On Mon, May 9, 2022 at 3:44 PM Joanne Koong <joannelkoong@xxxxxxxxx> wrote: > > Currently, our only way of writing dynamically-sized data into a ring > buffer is through bpf_ringbuf_output but this incurs an extra memcpy > cost. bpf_ringbuf_reserve + bpf_ringbuf_commit avoids this extra > memcpy, but it can only safely support reservation sizes that are > statically known since the verifier cannot guarantee that the bpf > program won’t access memory outside the reserved space. > > The bpf_dynptr abstraction allows for dynamically-sized ring buffer > reservations without the extra memcpy. > > There are 3 new APIs: > > long bpf_ringbuf_reserve_dynptr(void *ringbuf, u32 size, u64 flags, struct bpf_dynptr *ptr); > void bpf_ringbuf_submit_dynptr(struct bpf_dynptr *ptr, u64 flags); > void bpf_ringbuf_discard_dynptr(struct bpf_dynptr *ptr, u64 flags); > > These closely follow the functionalities of the original ringbuf APIs. > For example, all ringbuffer dynptrs that have been reserved must be > either submitted or discarded before the program exits. > > Signed-off-by: Joanne Koong <joannelkoong@xxxxxxxxx> > --- LGTM Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx> > include/linux/bpf.h | 14 +++++- > include/uapi/linux/bpf.h | 35 +++++++++++++++ > kernel/bpf/helpers.c | 6 +++ > kernel/bpf/ringbuf.c | 78 ++++++++++++++++++++++++++++++++++ > kernel/bpf/verifier.c | 16 ++++++- > tools/include/uapi/linux/bpf.h | 35 +++++++++++++++ > 6 files changed, 180 insertions(+), 4 deletions(-) > [...]
