Commit 8f7a86ec authored by Xu Kuohai's avatar Xu Kuohai Committed by Andrii Nakryiko
Browse files

selftests/bpf: Add overwrite mode test for BPF ring buffer 



Add overwrite mode test for BPF ring buffer. The test creates a BPF ring
buffer in overwrite mode, then repeatedly reserves and commits records
to check if the ring buffer works as expected both before and after
overwriting occurs.

Signed-off-by: default avatarXu Kuohai <xukuohai@huawei.com>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20251018035738.4039621-3-xukuohai@huaweicloud.com
parent feeaf134

tools/testing/selftests/bpf/Makefile

+2 −1
Original line number Diff line number Diff line
@@ -499,7 +499,8 @@ LINKED_SKELS := test_static_linked.skel.h linked_funcs.skel.h \ 


LSKELS := fexit_sleep.c trace_printk.c trace_vprintk.c map_ptr_kern.c 	\

	core_kern.c core_kern_overflow.c test_ringbuf.c			\

	test_ringbuf_n.c test_ringbuf_map_key.c test_ringbuf_write.c

	test_ringbuf_n.c test_ringbuf_map_key.c test_ringbuf_write.c    \

	test_ringbuf_overwrite.c



LSKELS_SIGNED := fentry_test.c fexit_test.c atomics.c

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

+65 −0
Original line number Diff line number Diff line
@@ -17,6 +17,7 @@ 
#include "test_ringbuf_n.lskel.h"

#include "test_ringbuf_map_key.lskel.h"

#include "test_ringbuf_write.lskel.h"

#include "test_ringbuf_overwrite.lskel.h"



#define EDONE 7777
@@ -497,6 +498,68 @@ static void ringbuf_map_key_subtest(void) 
	test_ringbuf_map_key_lskel__destroy(skel_map_key);

}



static void ringbuf_overwrite_mode_subtest(void)

{

	unsigned long size, len1, len2, len3, len4, len5;

	unsigned long expect_avail_data, expect_prod_pos, expect_over_pos;

	struct test_ringbuf_overwrite_lskel *skel;

	int page_size = getpagesize();

	int err;



	skel = test_ringbuf_overwrite_lskel__open();

	if (!ASSERT_OK_PTR(skel, "skel_open"))

		return;



	size = page_size;

	len1 = page_size / 2;

	len2 = page_size / 4;

	len3 = size - len1 - len2 - BPF_RINGBUF_HDR_SZ * 3;

	len4 = len3 - 8;

	len5 = len3; /* retry with len3 */



	skel->maps.ringbuf.max_entries = size;

	skel->rodata->LEN1 = len1;

	skel->rodata->LEN2 = len2;

	skel->rodata->LEN3 = len3;

	skel->rodata->LEN4 = len4;

	skel->rodata->LEN5 = len5;



	skel->bss->pid = getpid();



	err = test_ringbuf_overwrite_lskel__load(skel);

	if (!ASSERT_OK(err, "skel_load"))

		goto cleanup;



	err = test_ringbuf_overwrite_lskel__attach(skel);

	if (!ASSERT_OK(err, "skel_attach"))

		goto cleanup;



	syscall(__NR_getpgid);



	ASSERT_EQ(skel->bss->reserve1_fail, 0, "reserve 1");

	ASSERT_EQ(skel->bss->reserve2_fail, 0, "reserve 2");

	ASSERT_EQ(skel->bss->reserve3_fail, 1, "reserve 3");

	ASSERT_EQ(skel->bss->reserve4_fail, 0, "reserve 4");

	ASSERT_EQ(skel->bss->reserve5_fail, 0, "reserve 5");



	ASSERT_EQ(skel->bss->ring_size, size, "check_ring_size");



	expect_avail_data = len2 + len4 + len5 + 3 * BPF_RINGBUF_HDR_SZ;

	ASSERT_EQ(skel->bss->avail_data, expect_avail_data, "check_avail_size");



	ASSERT_EQ(skel->bss->cons_pos, 0, "check_cons_pos");



	expect_prod_pos = len1 + len2 + len4 + len5 + 4 * BPF_RINGBUF_HDR_SZ;

	ASSERT_EQ(skel->bss->prod_pos, expect_prod_pos, "check_prod_pos");



	expect_over_pos = len1 + BPF_RINGBUF_HDR_SZ;

	ASSERT_EQ(skel->bss->over_pos, expect_over_pos, "check_over_pos");



	test_ringbuf_overwrite_lskel__detach(skel);

cleanup:

	test_ringbuf_overwrite_lskel__destroy(skel);

}



void test_ringbuf(void)

{

	if (test__start_subtest("ringbuf"))
@@ -507,4 +570,6 @@ void test_ringbuf(void) 
		ringbuf_map_key_subtest();

	if (test__start_subtest("ringbuf_write"))

		ringbuf_write_subtest();

	if (test__start_subtest("ringbuf_overwrite_mode"))

		ringbuf_overwrite_mode_subtest();

}

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

0 → 100644
+98 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/* Copyright (C) 2025. Huawei Technologies Co., Ltd */



#include <linux/bpf.h>

#include <bpf/bpf_helpers.h>

#include "bpf_misc.h"



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



struct {

	__uint(type, BPF_MAP_TYPE_RINGBUF);

	__uint(map_flags, BPF_F_RB_OVERWRITE);

} ringbuf SEC(".maps");



int pid;



const volatile unsigned long LEN1;

const volatile unsigned long LEN2;

const volatile unsigned long LEN3;

const volatile unsigned long LEN4;

const volatile unsigned long LEN5;



long reserve1_fail = 0;

long reserve2_fail = 0;

long reserve3_fail = 0;

long reserve4_fail = 0;

long reserve5_fail = 0;



unsigned long avail_data = 0;

unsigned long ring_size = 0;

unsigned long cons_pos = 0;

unsigned long prod_pos = 0;

unsigned long over_pos = 0;



SEC("fentry/" SYS_PREFIX "sys_getpgid")

int test_overwrite_ringbuf(void *ctx)

{

	char *rec1, *rec2, *rec3, *rec4, *rec5;

	int cur_pid = bpf_get_current_pid_tgid() >> 32;



	if (cur_pid != pid)

		return 0;



	rec1 = bpf_ringbuf_reserve(&ringbuf, LEN1, 0);

	if (!rec1) {

		reserve1_fail = 1;

		return 0;

	}



	rec2 = bpf_ringbuf_reserve(&ringbuf, LEN2, 0);

	if (!rec2) {

		bpf_ringbuf_discard(rec1, 0);

		reserve2_fail = 1;

		return 0;

	}



	rec3 = bpf_ringbuf_reserve(&ringbuf, LEN3, 0);

	/* expect failure */

	if (!rec3) {

		reserve3_fail = 1;

	} else {

		bpf_ringbuf_discard(rec1, 0);

		bpf_ringbuf_discard(rec2, 0);

		bpf_ringbuf_discard(rec3, 0);

		return 0;

	}



	rec4 = bpf_ringbuf_reserve(&ringbuf, LEN4, 0);

	if (!rec4) {

		reserve4_fail = 1;

		bpf_ringbuf_discard(rec1, 0);

		bpf_ringbuf_discard(rec2, 0);

		return 0;

	}



	bpf_ringbuf_submit(rec1, 0);

	bpf_ringbuf_submit(rec2, 0);

	bpf_ringbuf_submit(rec4, 0);



	rec5 = bpf_ringbuf_reserve(&ringbuf, LEN5, 0);

	if (!rec5) {

		reserve5_fail = 1;

		return 0;

	}



	for (int i = 0; i < LEN3; i++)

		rec5[i] = 0xdd;



	bpf_ringbuf_submit(rec5, 0);



	ring_size = bpf_ringbuf_query(&ringbuf, BPF_RB_RING_SIZE);

	avail_data = bpf_ringbuf_query(&ringbuf, BPF_RB_AVAIL_DATA);

	cons_pos = bpf_ringbuf_query(&ringbuf, BPF_RB_CONS_POS);

	prod_pos = bpf_ringbuf_query(&ringbuf, BPF_RB_PROD_POS);

	over_pos = bpf_ringbuf_query(&ringbuf, BPF_RB_OVERWRITE_POS);



	return 0;

}