpf.h   |  2 ++
>  kernel/bpf/btf.c      | 31 +++++++++++++++++++++++++++++++
>  kernel/bpf/verifier.c | 17 +++++++++++------
>  3 files changed, 44 insertions(+), 6 deletions(-)
>

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