selftests/bpf: Switch perf_buffer test to tracepoint and skeleton

Switch perf_buffer test to use skeleton to avoid use of bpf_prog_load() and
make test a bit more succinct. Also switch BPF program to use tracepoint
instead of kprobe, as that allows to support older kernels, which had
tracepoint support before kprobe support in the form that libbpf expects
(i.e., libbpf expects /sys/bus/event_source/devices/kprobe/type, which doesn't
always exist on old kernels).

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200708015318.3827358-7-andriin@fb.com

diff --git a/tools/testing/selftests/bpf/prog_tests/perf_buffer.c b/tools/testing/selftests/bpf/prog_tests/perf_buffer.c
index a122ce3b360ebc514df23144d0c25bd532f100fd..c33ec180b3f2dcb7464071823366ab42eea1bf34 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/perf_buffer.c
+++ b/tools/testing/selftests/bpf/prog_tests/perf_buffer.c
@@ -4,6 +4,7 @@
 #include <sched.h>
 #include <sys/socket.h>
 #include <test_progs.h>
+#include "test_perf_buffer.skel.h"
 #include "bpf/libbpf_internal.h"
 
 /* AddressSanitizer sometimes crashes due to data dereference below, due to
@@ -25,16 +26,11 @@ static void on_sample(void *ctx, int cpu, void *data, __u32 size)
 
 void test_perf_buffer(void)
 {
-       int err, prog_fd, on_len, nr_on_cpus = 0,  nr_cpus, i, duration = 0;
-       const char *prog_name = "kprobe/sys_nanosleep";
-       const char *file = "./test_perf_buffer.o";
+       int err, on_len, nr_on_cpus = 0,  nr_cpus, i, duration = 0;
        struct perf_buffer_opts pb_opts = {};
-       struct bpf_map *perf_buf_map;
+       struct test_perf_buffer *skel;
        cpu_set_t cpu_set, cpu_seen;
-       struct bpf_program *prog;
-       struct bpf_object *obj;
        struct perf_buffer *pb;
-       struct bpf_link *link;
        bool *online;
 
        nr_cpus = libbpf_num_possible_cpus();
@@ -51,33 +47,21 @@ void test_perf_buffer(void)
                        nr_on_cpus++;
 
        /* load program */
-       err = bpf_prog_load(file, BPF_PROG_TYPE_KPROBE, &obj, &prog_fd);
-       if (CHECK(err, "obj_load", "err %d errno %d\n", err, errno)) {
-               obj = NULL;
-               goto out_close;
-       }
-
-       prog = bpf_object__find_program_by_title(obj, prog_name);
-       if (CHECK(!prog, "find_probe", "prog '%s' not found\n", prog_name))
+       skel = test_perf_buffer__open_and_load();
+       if (CHECK(!skel, "skel_load", "skeleton open/load failed\n"))
                goto out_close;
 
-       /* load map */
-       perf_buf_map = bpf_object__find_map_by_name(obj, "perf_buf_map");
-       if (CHECK(!perf_buf_map, "find_perf_buf_map", "not found\n"))
-               goto out_close;
-
-       /* attach kprobe */
-       link = bpf_program__attach_kprobe(prog, false /* retprobe */,
-                                         SYS_NANOSLEEP_KPROBE_NAME);
-       if (CHECK(IS_ERR(link), "attach_kprobe", "err %ld\n", PTR_ERR(link)))
+       /* attach probe */
+       err = test_perf_buffer__attach(skel);
+       if (CHECK(err, "attach_kprobe", "err %d\n", err))
                goto out_close;
 
        /* set up perf buffer */
        pb_opts.sample_cb = on_sample;
        pb_opts.ctx = &cpu_seen;
-       pb = perf_buffer__new(bpf_map__fd(perf_buf_map), 1, &pb_opts);
+       pb = perf_buffer__new(bpf_map__fd(skel->maps.perf_buf_map), 1, &pb_opts);
        if (CHECK(IS_ERR(pb), "perf_buf__new", "err %ld\n", PTR_ERR(pb)))
-               goto out_detach;
+               goto out_close;
 
        /* trigger kprobe on every CPU */
        CPU_ZERO(&cpu_seen);
@@ -94,7 +78,7 @@ void test_perf_buffer(void)
                                             &cpu_set);
                if (err && CHECK(err, "set_affinity", "cpu #%d, err %d\n",
                                 i, err))
-                       goto out_detach;
+                       goto out_close;
 
                usleep(1);
        }
@@ -110,9 +94,7 @@ void test_perf_buffer(void)
 
 out_free_pb:
        perf_buffer__free(pb);
-out_detach:
-       bpf_link__destroy(link);
 out_close:
-       bpf_object__close(obj);
+       test_perf_buffer__destroy(skel);
        free(online);
 }

diff --git a/tools/testing/selftests/bpf/progs/test_perf_buffer.c b/tools/testing/selftests/bpf/progs/test_perf_buffer.c
index ad59c4c9aba8bcd3a361a8a8fadfaa61132880d0..8207a2dc2f9da03858ad8929097e0d6d9b0c478a 100644 (file)
--- a/tools/testing/selftests/bpf/progs/test_perf_buffer.c
+++ b/tools/testing/selftests/bpf/progs/test_perf_buffer.c
@@ -12,8 +12,8 @@ struct {
        __uint(value_size, sizeof(int));
 } perf_buf_map SEC(".maps");
 
-SEC("kprobe/sys_nanosleep")
-int BPF_KPROBE(handle_sys_nanosleep_entry)
+SEC("tp/raw_syscalls/sys_enter")
+int handle_sys_enter(void *ctx)
 {
        int cpu = bpf_get_smp_processor_id();