On Tue, 2025-02-18 at 19:00 +0000, Mykyta Yatsenko wrote:
> From: Mykyta Yatsenko <yatsenko@xxxxxxxx>
>
> Add XDP setup type for dynptr tests, enabling testing for
> non-contiguous buffer.
> Add 2 tests:
> - test_dynptr_copy - verify correctness for the fast (contiguous
> buffer) code path.
> - test_dynptr_copy_xdp - verifies code paths that handle
> non-contiguous buffer.
>
> Signed-off-by: Mykyta Yatsenko <yatsenko@xxxxxxxx>
> ---
Acked-by: Eduard Zingerman <eddyz87@xxxxxxxxx>
[...]
> +SEC("xdp")
> +int test_dynptr_copy_xdp(struct xdp_md *xdp)
> +{
Nit: it would be helpful if there were a few comments
explaining which special cases are tested at each step.
> + struct bpf_dynptr ptr_buf, ptr_xdp;
> + char *data = "qwertyuiopasdfghjkl;";
> + char buf[32] = {'\0'};
> + __u32 len = strlen(data);
> + int i, chunks = 200;
> +
> + bpf_dynptr_from_xdp(xdp, 0, &ptr_xdp);
> + bpf_ringbuf_reserve_dynptr(&ringbuf, len * chunks, 0, &ptr_buf);
> +
> + bpf_for(i, 0, chunks) {
> + err = err ?: bpf_dynptr_write(&ptr_buf, i * len, data, len, 0);
> + }
> +
> + err = err ?: bpf_dynptr_copy(&ptr_xdp, 0, &ptr_buf, 0, len * chunks);
> +
> + bpf_for(i, 0, chunks) {
> + memset(buf, 0, sizeof(buf));
> + err = err ?: bpf_dynptr_read(&buf, len, &ptr_xdp, i * len, 0);
> + err = err ?: memcmp(data, buf, len);
> + }
> +
> + memset(buf, 0, sizeof(buf));
> + bpf_for(i, 0, chunks) {
> + err = err ?: bpf_dynptr_write(&ptr_buf, i * len, buf, len, 0);
> + }
> +
> + err = err ?: bpf_dynptr_copy(&ptr_buf, 0, &ptr_xdp, 0, len * chunks);
> +
> + bpf_for(i, 0, chunks) {
> + memset(buf, 0, sizeof(buf));
> + err = err ?: bpf_dynptr_read(&buf, len, &ptr_buf, i * len, 0);
> + err = err ?: memcmp(data, buf, len);
> + }
> +
> + bpf_ringbuf_discard_dynptr(&ptr_buf, 0);
> +
> + err = err ?: bpf_dynptr_copy(&ptr_xdp, 2, &ptr_xdp, len, len * (chunks - 1));
> +
> + bpf_for(i, 0, chunks - 1) {
> + memset(buf, 0, sizeof(buf));
> + err = err ?: bpf_dynptr_read(&buf, len, &ptr_xdp, 2 + i * len, 0);
> + err = err ?: memcmp(data, buf, len);
> + }
> +
> + err = err ?: (bpf_dynptr_copy(&ptr_xdp, 2000, &ptr_xdp, 0, len * chunks) == -E2BIG ? 0 : 1);
> +
> + return XDP_DROP;
> +}
