Commit 9e80114b authored by Andrii Nakryiko's avatar Andrii Nakryiko Committed by Alexei Starovoitov
Browse files

selftests/bpf: Add tests for user- and non-CO-RE BPF_CORE_READ() variants 



Add selftests validating that newly added variations of BPF_CORE_READ(), for
use with user-space addresses and for non-CO-RE reads, work as expected.

Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20201218235614.2284956-4-andrii@kernel.org


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent a4b09a9e

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

0 → 100644
+64 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/* Copyright (c) 2020 Facebook */



#include <test_progs.h>



struct callback_head {

	struct callback_head *next;

	void (*func)(struct callback_head *head);

};



/* ___shuffled flavor is just an illusion for BPF code, it doesn't really

 * exist and user-space needs to provide data in the memory layout that

 * matches callback_head. We just defined ___shuffled flavor to make it easier

 * to work with the skeleton

 */

struct callback_head___shuffled {

	struct callback_head___shuffled *next;

	void (*func)(struct callback_head *head);

};



#include "test_core_read_macros.skel.h"



void test_core_read_macros(void)

{

	int duration = 0, err;

	struct test_core_read_macros* skel;

	struct test_core_read_macros__bss *bss;

	struct callback_head u_probe_in;

	struct callback_head___shuffled u_core_in;



	skel = test_core_read_macros__open_and_load();

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

		return;

	bss = skel->bss;

	bss->my_pid = getpid();



	/* next pointers have to be set from the kernel side */

	bss->k_probe_in.func = (void *)(long)0x1234;

	bss->k_core_in.func = (void *)(long)0xabcd;



	u_probe_in.next = &u_probe_in;

	u_probe_in.func = (void *)(long)0x5678;

	bss->u_probe_in = &u_probe_in;



	u_core_in.next = &u_core_in;

	u_core_in.func = (void *)(long)0xdbca;

	bss->u_core_in = &u_core_in;



	err = test_core_read_macros__attach(skel);

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

		goto cleanup;



	/* trigger tracepoint */

	usleep(1);



	ASSERT_EQ(bss->k_probe_out, 0x1234, "k_probe_out");

	ASSERT_EQ(bss->k_core_out, 0xabcd, "k_core_out");



	ASSERT_EQ(bss->u_probe_out, 0x5678, "u_probe_out");

	ASSERT_EQ(bss->u_core_out, 0xdbca, "u_core_out");



cleanup:

	test_core_read_macros__destroy(skel);

}

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

0 → 100644
+50 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

// Copyright (c) 2020 Facebook



#include "vmlinux.h"

#include <bpf/bpf_helpers.h>

#include <bpf/bpf_core_read.h>



char _license[] SEC("license") = "GPL";



/* shuffled layout for relocatable (CO-RE) reads */

struct callback_head___shuffled {

	void (*func)(struct callback_head___shuffled *head);

	struct callback_head___shuffled *next;

};



struct callback_head k_probe_in = {};

struct callback_head___shuffled k_core_in = {};



struct callback_head *u_probe_in = 0;

struct callback_head___shuffled *u_core_in = 0;



long k_probe_out = 0;

long u_probe_out = 0;



long k_core_out = 0;

long u_core_out = 0;



int my_pid = 0;



SEC("raw_tracepoint/sys_enter")

int handler(void *ctx)

{

	int pid = bpf_get_current_pid_tgid() >> 32;



	if (my_pid != pid)

		return 0;



	/* next pointers for kernel address space have to be initialized from

	 * BPF side, user-space mmaped addresses are stil user-space addresses

	 */

	k_probe_in.next = &k_probe_in;

	__builtin_preserve_access_index(({k_core_in.next = &k_core_in;}));



	k_probe_out = (long)BPF_PROBE_READ(&k_probe_in, next, next, func);

	k_core_out = (long)BPF_CORE_READ(&k_core_in, next, next, func);

	u_probe_out = (long)BPF_PROBE_READ_USER(u_probe_in, next, next, func);

	u_core_out = (long)BPF_CORE_READ_USER(u_core_in, next, next, func);



	return 0;

}