On 6/11/25 12:24 PM, Alexei Starovoitov wrote:
On Wed, Jun 11, 2025 at 10:15 AM Yonghong Song <yonghong.song@xxxxxxxxx> wrote:The bpf selftest xdp_adjust_tail/xdp_adjust_frags_tail_grow failed on arm64 with 64KB page: xdp_adjust_tail/xdp_adjust_frags_tail_grow:FAIL In bpf_prog_test_run_xdp(), the xdp->frame_sz is set to 4K, but later on when constructing frags, with 64K page size, the frag data_len could be more than 4K. This will cause problems in bpf_xdp_frags_increase_tail(). To fix the failure, the xdp->frame_sz is set to be PAGE_SIZE so kernel can test different page size properly. With the kernel change, the user space and bpf prog needs adjustment. Currently, the MAX_SKB_FRAGS default value is 17, so for 4K page, the maximum packet size will be less than 68K. To test 64K page, a bigger maximum packet size than 68K is desired. So two different functions are implemented for subtest xdp_adjust_frags_tail_grow. Depending on different page size, different data input/output sizes are used to adapt with different page size. Signed-off-by: Yonghong Song <yonghong.song@xxxxxxxxx> --- net/bpf/test_run.c | 2 +- .../bpf/prog_tests/xdp_adjust_tail.c | 95 +++++++++++++++++-- .../bpf/progs/test_xdp_adjust_tail_grow.c | 8 +- 3 files changed, 96 insertions(+), 9 deletions(-) diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c index aaf13a7d58ed..9728dbd4c66c 100644 --- a/net/bpf/test_run.c +++ b/net/bpf/test_run.c @@ -1255,7 +1255,7 @@ int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr, headroom -= ctx->data; } - max_data_sz = 4096 - headroom - tailroom; + max_data_sz = PAGE_SIZE - headroom - tailroom; if (size > max_data_sz) { /* disallow live data mode for jumbo frames */ if (do_live) diff --git a/tools/testing/selftests/bpf/prog_tests/xdp_adjust_tail.c b/tools/testing/selftests/bpf/prog_tests/xdp_adjust_tail.c index e361129402a1..133bde28a489 100644 --- a/tools/testing/selftests/bpf/prog_tests/xdp_adjust_tail.c +++ b/tools/testing/selftests/bpf/prog_tests/xdp_adjust_tail.c @@ -37,21 +37,25 @@ static void test_xdp_adjust_tail_shrink(void) bpf_object__close(obj); } -static void test_xdp_adjust_tail_grow(void) +static void test_xdp_adjust_tail_grow(bool is_64k_pagesize) { const char *file = "./test_xdp_adjust_tail_grow.bpf.o"; struct bpf_object *obj; - char buf[4096]; /* avoid segfault: large buf to hold grow results */ + char buf[8192]; /* avoid segfault: large buf to hold grow results */ __u32 expect_sz; int err, prog_fd; LIBBPF_OPTS(bpf_test_run_opts, topts, .data_in = &pkt_v4, - .data_size_in = sizeof(pkt_v4), .data_out = buf, .data_size_out = sizeof(buf), .repeat = 1, ); + if (is_64k_pagesize) + topts.data_size_in = sizeof(pkt_v4) - 1; + else + topts.data_size_in = sizeof(pkt_v4);Please add a comment that magic data size is a special signal to bpf prog:
Ok, will add a comment to explain this.
if (data_len == 54) { /* sizeof(pkt_v4) */ - offset = 4096; /* test too large offset */ + offset = 4096; /* test too large offset, 4k page size */ + } else if (data_len == 53) { /* sizeof(pkt_v4) - 1 */ + offset = 65536; /* test too large offset, 64k page size */ } else if (data_len == 74) { /* sizeof(pkt_v6) */ offset = 40;and comment about 90000, 90001 sizes.
Ack as well.
