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author | Yonghong Song <yhs@fb.com> | 2020-05-09 20:59:22 +0300 |
---|---|---|
committer | Alexei Starovoitov <ast@kernel.org> | 2020-05-10 03:05:27 +0300 |
commit | acf61631746c01850a9df0cd5617c5c29214776c (patch) | |
tree | 6be8f88c4a6646cff6c3bcdeedd0b9f467ceef89 /tools/testing/selftests/bpf/progs/bpf_iter_task_file.c | |
parent | 7c128a6bbd4f5b6780a90f3ce9aff192b7dd9d6a (diff) | |
download | linux-acf61631746c01850a9df0cd5617c5c29214776c.tar.xz |
tools/bpf: selftests: Add iter progs for bpf_map/task/task_file
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@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200509175922.2477576-1-yhs@fb.com
Diffstat (limited to 'tools/testing/selftests/bpf/progs/bpf_iter_task_file.c')
-rw-r--r-- | tools/testing/selftests/bpf/progs/bpf_iter_task_file.c | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/progs/bpf_iter_task_file.c b/tools/testing/selftests/bpf/progs/bpf_iter_task_file.c new file mode 100644 index 000000000000..c6ced38f0880 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/bpf_iter_task_file.c @@ -0,0 +1,26 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2020 Facebook */ +#include "vmlinux.h" +#include <bpf/bpf_helpers.h> +#include <bpf/bpf_tracing.h> + +char _license[] SEC("license") = "GPL"; + +SEC("iter/task_file") +int dump_task_file(struct bpf_iter__task_file *ctx) +{ + struct seq_file *seq = ctx->meta->seq; + struct task_struct *task = ctx->task; + __u32 fd = ctx->fd; + struct file *file = ctx->file; + + if (task == (void *)0 || file == (void *)0) + return 0; + + if (ctx->meta->seq_num == 0) + BPF_SEQ_PRINTF(seq, " tgid gid fd file\n"); + + BPF_SEQ_PRINTF(seq, "%8d %8d %8d %lx\n", task->tgid, task->pid, fd, + (long)file->f_op); + return 0; +} |