[PATCHv6 perf/core 15/22] selftests/bpf: Add hit/attach/detach race optimized uprobe test

[Jiri Olsa <jolsa@kernel.org>]

Adding test that makes sure parallel execution of the uprobe and
attach/detach of optimized uprobe on it works properly.

By default the test runs for 500ms, which is adjustable by using
BPF_SELFTESTS_UPROBE_SYSCALL_RACE_MSEC env variable.

Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 .../selftests/bpf/prog_tests/uprobe_syscall.c | 108 ++++++++++++++++++
 1 file changed, 108 insertions(+)

diff --git a/tools/testing/selftests/bpf/prog_tests/uprobe_syscall.c b/tools/testing/selftests/bpf/prog_tests/uprobe_syscall.c
index b91135abcf8a..3d27c8bc019e 100644
--- a/tools/testing/selftests/bpf/prog_tests/uprobe_syscall.c
+++ b/tools/testing/selftests/bpf/prog_tests/uprobe_syscall.c
@@ -15,6 +15,7 @@
 #include <asm/prctl.h>
 #include "uprobe_syscall.skel.h"
 #include "uprobe_syscall_executed.skel.h"
+#include "bpf/libbpf_internal.h"
 
 #define USDT_NOP .byte 0x0f, 0x1f, 0x44, 0x00, 0x00
 #include "usdt.h"
@@ -629,6 +630,111 @@ static void test_uretprobe_shadow_stack(void)
 	ARCH_PRCTL(ARCH_SHSTK_DISABLE, ARCH_SHSTK_SHSTK);
 }
 
+static volatile bool race_stop;
+
+static USDT_DEFINE_SEMA(race);
+
+static void *worker_trigger(void *arg)
+{
+	unsigned long rounds = 0;
+
+	while (!race_stop) {
+		uprobe_test();
+		rounds++;
+	}
+
+	printf("tid %d trigger rounds: %lu\n", gettid(), rounds);
+	return NULL;
+}
+
+static void *worker_attach(void *arg)
+{
+	LIBBPF_OPTS(bpf_uprobe_opts, opts);
+	struct uprobe_syscall_executed *skel;
+	unsigned long rounds = 0, offset;
+	const char *sema[2] = {
+		__stringify(USDT_SEMA(race)),
+		NULL,
+	};
+	unsigned long *ref;
+	int err;
+
+	offset = get_uprobe_offset(&uprobe_test);
+	if (!ASSERT_GE(offset, 0, "get_uprobe_offset"))
+		return NULL;
+
+	err = elf_resolve_syms_offsets("/proc/self/exe", 1, (const char **) &sema, &ref, STT_OBJECT);
+	if (!ASSERT_OK(err, "elf_resolve_syms_offsets_sema"))
+		return NULL;
+
+	opts.ref_ctr_offset = *ref;
+
+	skel = uprobe_syscall_executed__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "uprobe_syscall_executed__open_and_load"))
+		return NULL;
+
+	skel->bss->pid = getpid();
+
+	while (!race_stop) {
+		skel->links.test_uprobe = bpf_program__attach_uprobe_opts(skel->progs.test_uprobe,
+					0, "/proc/self/exe", offset, &opts);
+		if (!ASSERT_OK_PTR(skel->links.test_uprobe, "bpf_program__attach_uprobe_opts"))
+			break;
+
+		bpf_link__destroy(skel->links.test_uprobe);
+		skel->links.test_uprobe = NULL;
+		rounds++;
+	}
+
+	printf("tid %d attach rounds: %lu hits: %d\n", gettid(), rounds, skel->bss->executed);
+	uprobe_syscall_executed__destroy(skel);
+	free(ref);
+	return NULL;
+}
+
+static useconds_t race_msec(void)
+{
+	char *env;
+
+	env = getenv("BPF_SELFTESTS_UPROBE_SYSCALL_RACE_MSEC");
+	if (env)
+		return atoi(env);
+
+	/* default duration is 500ms */
+	return 500;
+}
+
+static void test_uprobe_race(void)
+{
+	int err, i, nr_threads;
+	pthread_t *threads;
+
+	nr_threads = libbpf_num_possible_cpus();
+	if (!ASSERT_GT(nr_threads, 0, "libbpf_num_possible_cpus"))
+		return;
+	nr_threads = max(2, nr_threads);
+
+	threads = alloca(sizeof(*threads) * nr_threads);
+	if (!ASSERT_OK_PTR(threads, "malloc"))
+		return;
+
+	for (i = 0; i < nr_threads; i++) {
+		err = pthread_create(&threads[i], NULL, i % 2 ? worker_trigger : worker_attach,
+				     NULL);
+		if (!ASSERT_OK(err, "pthread_create"))
+			goto cleanup;
+	}
+
+	usleep(race_msec() * 1000);
+
+cleanup:
+	race_stop = true;
+	for (nr_threads = i, i = 0; i < nr_threads; i++)
+		pthread_join(threads[i], NULL);
+
+	ASSERT_FALSE(USDT_SEMA_IS_ACTIVE(race), "race_semaphore");
+}
+
 static void __test_uprobe_syscall(void)
 {
 	if (test__start_subtest("uretprobe_regs_equal"))
@@ -647,6 +753,8 @@ static void __test_uprobe_syscall(void)
 		test_uprobe_session();
 	if (test__start_subtest("uprobe_usdt"))
 		test_uprobe_usdt();
+	if (test__start_subtest("uprobe_race"))
+		test_uprobe_race();
 }
 #else
 static void __test_uprobe_syscall(void)
-- 
2.50.1