On Tue, Feb 18, 2025 at 11:01 AM Mykyta Yatsenko
<mykyta.yatsenko5@xxxxxxxxx> 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>
> ---
> tools/testing/selftests/bpf/bpf_kfuncs.h | 8 ++
> .../testing/selftests/bpf/prog_tests/dynptr.c | 25 ++++++
> .../selftests/bpf/progs/dynptr_success.c | 77 +++++++++++++++++++
> 3 files changed, 110 insertions(+)
>
> diff --git a/tools/testing/selftests/bpf/bpf_kfuncs.h b/tools/testing/selftests/bpf/bpf_kfuncs.h
> index 8215c9b3115e..e9c193036c82 100644
> --- a/tools/testing/selftests/bpf/bpf_kfuncs.h
> +++ b/tools/testing/selftests/bpf/bpf_kfuncs.h
> @@ -43,6 +43,14 @@ extern bool bpf_dynptr_is_rdonly(const struct bpf_dynptr *ptr) __ksym __weak;
> extern __u32 bpf_dynptr_size(const struct bpf_dynptr *ptr) __ksym __weak;
> extern int bpf_dynptr_clone(const struct bpf_dynptr *ptr, struct bpf_dynptr *clone__init) __ksym __weak;
>
> +/* Description
> + * Copy data from one dynptr to another
> + * Returns
> + * Error code
> + */
> +extern int bpf_dynptr_copy(struct bpf_dynptr *dst, __u32 dst_off,
> + struct bpf_dynptr *src, __u32 src_off, __u32 size) __ksym __weak;
> +
Do we *need* this? Doesn't all this come from vmlinux.h nowadays?
> /* Description
> * Modify the address of a AF_UNIX sockaddr.
> * Returns
> diff --git a/tools/testing/selftests/bpf/prog_tests/dynptr.c b/tools/testing/selftests/bpf/prog_tests/dynptr.c
> index b614a5272dfd..247618958155 100644
> --- a/tools/testing/selftests/bpf/prog_tests/dynptr.c
> +++ b/tools/testing/selftests/bpf/prog_tests/dynptr.c
> @@ -10,6 +10,7 @@ enum test_setup_type {
> SETUP_SYSCALL_SLEEP,
> SETUP_SKB_PROG,
> SETUP_SKB_PROG_TP,
> + SETUP_XDP_PROG,
> };
>
> static struct {
> @@ -18,6 +19,8 @@ static struct {
> } success_tests[] = {
> {"test_read_write", SETUP_SYSCALL_SLEEP},
> {"test_dynptr_data", SETUP_SYSCALL_SLEEP},
> + {"test_dynptr_copy", SETUP_SYSCALL_SLEEP},
> + {"test_dynptr_copy_xdp", SETUP_XDP_PROG},
> {"test_ringbuf", SETUP_SYSCALL_SLEEP},
> {"test_skb_readonly", SETUP_SKB_PROG},
> {"test_dynptr_skb_data", SETUP_SKB_PROG},
> @@ -120,6 +123,28 @@ static void verify_success(const char *prog_name, enum test_setup_type setup_typ
>
> break;
> }
> + case SETUP_XDP_PROG:
> + {
> + char data[5000];
> + int err, prog_fd;
> +
no empty line here, opts is a variable
> + LIBBPF_OPTS(bpf_test_run_opts, opts,
> + .data_in = &data,
> + .data_size_in = sizeof(data),
> + .repeat = 1,
> + );
> +
> + prog_fd = bpf_program__fd(prog);
> + if (!ASSERT_GE(prog_fd, 0, "prog_fd"))
> + goto cleanup;
we shouldn't check this, if program loaded successfully this will
always be true (and yeah, I know that existing code does that, we
should remove or at least not duplicate this)
> +
> + err = bpf_prog_test_run_opts(prog_fd, &opts);
> +
> + if (!ASSERT_OK(err, "test_run"))
> + goto cleanup;
> +
> + break;
> + }
> }
>
> ASSERT_EQ(skel->bss->err, 0, "err");
> diff --git a/tools/testing/selftests/bpf/progs/dynptr_success.c b/tools/testing/selftests/bpf/progs/dynptr_success.c
> index bfcc85686cf0..8a6b35418e39 100644
> --- a/tools/testing/selftests/bpf/progs/dynptr_success.c
> +++ b/tools/testing/selftests/bpf/progs/dynptr_success.c
> @@ -567,3 +567,80 @@ int BPF_PROG(test_dynptr_skb_tp_btf, void *skb, void *location)
>
> return 1;
> }
> +
> +SEC("?tp/syscalls/sys_enter_nanosleep")
> +int test_dynptr_copy(void *ctx)
> +{
> + char *data = "hello there, world!!";
> + char buf[32] = {'\0'};
> + __u32 sz = strlen(data);
this is fragile, this is not guaranteed to work (only if compiler just
substituted a constant value). maybe just use data[] = "hello
there..." and use sizeof(data) then?
> + struct bpf_dynptr src, dst;
> +
> + bpf_ringbuf_reserve_dynptr(&ringbuf, sz, 0, &src);
> + bpf_ringbuf_reserve_dynptr(&ringbuf, sz, 0, &dst);
> +
> + err = bpf_dynptr_write(&src, 0, data, sz, 0);
> + err = err ?: bpf_dynptr_copy(&dst, 0, &src, 0, sz);
> + err = err ?: bpf_dynptr_read(buf, sz, &dst, 0, 0);
> + err = err ?: __builtin_memcmp(data, buf, sz);
> +
> + err = err ?: bpf_dynptr_copy(&dst, 3, &src, 5, sz - 5);
> + err = err ?: bpf_dynptr_read(buf, sz - 5, &dst, 3, 0);
> + err = err ?: __builtin_memcmp(data + 5, buf, sz - 5);
> +
> + bpf_ringbuf_discard_dynptr(&src, 0);
> + bpf_ringbuf_discard_dynptr(&dst, 0);
> + return 0;
> +}
> +
> +SEC("xdp")
> +int test_dynptr_copy_xdp(struct xdp_md *xdp)
> +{
> + struct bpf_dynptr ptr_buf, ptr_xdp;
> + char *data = "qwertyuiopasdfghjkl;";
> + char buf[32] = {'\0'};
> + __u32 len = strlen(data);
ditto
> + 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));
__builtin_memset(), memset() works only because compiler optimizes it
to built-in, but let's not rely on that
> + err = err ?: bpf_dynptr_read(&buf, len, &ptr_xdp, i * len, 0);
> + err = err ?: memcmp(data, buf, len);
__builtin_memcmp() and all the other cases below, please
> + }
> +
> + 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);
overdoing it a bit with the whole `err ?: ` pattern, IMO
BTW, more questions to networking folks (maybe Martin knows). Is there
a way to setup SKB or XDP packet with a non-linear region for testing?
> +
> + return XDP_DROP;
> +}
> --
> 2.48.1
>
