On Wed, Feb 22, 2023 at 5:29 AM Xiaoguang Wang
<xiaoguang.wang@xxxxxxxxxxxxxxxxx> wrote:
>
> Currenly only one bpf_ublk_queue_sqe() ebpf is added, ublksrv target
> can use this helper to write ebpf prog to support ublk kernel & usersapce
> zero copy, please see ublksrv test codes for more info.
>
> Signed-off-by: Xiaoguang Wang <xiaoguang.wang@xxxxxxxxxxxxxxxxx>
> ---
> drivers/block/ublk_drv.c | 263 +++++++++++++++++++++++++++++++--
> include/uapi/linux/bpf.h | 1 +
> include/uapi/linux/ublk_cmd.h | 18 +++
> kernel/bpf/verifier.c | 3 +-
> scripts/bpf_doc.py | 4 +
> tools/include/uapi/linux/bpf.h | 9 ++
> 6 files changed, 286 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
> index b628e9eaefa6..d17ddb6fc27f 100644
> --- a/drivers/block/ublk_drv.c
> +++ b/drivers/block/ublk_drv.c
> @@ -105,6 +105,12 @@ struct ublk_uring_cmd_pdu {
> */
> #define UBLK_IO_FLAG_NEED_GET_DATA 0x08
>
> +/*
> + * UBLK_IO_FLAG_BPF is set if IO command has be handled by ebpf prog instead
> + * of user space daemon.
> + */
> +#define UBLK_IO_FLAG_BPF 0x10
> +
> struct ublk_io {
> /* userspace buffer address from io cmd */
> __u64 addr;
> @@ -114,6 +120,11 @@ struct ublk_io {
> struct io_uring_cmd *cmd;
> };
>
> +struct ublk_req_iter {
> + struct io_fixed_iter fixed_iter;
> + struct bio_vec *bvec;
> +};
> +
> struct ublk_queue {
> int q_id;
> int q_depth;
> @@ -163,6 +174,9 @@ struct ublk_device {
> unsigned int nr_queues_ready;
> atomic_t nr_aborted_queues;
>
> + struct bpf_prog *io_bpf_prog;
> + struct ublk_req_iter *iter_table;
> +
> /*
> * Our ubq->daemon may be killed without any notification, so
> * monitor each queue's daemon periodically
> @@ -189,10 +203,48 @@ static DEFINE_MUTEX(ublk_ctl_mutex);
>
> static struct miscdevice ublk_misc;
>
> +struct ublk_io_bpf_ctx {
> + struct ublk_bpf_ctx ctx;
> + struct ublk_device *ub;
> +};
> +
> +static inline struct ublk_req_iter *ublk_get_req_iter(struct ublk_device *ub,
> + int qid, int tag)
> +{
> + return &(ub->iter_table[qid * ub->dev_info.queue_depth + tag]);
> +}
> +
> +BPF_CALL_4(bpf_ublk_queue_sqe, struct ublk_io_bpf_ctx *, bpf_ctx,
> + struct io_uring_sqe *, sqe, u32, sqe_len, u32, fd)
> +{
> + struct ublk_req_iter *req_iter;
> + u16 q_id = bpf_ctx->ctx.q_id;
> + u16 tag = bpf_ctx->ctx.tag;
> +
> + req_iter = ublk_get_req_iter(bpf_ctx->ub, q_id, tag);
> + io_uring_submit_sqe(fd, sqe, sqe_len, &(req_iter->fixed_iter));
> + return 0;
> +}
> +
> +const struct bpf_func_proto ublk_bpf_queue_sqe_proto = {
> + .func = bpf_ublk_queue_sqe,
> + .gpl_only = false,
> + .ret_type = RET_INTEGER,
> + .arg1_type = ARG_ANYTHING,
> + .arg2_type = ARG_ANYTHING,
> + .arg3_type = ARG_ANYTHING,
> + .arg4_type = ARG_ANYTHING,
> +};
You know that the above is unsafe, right?
> +
> static const struct bpf_func_proto *
> ublk_bpf_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
> {
> - return bpf_base_func_proto(func_id);
> + switch (func_id) {
> + case BPF_FUNC_ublk_queue_sqe:
> + return &ublk_bpf_queue_sqe_proto;
> + default:
> + return bpf_base_func_proto(func_id);
> + }
> }
>
> static bool ublk_bpf_is_valid_access(int off, int size,
> @@ -200,6 +252,23 @@ static bool ublk_bpf_is_valid_access(int off, int size,
> const struct bpf_prog *prog,
> struct bpf_insn_access_aux *info)
> {
> + if (off < 0 || off >= sizeof(struct ublk_bpf_ctx))
> + return false;
> + if (off % size != 0)
> + return false;
> +
> + switch (off) {
> + case offsetof(struct ublk_bpf_ctx, q_id):
> + return size == sizeof_field(struct ublk_bpf_ctx, q_id);
> + case offsetof(struct ublk_bpf_ctx, tag):
> + return size == sizeof_field(struct ublk_bpf_ctx, tag);
> + case offsetof(struct ublk_bpf_ctx, op):
> + return size == sizeof_field(struct ublk_bpf_ctx, op);
> + case offsetof(struct ublk_bpf_ctx, nr_sectors):
> + return size == sizeof_field(struct ublk_bpf_ctx, nr_sectors);
> + case offsetof(struct ublk_bpf_ctx, start_sector):
> + return size == sizeof_field(struct ublk_bpf_ctx, start_sector);
> + }
> return false;
We don't introduce stable 'ctx' anymore.
Please see how hid-bpf is doing things.
