On 5/8/20 12:51 PM, Andrii Nakryiko wrote:
On Wed, May 6, 2020 at 10:40 PM Yonghong Song <yhs@xxxxxx> wrote:
Currently, only one command is supported
bpftool iter pin <bpf_prog.o> <path>
It will pin the trace/iter bpf program in
the object file <bpf_prog.o> to the <path>
where <path> should be on a bpffs mount.
For example,
$ bpftool iter pin ./bpf_iter_ipv6_route.o \
/sys/fs/bpf/my_route
User can then do a `cat` to print out the results:
$ cat /sys/fs/bpf/my_route
fe800000000000000000000000000000 40 00000000000000000000000000000000 ...
00000000000000000000000000000000 00 00000000000000000000000000000000 ...
00000000000000000000000000000001 80 00000000000000000000000000000000 ...
fe800000000000008c0162fffebdfd57 80 00000000000000000000000000000000 ...
ff000000000000000000000000000000 08 00000000000000000000000000000000 ...
00000000000000000000000000000000 00 00000000000000000000000000000000 ...
The implementation for ipv6_route iterator is in one of subsequent
patches.
This patch also added BPF_LINK_TYPE_ITER to link query.
In the future, we may add additional parameters to pin command
by parameterizing the bpf iterator. For example, a map_id or pid
may be added to let bpf program only traverses a single map or task,
similar to kernel seq_file single_open().
We may also add introspection command for targets/iterators by
leveraging the bpf_iter itself.
Signed-off-by: Yonghong Song <yhs@xxxxxx>
---
.../bpftool/Documentation/bpftool-iter.rst | 83 ++++++++++++++++++
tools/bpf/bpftool/bash-completion/bpftool | 13 +++
tools/bpf/bpftool/iter.c | 84 +++++++++++++++++++
tools/bpf/bpftool/link.c | 1 +
tools/bpf/bpftool/main.c | 3 +-
tools/bpf/bpftool/main.h | 1 +
6 files changed, 184 insertions(+), 1 deletion(-)
create mode 100644 tools/bpf/bpftool/Documentation/bpftool-iter.rst
create mode 100644 tools/bpf/bpftool/iter.c
[...]
diff --git a/tools/bpf/bpftool/iter.c b/tools/bpf/bpftool/iter.c
new file mode 100644
index 000000000000..a8fb1349c103
--- /dev/null
+++ b/tools/bpf/bpftool/iter.c
@@ -0,0 +1,84 @@
+// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+// Copyright (C) 2020 Facebook
+
+#define _GNU_SOURCE
+#include <linux/err.h>
+#include <bpf/libbpf.h>
+
+#include "main.h"
+
+static int do_pin(int argc, char **argv)
+{
+ const char *objfile, *path;
+ struct bpf_program *prog;
+ struct bpf_object *obj;
+ struct bpf_link *link;
+ int err;
+
+ if (!REQ_ARGS(2))
+ usage();
+
+ objfile = GET_ARG();
+ path = GET_ARG();
+
+ obj = bpf_object__open(objfile);
+ if (IS_ERR_OR_NULL(obj)) {
nit: can't be NULL
Ack. Will change.
+ p_err("can't open objfile %s", objfile);
+ return -1;
+ }
+
+ err = bpf_object__load(obj);
+ if (err) {
+ p_err("can't load objfile %s", objfile);
+ goto close_obj;
+ }
+
+ prog = bpf_program__next(NULL, obj);
check for null and printf error? Crashing is not good.
Make sense. Will change.
+ link = bpf_program__attach_iter(prog, NULL);
+ if (IS_ERR(link)) {
+ err = PTR_ERR(link);
+ p_err("attach_iter failed for program %s",
+ bpf_program__name(prog));
+ goto close_obj;
+ }
+
+ err = mount_bpffs_for_pin(path);
+ if (err)
+ goto close_link;
+
+ err = bpf_link__pin(link, path);
+ if (err) {
+ p_err("pin_iter failed for program %s to path %s",
+ bpf_program__name(prog), path);
+ goto close_link;
+ }
+
+close_link:
+ bpf_link__disconnect(link);
this is wrong, just destroy()
Will change.
+ bpf_link__destroy(link);
+close_obj:
+ bpf_object__close(obj);
+ return err;
+}
+
[...]
