Re: [PATCH v4 bpf-next 2/2] selftests/bpf: Add selftest for fill_link_info

[Jiri Olsa <olsajiri@gmail.com>]

On Fri, Aug 04, 2023 at 10:57:32AM +0000, Yafang Shao wrote:

SNIP

> +
> +static void kprobe_fill_invalid_user_buffer(int fd)
> +{
> +	struct bpf_link_info info;
> +	__u32 len = sizeof(info);
> +	int err;
> +
> +	memset(&info, 0, sizeof(info));
> +
> +	info.perf_event.kprobe.func_name = 0x1; /* invalid address */
> +	err = bpf_link_get_info_by_fd(fd, &info, &len);
> +	ASSERT_EQ(err, -EINVAL, "invalid_buff_and_len");
> +
> +	info.perf_event.kprobe.name_len = 64;
> +	err = bpf_link_get_info_by_fd(fd, &info, &len);
> +	ASSERT_EQ(err, -EFAULT, "invalid_buff");
> +
> +	info.perf_event.kprobe.func_name = 0;
> +	err = bpf_link_get_info_by_fd(fd, &info, &len);
> +	ASSERT_EQ(err, -EINVAL, "invalid_len");
> +
> +	ASSERT_EQ(info.perf_event.kprobe.addr, 0, "func_addr");
> +	ASSERT_EQ(info.perf_event.kprobe.offset, 0, "func_offset");
> +	ASSERT_EQ(info.perf_event.type, 0, "type");
> +}
> +
> +static void test_kprobe_fill_link_info(struct test_fill_link_info *skel,
> +				       enum bpf_perf_event_type type,
> +				       bool retprobe, bool invalid)
> +{
> +	DECLARE_LIBBPF_OPTS(bpf_kprobe_opts, opts,
> +		.attach_mode = PROBE_ATTACH_MODE_LINK,
> +		.retprobe = retprobe,

you could got rid of the retprobe argument and just do

		.retprobe = retprobe == BPF_PERF_EVENT_KRETPROBE,


> +	);
> +	ssize_t offset = 0, entry_offset = 0;
> +	int link_fd, err;
> +	long addr;
> +
> +	skel->links.kprobe_run = bpf_program__attach_kprobe_opts(skel->progs.kprobe_run,
> +								 KPROBE_FUNC, &opts);
> +	if (!ASSERT_OK_PTR(skel->links.kprobe_run, "attach_kprobe"))
> +		return;
> +
> +	link_fd = bpf_link__fd(skel->links.kprobe_run);
> +	addr = ksym_get_addr(KPROBE_FUNC);
> +	if (!invalid) {
> +		/* See also arch_adjust_kprobe_addr(). */
> +		if (skel->kconfig->CONFIG_X86_KERNEL_IBT)
> +			entry_offset = 4;
> +		err = verify_perf_link_info(link_fd, type, addr, offset, entry_offset);
> +		ASSERT_OK(err, "verify_perf_link_info");
> +	} else {
> +		kprobe_fill_invalid_user_buffer(link_fd);
> +	}
> +	bpf_link__detach(skel->links.kprobe_run);
> +}
> +
> +static void test_tp_fill_link_info(struct test_fill_link_info *skel)
> +{
> +	int link_fd, err;
> +
> +	skel->links.tp_run = bpf_program__attach_tracepoint(skel->progs.tp_run, TP_CAT, TP_NAME);
> +	if (!ASSERT_OK_PTR(skel->links.tp_run, "attach_tp"))
> +		return;
> +
> +	link_fd = bpf_link__fd(skel->links.tp_run);
> +	err = verify_perf_link_info(link_fd, BPF_PERF_EVENT_TRACEPOINT, 0, 0, 0);
> +	ASSERT_OK(err, "verify_perf_link_info");
> +	bpf_link__detach(skel->links.tp_run);
> +}
> +
> +static void test_uprobe_fill_link_info(struct test_fill_link_info *skel,
> +				       enum bpf_perf_event_type type, ssize_t offset,
> +				       bool retprobe)
> +{
> +	int link_fd, err;
> +
> +	skel->links.uprobe_run = bpf_program__attach_uprobe(skel->progs.uprobe_run, retprobe,
> +							    0, /* self pid */
> +							    UPROBE_FILE, offset);

same here with 'type == BPF_PERF_EVENT_URETPROBE'


> +	if (!ASSERT_OK_PTR(skel->links.uprobe_run, "attach_uprobe"))
> +		return;
> +
> +	link_fd = bpf_link__fd(skel->links.uprobe_run);
> +	err = verify_perf_link_info(link_fd, type, 0, offset, 0);
> +	ASSERT_OK(err, "verify_perf_link_info");
> +	bpf_link__detach(skel->links.uprobe_run);
> +}
> +

SNIP

> +
> +static void test_kprobe_multi_fill_link_info(struct test_fill_link_info *skel,
> +					     bool retprobe, bool buffer)
> +{
> +	LIBBPF_OPTS(bpf_kprobe_multi_opts, opts);
> +	const char *syms[KMULTI_CNT] = {
> +		"schedule_timeout_interruptible",
> +		"schedule_timeout_uninterruptible",
> +		"schedule_timeout_idle",
> +		"schedule_timeout_killable",

nit, might be better to use some of the bpf_fentry_test[1-9] functions,
also for KPROBE_FUNC

> +	};
> +	__u64 addrs[KMULTI_CNT];
> +	int link_fd, i, err = 0;
> +
> +	qsort(syms, KMULTI_CNT, sizeof(syms[0]), symbols_cmp_r);
> +	opts.syms = syms;
> +	opts.cnt = KMULTI_CNT;
> +	opts.retprobe = retprobe;
> +	skel->links.kmulti_run = bpf_program__attach_kprobe_multi_opts(skel->progs.kmulti_run,
> +								       NULL, &opts);
> +	if (!ASSERT_OK_PTR(skel->links.kmulti_run, "attach_kprobe_multi"))
> +		return;
> +
> +	link_fd = bpf_link__fd(skel->links.kmulti_run);
> +	for (i = 0; i < KMULTI_CNT; i++)
> +		addrs[i] = ksym_get_addr(syms[i]);
> +
> +	if (!buffer)
> +		err = verify_kmulti_link_info(link_fd, addrs, retprobe);
> +	else
> +		verify_kmulti_user_buffer(link_fd, addrs);

verify_kmulti_user_buffer is actually what you call 'invalid' in other
tests right? seems better to keep it in here unless I miss something

thanks,
jirka

> +	ASSERT_OK(err, "verify_kmulti_link_info");
> +	bpf_link__detach(skel->links.kmulti_run);
> +}
> +

SNIP