selftests/bpf: Add selftest for multi-prog sections and bpf-to-bpf calls

// SPDX-License-Identifier: GPL-2.0

/* Copyright (c) 2020 Facebook */

#include <test_progs.h>

#include <time.h>

#include "test_subprogs.skel.h"

static int duration;

void test_subprogs(void)

{

	struct test_subprogs *skel;

	int err;

	skel = test_subprogs__open_and_load();

	if (CHECK(!skel, "skel_open", "failed to open skeleton\n"))

		return;

	err = test_subprogs__attach(skel);

	if (CHECK(err, "skel_attach", "failed to attach skeleton: %d\n", err))

		goto cleanup;

	usleep(1);

	CHECK(skel->bss->res1 != 12, "res1", "got %d, exp %d\n", skel->bss->res1, 12);

	CHECK(skel->bss->res2 != 17, "res2", "got %d, exp %d\n", skel->bss->res2, 17);

	CHECK(skel->bss->res3 != 19, "res3", "got %d, exp %d\n", skel->bss->res3, 19);

	CHECK(skel->bss->res4 != 36, "res4", "got %d, exp %d\n", skel->bss->res4, 36);

cleanup:

	test_subprogs__destroy(skel);

}

#include "vmlinux.h"

#include <bpf/bpf_helpers.h>

#include <bpf/bpf_core_read.h>

const char LICENSE[] SEC("license") = "GPL";

__noinline int sub1(int x)

{

	return x + 1;

}

static __noinline int sub5(int v);

__noinline int sub2(int y)

{

	return sub5(y + 2);

}

static __noinline int sub3(int z)

{

	return z + 3 + sub1(4);

}

static __noinline int sub4(int w)

{

	return w + sub3(5) + sub1(6);

}

/* sub5() is an identitify function, just to test weirder functions layout and

 * call patterns

 */

static __noinline int sub5(int v)

{

	return sub1(v) - 1; /* compensates sub1()'s + 1 */

}

/* unfortunately verifier rejects `struct task_struct *t` as an unkown pointer

 * type, so we need to accept pointer as integer and then cast it inside the

 * function

 */

__noinline int get_task_tgid(uintptr_t t)

{

	/* this ensures that CO-RE relocs work in multi-subprogs .text */

	return BPF_CORE_READ((struct task_struct *)(void *)t, tgid);

}

int res1 = 0;

int res2 = 0;

int res3 = 0;

int res4 = 0;

SEC("raw_tp/sys_enter")

int prog1(void *ctx)

{

	/* perform some CO-RE relocations to ensure they work with multi-prog

	 * sections correctly

	 */

	struct task_struct *t = (void *)bpf_get_current_task();

	if (!BPF_CORE_READ(t, pid) || !get_task_tgid((uintptr_t)t))

		return 1;

	res1 = sub1(1) + sub3(2); /* (1 + 1) + (2 + 3 + (4 + 1)) = 12 */

	return 0;

}

SEC("raw_tp/sys_exit")

int prog2(void *ctx)

{

	struct task_struct *t = (void *)bpf_get_current_task();

	if (!BPF_CORE_READ(t, pid) || !get_task_tgid((uintptr_t)t))

		return 1;

	res2 = sub2(3) + sub3(4); /* (3 + 2) + (4 + 3 + (4 + 1)) = 17 */

	return 0;

}

/* prog3 has the same section name as prog1 */

SEC("raw_tp/sys_enter")

int prog3(void *ctx)

{

	struct task_struct *t = (void *)bpf_get_current_task();

	if (!BPF_CORE_READ(t, pid) || !get_task_tgid((uintptr_t)t))

		return 1;

	res3 = sub3(5) + 6; /* (5 + 3 + (4 + 1)) + 6 = 19 */

	return 0;

}

/* prog4 has the same section name as prog2 */

SEC("raw_tp/sys_exit")

int prog4(void *ctx)

{

	struct task_struct *t = (void *)bpf_get_current_task();

	if (!BPF_CORE_READ(t, pid) || !get_task_tgid((uintptr_t)t))

		return 1;

	res4 = sub4(7) + sub1(8); /* (7 + (5 + 3 + (4 + 1)) + (6 + 1)) + (8 + 1) = 36 */

	return 0;

}