2021-01-12 09:04:26

by Yonghong Song

[permalink] [raw]
Subject: Re: [PATCH bpf-next 2/4] selftests/bpf: add non-BPF_LSM test for task local storage



On 1/8/21 3:19 PM, Song Liu wrote:
> Task local storage is enabled for tracing programs. Add a test for it
> without CONFIG_BPF_LSM.
>
> Signed-off-by: Song Liu <[email protected]>
> ---
> .../bpf/prog_tests/test_task_local_storage.c | 34 +++++++++++++++++
> .../selftests/bpf/progs/task_local_storage.c | 37 +++++++++++++++++++
> 2 files changed, 71 insertions(+)
> create mode 100644 tools/testing/selftests/bpf/prog_tests/test_task_local_storage.c
> create mode 100644 tools/testing/selftests/bpf/progs/task_local_storage.c
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/test_task_local_storage.c b/tools/testing/selftests/bpf/prog_tests/test_task_local_storage.c
> new file mode 100644
> index 0000000000000..7de7a154ebbe6
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/prog_tests/test_task_local_storage.c
> @@ -0,0 +1,34 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright (c) 2020 Facebook */

2020 -> 2021

> +
> +#include <sys/types.h>
> +#include <unistd.h>
> +#include <test_progs.h>
> +#include "task_local_storage.skel.h"
> +
> +static unsigned int duration;
> +
> +void test_test_task_local_storage(void)
> +{
> + struct task_local_storage *skel;
> + const int count = 10;
> + int i, err;
> +
> + skel = task_local_storage__open_and_load();
> +

Extra line is unnecessary here.

> + if (CHECK(!skel, "skel_open_and_load", "skeleton open and load failed\n"))
> + return;
> +
> + err = task_local_storage__attach(skel);
> +

ditto.

> + if (CHECK(err, "skel_attach", "skeleton attach failed\n"))
> + goto out;
> +
> + for (i = 0; i < count; i++)
> + usleep(1000);

Does a smaller usleep value will work? If it is, recommend to have a
smaller value here to reduce test_progs running time.

> + CHECK(skel->bss->value < count, "task_local_storage_value",
> + "task local value too small\n");
> +
> +out:
> + task_local_storage__destroy(skel);
> +}
> diff --git a/tools/testing/selftests/bpf/progs/task_local_storage.c b/tools/testing/selftests/bpf/progs/task_local_storage.c
> new file mode 100644
> index 0000000000000..807255c5c162d
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/task_local_storage.c
> @@ -0,0 +1,37 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright (c) 2020 Facebook */

2020 -> 2021

> +
> +#include "vmlinux.h"
> +#include <bpf/bpf_helpers.h>
> +#include <bpf/bpf_tracing.h>
> +
> +char _license[] SEC("license") = "GPL";
> +
> +struct local_data {
> + __u64 val;
> +};
> +
> +struct {
> + __uint(type, BPF_MAP_TYPE_TASK_STORAGE);
> + __uint(map_flags, BPF_F_NO_PREALLOC);
> + __type(key, int);
> + __type(value, struct local_data);
> +} task_storage_map SEC(".maps");
> +
> +int value = 0;
> +
> +SEC("tp_btf/sched_switch")
> +int BPF_PROG(on_switch, bool preempt, struct task_struct *prev,
> + struct task_struct *next)
> +{
> + struct local_data *storage;

If it possible that we do some filtering based on test_progs pid
so below bpf_task_storage_get is only called for test_progs process?
This is more targeted and can avoid counter contributions from
other unrelated processes and make test_task_local_storage.c result
comparison more meaningful.

> +
> + storage = bpf_task_storage_get(&task_storage_map,
> + next, 0,
> + BPF_LOCAL_STORAGE_GET_F_CREATE);
> + if (storage) {
> + storage->val++;
> + value = storage->val;
> + }
> + return 0;
> +}
>


2021-01-12 09:05:39

by KP Singh

[permalink] [raw]
Subject: Re: [PATCH bpf-next 2/4] selftests/bpf: add non-BPF_LSM test for task local storage

On Mon, Jan 11, 2021 at 6:31 PM Yonghong Song <[email protected]> wrote:
>
>
>
> On 1/8/21 3:19 PM, Song Liu wrote:
> > Task local storage is enabled for tracing programs. Add a test for it
> > without CONFIG_BPF_LSM.

Can you also explain what the test does in the commit log?

It would also be nicer to have a somewhat more realistic selftest which
represents a simple tracing + task local storage use case.

> >
> > Signed-off-by: Song Liu <[email protected]>
> > ---
> > .../bpf/prog_tests/test_task_local_storage.c | 34 +++++++++++++++++
> > .../selftests/bpf/progs/task_local_storage.c | 37 +++++++++++++++++++
> > 2 files changed, 71 insertions(+)
> > create mode 100644 tools/testing/selftests/bpf/prog_tests/test_task_local_storage.c
> > create mode 100644 tools/testing/selftests/bpf/progs/task_local_storage.c
> >
> > diff --git a/tools/testing/selftests/bpf/prog_tests/test_task_local_storage.c b/tools/testing/selftests/bpf/prog_tests/test_task_local_storage.c
> > new file mode 100644
> > index 0000000000000..7de7a154ebbe6
> > --- /dev/null
> > +++ b/tools/testing/selftests/bpf/prog_tests/test_task_local_storage.c
> > @@ -0,0 +1,34 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/* Copyright (c) 2020 Facebook */
>
> 2020 -> 2021
>
> > +
> > +#include <sys/types.h>
> > +#include <unistd.h>
> > +#include <test_progs.h>
> > +#include "task_local_storage.skel.h"
> > +
> > +static unsigned int duration;
> > +
> > +void test_test_task_local_storage(void)
> > +{
> > + struct task_local_storage *skel;
> > + const int count = 10;
> > + int i, err;
> > +
> > + skel = task_local_storage__open_and_load();
> > +
>
> Extra line is unnecessary here.
>
> > + if (CHECK(!skel, "skel_open_and_load", "skeleton open and load failed\n"))
> > + return;
> > +
> > + err = task_local_storage__attach(skel);
> > +
>
> ditto.
>
> > + if (CHECK(err, "skel_attach", "skeleton attach failed\n"))
> > + goto out;
> > +
> > + for (i = 0; i < count; i++)
> > + usleep(1000);
>
> Does a smaller usleep value will work? If it is, recommend to have a
> smaller value here to reduce test_progs running time.
>
> > + CHECK(skel->bss->value < count, "task_local_storage_value",
> > + "task local value too small\n");

[...]

> > +// SPDX-License-Identifier: GPL-2.0
> > +/* Copyright (c) 2020 Facebook */
>
> 2020 -> 2021
>
> > +
> > +#include "vmlinux.h"
> > +#include <bpf/bpf_helpers.h>
> > +#include <bpf/bpf_tracing.h>
> > +
> > +char _license[] SEC("license") = "GPL";

[...]

> > +{
> > + struct local_data *storage;
>
> If it possible that we do some filtering based on test_progs pid
> so below bpf_task_storage_get is only called for test_progs process?
> This is more targeted and can avoid counter contributions from
> other unrelated processes and make test_task_local_storage.c result
> comparison more meaningful.

Indeed, have a look at the monitored_pid approach some of the LSM programs
do.

>
> > +
> > + storage = bpf_task_storage_get(&task_storage_map,
> > + next, 0,
> > + BPF_LOCAL_STORAGE_GET_F_CREATE);
> > + if (storage) {
> > + storage->val++;
> > + value = storage->val;
> > + }
> > + return 0;
> > +}
> >

2021-01-12 09:58:34

by Song Liu

[permalink] [raw]
Subject: Re: [PATCH bpf-next 2/4] selftests/bpf: add non-BPF_LSM test for task local storage



> On Jan 11, 2021, at 9:30 AM, Yonghong Song <[email protected]> wrote:
>
>
>
> On 1/8/21 3:19 PM, Song Liu wrote:
>> Task local storage is enabled for tracing programs. Add a test for it
>> without CONFIG_BPF_LSM.
>> Signed-off-by: Song Liu <[email protected]>
>> ---
>> .../bpf/prog_tests/test_task_local_storage.c | 34 +++++++++++++++++
>> .../selftests/bpf/progs/task_local_storage.c | 37 +++++++++++++++++++
>> 2 files changed, 71 insertions(+)
>> create mode 100644 tools/testing/selftests/bpf/prog_tests/test_task_local_storage.c
>> create mode 100644 tools/testing/selftests/bpf/progs/task_local_storage.c
>> diff --git a/tools/testing/selftests/bpf/prog_tests/test_task_local_storage.c b/tools/testing/selftests/bpf/prog_tests/test_task_local_storage.c
>> new file mode 100644
>> index 0000000000000..7de7a154ebbe6
>> --- /dev/null
>> +++ b/tools/testing/selftests/bpf/prog_tests/test_task_local_storage.c
>> @@ -0,0 +1,34 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/* Copyright (c) 2020 Facebook */
>
> 2020 -> 2021
>
>> +
>> +#include <sys/types.h>
>> +#include <unistd.h>
>> +#include <test_progs.h>
>> +#include "task_local_storage.skel.h"
>> +
>> +static unsigned int duration;
>> +
>> +void test_test_task_local_storage(void)
>> +{
>> + struct task_local_storage *skel;
>> + const int count = 10;
>> + int i, err;
>> +
>> + skel = task_local_storage__open_and_load();
>> +
>
> Extra line is unnecessary here.
>
>> + if (CHECK(!skel, "skel_open_and_load", "skeleton open and load failed\n"))
>> + return;
>> +
>> + err = task_local_storage__attach(skel);
>> +
>
> ditto.
>
>> + if (CHECK(err, "skel_attach", "skeleton attach failed\n"))
>> + goto out;
>> +
>> + for (i = 0; i < count; i++)
>> + usleep(1000);
>
> Does a smaller usleep value will work? If it is, recommend to have a smaller value here to reduce test_progs running time.

I thought 10ms total was acceptable. But yeah, smaller value should still work.

>
>> + CHECK(skel->bss->value < count, "task_local_storage_value",
>> + "task local value too small\n");
>> +
>> +out:
>> + task_local_storage__destroy(skel);
>> +}
>> diff --git a/tools/testing/selftests/bpf/progs/task_local_storage.c b/tools/testing/selftests/bpf/progs/task_local_storage.c
>> new file mode 100644
>> index 0000000000000..807255c5c162d
>> --- /dev/null
>> +++ b/tools/testing/selftests/bpf/progs/task_local_storage.c
>> @@ -0,0 +1,37 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/* Copyright (c) 2020 Facebook */
>
> 2020 -> 2021
>
>> +
>> +#include "vmlinux.h"
>> +#include <bpf/bpf_helpers.h>
>> +#include <bpf/bpf_tracing.h>
>> +
>> +char _license[] SEC("license") = "GPL";
>> +
>> +struct local_data {
>> + __u64 val;
>> +};
>> +
>> +struct {
>> + __uint(type, BPF_MAP_TYPE_TASK_STORAGE);
>> + __uint(map_flags, BPF_F_NO_PREALLOC);
>> + __type(key, int);
>> + __type(value, struct local_data);
>> +} task_storage_map SEC(".maps");
>> +
>> +int value = 0;
>> +
>> +SEC("tp_btf/sched_switch")
>> +int BPF_PROG(on_switch, bool preempt, struct task_struct *prev,
>> + struct task_struct *next)
>> +{
>> + struct local_data *storage;
>
> If it possible that we do some filtering based on test_progs pid
> so below bpf_task_storage_get is only called for test_progs process?
> This is more targeted and can avoid counter contributions from
> other unrelated processes and make test_task_local_storage.c result
> comparison more meaningful.

Make sense. Will fix in the next version.

>
>> +
>> + storage = bpf_task_storage_get(&task_storage_map,
>> + next, 0,
>> + BPF_LOCAL_STORAGE_GET_F_CREATE);
>> + if (storage) {
>> + storage->val++;
>> + value = storage->val;
>> + }
>> + return 0;
>> +}

2021-01-12 09:59:15

by Song Liu

[permalink] [raw]
Subject: Re: [PATCH bpf-next 2/4] selftests/bpf: add non-BPF_LSM test for task local storage



> On Jan 11, 2021, at 9:44 AM, KP Singh <[email protected]> wrote:
>
> On Mon, Jan 11, 2021 at 6:31 PM Yonghong Song <[email protected]> wrote:
>>
>>
>>
>> On 1/8/21 3:19 PM, Song Liu wrote:
>>> Task local storage is enabled for tracing programs. Add a test for it
>>> without CONFIG_BPF_LSM.
>
> Can you also explain what the test does in the commit log?
>
> It would also be nicer to have a somewhat more realistic selftest which
> represents a simple tracing + task local storage use case.

Let me try to make this more realistic.

Thanks,
Song

[...]