selftests/bpf: Add uprobe_multi skel test

Adding uprobe_multi test for skeleton load/attach functions,
to test skeleton auto attach for uprobe_multi link.

Test that bpf_get_func_ip works properly for uprobe_multi
attachment.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20230809083440.3209381-20-jolsa@kernel.orgSigned-off-by: Alexei Starovoitov <ast@kernel.org>

tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c

+// SPDX-License-Identifier: GPL-2.0
+
+#include <unistd.h>
+#include <test_progs.h>
+#include "uprobe_multi.skel.h"
+
+static char test_data[] = "test_data";
+
+noinline void uprobe_multi_func_1(void)
+{
+	asm volatile ("");
+}
+
+noinline void uprobe_multi_func_2(void)
+{
+	asm volatile ("");
+}
+
+noinline void uprobe_multi_func_3(void)
+{
+	asm volatile ("");
+}
+
+static void uprobe_multi_test_run(struct uprobe_multi *skel)
+{
+	skel->bss->uprobe_multi_func_1_addr = (__u64) uprobe_multi_func_1;
+	skel->bss->uprobe_multi_func_2_addr = (__u64) uprobe_multi_func_2;
+	skel->bss->uprobe_multi_func_3_addr = (__u64) uprobe_multi_func_3;
+
+	skel->bss->user_ptr = test_data;
+	skel->bss->pid = getpid();
+
+	/* trigger all probes */
+	uprobe_multi_func_1();
+	uprobe_multi_func_2();
+	uprobe_multi_func_3();
+
+	/*
+	 * There are 2 entry and 2 exit probe called for each uprobe_multi_func_[123]
+	 * function and each slepable probe (6) increments uprobe_multi_sleep_result.
+	 */
+	ASSERT_EQ(skel->bss->uprobe_multi_func_1_result, 2, "uprobe_multi_func_1_result");
+	ASSERT_EQ(skel->bss->uprobe_multi_func_2_result, 2, "uprobe_multi_func_2_result");
+	ASSERT_EQ(skel->bss->uprobe_multi_func_3_result, 2, "uprobe_multi_func_3_result");
+
+	ASSERT_EQ(skel->bss->uretprobe_multi_func_1_result, 2, "uretprobe_multi_func_1_result");
+	ASSERT_EQ(skel->bss->uretprobe_multi_func_2_result, 2, "uretprobe_multi_func_2_result");
+	ASSERT_EQ(skel->bss->uretprobe_multi_func_3_result, 2, "uretprobe_multi_func_3_result");
+
+	ASSERT_EQ(skel->bss->uprobe_multi_sleep_result, 6, "uprobe_multi_sleep_result");
+}
+
+static void test_skel_api(void)
+{
+	struct uprobe_multi *skel = NULL;
+	int err;
+
+	skel = uprobe_multi__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "uprobe_multi__open_and_load"))
+		goto cleanup;
+
+	err = uprobe_multi__attach(skel);
+	if (!ASSERT_OK(err, "uprobe_multi__attach"))
+		goto cleanup;
+
+	uprobe_multi_test_run(skel);
+
+cleanup:
+	uprobe_multi__destroy(skel);
+}
+
+void test_uprobe_multi_test(void)
+{
+	if (test__start_subtest("skel_api"))
+		test_skel_api();
+}

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

+// SPDX-License-Identifier: GPL-2.0
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include <stdbool.h>
+
+char _license[] SEC("license") = "GPL";
+
+__u64 uprobe_multi_func_1_addr = 0;
+__u64 uprobe_multi_func_2_addr = 0;
+__u64 uprobe_multi_func_3_addr = 0;
+
+__u64 uprobe_multi_func_1_result = 0;
+__u64 uprobe_multi_func_2_result = 0;
+__u64 uprobe_multi_func_3_result = 0;
+
+__u64 uretprobe_multi_func_1_result = 0;
+__u64 uretprobe_multi_func_2_result = 0;
+__u64 uretprobe_multi_func_3_result = 0;
+
+__u64 uprobe_multi_sleep_result = 0;
+
+int pid = 0;
+bool test_cookie = false;
+void *user_ptr = 0;
+
+static __always_inline bool verify_sleepable_user_copy(void)
+{
+	char data[9];
+
+	bpf_copy_from_user(data, sizeof(data), user_ptr);
+	return bpf_strncmp(data, sizeof(data), "test_data") == 0;
+}
+
+static void uprobe_multi_check(void *ctx, bool is_return, bool is_sleep)
+{
+	if (bpf_get_current_pid_tgid() >> 32 != pid)
+		return;
+
+	__u64 cookie = test_cookie ? bpf_get_attach_cookie(ctx) : 0;
+	__u64 addr = bpf_get_func_ip(ctx);
+
+#define SET(__var, __addr, __cookie) ({			\
+	if (addr == __addr &&				\
+	   (!test_cookie || (cookie == __cookie)))	\
+		__var += 1;				\
+})
+
+	if (is_return) {
+		SET(uretprobe_multi_func_1_result, uprobe_multi_func_1_addr, 2);
+		SET(uretprobe_multi_func_2_result, uprobe_multi_func_2_addr, 3);
+		SET(uretprobe_multi_func_3_result, uprobe_multi_func_3_addr, 1);
+	} else {
+		SET(uprobe_multi_func_1_result, uprobe_multi_func_1_addr, 3);
+		SET(uprobe_multi_func_2_result, uprobe_multi_func_2_addr, 1);
+		SET(uprobe_multi_func_3_result, uprobe_multi_func_3_addr, 2);
+	}
+
+#undef SET
+
+	if (is_sleep && verify_sleepable_user_copy())
+		uprobe_multi_sleep_result += 1;
+}
+
+SEC("uprobe.multi//proc/self/exe:uprobe_multi_func_*")
+int uprobe(struct pt_regs *ctx)
+{
+	uprobe_multi_check(ctx, false, false);
+	return 0;
+}
+
+SEC("uretprobe.multi//proc/self/exe:uprobe_multi_func_*")
+int uretprobe(struct pt_regs *ctx)
+{
+	uprobe_multi_check(ctx, true, false);
+	return 0;
+}
+
+SEC("uprobe.multi.s//proc/self/exe:uprobe_multi_func_*")
+int uprobe_sleep(struct pt_regs *ctx)
+{
+	uprobe_multi_check(ctx, false, true);
+	return 0;
+}
+
+SEC("uretprobe.multi.s//proc/self/exe:uprobe_multi_func_*")
+int uretprobe_sleep(struct pt_regs *ctx)
+{
+	uprobe_multi_check(ctx, true, true);
+	return 0;
+}