selftests/bpf: add benchmark testing for kprobe-multi-all

For now, the benchmark for kprobe-multi is single, which means there is
only 1 function is hooked during testing. Add the testing
"kprobe-multi-all", which will hook all the kernel functions during
the benchmark. And the "kretprobe-multi-all" is added too.

Signed-off-by: Menglong Dong <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Alexei Starovoitov <[e-mail]>

tools/testing/selftests/bpf/bench.c

···
 extern const struct bench bench_trig_kprobe_multi;
 extern const struct bench bench_trig_kretprobe_multi;
 extern const struct bench bench_trig_fentry;
+extern const struct bench bench_trig_kprobe_multi_all;
+extern const struct bench bench_trig_kretprobe_multi_all;
 extern const struct bench bench_trig_fexit;
 extern const struct bench bench_trig_fmodret;
 extern const struct bench bench_trig_tp;
···
 	&bench_trig_kprobe_multi,
 	&bench_trig_kretprobe_multi,
 	&bench_trig_fentry,
+	&bench_trig_kprobe_multi_all,
+	&bench_trig_kretprobe_multi_all,
 	&bench_trig_fexit,
 	&bench_trig_fmodret,
 	&bench_trig_tp,

tools/testing/selftests/bpf/benchs/bench_trigger.c

···
 	attach_bpf(ctx.skel->progs.bench_trigger_fentry);
 }
 
+static void attach_ksyms_all(struct bpf_program *empty, bool kretprobe)
+{
+	LIBBPF_OPTS(bpf_kprobe_multi_opts, opts);
+	char **syms = NULL;
+	size_t cnt = 0;
+
+	/* Some recursive functions will be skipped in
+	 * bpf_get_ksyms -> skip_entry, as they can introduce sufficient
+	 * overhead. However, it's difficut to skip all the recursive
+	 * functions for a debug kernel.
+	 *
+	 * So, don't run the kprobe-multi-all and kretprobe-multi-all on
+	 * a debug kernel.
+	 */
+	if (bpf_get_ksyms(&syms, &cnt, true)) {
+		fprintf(stderr, "failed to get ksyms\n");
+		exit(1);
+	}
+
+	opts.syms = (const char **) syms;
+	opts.cnt = cnt;
+	opts.retprobe = kretprobe;
+	/* attach empty to all the kernel functions except bpf_get_numa_node_id. */
+	if (!bpf_program__attach_kprobe_multi_opts(empty, NULL, &opts)) {
+		fprintf(stderr, "failed to attach bpf_program__attach_kprobe_multi_opts to all\n");
+		exit(1);
+	}
+}
+
+static void trigger_kprobe_multi_all_setup(void)
+{
+	struct bpf_program *prog, *empty;
+
+	setup_ctx();
+	empty = ctx.skel->progs.bench_kprobe_multi_empty;
+	prog = ctx.skel->progs.bench_trigger_kprobe_multi;
+	bpf_program__set_autoload(empty, true);
+	bpf_program__set_autoload(prog, true);
+	load_ctx();
+
+	attach_ksyms_all(empty, false);
+	attach_bpf(prog);
+}
+
+static void trigger_kretprobe_multi_all_setup(void)
+{
+	struct bpf_program *prog, *empty;
+
+	setup_ctx();
+	empty = ctx.skel->progs.bench_kretprobe_multi_empty;
+	prog = ctx.skel->progs.bench_trigger_kretprobe_multi;
+	bpf_program__set_autoload(empty, true);
+	bpf_program__set_autoload(prog, true);
+	load_ctx();
+
+	attach_ksyms_all(empty, true);
+	attach_bpf(prog);
+}
+
 static void trigger_fexit_setup(void)
 {
 	setup_ctx();
···
 BENCH_TRIG_KERNEL(kprobe_multi, "kprobe-multi");
 BENCH_TRIG_KERNEL(kretprobe_multi, "kretprobe-multi");
 BENCH_TRIG_KERNEL(fentry, "fentry");
+BENCH_TRIG_KERNEL(kprobe_multi_all, "kprobe-multi-all");
+BENCH_TRIG_KERNEL(kretprobe_multi_all, "kretprobe-multi-all");
 BENCH_TRIG_KERNEL(fexit, "fexit");
 BENCH_TRIG_KERNEL(fmodret, "fmodret");
 BENCH_TRIG_KERNEL(tp, "tp");

tools/testing/selftests/bpf/benchs/run_bench_trigger.sh

···
 	usermode-count kernel-count syscall-count \
 	fentry fexit fmodret \
 	rawtp tp \
-	kprobe kprobe-multi \
-	kretprobe kretprobe-multi \
+	kprobe kprobe-multi kprobe-multi-all \
+	kretprobe kretprobe-multi kretprobe-multi-all \
 )
 
 tests=("$@")

tools/testing/selftests/bpf/progs/trigger_bench.c

···
 	return 0;
 }
 
+SEC("?kprobe.multi/bpf_get_numa_node_id")
+int bench_kprobe_multi_empty(void *ctx)
+{
+	return 0;
+}
+
 SEC("?kretprobe.multi/bpf_get_numa_node_id")
 int bench_trigger_kretprobe_multi(void *ctx)
 {
 	inc_counter();
+	return 0;
+}
+
+SEC("?kretprobe.multi/bpf_get_numa_node_id")
+int bench_kretprobe_multi_empty(void *ctx)
+{
 	return 0;
 }
 

tools/testing/selftests/bpf/trace_helpers.c

···
 	"preempt_count_sub",
 	"__rcu_read_lock",
 	"__rcu_read_unlock",
+	"bpf_get_numa_node_id",
 };
 
 static bool skip_entry(char *name)