From 1e54ad251a93a524f1a2950b1d65bc7437c57a53 Mon Sep 17 00:00:00 2001 From: Toke Høiland-Jørgensen Date: Mon, 25 Jun 2018 14:25:02 +0200 Subject: samples/bpf: Add xdp_sample_pkts example MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Add an example program showing how to sample packets from XDP using the perf event buffer. The example userspace program just prints the ethernet header for every packet sampled. Reviewed-by: Jakub Kicinski Signed-off-by: Toke Høiland-Jørgensen Acked-by: Song Liu Signed-off-by: Daniel Borkmann --- samples/bpf/Makefile | 4 + samples/bpf/xdp_sample_pkts_kern.c | 66 +++++++++++++++ samples/bpf/xdp_sample_pkts_user.c | 169 +++++++++++++++++++++++++++++++++++++ 3 files changed, 239 insertions(+) create mode 100644 samples/bpf/xdp_sample_pkts_kern.c create mode 100644 samples/bpf/xdp_sample_pkts_user.c (limited to 'samples') diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile index 1303af10e54d..9ea2f7b64869 100644 --- a/samples/bpf/Makefile +++ b/samples/bpf/Makefile @@ -52,6 +52,7 @@ hostprogs-y += xdp_adjust_tail hostprogs-y += xdpsock hostprogs-y += xdp_fwd hostprogs-y += task_fd_query +hostprogs-y += xdp_sample_pkts # Libbpf dependencies LIBBPF = $(TOOLS_PATH)/lib/bpf/libbpf.a @@ -107,6 +108,7 @@ xdp_adjust_tail-objs := xdp_adjust_tail_user.o xdpsock-objs := bpf_load.o xdpsock_user.o xdp_fwd-objs := bpf_load.o xdp_fwd_user.o task_fd_query-objs := bpf_load.o task_fd_query_user.o $(TRACE_HELPERS) +xdp_sample_pkts-objs := xdp_sample_pkts_user.o $(TRACE_HELPERS) # Tell kbuild to always build the programs always := $(hostprogs-y) @@ -163,6 +165,7 @@ always += xdp_adjust_tail_kern.o always += xdpsock_kern.o always += xdp_fwd_kern.o always += task_fd_query_kern.o +always += xdp_sample_pkts_kern.o HOSTCFLAGS += -I$(objtree)/usr/include HOSTCFLAGS += -I$(srctree)/tools/lib/ @@ -179,6 +182,7 @@ HOSTCFLAGS_spintest_user.o += -I$(srctree)/tools/lib/bpf/ HOSTCFLAGS_trace_event_user.o += -I$(srctree)/tools/lib/bpf/ HOSTCFLAGS_sampleip_user.o += -I$(srctree)/tools/lib/bpf/ HOSTCFLAGS_task_fd_query_user.o += -I$(srctree)/tools/lib/bpf/ +HOSTCFLAGS_xdp_sample_pkts_user.o += -I$(srctree)/tools/lib/bpf/ HOST_LOADLIBES += $(LIBBPF) -lelf HOSTLOADLIBES_tracex4 += -lrt diff --git a/samples/bpf/xdp_sample_pkts_kern.c b/samples/bpf/xdp_sample_pkts_kern.c new file mode 100644 index 000000000000..f7ca8b850978 --- /dev/null +++ b/samples/bpf/xdp_sample_pkts_kern.c @@ -0,0 +1,66 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include "bpf_helpers.h" + +#define SAMPLE_SIZE 64ul +#define MAX_CPUS 128 + +#define bpf_printk(fmt, ...) \ +({ \ + char ____fmt[] = fmt; \ + bpf_trace_printk(____fmt, sizeof(____fmt), \ + ##__VA_ARGS__); \ +}) + +struct bpf_map_def SEC("maps") my_map = { + .type = BPF_MAP_TYPE_PERF_EVENT_ARRAY, + .key_size = sizeof(int), + .value_size = sizeof(u32), + .max_entries = MAX_CPUS, +}; + +SEC("xdp_sample") +int xdp_sample_prog(struct xdp_md *ctx) +{ + void *data_end = (void *)(long)ctx->data_end; + void *data = (void *)(long)ctx->data; + + /* Metadata will be in the perf event before the packet data. */ + struct S { + u16 cookie; + u16 pkt_len; + } __packed metadata; + + if (data < data_end) { + /* The XDP perf_event_output handler will use the upper 32 bits + * of the flags argument as a number of bytes to include of the + * packet payload in the event data. If the size is too big, the + * call to bpf_perf_event_output will fail and return -EFAULT. + * + * See bpf_xdp_event_output in net/core/filter.c. + * + * The BPF_F_CURRENT_CPU flag means that the event output fd + * will be indexed by the CPU number in the event map. + */ + u64 flags = BPF_F_CURRENT_CPU; + u16 sample_size; + int ret; + + metadata.cookie = 0xdead; + metadata.pkt_len = (u16)(data_end - data); + sample_size = min(metadata.pkt_len, SAMPLE_SIZE); + flags |= (u64)sample_size << 32; + + ret = bpf_perf_event_output(ctx, &my_map, flags, + &metadata, sizeof(metadata)); + if (ret) + bpf_printk("perf_event_output failed: %d\n", ret); + } + + return XDP_PASS; +} + +char _license[] SEC("license") = "GPL"; +u32 _version SEC("version") = LINUX_VERSION_CODE; diff --git a/samples/bpf/xdp_sample_pkts_user.c b/samples/bpf/xdp_sample_pkts_user.c new file mode 100644 index 000000000000..8dd87c1eb560 --- /dev/null +++ b/samples/bpf/xdp_sample_pkts_user.c @@ -0,0 +1,169 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "perf-sys.h" +#include "trace_helpers.h" + +#define MAX_CPUS 128 +static int pmu_fds[MAX_CPUS], if_idx; +static struct perf_event_mmap_page *headers[MAX_CPUS]; +static char *if_name; + +static int do_attach(int idx, int fd, const char *name) +{ + int err; + + err = bpf_set_link_xdp_fd(idx, fd, 0); + if (err < 0) + printf("ERROR: failed to attach program to %s\n", name); + + return err; +} + +static int do_detach(int idx, const char *name) +{ + int err; + + err = bpf_set_link_xdp_fd(idx, -1, 0); + if (err < 0) + printf("ERROR: failed to detach program from %s\n", name); + + return err; +} + +#define SAMPLE_SIZE 64 + +static int print_bpf_output(void *data, int size) +{ + struct { + __u16 cookie; + __u16 pkt_len; + __u8 pkt_data[SAMPLE_SIZE]; + } __packed *e = data; + int i; + + if (e->cookie != 0xdead) { + printf("BUG cookie %x sized %d\n", + e->cookie, size); + return LIBBPF_PERF_EVENT_ERROR; + } + + printf("Pkt len: %-5d bytes. Ethernet hdr: ", e->pkt_len); + for (i = 0; i < 14 && i < e->pkt_len; i++) + printf("%02x ", e->pkt_data[i]); + printf("\n"); + + return LIBBPF_PERF_EVENT_CONT; +} + +static void test_bpf_perf_event(int map_fd, int num) +{ + struct perf_event_attr attr = { + .sample_type = PERF_SAMPLE_RAW, + .type = PERF_TYPE_SOFTWARE, + .config = PERF_COUNT_SW_BPF_OUTPUT, + .wakeup_events = 1, /* get an fd notification for every event */ + }; + int i; + + for (i = 0; i < num; i++) { + int key = i; + + pmu_fds[i] = sys_perf_event_open(&attr, -1/*pid*/, i/*cpu*/, + -1/*group_fd*/, 0); + + assert(pmu_fds[i] >= 0); + assert(bpf_map_update_elem(map_fd, &key, + &pmu_fds[i], BPF_ANY) == 0); + ioctl(pmu_fds[i], PERF_EVENT_IOC_ENABLE, 0); + } +} + +static void sig_handler(int signo) +{ + do_detach(if_idx, if_name); + exit(0); +} + +int main(int argc, char **argv) +{ + struct bpf_prog_load_attr prog_load_attr = { + .prog_type = BPF_PROG_TYPE_XDP, + }; + struct bpf_object *obj; + struct bpf_map *map; + int prog_fd, map_fd; + char filename[256]; + int ret, err, i; + int numcpus; + + if (argc < 2) { + printf("Usage: %s \n", argv[0]); + return 1; + } + + numcpus = get_nprocs(); + if (numcpus > MAX_CPUS) + numcpus = MAX_CPUS; + + snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]); + prog_load_attr.file = filename; + + if (bpf_prog_load_xattr(&prog_load_attr, &obj, &prog_fd)) + return 1; + + if (!prog_fd) { + printf("load_bpf_file: %s\n", strerror(errno)); + return 1; + } + + map = bpf_map__next(NULL, obj); + if (!map) { + printf("finding a map in obj file failed\n"); + return 1; + } + map_fd = bpf_map__fd(map); + + if_idx = if_nametoindex(argv[1]); + if (!if_idx) + if_idx = strtoul(argv[1], NULL, 0); + + if (!if_idx) { + fprintf(stderr, "Invalid ifname\n"); + return 1; + } + if_name = argv[1]; + err = do_attach(if_idx, prog_fd, argv[1]); + if (err) + return err; + + if (signal(SIGINT, sig_handler) || + signal(SIGHUP, sig_handler) || + signal(SIGTERM, sig_handler)) { + perror("signal"); + return 1; + } + + test_bpf_perf_event(map_fd, numcpus); + + for (i = 0; i < numcpus; i++) + if (perf_event_mmap_header(pmu_fds[i], &headers[i]) < 0) + return 1; + + ret = perf_event_poller_multi(pmu_fds, headers, numcpus, + print_bpf_output); + kill(0, SIGINT); + return ret; +} -- cgit v1.2.3