Re: [PATCH bpf-next v1 2/2] selftests/bpf: Add tests for preempt kfuncs

[Jiri Olsa <olsajiri@gmail.com>]

On Tue, Apr 23, 2024 at 06:19:22AM +0000, Kumar Kartikeya Dwivedi wrote:
> Add tests for nested cases, nested count preservation upon different
> subprog calls that disable/enable preemption, and test sleepable helper
> call in non-preemptible regions.
> 
> 181/1   preempt_lock/preempt_lock_missing_1:OK
> 181/2   preempt_lock/preempt_lock_missing_2:OK
> 181/3   preempt_lock/preempt_lock_missing_3:OK
> 181/4   preempt_lock/preempt_lock_missing_3_minus_2:OK
> 181/5   preempt_lock/preempt_lock_missing_1_subprog:OK
> 181/6   preempt_lock/preempt_lock_missing_2_subprog:OK
> 181/7   preempt_lock/preempt_lock_missing_2_minus_1_subprog:OK
> 181/8   preempt_lock/preempt_balance:OK
> 181/9   preempt_lock/preempt_balance_subprog_test:OK
> 181/10  preempt_lock/preempt_sleepable_helper:OK

should we also check that the global function call is not allowed?

jirka

> 181     preempt_lock:OK
> Summary: 1/10 PASSED, 0 SKIPPED, 0 FAILED
> 
> Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
> ---
>  .../selftests/bpf/prog_tests/preempt_lock.c   |   9 ++
>  .../selftests/bpf/progs/preempt_lock.c        | 119 ++++++++++++++++++
>  2 files changed, 128 insertions(+)
>  create mode 100644 tools/testing/selftests/bpf/prog_tests/preempt_lock.c
>  create mode 100644 tools/testing/selftests/bpf/progs/preempt_lock.c
> 
> diff --git a/tools/testing/selftests/bpf/prog_tests/preempt_lock.c b/tools/testing/selftests/bpf/prog_tests/preempt_lock.c
> new file mode 100644
> index 000000000000..02917c672441
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/prog_tests/preempt_lock.c
> @@ -0,0 +1,9 @@
> +// SPDX-License-Identifier: GPL-2.0
> +#include <test_progs.h>
> +#include <network_helpers.h>
> +#include <preempt_lock.skel.h>
> +
> +void test_preempt_lock(void)
> +{
> +	RUN_TESTS(preempt_lock);
> +}
> diff --git a/tools/testing/selftests/bpf/progs/preempt_lock.c b/tools/testing/selftests/bpf/progs/preempt_lock.c
> new file mode 100644
> index 000000000000..53320ea80fa4
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/preempt_lock.c
> @@ -0,0 +1,119 @@
> +// SPDX-License-Identifier: GPL-2.0
> +#include <vmlinux.h>
> +#include <bpf/bpf_helpers.h>
> +#include <bpf/bpf_tracing.h>
> +#include "bpf_misc.h"
> +
> +void bpf_preempt_disable(void) __ksym;
> +void bpf_preempt_enable(void) __ksym;
> +
> +SEC("?tc")
> +__failure __msg("1 bpf_preempt_enable is missing")
> +int preempt_lock_missing_1(struct __sk_buff *ctx)
> +{
> +	bpf_preempt_disable();
> +	return 0;
> +}
> +
> +SEC("?tc")
> +__failure __msg("2 bpf_preempt_enable(s) are missing")
> +int preempt_lock_missing_2(struct __sk_buff *ctx)
> +{
> +	bpf_preempt_disable();
> +	bpf_preempt_disable();
> +	return 0;
> +}
> +
> +SEC("?tc")
> +__failure __msg("3 bpf_preempt_enable(s) are missing")
> +int preempt_lock_missing_3(struct __sk_buff *ctx)
> +{
> +	bpf_preempt_disable();
> +	bpf_preempt_disable();
> +	bpf_preempt_disable();
> +	return 0;
> +}
> +
> +SEC("?tc")
> +__failure __msg("1 bpf_preempt_enable is missing")
> +int preempt_lock_missing_3_minus_2(struct __sk_buff *ctx)
> +{
> +	bpf_preempt_disable();
> +	bpf_preempt_disable();
> +	bpf_preempt_disable();
> +	bpf_preempt_enable();
> +	bpf_preempt_enable();
> +	return 0;
> +}
> +
> +static __noinline void preempt_disable(void)
> +{
> +	bpf_preempt_disable();
> +}
> +
> +static __noinline void preempt_enable(void)
> +{
> +	bpf_preempt_enable();
> +}
> +
> +SEC("?tc")
> +__failure __msg("1 bpf_preempt_enable is missing")
> +int preempt_lock_missing_1_subprog(struct __sk_buff *ctx)
> +{
> +	preempt_disable();
> +	return 0;
> +}
> +
> +SEC("?tc")
> +__failure __msg("2 bpf_preempt_enable(s) are missing")
> +int preempt_lock_missing_2_subprog(struct __sk_buff *ctx)
> +{
> +	preempt_disable();
> +	preempt_disable();
> +	return 0;
> +}
> +
> +SEC("?tc")
> +__failure __msg("1 bpf_preempt_enable is missing")
> +int preempt_lock_missing_2_minus_1_subprog(struct __sk_buff *ctx)
> +{
> +	preempt_disable();
> +	preempt_disable();
> +	preempt_enable();
> +	return 0;
> +}
> +
> +static __noinline void preempt_balance_subprog(void)
> +{
> +	preempt_disable();
> +	preempt_enable();
> +}
> +
> +SEC("?tc")
> +__success int preempt_balance(struct __sk_buff *ctx)
> +{
> +	bpf_preempt_disable();
> +	bpf_preempt_enable();
> +	return 0;
> +}
> +
> +SEC("?tc")
> +__success int preempt_balance_subprog_test(struct __sk_buff *ctx)
> +{
> +	preempt_balance_subprog();
> +	return 0;
> +}
> +
> +SEC("?fentry.s/" SYS_PREFIX "sys_getpgid")
> +__failure __msg("sleepable helper bpf_copy_from_user#")
> +int preempt_sleepable_helper(void *ctx)
> +{
> +	u32 data;
> +
> +	bpf_preempt_disable();
> +	bpf_copy_from_user(&data, sizeof(data), NULL);
> +	bpf_preempt_enable();
> +	return 0;
> +}
> +
> +char _license[] SEC("license") = "GPL";
> -- 
> 2.43.0
> 
>