samples/bpf/trace_output_user.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 #include <stdio.h>
0003 #include <fcntl.h>
0004 #include <poll.h>
0005 #include <time.h>
0006 #include <signal.h>
0007 #include <bpf/libbpf.h>
0008
0009 static __u64 time_get_ns(void)
0010 {
0011     struct timespec ts;
0012
0013     clock_gettime(CLOCK_MONOTONIC, &ts);
0014     return ts.tv_sec * 1000000000ull + ts.tv_nsec;
0015 }
0016
0017 static __u64 start_time;
0018 static __u64 cnt;
0019
0020 #define MAX_CNT 100000ll
0021
0022 static void print_bpf_output(void *ctx, int cpu, void *data, __u32 size)
0023 {
0024     struct {
0025         __u64 pid;
0026         __u64 cookie;
0027     } *e = data;
0028
0029     if (e->cookie != 0x12345678) {
0030         printf("BUG pid %llx cookie %llx sized %d\n",
0031                e->pid, e->cookie, size);
0032         return;
0033     }
0034
0035     cnt++;
0036
0037     if (cnt == MAX_CNT) {
0038         printf("recv %lld events per sec\n",
0039                MAX_CNT * 1000000000ll / (time_get_ns() - start_time));
0040         return;
0041     }
0042 }
0043
0044 int main(int argc, char **argv)
0045 {
0046     struct bpf_link *link = NULL;
0047     struct bpf_program *prog;
0048     struct perf_buffer *pb;
0049     struct bpf_object *obj;
0050     int map_fd, ret = 0;
0051     char filename[256];
0052     FILE *f;
0053
0054     snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
0055     obj = bpf_object__open_file(filename, NULL);
0056     if (libbpf_get_error(obj)) {
0057         fprintf(stderr, "ERROR: opening BPF object file failed\n");
0058         return 0;
0059     }
0060
0061     /* load BPF program */
0062     if (bpf_object__load(obj)) {
0063         fprintf(stderr, "ERROR: loading BPF object file failed\n");
0064         goto cleanup;
0065     }
0066
0067     map_fd = bpf_object__find_map_fd_by_name(obj, "my_map");
0068     if (map_fd < 0) {
0069         fprintf(stderr, "ERROR: finding a map in obj file failed\n");
0070         goto cleanup;
0071     }
0072
0073     prog = bpf_object__find_program_by_name(obj, "bpf_prog1");
0074     if (libbpf_get_error(prog)) {
0075         fprintf(stderr, "ERROR: finding a prog in obj file failed\n");
0076         goto cleanup;
0077     }
0078
0079     link = bpf_program__attach(prog);
0080     if (libbpf_get_error(link)) {
0081         fprintf(stderr, "ERROR: bpf_program__attach failed\n");
0082         link = NULL;
0083         goto cleanup;
0084     }
0085
0086     pb = perf_buffer__new(map_fd, 8, print_bpf_output, NULL, NULL, NULL);
0087     ret = libbpf_get_error(pb);
0088     if (ret) {
0089         printf("failed to setup perf_buffer: %d\n", ret);
0090         return 1;
0091     }
0092
0093     f = popen("taskset 1 dd if=/dev/zero of=/dev/null", "r");
0094     (void) f;
0095
0096     start_time = time_get_ns();
0097     while ((ret = perf_buffer__poll(pb, 1000)) >= 0 && cnt < MAX_CNT) {
0098     }
0099     kill(0, SIGINT);
0100
0101 cleanup:
0102     bpf_link__destroy(link);
0103     bpf_object__close(obj);
0104     return ret;
0105 }