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From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Kenny Yu <kennyyu@fb.com>
Cc: bpf <bpf@vger.kernel.org>, Alexei Starovoitov <ast@kernel.org>,
	Andrii Nakryiko <andrii@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Yonghong Song <yhs@fb.com>
Subject: Re: [PATCH v2 bpf-next 4/4] selftests/bpf: Add test for sleepable bpf iterator programs
Date: Thu, 13 Jan 2022 18:39:23 -0800	[thread overview]
Message-ID: <CAADnVQ+nS1++7NwcAPuwO26CcuvNnPVMQgtwi4FDNcmHQEBm8g@mail.gmail.com> (raw)
In-Reply-To: <20220114004900.3756025-5-kennyyu@fb.com>

On Thu, Jan 13, 2022 at 4:49 PM Kenny Yu <kennyyu@fb.com> wrote:
>
> This adds a test for bpf iterator programs to make use of sleepable
> bpf helpers.
>
> Signed-off-by: Kenny Yu <kennyyu@fb.com>
> ---
>  .../selftests/bpf/prog_tests/bpf_iter.c       | 16 ++++++
>  .../selftests/bpf/progs/bpf_iter_task.c       | 54 +++++++++++++++++++
>  2 files changed, 70 insertions(+)
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_iter.c b/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
> index b84f859b1267..fcda0ecd8746 100644
> --- a/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
> +++ b/tools/testing/selftests/bpf/prog_tests/bpf_iter.c
> @@ -138,6 +138,20 @@ static void test_task(void)
>         bpf_iter_task__destroy(skel);
>  }
>
> +static void test_task_sleepable(void)
> +{
> +       struct bpf_iter_task *skel;
> +
> +       skel = bpf_iter_task__open_and_load();
> +       if (CHECK(!skel, "bpf_iter_task__open_and_load",
> +                 "skeleton open_and_load failed\n"))
> +               return;
> +
> +       do_dummy_read(skel->progs.dump_task_sleepable);
> +
> +       bpf_iter_task__destroy(skel);
> +}
> +
>  static void test_task_stack(void)
>  {
>         struct bpf_iter_task_stack *skel;
> @@ -1252,6 +1266,8 @@ void test_bpf_iter(void)
>                 test_bpf_map();
>         if (test__start_subtest("task"))
>                 test_task();
> +       if (test__start_subtest("task_sleepable"))
> +               test_task_sleepable();
>         if (test__start_subtest("task_stack"))
>                 test_task_stack();
>         if (test__start_subtest("task_file"))
> diff --git a/tools/testing/selftests/bpf/progs/bpf_iter_task.c b/tools/testing/selftests/bpf/progs/bpf_iter_task.c
> index c86b93f33b32..bb4b63043533 100644
> --- a/tools/testing/selftests/bpf/progs/bpf_iter_task.c
> +++ b/tools/testing/selftests/bpf/progs/bpf_iter_task.c
> @@ -2,6 +2,7 @@
>  /* Copyright (c) 2020 Facebook */
>  #include "bpf_iter.h"
>  #include <bpf/bpf_helpers.h>
> +#include <bpf/bpf_tracing.h>
>
>  char _license[] SEC("license") = "GPL";
>
> @@ -23,3 +24,56 @@ int dump_task(struct bpf_iter__task *ctx)
>         BPF_SEQ_PRINTF(seq, "%8d %8d\n", task->tgid, task->pid);
>         return 0;
>  }
> +
> +// New helper added
> +static long (*bpf_access_process_vm)(
> +       struct task_struct *tsk,
> +       unsigned long addr,
> +       void *buf,
> +       int len,
> +       unsigned int gup_flags) = (void *)186;

This shouldn't be needed.
Since patch 1 updates tools/include/uapi/linux/bpf.h
it will be in bpf_helper_defs.h automatically.

> +
> +// Copied from include/linux/mm.h
> +#define FOLL_REMOTE 0x2000 /* we are working on non-current tsk/mm */

Please use C style comments only.

> +       numread = bpf_access_process_vm(task,
> +                                       (unsigned long)ptr,
> +                                       (void *)&user_data,
> +                                       sizeof(uint32_t),
> +                                       FOLL_REMOTE);

We probably would need to hide flags like FOLL_REMOTE
inside the helper otherwise prog might confuse the kernel.
In this case I'm not even sure that FOLL_REMOTE is needed.
I suspect gup_flags=0 in all cases will work fine.
We're not doing write here and not pining anything.
fast_gup is not necessary either.

  reply	other threads:[~2022-01-14  2:39 UTC|newest]

Thread overview: 62+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-01-13 23:31 [PATCH bpf-next 0/3] Add bpf_access_process_vm helper and sleepable bpf iterator programs Kenny Yu
2022-01-13 23:31 ` [PATCH bpf-next 1/3] bpf: Add bpf_access_process_vm() helper Kenny Yu
2022-01-13 23:31 ` [PATCH bpf-next 2/3] libbpf: Add "iter.s" section for sleepable bpf iterator programs Kenny Yu
2022-01-13 23:31 ` [PATCH bpf-next 3/3] selftests/bpf: Add test " Kenny Yu
2022-01-14  0:48 ` [PATCH v2 bpf-next 0/4] Add bpf_access_process_vm helper and " Kenny Yu
2022-01-14  0:48   ` [PATCH v2 bpf-next 1/4] bpf: Add bpf_access_process_vm() helper Kenny Yu
2022-01-14  0:48   ` [PATCH v2 bpf-next 2/4] bpf: Add support for sleepable programs in bpf_iter_run_prog Kenny Yu
2022-01-14  2:50     ` Alexei Starovoitov
2022-01-14 23:15       ` Kenny Yu
2022-01-14  0:48   ` [PATCH v2 bpf-next 3/4] libbpf: Add "iter.s" section for sleepable bpf iterator programs Kenny Yu
2022-01-14  0:49   ` [PATCH v2 bpf-next 4/4] selftests/bpf: Add test " Kenny Yu
2022-01-14  2:39     ` Alexei Starovoitov [this message]
2022-01-14 23:14       ` Kenny Yu
2022-01-15  1:38         ` Andrii Nakryiko
2022-01-15  4:30           ` Kenny Yu
2022-01-15 16:27           ` Gabriele
2022-01-19 16:56             ` Kenny Yu
2022-01-19 18:02 ` [PATCH v3 bpf-next 0/3] Add bpf_access_process_vm helper and " Kenny Yu
2022-01-19 18:02   ` [PATCH v3 bpf-next 1/3] bpf: Add bpf_access_process_vm() helper Kenny Yu
2022-01-19 20:16     ` Alexei Starovoitov
2022-01-19 22:51       ` Kenny Yu
2022-01-19 18:02   ` [PATCH v3 bpf-next 2/3] libbpf: Add "iter.s" section for sleepable bpf iterator programs Kenny Yu
2022-01-19 18:02   ` [PATCH v3 bpf-next 3/3] selftests/bpf: Add test " Kenny Yu
2022-01-19 22:59 ` [PATCH v4 bpf-next 0/3] Add bpf_access_process_vm helper and " Kenny Yu
2022-01-19 22:59   ` [PATCH v4 bpf-next 1/3] bpf: Add bpf_access_process_vm() helper Kenny Yu
2022-01-20  3:45     ` Yonghong Song
2022-01-20 17:11       ` Kenny Yu
2022-01-19 22:59   ` [PATCH v4 bpf-next 2/3] libbpf: Add "iter.s" section for sleepable bpf iterator programs Kenny Yu
2022-01-19 22:59   ` [PATCH v4 bpf-next 3/3] selftests/bpf: Add test " Kenny Yu
2022-01-20 17:29 ` [PATCH v5 bpf-next 0/3] Add bpf_access_process_vm helper and " Kenny Yu
2022-01-20 17:29   ` [PATCH v5 bpf-next 1/3] bpf: Add bpf_access_process_vm() helper Kenny Yu
2022-01-20 22:45     ` Andrii Nakryiko
2022-01-21  2:27       ` Alexei Starovoitov
2022-01-21 17:20         ` Andrii Nakryiko
2022-01-21 17:41           ` Kenny Yu
2022-01-21 17:47             ` Alexei Starovoitov
2022-01-21 18:30               ` Kenny Yu
2022-01-20 17:29   ` [PATCH v5 bpf-next 2/3] libbpf: Add "iter.s" section for sleepable bpf iterator programs Kenny Yu
2022-01-20 17:29   ` [PATCH v5 bpf-next 3/3] selftests/bpf: Add test " Kenny Yu
2022-01-20 22:48     ` Andrii Nakryiko
2022-01-21 19:30 ` [PATCH v6 bpf-next 0/3] Add bpf_copy_from_user_task helper and " Kenny Yu
2022-01-21 19:30   ` [PATCH v6 bpf-next 1/3] bpf: Add bpf_copy_from_user_task() helper Kenny Yu
2022-01-21 19:53     ` Andrii Nakryiko
2022-01-21 20:04       ` Yonghong Song
2022-01-21 20:07         ` Andrii Nakryiko
2022-01-21 21:15           ` Yonghong Song
2022-01-24 17:30             ` Kenny Yu
2022-01-22  9:58       ` Gabriele
2022-01-22 10:08         ` Gabriele
2022-01-21 19:30   ` [PATCH v6 bpf-next 2/3] libbpf: Add "iter.s" section for sleepable bpf iterator programs Kenny Yu
2022-01-21 19:54     ` Andrii Nakryiko
2022-01-21 19:30   ` [PATCH v6 bpf-next 3/3] selftests/bpf: Add test " Kenny Yu
2022-01-21 19:55     ` Andrii Nakryiko
2022-01-24 18:53 ` [PATCH v7 bpf-next 0/4] Add bpf_copy_from_user_task helper and " Kenny Yu
2022-01-24 18:54   ` [PATCH v7 bpf-next 1/4] bpf: Add support for bpf iterator programs to use sleepable helpers Kenny Yu
2022-01-24 22:19     ` Andrii Nakryiko
2022-01-24 18:54   ` [PATCH v7 bpf-next 2/4] bpf: Add bpf_copy_from_user_task() helper Kenny Yu
2022-01-24 22:18     ` Andrii Nakryiko
2022-01-25  4:06       ` Alexei Starovoitov
2022-01-24 18:54   ` [PATCH v7 bpf-next 3/4] libbpf: Add "iter.s" section for sleepable bpf iterator programs Kenny Yu
2022-01-24 18:54   ` [PATCH v7 bpf-next 4/4] selftests/bpf: Add test " Kenny Yu
2022-01-25  4:10   ` [PATCH v7 bpf-next 0/4] Add bpf_copy_from_user_task helper and " patchwork-bot+netdevbpf

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