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Wed, 17 Sep 2025 15:55:19 -0700 (PDT) Received: from localhost ([2a03:2880:ff:5e::]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-77cfbb7c127sm458672b3a.21.2025.09.17.15.55.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 17 Sep 2025 15:55:19 -0700 (PDT) From: Amery Hung To: bpf@vger.kernel.org Cc: netdev@vger.kernel.org, alexei.starovoitov@gmail.com, andrii@kernel.org, daniel@iogearbox.net, paul.chaignon@gmail.com, kuba@kernel.org, stfomichev@gmail.com, martin.lau@kernel.org, mohsin.bashr@gmail.com, noren@nvidia.com, dtatulea@nvidia.com, saeedm@nvidia.com, tariqt@nvidia.com, mbloch@nvidia.com, maciej.fijalkowski@intel.com, kernel-team@meta.com Subject: [PATCH bpf-next v4 5/6] selftests/bpf: Test bpf_xdp_pull_data Date: Wed, 17 Sep 2025 15:55:12 -0700 Message-ID: <20250917225513.3388199-6-ameryhung@gmail.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20250917225513.3388199-1-ameryhung@gmail.com> References: <20250917225513.3388199-1-ameryhung@gmail.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Test bpf_xdp_pull_data() with xdp packets with different layouts. The xdp bpf program first checks if the layout is as expected. Then, it calls bpf_xdp_pull_data(). Finally, it checks the 0xbb marker at offset 1024 using directly packet access. Signed-off-by: Amery Hung --- .../selftests/bpf/prog_tests/xdp_pull_data.c | 176 ++++++++++++++++++ .../selftests/bpf/progs/test_xdp_pull_data.c | 48 +++++ 2 files changed, 224 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/xdp_pull_data.c create mode 100644 tools/testing/selftests/bpf/progs/test_xdp_pull_data.c diff --git a/tools/testing/selftests/bpf/prog_tests/xdp_pull_data.c b/tools/testing/selftests/bpf/prog_tests/xdp_pull_data.c new file mode 100644 index 000000000000..c16801b73fed --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/xdp_pull_data.c @@ -0,0 +1,176 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include +#include +#include "test_xdp_pull_data.skel.h" + +#define PULL_MAX (1 << 31) +#define PULL_PLUS_ONE (1 << 30) + +#define XDP_PACKET_HEADROOM 256 + +/* Find sizes of struct skb_shared_info and struct xdp_frame so that + * we can calculate the maximum pull lengths for test cases + */ +static int find_xdp_sizes(struct test_xdp_pull_data *skel, int frame_sz) +{ + LIBBPF_OPTS(bpf_test_run_opts, topts); + struct xdp_md ctx = {}; + int prog_fd, err; + __u8 *buf; + + buf = calloc(frame_sz, sizeof(__u8)); + if (!ASSERT_OK_PTR(buf, "calloc buf")) + return -ENOMEM; + + topts.data_in = buf; + topts.data_out = buf; + topts.data_size_in = frame_sz; + topts.data_size_out = frame_sz; + /* Pass a data_end larger than the linear space available to make sure + * bpf_prog_test_run_xdp() will fill the linear data area so that + * xdp_find_data_hard_end can infer the size of struct skb_shared_info + */ + ctx.data_end = frame_sz; + topts.ctx_in = &ctx; + topts.ctx_out = &ctx; + topts.ctx_size_in = sizeof(ctx); + topts.ctx_size_out = sizeof(ctx); + + prog_fd = bpf_program__fd(skel->progs.xdp_find_sizes); + err = bpf_prog_test_run_opts(prog_fd, &topts); + ASSERT_OK(err, "bpf_prog_test_run_opts"); + + free(buf); + + return err; +} + +/* xdp_pull_data_prog will directly read a marker 0xbb stored at buf[1024] + * so caller expecting XDP_PASS should always pass pull_len no less than 1024 + */ +static void run_test(struct test_xdp_pull_data *skel, int retval, + int frame_sz, int buff_len, int meta_len, int data_len, + int pull_len) +{ + LIBBPF_OPTS(bpf_test_run_opts, topts); + struct xdp_md ctx = {}; + int prog_fd, err; + __u8 *buf; + + buf = calloc(buff_len, sizeof(__u8)); + if (!ASSERT_OK_PTR(buf, "calloc buf")) + return; + + buf[meta_len + 1023] = 0xaa; + buf[meta_len + 1024] = 0xbb; + buf[meta_len + 1025] = 0xcc; + + topts.data_in = buf; + topts.data_out = buf; + topts.data_size_in = buff_len; + topts.data_size_out = buff_len; + ctx.data = meta_len; + ctx.data_end = meta_len + data_len; + topts.ctx_in = &ctx; + topts.ctx_out = &ctx; + topts.ctx_size_in = sizeof(ctx); + topts.ctx_size_out = sizeof(ctx); + + skel->bss->data_len = data_len; + if (pull_len & PULL_MAX) { + int headroom = XDP_PACKET_HEADROOM - meta_len - skel->bss->xdpf_sz; + int tailroom = frame_sz - XDP_PACKET_HEADROOM - + data_len - skel->bss->sinfo_sz; + + pull_len = pull_len & PULL_PLUS_ONE ? 1 : 0; + pull_len += headroom + tailroom + data_len; + } + skel->bss->pull_len = pull_len; + + prog_fd = bpf_program__fd(skel->progs.xdp_pull_data_prog); + err = bpf_prog_test_run_opts(prog_fd, &topts); + ASSERT_OK(err, "bpf_prog_test_run_opts"); + ASSERT_EQ(topts.retval, retval, "xdp_pull_data_prog retval"); + + if (retval == XDP_DROP) + goto out; + + ASSERT_EQ(ctx.data_end, meta_len + pull_len, "linear data size"); + ASSERT_EQ(topts.data_size_out, buff_len, "linear + non-linear data size"); + /* Make sure data around xdp->data_end was not messed up by + * bpf_xdp_pull_data() + */ + ASSERT_EQ(buf[meta_len + 1023], 0xaa, "data[1023]"); + ASSERT_EQ(buf[meta_len + 1024], 0xbb, "data[1024]"); + ASSERT_EQ(buf[meta_len + 1025], 0xcc, "data[1025]"); +out: + free(buf); +} + +static void test_xdp_pull_data_basic(void) +{ + u32 pg_sz, max_meta_len, max_data_len; + struct test_xdp_pull_data *skel; + + skel = test_xdp_pull_data__open_and_load(); + if (!ASSERT_OK_PTR(skel, "test_xdp_pull_data__open_and_load")) + return; + + pg_sz = sysconf(_SC_PAGE_SIZE); + + if (find_xdp_sizes(skel, pg_sz)) + goto out; + + max_meta_len = XDP_PACKET_HEADROOM - skel->bss->xdpf_sz; + max_data_len = pg_sz - XDP_PACKET_HEADROOM - skel->bss->sinfo_sz; + + /* linear xdp pkt, pull 0 byte */ + run_test(skel, XDP_PASS, pg_sz, 2048, 0, 2048, 2048); + + /* multi-buf pkt, pull results in linear xdp pkt */ + run_test(skel, XDP_PASS, pg_sz, 2048, 0, 1024, 2048); + + /* multi-buf pkt, pull 1 byte to linear data area */ + run_test(skel, XDP_PASS, pg_sz, 9000, 0, 1024, 1025); + + /* multi-buf pkt, pull 0 byte to linear data area */ + run_test(skel, XDP_PASS, pg_sz, 9000, 0, 1025, 1025); + + /* multi-buf pkt, empty linear data area, pull requires memmove */ + run_test(skel, XDP_PASS, pg_sz, 9000, 0, 0, PULL_MAX); + + /* multi-buf pkt, no headroom */ + run_test(skel, XDP_PASS, pg_sz, 9000, max_meta_len, 1024, PULL_MAX); + + /* multi-buf pkt, no tailroom, pull requires memmove */ + run_test(skel, XDP_PASS, pg_sz, 9000, 0, max_data_len, PULL_MAX); + + + /* linear xdp pkt, pull more than total data len */ + run_test(skel, XDP_DROP, pg_sz, 2048, 0, 2048, 2049); + + /* multi-buf pkt with no space left in linear data area */ + run_test(skel, XDP_DROP, pg_sz, 9000, max_meta_len, max_data_len, + PULL_MAX | PULL_PLUS_ONE); + + /* multi-buf pkt, empty linear data area */ + run_test(skel, XDP_DROP, pg_sz, 9000, 0, 0, PULL_MAX | PULL_PLUS_ONE); + + /* multi-buf pkt, no headroom */ + run_test(skel, XDP_DROP, pg_sz, 9000, max_meta_len, 1024, + PULL_MAX | PULL_PLUS_ONE); + + /* multi-buf pkt, no tailroom */ + run_test(skel, XDP_DROP, pg_sz, 9000, 0, max_data_len, + PULL_MAX | PULL_PLUS_ONE); + +out: + test_xdp_pull_data__destroy(skel); +} + +void test_xdp_pull_data(void) +{ + if (test__start_subtest("xdp_pull_data")) + test_xdp_pull_data_basic(); +} diff --git a/tools/testing/selftests/bpf/progs/test_xdp_pull_data.c b/tools/testing/selftests/bpf/progs/test_xdp_pull_data.c new file mode 100644 index 000000000000..dd901bb109b6 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/test_xdp_pull_data.c @@ -0,0 +1,48 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include "vmlinux.h" +#include + +int xdpf_sz; +int sinfo_sz; +int data_len; +int pull_len; + +#define XDP_PACKET_HEADROOM 256 + +SEC("xdp.frags") +int xdp_find_sizes(struct xdp_md *ctx) +{ + xdpf_sz = sizeof(struct xdp_frame); + sinfo_sz = __PAGE_SIZE - XDP_PACKET_HEADROOM - + (ctx->data_end - ctx->data); + + return XDP_PASS; +} + +SEC("xdp.frags") +int xdp_pull_data_prog(struct xdp_md *ctx) +{ + __u8 *data_end = (void *)(long)ctx->data_end; + __u8 *data = (void *)(long)ctx->data; + __u8 *val_p; + int err; + + if (data_len != data_end - data) + return XDP_DROP; + + err = bpf_xdp_pull_data(ctx, pull_len); + if (err) + return XDP_DROP; + + val_p = (void *)(long)ctx->data + 1024; + if (val_p + 1 > (void *)(long)ctx->data_end) + return XDP_DROP; + + if (*val_p != 0xbb) + return XDP_DROP; + + return XDP_PASS; +} + +char _license[] SEC("license") = "GPL"; -- 2.47.3