On Sun, May 3, 2020 at 11:27 PM Yonghong Song <yhs@xxxxxx> wrote:
>
> The implementation is arbitrary, just to show how the bpf programs
> can be written for bpf_map/task/task_file. They can be costomized
> for specific needs.
>
> For example, for bpf_map, the iterator prints out:
> $ cat /sys/fs/bpf/my_bpf_map
> id refcnt usercnt locked_vm
> 3 2 0 20
> 6 2 0 20
> 9 2 0 20
> 12 2 0 20
> 13 2 0 20
> 16 2 0 20
> 19 2 0 20
> === END ===
>
> For task, the iterator prints out:
> $ cat /sys/fs/bpf/my_task
> tgid gid
> 1 1
> 2 2
> ....
> 1944 1944
> 1948 1948
> 1949 1949
> 1953 1953
> === END ===
>
> For task/file, the iterator prints out:
> $ cat /sys/fs/bpf/my_task_file
> tgid gid fd file
> 1 1 0 ffffffff95c97600
> 1 1 1 ffffffff95c97600
> 1 1 2 ffffffff95c97600
> ....
> 1895 1895 255 ffffffff95c8fe00
> 1932 1932 0 ffffffff95c8fe00
> 1932 1932 1 ffffffff95c8fe00
> 1932 1932 2 ffffffff95c8fe00
> 1932 1932 3 ffffffff95c185c0
>
> This is able to print out all open files (fd and file->f_op), so user can compare
> f_op against a particular kernel file operations to find what it is.
> For example, from /proc/kallsyms, we can find
> ffffffff95c185c0 r eventfd_fops
> so we will know tgid 1932 fd 3 is an eventfd file descriptor.
>
> Signed-off-by: Yonghong Song <yhs@xxxxxx>
> ---
LGTM.
Acked-by: Andrii Nakryiko <andriin@xxxxxx>
> .../selftests/bpf/progs/bpf_iter_bpf_map.c | 29 +++++++++++++++++++
> .../selftests/bpf/progs/bpf_iter_task.c | 26 +++++++++++++++++
> .../selftests/bpf/progs/bpf_iter_task_file.c | 27 +++++++++++++++++
> 3 files changed, 82 insertions(+)
> create mode 100644 tools/testing/selftests/bpf/progs/bpf_iter_bpf_map.c
> create mode 100644 tools/testing/selftests/bpf/progs/bpf_iter_task.c
> create mode 100644 tools/testing/selftests/bpf/progs/bpf_iter_task_file.c
>
> diff --git a/tools/testing/selftests/bpf/progs/bpf_iter_bpf_map.c b/tools/testing/selftests/bpf/progs/bpf_iter_bpf_map.c
> new file mode 100644
> index 000000000000..d0af0e82b74c
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/bpf_iter_bpf_map.c
> @@ -0,0 +1,29 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright (c) 2020 Facebook */
> +#include "vmlinux.h"
> +#include <bpf/bpf_helpers.h>
> +#include <bpf/bpf_tracing.h>
> +#include <bpf/bpf_endian.h>
bpf_endian.h doesn't seem to be really used and it's actually
incompatible with vmlinux.h, so maybe let's drop it?
Same for previous patch, I believe.
> +
> +char _license[] SEC("license") = "GPL";
> +
[...]
