linux-kernel - Re: [PATCH bpf-next v8 4/4] selftests/bpf: Add libbpf_probe_bpf

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Message-ID: <d3dacc81d79d67f1c4372adc2517176bed57fadd.camel@gmail.com>
Date: Fri, 21 Feb 2025 10:19:53 -0800
From: Eduard Zingerman <eddyz87@...il.com>
To: Tao Chen <chen.dylane@...ux.dev>, ast@...nel.org, daniel@...earbox.net, 
	andrii@...nel.org, haoluo@...gle.com, jolsa@...nel.org, qmo@...nel.org
Cc: bpf@...r.kernel.org, linux-kernel@...r.kernel.org,
 chen.dylane@...il.com,  Tao Chen <dylane.chen@...iglobal.com>
Subject: Re: [PATCH bpf-next v8 4/4] selftests/bpf: Add
 libbpf_probe_bpf_kfunc API selftests

On Sat, 2025-02-22 at 00:33 +0800, Tao Chen wrote:

[...]

> +static const struct {
> +	const char *name;
> +	int code;
> +} program_types[] = {
> +#define _T(n) { #n, BPF_PROG_TYPE_##n }
> +	_T(KPROBE),
> +	_T(XDP),
> +	_T(SYSCALL),
> +	_T(SCHED_CLS),
> +	_T(SCHED_ACT),
> +	_T(SK_SKB),
> +	_T(SOCKET_FILTER),
> +	_T(CGROUP_SKB),
> +	_T(LWT_OUT),
> +	_T(LWT_IN),
> +	_T(LWT_XMIT),
> +	_T(LWT_SEG6LOCAL),
> +	_T(NETFILTER),
> +	_T(CGROUP_SOCK_ADDR),
> +	_T(SCHED_ACT)
> +#undef _T
> +};
> +
> +void test_libbpf_probe_kfuncs_many(void)
> +{

Hi Tao,

Sorry, probably some miscommunication from my side.
I did not mean this test for inclusion, it was meant as a one time
manual inspection of libbpf_probe_bpf_kfunc results.
Just as a sanity check before series is merged.
As an automated test it does not provide much meaningful signal.

> +	int i, kfunc_id, ret, id;
> +	const struct btf_type *t;
> +	struct btf *btf = NULL;
> +	const char *kfunc;
> +	const char *tag;
> +
> +	btf = btf__parse("/sys/kernel/btf/vmlinux", NULL);
> +	if (!ASSERT_OK_PTR(btf, "btf_parse"))
> +		return;
> +	for (id = 0; id < btf__type_cnt(btf); ++id) {
> +		t = btf__type_by_id(btf, id);
> +		if (!t)
> +			continue;
> +		if (!btf_is_decl_tag(t))
> +			continue;
> +		tag = btf__name_by_offset(btf, t->name_off);
> +		if (strcmp(tag, "bpf_kfunc") != 0)
> +			continue;
> +		kfunc_id = t->type;
> +		t = btf__type_by_id(btf, kfunc_id);
> +		if (!btf_is_func(t))
> +			continue;
> +		kfunc = btf__name_by_offset(btf, t->name_off);
> +		for (i = 0; i < ARRAY_SIZE(program_types); ++i) {
> +			ret = libbpf_probe_bpf_kfunc(program_types[i].code,
> +						     kfunc_id, -1, NULL);
> +			if (ret < 0) {
> +				ASSERT_FAIL("kfunc:%s use prog type:%d",
> +				      kfunc, program_types[i].code);
> +				goto cleanup;
> +			}
> +		}
> +	}
> +cleanup:
> +	btf__free(btf);
> +}