The optional parameter "map MAP" can be added to "bpftool iter"
command to create a bpf iterator for map elements. For example,
bpftool iter pin ./prog.o /sys/fs/bpf/p1 map id 333
For map element bpf iterator "map MAP" parameter is required.
Otherwise, bpf link creation will return an error.
Signed-off-by: Yonghong Song <y...@fb.com>
---
.../bpftool/Documentation/bpftool-iter.rst | 16 ++++++++--
tools/bpf/bpftool/iter.c | 32 ++++++++++++++++---
2 files changed, 42 insertions(+), 6 deletions(-)
diff --git a/tools/bpf/bpftool/Documentation/bpftool-iter.rst
b/tools/bpf/bpftool/Documentation/bpftool-iter.rst
index 8dce698eab79..53ee4fb188b4 100644
--- a/tools/bpf/bpftool/Documentation/bpftool-iter.rst
+++ b/tools/bpf/bpftool/Documentation/bpftool-iter.rst
@@ -17,14 +17,15 @@ SYNOPSIS
ITER COMMANDS
===================
-| **bpftool** **iter pin** *OBJ* *PATH*
+| **bpftool** **iter pin** *OBJ* *PATH* [**map** *MAP*]
| **bpftool** **iter help**
|
| *OBJ* := /a/file/of/bpf_iter_target.o
+| *MAP* := { **id** *MAP_ID* | **pinned** *FILE* }
DESCRIPTION
===========
- **bpftool iter pin** *OBJ* *PATH*
+ **bpftool iter pin** *OBJ* *PATH* [**map** *MAP*]
A bpf iterator combines a kernel iterating of
particular kernel data (e.g., tasks, bpf_maps, etc.)
and a bpf program called for each kernel data object
@@ -37,6 +38,10 @@ DESCRIPTION
character ('.'), which is reserved for future extensions
of *bpffs*.
+ Map element bpf iterator requires an additional parameter
+ *MAP* so bpf program can iterate over map elements for
+ that map.
+
User can then *cat PATH* to see the bpf iterator output.
**bpftool iter help**
@@ -64,6 +69,13 @@ EXAMPLES
Create a file-based bpf iterator from bpf_iter_netlink.o and pin it
to /sys/fs/bpf/my_netlink
+**# bpftool iter pin bpf_iter_hashmap.o /sys/fs/bpf/my_hashmap map id 20**
+
+::
+
+ Create a file-based bpf iterator from bpf_iter_hashmap.o and map with
+ id 20, and pin it to /sys/fs/bpf/my_hashmap
+
SEE ALSO
========
**bpf**\ (2),
diff --git a/tools/bpf/bpftool/iter.c b/tools/bpf/bpftool/iter.c
index 33240fcc6319..cc1d9bdf6e9d 100644
--- a/tools/bpf/bpftool/iter.c
+++ b/tools/bpf/bpftool/iter.c
@@ -2,6 +2,7 @@
// Copyright (C) 2020 Facebook
#define _GNU_SOURCE
+#include <unistd.h>
#include <linux/err.h>
#include <bpf/libbpf.h>
@@ -9,11 +10,12 @@
static int do_pin(int argc, char **argv)
{
+ DECLARE_LIBBPF_OPTS(bpf_iter_attach_opts, iter_opts);
const char *objfile, *path;
struct bpf_program *prog;
struct bpf_object *obj;
struct bpf_link *link;
- int err;
+ int err = -1, map_fd = -1;
if (!REQ_ARGS(2))
usage();
@@ -21,10 +23,26 @@ static int do_pin(int argc, char **argv)
objfile = GET_ARG();
path = GET_ARG();
+ /* optional arguments */
+ if (argc) {
+ if (is_prefix(*argv, "map")) {
+ NEXT_ARG();
+
+ if (!REQ_ARGS(2)) {
+ p_err("incorrect map spec");
+ return -1;
+ }
+
+ map_fd = map_parse_fd(&argc, &argv);
+ if (map_fd < 0)
+ return -1;
+ }
+ }
+
obj = bpf_object__open(objfile);
if (IS_ERR(obj)) {
p_err("can't open objfile %s", objfile);
- return -1;
+ goto close_map_fd;
}
err = bpf_object__load(obj);
@@ -39,7 +57,10 @@ static int do_pin(int argc, char **argv)
goto close_obj;
}
- link = bpf_program__attach_iter(prog, NULL);
+ if (map_fd >= 0)
+ iter_opts.map_fd = map_fd;
+
+ link = bpf_program__attach_iter(prog, &iter_opts);
if (IS_ERR(link)) {
err = PTR_ERR(link);
p_err("attach_iter failed for program %s",
@@ -62,13 +83,16 @@ static int do_pin(int argc, char **argv)
bpf_link__destroy(link);
close_obj:
bpf_object__close(obj);
+close_map_fd:
+ if (map_fd >= 0)
+ close(map_fd);
return err;
}
static int do_help(int argc, char **argv)
{
fprintf(stderr,
- "Usage: %1$s %2$s pin OBJ PATH\n"
+ "Usage: %1$s %2$s pin OBJ PATH [map MAP]\n"
" %1$s %2$s help\n"
"",
bin_name, "iter");
--
2.24.1
