From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mga07.intel.com (mga07.intel.com [134.134.136.100]) by mail.toke.dk (Postfix) with ESMTPS id C536586C9EA for ; Tue, 3 Aug 2021 03:03:59 +0200 (CEST) X-IronPort-AV: E=McAfee;i="6200,9189,10064"; a="277327862" X-IronPort-AV: E=Sophos;i="5.84,290,1620716400"; d="scan'208";a="277327862" Received: from orsmga003.jf.intel.com ([10.7.209.27]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 02 Aug 2021 18:03:51 -0700 X-IronPort-AV: E=Sophos;i="5.84,290,1620716400"; d="scan'208";a="419480141" Received: from ticela-or-032.amr.corp.intel.com (HELO localhost.localdomain) ([10.212.166.34]) by orsmga003-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 02 Aug 2021 18:03:51 -0700 From: Ederson de Souza To: xdp-hints@xdp-project.net Subject: [[RFC xdp-hints] 16/16] samples/bpf: Show XDP hints usage Date: Mon, 2 Aug 2021 18:03:31 -0700 Message-Id: <20210803010331.39453-17-ederson.desouza@intel.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210803010331.39453-1-ederson.desouza@intel.com> References: <20210803010331.39453-1-ederson.desouza@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Message-ID-Hash: 2K3VY4WCMXSLBZTBCIX2BVURHJZAF73Y X-Message-ID-Hash: 2K3VY4WCMXSLBZTBCIX2BVURHJZAF73Y X-MailFrom: ederson.desouza@intel.com X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; digests; suspicious-header CC: bpf@vger.kernel.org X-Mailman-Version: 3.3.4 Precedence: list List-Id: XDP hardware hints design discussion Archived-At: List-Archive: List-Help: List-Owner: List-Post: List-Subscribe: List-Unsubscribe: An example of how to retrieve XDP hints/metadata from an XDP frame. To get the xdp_hints struct, one can use: $ bpftool net xdp show xdp: enp6s0(2) md_btf_id(44) md_btf_enabled(0) To get the BTF id, and then: $ bpftool btf dump id 44 format c > btf.h But, in this example, to demonstrate BTF and CORE features, a simpler struct was defined, containing the only field used by the sample. A lowpoint is that it's not currently possible to use some CORE features from "samples/bpf" directory, as those samples are currently built without using "clang -target bpf". This way, it was not possible to use "bpf_core_field_exists" macro to check, in runtime, the presence of a given XDP hints field. --- samples/bpf/xdp_sample_pkts_kern.c | 21 +++++++++++++++++++++ samples/bpf/xdp_sample_pkts_user.c | 4 +++- 2 files changed, 24 insertions(+), 1 deletion(-) diff --git a/samples/bpf/xdp_sample_pkts_kern.c b/samples/bpf/xdp_sample_pkts_kern.c index 9cf76b340dd7..9f0b0c5a6237 100644 --- a/samples/bpf/xdp_sample_pkts_kern.c +++ b/samples/bpf/xdp_sample_pkts_kern.c @@ -3,6 +3,7 @@ #include #include #include +#include #define SAMPLE_SIZE 64ul @@ -12,16 +13,23 @@ struct { __uint(value_size, sizeof(u32)); } my_map SEC(".maps"); +struct xdp_hints { + u64 rx_timestamp; +}; + SEC("xdp_sample") int xdp_sample_prog(struct xdp_md *ctx) { + void *meta_data = (void *)(long)ctx->data_meta; void *data_end = (void *)(long)ctx->data_end; void *data = (void *)(long)ctx->data; + struct xdp_hints *hints; /* Metadata will be in the perf event before the packet data. */ struct S { u16 cookie; u16 pkt_len; + u64 rx_timestamp; } __packed metadata; if (data < data_end) { @@ -41,9 +49,22 @@ int xdp_sample_prog(struct xdp_md *ctx) metadata.cookie = 0xdead; metadata.pkt_len = (u16)(data_end - data); + metadata.rx_timestamp = 0; sample_size = min(metadata.pkt_len, SAMPLE_SIZE); flags |= (u64)sample_size << 32; + if (meta_data < data) { + hints = meta_data; + /* bpf_core_field_exists doesn't work from samples/bpf, + * as it is only available for "clang -target bpf", which + * is not used on samples/bpf. A program that can use + * the "vmlinux.h" and "clang -target btf" could use this + * call to check the existence of a given field in runtime + */ + /*if (bpf_core_field_exists(hints->rx_timestamp))*/ + metadata.rx_timestamp = BPF_CORE_READ(hints, rx_timestamp); + } + ret = bpf_perf_event_output(ctx, &my_map, flags, &metadata, sizeof(metadata)); if (ret) diff --git a/samples/bpf/xdp_sample_pkts_user.c b/samples/bpf/xdp_sample_pkts_user.c index 495e09897bd3..b87e0ae8eb3d 100644 --- a/samples/bpf/xdp_sample_pkts_user.c +++ b/samples/bpf/xdp_sample_pkts_user.c @@ -76,6 +76,7 @@ static void print_bpf_output(void *ctx, int cpu, void *data, __u32 size) struct { __u16 cookie; __u16 pkt_len; + __u64 rx_timestamp; __u8 pkt_data[SAMPLE_SIZE]; } __packed *e = data; int i; @@ -85,7 +86,8 @@ static void print_bpf_output(void *ctx, int cpu, void *data, __u32 size) return; } - printf("Pkt len: %-5d bytes. Ethernet hdr: ", e->pkt_len); + printf("Pkt len: %-5d bytes. RX timestamp: %llu Ethernet hdr: ", e->pkt_len, + e->rx_timestamp); for (i = 0; i < 14 && i < e->pkt_len; i++) printf("%02x ", e->pkt_data[i]); printf("\n"); -- 2.32.0