On Tue, Jul 11, 2023 at 11:00 AM Dave Marchevsky <davemarchevsky@xxxxxx> wrote:
>
> Structs bpf_rb_node and bpf_list_node are opaquely defined in
> uapi/linux/bpf.h, as BPF program writers are not expected to touch their
> fields - nor does the verifier allow them to do so.
>
> Currently these structs are simple wrappers around structs rb_node and
> list_head and linked_list / rbtree implementation just casts and passes
> to library functions for those data structures. Later patches in this
> series, though, will add an "owner" field to bpf_{rb,list}_node, such
> that they're not just wrapping an underlying node type. Moreover, the
> bpf linked_list and rbtree implementations will deal with these owner
> pointers directly in a few different places.
>
> To avoid having to do
>
> void *owner = (void*)bpf_list_node + sizeof(struct list_head)
>
> with opaque UAPI node types, add bpf_{list,rb}_node_internal struct
> definitions to internal headers and modify linked_list and rbtree to use
> the internal types where appropriate.
>
> Signed-off-by: Dave Marchevsky <davemarchevsky@xxxxxx>
> ---
> include/linux/bpf.h | 10 ++++++++++
> kernel/bpf/helpers.c | 23 +++++++++++++----------
> 2 files changed, 23 insertions(+), 10 deletions(-)
>
> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> index 360433f14496..d5841059fd2f 100644
> --- a/include/linux/bpf.h
> +++ b/include/linux/bpf.h
> @@ -228,6 +228,16 @@ struct btf_record {
> struct btf_field fields[];
> };
>
> +/* Non-opaque version of bpf_rb_node in uapi/linux/bpf.h */
> +struct bpf_rb_node_internal {
> + struct rb_node rb_node;
> +} __attribute__((aligned(8)));
> +
> +/* Non-opaque version of bpf_list_node in uapi/linux/bpf.h */
> +struct bpf_list_node_internal {
> + struct list_head list_head;
> +} __attribute__((aligned(8)));
We typically use _kern suffix for data structs that
mirror bpf.h structs.
Let's use it here as well instead of _internal.
