samples, bpf: Refactor perf_event user program with libbpf bpf_link
The bpf_program__attach of libbpf(using bpf_link) is much more intuitive than the previous method using ioctl. bpf_program__attach_perf_event manages the enable of perf_event and attach of BPF programs to it, so there's no neeed to do this directly with ioctl. In addition, bpf_link provides consistency in the use of API because it allows disable (detach, destroy) for multiple events to be treated as one bpf_link__destroy. Also, bpf_link__destroy manages the close() of perf_event fd. This commit refactors samples that attach the bpf program to perf_event by using libbbpf instead of ioctl. Also the bpf_load in the samples were removed and migrated to use libbbpf API. Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/20200321100424.1593964-3-danieltimlee@gmail.com
This commit is contained in:
Daniel T. Lee
Daniel Borkmann
parent
24a6034acc
commit
aa5e2af660
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@ -88,8 +88,8 @@ xdp2-objs := xdp1_user.o
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xdp_router_ipv4-objs := xdp_router_ipv4_user.o
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test_current_task_under_cgroup-objs := bpf_load.o $(CGROUP_HELPERS) \
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test_current_task_under_cgroup_user.o
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trace_event-objs := bpf_load.o trace_event_user.o $(TRACE_HELPERS)
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sampleip-objs := bpf_load.o sampleip_user.o $(TRACE_HELPERS)
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trace_event-objs := trace_event_user.o $(TRACE_HELPERS)
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sampleip-objs := sampleip_user.o $(TRACE_HELPERS)
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tc_l2_redirect-objs := bpf_load.o tc_l2_redirect_user.o
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lwt_len_hist-objs := bpf_load.o lwt_len_hist_user.o
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xdp_tx_iptunnel-objs := xdp_tx_iptunnel_user.o
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@ -10,21 +10,23 @@
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#include <errno.h>
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#include <signal.h>
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#include <string.h>
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#include <assert.h>
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#include <linux/perf_event.h>
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#include <linux/ptrace.h>
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#include <linux/bpf.h>
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#include <sys/ioctl.h>
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#include <bpf/bpf.h>
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#include <bpf/libbpf.h>
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#include "bpf_load.h"
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#include "perf-sys.h"
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#include "trace_helpers.h"
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#define __must_check
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#include <linux/err.h>
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#define DEFAULT_FREQ 99
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#define DEFAULT_SECS 5
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#define MAX_IPS 8192
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#define PAGE_OFFSET 0xffff880000000000
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static int map_fd;
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static int nr_cpus;
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static void usage(void)
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@ -34,9 +36,10 @@ static void usage(void)
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printf(" duration # sampling duration (seconds), default 5\n");
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}
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static int sampling_start(int *pmu_fd, int freq)
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static int sampling_start(int freq, struct bpf_program *prog,
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struct bpf_link *links[])
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{
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int i;
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int i, pmu_fd;
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struct perf_event_attr pe_sample_attr = {
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.type = PERF_TYPE_SOFTWARE,
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@ -47,26 +50,30 @@ static int sampling_start(int *pmu_fd, int freq)
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};
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for (i = 0; i < nr_cpus; i++) {
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pmu_fd[i] = sys_perf_event_open(&pe_sample_attr, -1 /* pid */, i,
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pmu_fd = sys_perf_event_open(&pe_sample_attr, -1 /* pid */, i,
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-1 /* group_fd */, 0 /* flags */);
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if (pmu_fd[i] < 0) {
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if (pmu_fd < 0) {
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fprintf(stderr, "ERROR: Initializing perf sampling\n");
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return 1;
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}
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assert(ioctl(pmu_fd[i], PERF_EVENT_IOC_SET_BPF,
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prog_fd[0]) == 0);
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assert(ioctl(pmu_fd[i], PERF_EVENT_IOC_ENABLE, 0) == 0);
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links[i] = bpf_program__attach_perf_event(prog, pmu_fd);
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if (IS_ERR(links[i])) {
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fprintf(stderr, "ERROR: Attach perf event\n");
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links[i] = NULL;
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close(pmu_fd);
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return 1;
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}
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}
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return 0;
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}
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static void sampling_end(int *pmu_fd)
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static void sampling_end(struct bpf_link *links[])
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{
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int i;
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for (i = 0; i < nr_cpus; i++)
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close(pmu_fd[i]);
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bpf_link__destroy(links[i]);
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}
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struct ipcount {
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@ -128,14 +135,17 @@ static void print_ip_map(int fd)
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static void int_exit(int sig)
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{
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printf("\n");
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print_ip_map(map_fd[0]);
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print_ip_map(map_fd);
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exit(0);
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}
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int main(int argc, char **argv)
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{
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int opt, freq = DEFAULT_FREQ, secs = DEFAULT_SECS, error = 1;
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struct bpf_object *obj = NULL;
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struct bpf_program *prog;
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struct bpf_link **links;
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char filename[256];
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int *pmu_fd, opt, freq = DEFAULT_FREQ, secs = DEFAULT_SECS;
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/* process arguments */
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while ((opt = getopt(argc, argv, "F:h")) != -1) {
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@ -163,38 +173,58 @@ int main(int argc, char **argv)
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}
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/* create perf FDs for each CPU */
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nr_cpus = sysconf(_SC_NPROCESSORS_CONF);
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pmu_fd = malloc(nr_cpus * sizeof(int));
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if (pmu_fd == NULL) {
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fprintf(stderr, "ERROR: malloc of pmu_fd\n");
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return 1;
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nr_cpus = sysconf(_SC_NPROCESSORS_ONLN);
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links = calloc(nr_cpus, sizeof(struct bpf_link *));
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if (!links) {
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fprintf(stderr, "ERROR: malloc of links\n");
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goto cleanup;
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}
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snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
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obj = bpf_object__open_file(filename, NULL);
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if (IS_ERR(obj)) {
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fprintf(stderr, "ERROR: opening BPF object file failed\n");
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obj = NULL;
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goto cleanup;
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}
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prog = bpf_object__find_program_by_name(obj, "do_sample");
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if (!prog) {
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fprintf(stderr, "ERROR: finding a prog in obj file failed\n");
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goto cleanup;
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}
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/* load BPF program */
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snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
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if (load_bpf_file(filename)) {
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fprintf(stderr, "ERROR: loading BPF program (errno %d):\n",
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errno);
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if (strcmp(bpf_log_buf, "") == 0)
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fprintf(stderr, "Try: ulimit -l unlimited\n");
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else
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fprintf(stderr, "%s", bpf_log_buf);
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return 1;
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if (bpf_object__load(obj)) {
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fprintf(stderr, "ERROR: loading BPF object file failed\n");
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goto cleanup;
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}
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map_fd = bpf_object__find_map_fd_by_name(obj, "ip_map");
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if (map_fd < 0) {
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fprintf(stderr, "ERROR: finding a map in obj file failed\n");
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goto cleanup;
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}
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signal(SIGINT, int_exit);
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signal(SIGTERM, int_exit);
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/* do sampling */
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printf("Sampling at %d Hertz for %d seconds. Ctrl-C also ends.\n",
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freq, secs);
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if (sampling_start(pmu_fd, freq) != 0)
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return 1;
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if (sampling_start(freq, prog, links) != 0)
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goto cleanup;
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sleep(secs);
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sampling_end(pmu_fd);
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free(pmu_fd);
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error = 0;
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cleanup:
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sampling_end(links);
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/* output sample counts */
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print_ip_map(map_fd[0]);
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if (!error)
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print_ip_map(map_fd);
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return 0;
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free(links);
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bpf_object__close(obj);
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return error;
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}
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@ -6,22 +6,25 @@
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#include <stdlib.h>
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#include <stdbool.h>
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#include <string.h>
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#include <fcntl.h>
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#include <poll.h>
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#include <sys/ioctl.h>
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#include <linux/perf_event.h>
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#include <linux/bpf.h>
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#include <signal.h>
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#include <assert.h>
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#include <errno.h>
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#include <sys/resource.h>
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#include <bpf/bpf.h>
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#include <bpf/libbpf.h>
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#include "bpf_load.h"
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#include "perf-sys.h"
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#include "trace_helpers.h"
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#define __must_check
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#include <linux/err.h>
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#define SAMPLE_FREQ 50
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static int pid;
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/* counts, stackmap */
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static int map_fd[2];
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struct bpf_program *prog;
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static bool sys_read_seen, sys_write_seen;
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static void print_ksym(__u64 addr)
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@ -91,10 +94,10 @@ static void print_stack(struct key_t *key, __u64 count)
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}
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}
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static void int_exit(int sig)
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static void err_exit(int err)
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{
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kill(0, SIGKILL);
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exit(0);
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kill(pid, SIGKILL);
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exit(err);
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}
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static void print_stacks(void)
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@ -102,7 +105,7 @@ static void print_stacks(void)
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struct key_t key = {}, next_key;
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__u64 value;
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__u32 stackid = 0, next_id;
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int fd = map_fd[0], stack_map = map_fd[1];
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int error = 1, fd = map_fd[0], stack_map = map_fd[1];
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sys_read_seen = sys_write_seen = false;
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while (bpf_map_get_next_key(fd, &key, &next_key) == 0) {
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@ -114,7 +117,7 @@ static void print_stacks(void)
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printf("\n");
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if (!sys_read_seen || !sys_write_seen) {
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printf("BUG kernel stack doesn't contain sys_read() and sys_write()\n");
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int_exit(0);
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err_exit(error);
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}
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/* clear stack map */
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@ -136,43 +139,52 @@ static inline int generate_load(void)
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static void test_perf_event_all_cpu(struct perf_event_attr *attr)
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{
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int nr_cpus = sysconf(_SC_NPROCESSORS_CONF);
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int *pmu_fd = malloc(nr_cpus * sizeof(int));
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int i, error = 0;
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int nr_cpus = sysconf(_SC_NPROCESSORS_ONLN);
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struct bpf_link **links = calloc(nr_cpus, sizeof(struct bpf_link *));
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int i, pmu_fd, error = 1;
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if (!links) {
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printf("malloc of links failed\n");
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goto err;
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}
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/* system wide perf event, no need to inherit */
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attr->inherit = 0;
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/* open perf_event on all cpus */
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for (i = 0; i < nr_cpus; i++) {
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pmu_fd[i] = sys_perf_event_open(attr, -1, i, -1, 0);
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if (pmu_fd[i] < 0) {
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pmu_fd = sys_perf_event_open(attr, -1, i, -1, 0);
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if (pmu_fd < 0) {
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printf("sys_perf_event_open failed\n");
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error = 1;
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goto all_cpu_err;
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}
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assert(ioctl(pmu_fd[i], PERF_EVENT_IOC_SET_BPF, prog_fd[0]) == 0);
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assert(ioctl(pmu_fd[i], PERF_EVENT_IOC_ENABLE) == 0);
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links[i] = bpf_program__attach_perf_event(prog, pmu_fd);
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if (IS_ERR(links[i])) {
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printf("bpf_program__attach_perf_event failed\n");
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links[i] = NULL;
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close(pmu_fd);
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goto all_cpu_err;
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}
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}
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if (generate_load() < 0) {
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error = 1;
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if (generate_load() < 0)
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goto all_cpu_err;
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}
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print_stacks();
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error = 0;
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all_cpu_err:
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for (i--; i >= 0; i--) {
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ioctl(pmu_fd[i], PERF_EVENT_IOC_DISABLE);
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close(pmu_fd[i]);
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}
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free(pmu_fd);
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for (i--; i >= 0; i--)
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bpf_link__destroy(links[i]);
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err:
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free(links);
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if (error)
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int_exit(0);
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err_exit(error);
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}
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static void test_perf_event_task(struct perf_event_attr *attr)
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{
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int pmu_fd, error = 0;
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struct bpf_link *link = NULL;
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int pmu_fd, error = 1;
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/* per task perf event, enable inherit so the "dd ..." command can be traced properly.
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* Enabling inherit will cause bpf_perf_prog_read_time helper failure.
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@ -183,21 +195,25 @@ static void test_perf_event_task(struct perf_event_attr *attr)
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pmu_fd = sys_perf_event_open(attr, 0, -1, -1, 0);
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if (pmu_fd < 0) {
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printf("sys_perf_event_open failed\n");
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int_exit(0);
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}
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assert(ioctl(pmu_fd, PERF_EVENT_IOC_SET_BPF, prog_fd[0]) == 0);
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assert(ioctl(pmu_fd, PERF_EVENT_IOC_ENABLE) == 0);
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if (generate_load() < 0) {
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error = 1;
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goto err;
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}
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link = bpf_program__attach_perf_event(prog, pmu_fd);
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if (IS_ERR(link)) {
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printf("bpf_program__attach_perf_event failed\n");
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link = NULL;
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close(pmu_fd);
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goto err;
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}
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if (generate_load() < 0)
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goto err;
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print_stacks();
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error = 0;
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err:
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ioctl(pmu_fd, PERF_EVENT_IOC_DISABLE);
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close(pmu_fd);
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bpf_link__destroy(link);
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if (error)
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int_exit(0);
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err_exit(error);
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}
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static void test_bpf_perf_event(void)
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@ -282,29 +298,60 @@ static void test_bpf_perf_event(void)
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int main(int argc, char **argv)
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{
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struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY};
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struct bpf_object *obj = NULL;
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char filename[256];
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int error = 1;
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snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
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setrlimit(RLIMIT_MEMLOCK, &r);
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signal(SIGINT, int_exit);
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signal(SIGTERM, int_exit);
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signal(SIGINT, err_exit);
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signal(SIGTERM, err_exit);
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if (load_kallsyms()) {
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printf("failed to process /proc/kallsyms\n");
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return 1;
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goto cleanup;
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}
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if (load_bpf_file(filename)) {
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printf("%s", bpf_log_buf);
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return 2;
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obj = bpf_object__open_file(filename, NULL);
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if (IS_ERR(obj)) {
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printf("opening BPF object file failed\n");
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obj = NULL;
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goto cleanup;
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}
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if (fork() == 0) {
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prog = bpf_object__find_program_by_name(obj, "bpf_prog1");
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if (!prog) {
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printf("finding a prog in obj file failed\n");
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goto cleanup;
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}
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/* load BPF program */
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if (bpf_object__load(obj)) {
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printf("loading BPF object file failed\n");
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goto cleanup;
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}
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map_fd[0] = bpf_object__find_map_fd_by_name(obj, "counts");
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map_fd[1] = bpf_object__find_map_fd_by_name(obj, "stackmap");
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if (map_fd[0] < 0 || map_fd[1] < 0) {
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printf("finding a counts/stackmap map in obj file failed\n");
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goto cleanup;
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}
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pid = fork();
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if (pid == 0) {
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read_trace_pipe();
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return 0;
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} else if (pid == -1) {
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printf("couldn't spawn process\n");
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goto cleanup;
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}
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test_bpf_perf_event();
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int_exit(0);
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return 0;
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error = 0;
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cleanup:
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bpf_object__close(obj);
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err_exit(error);
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}
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