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selftests/bpf: Add bpf_loop test
Add test for bpf_loop testing a variety of cases: various nr_loops, null callback ctx, invalid flags, nested callbacks. Signed-off-by: Joanne Koong <[email protected]> Acked-by: Andrii Nakryiko <[email protected]>
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‎tools/testing/selftests/bpf/prog_tests/bpf_loop.c

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// SPDX-License-Identifier: GPL-2.0
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/* Copyright (c) 2021 Facebook */
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#include <test_progs.h>
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#include <network_helpers.h>
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#include "bpf_loop.skel.h"
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static void check_nr_loops(struct bpf_loop *skel)
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{
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struct bpf_link *link;
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link = bpf_program__attach(skel->progs.test_prog);
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if (!ASSERT_OK_PTR(link, "link"))
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return;
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/* test 0 loops */
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skel->bss->nr_loops = 0;
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usleep(1);
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ASSERT_EQ(skel->bss->nr_loops_returned, skel->bss->nr_loops,
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"0 loops");
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/* test 500 loops */
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skel->bss->nr_loops = 500;
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usleep(1);
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ASSERT_EQ(skel->bss->nr_loops_returned, skel->bss->nr_loops,
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"500 loops");
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ASSERT_EQ(skel->bss->g_output, (500 * 499) / 2, "g_output");
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/* test exceeding the max limit */
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skel->bss->nr_loops = -1;
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usleep(1);
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ASSERT_EQ(skel->bss->err, -E2BIG, "over max limit");
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bpf_link__destroy(link);
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}
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static void check_callback_fn_stop(struct bpf_loop *skel)
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{
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struct bpf_link *link;
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link = bpf_program__attach(skel->progs.test_prog);
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if (!ASSERT_OK_PTR(link, "link"))
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return;
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/* testing that loop is stopped when callback_fn returns 1 */
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skel->bss->nr_loops = 400;
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skel->data->stop_index = 50;
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usleep(1);
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ASSERT_EQ(skel->bss->nr_loops_returned, skel->data->stop_index + 1,
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"nr_loops_returned");
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ASSERT_EQ(skel->bss->g_output, (50 * 49) / 2,
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"g_output");
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bpf_link__destroy(link);
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}
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static void check_null_callback_ctx(struct bpf_loop *skel)
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{
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struct bpf_link *link;
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/* check that user is able to pass in a null callback_ctx */
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link = bpf_program__attach(skel->progs.prog_null_ctx);
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if (!ASSERT_OK_PTR(link, "link"))
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return;
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skel->bss->nr_loops = 10;
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usleep(1);
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ASSERT_EQ(skel->bss->nr_loops_returned, skel->bss->nr_loops,
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"nr_loops_returned");
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bpf_link__destroy(link);
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}
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static void check_invalid_flags(struct bpf_loop *skel)
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{
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struct bpf_link *link;
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/* check that passing in non-zero flags returns -EINVAL */
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link = bpf_program__attach(skel->progs.prog_invalid_flags);
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if (!ASSERT_OK_PTR(link, "link"))
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return;
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usleep(1);
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ASSERT_EQ(skel->bss->err, -EINVAL, "err");
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bpf_link__destroy(link);
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}
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static void check_nested_calls(struct bpf_loop *skel)
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{
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__u32 nr_loops = 100, nested_callback_nr_loops = 4;
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struct bpf_link *link;
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/* check that nested calls are supported */
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link = bpf_program__attach(skel->progs.prog_nested_calls);
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if (!ASSERT_OK_PTR(link, "link"))
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return;
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skel->bss->nr_loops = nr_loops;
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skel->bss->nested_callback_nr_loops = nested_callback_nr_loops;
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usleep(1);
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ASSERT_EQ(skel->bss->nr_loops_returned, nr_loops * nested_callback_nr_loops
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* nested_callback_nr_loops, "nr_loops_returned");
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ASSERT_EQ(skel->bss->g_output, (4 * 3) / 2 * nested_callback_nr_loops
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* nr_loops, "g_output");
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bpf_link__destroy(link);
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}
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void test_bpf_loop(void)
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{
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struct bpf_loop *skel;
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skel = bpf_loop__open_and_load();
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if (!ASSERT_OK_PTR(skel, "bpf_loop__open_and_load"))
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return;
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skel->bss->pid = getpid();
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if (test__start_subtest("check_nr_loops"))
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check_nr_loops(skel);
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if (test__start_subtest("check_callback_fn_stop"))
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check_callback_fn_stop(skel);
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if (test__start_subtest("check_null_callback_ctx"))
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check_null_callback_ctx(skel);
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if (test__start_subtest("check_invalid_flags"))
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check_invalid_flags(skel);
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if (test__start_subtest("check_nested_calls"))
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check_nested_calls(skel);
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bpf_loop__destroy(skel);
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}

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

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// SPDX-License-Identifier: GPL-2.0
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/* Copyright (c) 2021 Facebook */
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#include "vmlinux.h"
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#include <bpf/bpf_helpers.h>
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char _license[] SEC("license") = "GPL";
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struct callback_ctx {
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int output;
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};
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/* These should be set by the user program */
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u32 nested_callback_nr_loops;
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u32 stop_index = -1;
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u32 nr_loops;
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int pid;
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/* Making these global variables so that the userspace program
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* can verify the output through the skeleton
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*/
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int nr_loops_returned;
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int g_output;
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int err;
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static int callback(__u32 index, void *data)
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{
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struct callback_ctx *ctx = data;
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if (index >= stop_index)
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return 1;
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ctx->output += index;
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return 0;
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}
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static int empty_callback(__u32 index, void *data)
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{
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return 0;
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}
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static int nested_callback2(__u32 index, void *data)
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{
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nr_loops_returned += bpf_loop(nested_callback_nr_loops, callback, data, 0);
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return 0;
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}
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static int nested_callback1(__u32 index, void *data)
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{
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bpf_loop(nested_callback_nr_loops, nested_callback2, data, 0);
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return 0;
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}
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SEC("fentry/__x64_sys_nanosleep")
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int test_prog(void *ctx)
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{
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struct callback_ctx data = {};
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if (bpf_get_current_pid_tgid() >> 32 != pid)
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return 0;
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nr_loops_returned = bpf_loop(nr_loops, callback, &data, 0);
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if (nr_loops_returned < 0)
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err = nr_loops_returned;
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else
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g_output = data.output;
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return 0;
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}
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SEC("fentry/__x64_sys_nanosleep")
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int prog_null_ctx(void *ctx)
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{
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if (bpf_get_current_pid_tgid() >> 32 != pid)
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return 0;
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nr_loops_returned = bpf_loop(nr_loops, empty_callback, NULL, 0);
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return 0;
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}
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SEC("fentry/__x64_sys_nanosleep")
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int prog_invalid_flags(void *ctx)
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{
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struct callback_ctx data = {};
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if (bpf_get_current_pid_tgid() >> 32 != pid)
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return 0;
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err = bpf_loop(nr_loops, callback, &data, 1);
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return 0;
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}
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SEC("fentry/__x64_sys_nanosleep")
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int prog_nested_calls(void *ctx)
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{
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struct callback_ctx data = {};
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if (bpf_get_current_pid_tgid() >> 32 != pid)
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return 0;
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nr_loops_returned = 0;
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bpf_loop(nr_loops, nested_callback1, &data, 0);
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g_output = data.output;
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return 0;
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}

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