[PATCH v5 bpf-next 8/8] selftests/bpf: implement and test custom testmod_seq iterator

Andrii Nakryiko
2023-03-08T18:41:48Z

Implement a trivial iterator returning same specified integer value
N times as part of bpf_testmod kernel module. Add selftests to validate
everything works end to end.

We also reuse these tests as "verification-only" tests to validate that
kernel prints the state of custom kernel module-defined iterator correctly:

fp-16=iter_testmod_seq(ref_id=1,state=drained,depth=0)

"testmod_seq" part is an iterator type, and is coming from module's BTF
data dynamically at runtime.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
tools/testing/selftests/bpf/DENYLIST.s390x | 1 +
.../selftests/bpf/bpf_testmod/bpf_testmod.c | 42 +++++++++-
.../selftests/bpf/bpf_testmod/bpf_testmod.h | 6 ++
.../testing/selftests/bpf/prog_tests/iters.c | 42 ++++++++++
.../selftests/bpf/progs/iters_testmod_seq.c | 79 +++++++++++++++++++
5 files changed, 169 insertions(+), 1 deletion(-)
create mode 100644 tools/testing/selftests/bpf/progs/iters_testmod_seq.c

diff --git a/tools/testing/selftests/bpf/DENYLIST.s390x b/tools/testing/selftests/bpf/DENYLIST.s390x
index a02a085e7f32..34cb8b2de8ca 100644
--- a/tools/testing/selftests/bpf/DENYLIST.s390x
+++ b/tools/testing/selftests/bpf/DENYLIST.s390x
@@ -8,6 +8,7 @@ dynptr/test_dynptr_skb_data
dynptr/test_skb_readonly
fexit_sleep # fexit_skel_load fexit skeleton failed (trampoline)
get_stack_raw_tp # user_stack corrupted user stack (no backchain userspace)
+iters/testmod_seq* # s390x doesn't support kfuncs in modules yet
kprobe_multi_bench_attach # bpf_program__attach_kprobe_multi_opts unexpected error: -95
kprobe_multi_test # relies on fentry
ksyms_module # test_ksyms_module__open_and_load unexpected error: -9 (?)
diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
index 46500636d8cd..5e6e85c8d77d 100644
--- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
+++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
@@ -65,6 +65,34 @@ bpf_testmod_test_mod_kfunc(int i)
*(int *)this_cpu_ptr(&bpf_testmod_ksym_percpu) = i;
}

+__bpf_kfunc int bpf_iter_testmod_seq_new(struct bpf_iter_testmod_seq *it, s64 value, int cnt)
+{
+ if (cnt < 0) {
+ it->cnt = 0;
+ return -EINVAL;
+ }
+
+ it->value = value;
+ it->cnt = cnt;
+
+ return 0;
+}
+
+__bpf_kfunc s64 *bpf_iter_testmod_seq_next(struct bpf_iter_testmod_seq* it)
+{
+ if (it->cnt <= 0)
+ return NULL;
+
+ it->cnt--;
+
+ return &it->value;
+}
+
+__bpf_kfunc void bpf_iter_testmod_seq_destroy(struct bpf_iter_testmod_seq *it)
+{
+ it->cnt = 0;
+}
+
struct bpf_testmod_btf_type_tag_1 {
int a;
};
@@ -220,6 +248,17 @@ static struct bin_attribute bin_attr_bpf_testmod_file __ro_after_init = {
.write = bpf_testmod_test_write,
};

+BTF_SET8_START(bpf_testmod_common_kfunc_ids)
+BTF_ID_FLAGS(func, bpf_iter_testmod_seq_new, KF_ITER_NEW)
+BTF_ID_FLAGS(func, bpf_iter_testmod_seq_next, KF_ITER_NEXT | KF_RET_NULL)
+BTF_ID_FLAGS(func, bpf_iter_testmod_seq_destroy, KF_ITER_DESTROY)
+BTF_SET8_END(bpf_testmod_common_kfunc_ids)
+
+static const struct btf_kfunc_id_set bpf_testmod_common_kfunc_set = {
+ .owner = THIS_MODULE,
+ .set = &bpf_testmod_common_kfunc_ids,
+};
+
BTF_SET8_START(bpf_testmod_check_kfunc_ids)
BTF_ID_FLAGS(func, bpf_testmod_test_mod_kfunc)
BTF_SET8_END(bpf_testmod_check_kfunc_ids)
@@ -235,7 +274,8 @@ static int bpf_testmod_init(void)
{
int ret;

- ret = register_btf_kfunc_id_set(BPF_PROG_TYPE_SCHED_CLS, &bpf_testmod_kfunc_set);
+ ret = register_btf_kfunc_id_set(BPF_PROG_TYPE_UNSPEC, &bpf_testmod_common_kfunc_set);
+ ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_SCHED_CLS, &bpf_testmod_kfunc_set);
if (ret < 0)
return ret;
if (bpf_fentry_test1(0) < 0)
diff --git a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h
index 0d71e2607832..f32793efe095 100644
--- a/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h
+++ b/tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h
@@ -22,4 +22,10 @@ struct bpf_testmod_test_writable_ctx {
int val;
};

+/* BPF iter that returns *value* *n* times in a row */
+struct bpf_iter_testmod_seq {
+ s64 value;
+ int cnt;
+};
+
#endif /* _BPF_TESTMOD_H */
diff --git a/tools/testing/selftests/bpf/prog_tests/iters.c b/tools/testing/selftests/bpf/prog_tests/iters.c
index 2e7caff9523e..10804ae5ae97 100644
--- a/tools/testing/selftests/bpf/prog_tests/iters.c
+++ b/tools/testing/selftests/bpf/prog_tests/iters.c
@@ -7,6 +7,7 @@
#include "iters_state_safety.skel.h"
#include "iters_looping.skel.h"
#include "iters_num.skel.h"
+#include "iters_testmod_seq.skel.h"

static void subtest_num_iters(void)
{
@@ -53,12 +54,53 @@ static void subtest_num_iters(void)
iters_num__destroy(skel);
}

+static void subtest_testmod_seq_iters(void)
+{
+ struct iters_testmod_seq *skel;
+ int err;
+
+ if (!env.has_testmod) {
+ test__skip();
+ return;
+ }
+
+ skel = iters_testmod_seq__open_and_load();
+ if (!ASSERT_OK_PTR(skel, "skel_open_and_load"))
+ return;
+
+ err = iters_testmod_seq__attach(skel);
+ if (!ASSERT_OK(err, "skel_attach"))
+ goto cleanup;
+
+ usleep(1);
+ iters_testmod_seq__detach(skel);
+
+#define VALIDATE_CASE(case_name) \
+ ASSERT_EQ(skel->bss->res_##case_name, \
+ skel->rodata->exp_##case_name, \
+ #case_name)
+
+ VALIDATE_CASE(empty);
+ VALIDATE_CASE(full);
+ VALIDATE_CASE(truncated);
+
+#undef VALIDATE_CASE
+
+cleanup:
+ iters_testmod_seq__destroy(skel);
+}
+
void test_iters(void)
{
RUN_TESTS(iters_state_safety);
RUN_TESTS(iters_looping);
RUN_TESTS(iters);

+ if (env.has_testmod)
+ RUN_TESTS(iters_testmod_seq);
+
if (test__start_subtest("num"))
subtest_num_iters();
+ if (test__start_subtest("testmod_seq"))
+ subtest_testmod_seq_iters();
}
diff --git a/tools/testing/selftests/bpf/progs/iters_testmod_seq.c b/tools/testing/selftests/bpf/progs/iters_testmod_seq.c
new file mode 100644
index 000000000000..3873fb6c292a
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/iters_testmod_seq.c
@@ -0,0 +1,79 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2023 Meta Platforms, Inc. and affiliates. */
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include "bpf_misc.h"
+
+struct bpf_iter_testmod_seq {
+ u64 :64;
+ u64 :64;
+};
+
+extern int bpf_iter_testmod_seq_new(struct bpf_iter_testmod_seq *it, s64 value, int cnt) __ksym;
+extern s64 *bpf_iter_testmod_seq_next(struct bpf_iter_testmod_seq *it) __ksym;
+extern void bpf_iter_testmod_seq_destroy(struct bpf_iter_testmod_seq *it) __ksym;
+
+const volatile __s64 exp_empty = 0 + 1;
+__s64 res_empty;
+
+SEC("raw_tp/sys_enter")
+__success __log_level(2)
+__msg("fp-16_w=iter_testmod_seq(ref_id=1,state=active,depth=0)")
+__msg("fp-16=iter_testmod_seq(ref_id=1,state=drained,depth=0)")
+__msg("call bpf_iter_testmod_seq_destroy")
+int testmod_seq_empty(const void *ctx)
+{
+ __s64 sum = 0, *i;
+
+ bpf_for_each(testmod_seq, i, 1000, 0) sum += *i;
+ res_empty = 1 + sum;
+
+ return 0;
+}
+
+const volatile __s64 exp_full = 1000000;
+__s64 res_full;
+
+SEC("raw_tp/sys_enter")
+__success __log_level(2)
+__msg("fp-16_w=iter_testmod_seq(ref_id=1,state=active,depth=0)")
+__msg("fp-16=iter_testmod_seq(ref_id=1,state=drained,depth=0)")
+__msg("call bpf_iter_testmod_seq_destroy")
+int testmod_seq_full(const void *ctx)
+{
+ __s64 sum = 0, *i;
+
+ bpf_for_each(testmod_seq, i, 1000, 1000) sum += *i;
+ res_full = sum;
+
+ return 0;
+}
+
+const volatile __s64 exp_truncated = 10 * 1000000;
+__s64 res_truncated;
+
+static volatile int zero = 0;
+
+SEC("raw_tp/sys_enter")
+__success __log_level(2)
+__msg("fp-16_w=iter_testmod_seq(ref_id=1,state=active,depth=0)")
+__msg("fp-16=iter_testmod_seq(ref_id=1,state=drained,depth=0)")
+__msg("call bpf_iter_testmod_seq_destroy")
+int testmod_seq_truncated(const void *ctx)
+{
+ __s64 sum = 0, *i;
+ int cnt = zero;
+
+ bpf_for_each(testmod_seq, i, 10, 2000000) {
+ sum += *i;
+ cnt++;
+ if (cnt >= 1000000)
+ break;
+ }
+ res_truncated = sum;
+
+ return 0;
+}
+
+char _license[] SEC("license") = "GPL";
--
2.34.1