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[93.72.16.93]) by smtp.gmail.com with ESMTPSA id o9-20020a170906600900b006fec8e5b8a9sm9596730ejj.152.2022.06.08.12.27.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 08 Jun 2022 12:27:42 -0700 (PDT) From: Eduard Zingerman To: bpf@vger.kernel.org, ast@kernel.org, andrii@kernel.org, daniel@iogearbox.net, kernel-team@fb.com, song@kernel.org, joannelkoong@gmail.com Cc: eddyz87@gmail.com Subject: [PATCH bpf-next v4 5/5] selftests/bpf: BPF test_prog selftests for bpf_loop inlining Date: Wed, 8 Jun 2022 22:26:30 +0300 Message-Id: <20220608192630.3710333-6-eddyz87@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220608192630.3710333-1-eddyz87@gmail.com> References: <20220608192630.3710333-1-eddyz87@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net Two new test BPF programs for test_prog selftests checking bpf_loop behavior. Both are corner cases for bpf_loop inlinig transformation: - check that bpf_loop behaves correctly when callback function is not a compile time constant - check that local function variables are not affected by allocating additional stack storage for registers spilled by loop inlining Signed-off-by: Eduard Zingerman Acked-by: Song Liu --- .../selftests/bpf/prog_tests/bpf_loop.c | 62 ++++++++++ tools/testing/selftests/bpf/progs/bpf_loop.c | 114 ++++++++++++++++++ 2 files changed, 176 insertions(+) diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_loop.c b/tools/testing/selftests/bpf/prog_tests/bpf_loop.c index 380d7a2072e3..4cd8a25afe68 100644 --- a/tools/testing/selftests/bpf/prog_tests/bpf_loop.c +++ b/tools/testing/selftests/bpf/prog_tests/bpf_loop.c @@ -120,6 +120,64 @@ static void check_nested_calls(struct bpf_loop *skel) bpf_link__destroy(link); } +static void check_non_constant_callback(struct bpf_loop *skel) +{ + struct bpf_link *link = + bpf_program__attach(skel->progs.prog_non_constant_callback); + + if (!ASSERT_OK_PTR(link, "link")) + return; + + skel->bss->callback_selector = 0x0F; + usleep(1); + ASSERT_EQ(skel->bss->g_output, 0x0F, "g_output #1"); + + skel->bss->callback_selector = 0xF0; + usleep(1); + ASSERT_EQ(skel->bss->g_output, 0xF0, "g_output #2"); + + bpf_link__destroy(link); +} + +static void check_stack(struct bpf_loop *skel) +{ + struct bpf_link *link = bpf_program__attach(skel->progs.stack_check); + const int max_key = 12; + int key; + int map_fd; + + if (!ASSERT_OK_PTR(link, "link")) + return; + + map_fd = bpf_map__fd(skel->maps.map1); + + if (!ASSERT_GE(map_fd, 0, "bpf_map__fd")) + goto out; + + for (key = 1; key <= max_key; ++key) { + int val = key; + int err = bpf_map_update_elem(map_fd, &key, &val, BPF_NOEXIST); + + if (!ASSERT_OK(err, "bpf_map_update_elem")) + goto out; + } + + usleep(1); + + for (key = 1; key <= max_key; ++key) { + int val; + int err = bpf_map_lookup_elem(map_fd, &key, &val); + + if (!ASSERT_OK(err, "bpf_map_lookup_elem")) + goto out; + if (!ASSERT_EQ(val, key + 1, "bad value in the map")) + goto out; + } + +out: + bpf_link__destroy(link); +} + void test_bpf_loop(void) { struct bpf_loop *skel; @@ -140,6 +198,10 @@ void test_bpf_loop(void) check_invalid_flags(skel); if (test__start_subtest("check_nested_calls")) check_nested_calls(skel); + if (test__start_subtest("check_non_constant_callback")) + check_non_constant_callback(skel); + if (test__start_subtest("check_stack")) + check_stack(skel); bpf_loop__destroy(skel); } diff --git a/tools/testing/selftests/bpf/progs/bpf_loop.c b/tools/testing/selftests/bpf/progs/bpf_loop.c index e08565282759..de1fc82d2710 100644 --- a/tools/testing/selftests/bpf/progs/bpf_loop.c +++ b/tools/testing/selftests/bpf/progs/bpf_loop.c @@ -11,11 +11,19 @@ struct callback_ctx { int output; }; +struct { + __uint(type, BPF_MAP_TYPE_HASH); + __uint(max_entries, 32); + __type(key, int); + __type(value, int); +} map1 SEC(".maps"); + /* These should be set by the user program */ u32 nested_callback_nr_loops; u32 stop_index = -1; u32 nr_loops; int pid; +int callback_selector; /* Making these global variables so that the userspace program * can verify the output through the skeleton @@ -111,3 +119,109 @@ int prog_nested_calls(void *ctx) return 0; } + +static int callback_set_f0(int i, void *ctx) +{ + g_output = 0xF0; + return 0; +} + +static int callback_set_0f(int i, void *ctx) +{ + g_output = 0x0F; + return 0; +} + +/* + * non-constant callback is a corner case for bpf_loop inline logic + */ +SEC("fentry/" SYS_PREFIX "sys_nanosleep") +int prog_non_constant_callback(void *ctx) +{ + struct callback_ctx data = {}; + + if (bpf_get_current_pid_tgid() >> 32 != pid) + return 0; + + int (*callback)(int i, void *ctx); + + g_output = 0; + + if (callback_selector == 0x0F) + callback = callback_set_0f; + else + callback = callback_set_f0; + + bpf_loop(1, callback, NULL, 0); + + return 0; +} + +static int stack_check_inner_callback(void *ctx) +{ + return 0; +} + +static int map1_lookup_elem(int key) +{ + int *val = bpf_map_lookup_elem(&map1, &key); + + return val ? *val : -1; +} + +static void map1_update_elem(int key, int val) +{ + bpf_map_update_elem(&map1, &key, &val, BPF_ANY); +} + +static int stack_check_outer_callback(void *ctx) +{ + int a = map1_lookup_elem(1); + int b = map1_lookup_elem(2); + int c = map1_lookup_elem(3); + int d = map1_lookup_elem(4); + int e = map1_lookup_elem(5); + int f = map1_lookup_elem(6); + + bpf_loop(1, stack_check_inner_callback, NULL, 0); + + map1_update_elem(1, a + 1); + map1_update_elem(2, b + 1); + map1_update_elem(3, c + 1); + map1_update_elem(4, d + 1); + map1_update_elem(5, e + 1); + map1_update_elem(6, f + 1); + + return 0; +} + +/* Some of the local variables in stack_check and + * stack_check_outer_callback would be allocated on stack by + * compiler. This test should verify that stack content for these + * variables is preserved between calls to bpf_loop (might be an issue + * if loop inlining allocates stack slots incorrectly). + */ +SEC("fentry/" SYS_PREFIX "sys_nanosleep") +int stack_check(void *ctx) +{ + if (bpf_get_current_pid_tgid() >> 32 != pid) + return 0; + + int a = map1_lookup_elem(7); + int b = map1_lookup_elem(8); + int c = map1_lookup_elem(9); + int d = map1_lookup_elem(10); + int e = map1_lookup_elem(11); + int f = map1_lookup_elem(12); + + bpf_loop(1, stack_check_outer_callback, NULL, 0); + + map1_update_elem(7, a + 1); + map1_update_elem(8, b + 1); + map1_update_elem(9, c + 1); + map1_update_elem(10, d + 1); + map1_update_elem(11, e + 1); + map1_update_elem(12, f + 1); + + return 0; +}