[PATCH bpf-next 0/2] bpf: adding support for mapinmap in libbpf

[PATCH bpf-next 0/2] bpf: adding support for mapinmap in libbpf

[Nikita V. Shirokov]

in this patch series i'm adding a helper for libbpf which would allow
it to load map-in-map(BPF_MAP_TYPE_ARRAY_OF_MAPS and
BPF_MAP_TYPE_HASH_OF_MAPS).
first patch contains new helper + explains proposed workflow
second patch contains tests which also could be used as example of
usage

Nikita V. Shirokov (2):
  bpf: adding support for map in map in libbpf
  bpf: adding tests for mapinmap helpber in libbpf

 tools/lib/bpf/libbpf.c                      |  7 +++
 tools/lib/bpf/libbpf.h                      |  2 +
 tools/testing/selftests/bpf/Makefile        |  3 +-
 tools/testing/selftests/bpf/test_mapinmap.c | 53 ++++++++++++++++++++
 tools/testing/selftests/bpf/test_maps.c     | 76 +++++++++++++++++++++++++++++
 5 files changed, 140 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/bpf/test_mapinmap.c

-- 
2.15.1

[PATCH bpf-next 1/2] bpf: adding support for map in map in libbpf

[Nikita V. Shirokov]

idea is pretty simple. for specified map (pointed by struct bpf_map)
we would provide descriptor of already loaded map, which is going to be
used as a prototype for inner map. proposed workflow:
1) open bpf's object (bpf_object__open)
2) create bpf's map which is going to be used as a prototype
3) find (by name) map-in-map which you want to load and update w/
descriptor of inner map w/ a new helper from this patch
4) load bpf program w/ bpf_object__load

inner_map_fd is ignored by any other maps asidef from (hash|array) of
maps

Signed-off-by: Nikita V. Shirokov <tehnerd@tehnerd.com>
---
 tools/lib/bpf/libbpf.c | 7 +++++++
 tools/lib/bpf/libbpf.h | 2 ++
 2 files changed, 9 insertions(+)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index a01eb9584e52..a2ee1b1a93b6 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -163,6 +163,7 @@ struct bpf_map {
 	char *name;
 	size_t offset;
 	int map_ifindex;
+	int inner_map_fd;
 	struct bpf_map_def def;
 	__u32 btf_key_type_id;
 	__u32 btf_value_type_id;
@@ -1146,6 +1147,7 @@ bpf_object__create_maps(struct bpf_object *obj)
 		create_attr.btf_fd = 0;
 		create_attr.btf_key_type_id = 0;
 		create_attr.btf_value_type_id = 0;
+		create_attr.inner_map_fd = map->inner_map_fd;
 
 		if (obj->btf && !bpf_map_find_btf_info(map, obj->btf)) {
 			create_attr.btf_fd = btf__fd(obj->btf);
@@ -2562,6 +2564,11 @@ void bpf_map__set_ifindex(struct bpf_map *map, __u32 ifindex)
 	map->map_ifindex = ifindex;
 }
 
+void bpf_map__add_inner_map_fd(struct bpf_map *map, const int fd)
+{
+	map->inner_map_fd = fd;
+}
+
 static struct bpf_map *
 __bpf_map__iter(struct bpf_map *m, struct bpf_object *obj, int i)
 {
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index b1686a787102..7cb00cd41789 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -293,6 +293,8 @@ LIBBPF_API void bpf_map__set_ifindex(struct bpf_map *map, __u32 ifindex);
 LIBBPF_API int bpf_map__pin(struct bpf_map *map, const char *path);
 LIBBPF_API int bpf_map__unpin(struct bpf_map *map, const char *path);
 
+LIBBPF_API void bpf_map__add_inner_map_fd(struct bpf_map *map, const int fd);
+
 LIBBPF_API long libbpf_get_error(const void *ptr);
 
 struct bpf_prog_load_attr {
-- 
2.15.1

[PATCH bpf-next 2/2] bpf: adding tests for mapinmap helpber in libbpf

[Nikita V. Shirokov]

adding test/example of bpf_map__add_inner_map_fd usage

Signed-off-by: Nikita V. Shirokov <tehnerd@tehnerd.com>
---
 tools/testing/selftests/bpf/Makefile        |  3 +-
 tools/testing/selftests/bpf/test_mapinmap.c | 53 ++++++++++++++++++++
 tools/testing/selftests/bpf/test_maps.c     | 76 +++++++++++++++++++++++++++++
 3 files changed, 131 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/bpf/test_mapinmap.c

diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index 57b4712a6276..a3ea69dc9bdf 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -38,7 +38,8 @@ TEST_GEN_FILES = test_pkt_access.o test_xdp.o test_l4lb.o test_tcp_estats.o test
 	test_lwt_seg6local.o sendmsg4_prog.o sendmsg6_prog.o test_lirc_mode2_kern.o \
 	get_cgroup_id_kern.o socket_cookie_prog.o test_select_reuseport_kern.o \
 	test_skb_cgroup_id_kern.o bpf_flow.o netcnt_prog.o \
-	test_sk_lookup_kern.o test_xdp_vlan.o test_queue_map.o test_stack_map.o
+	test_sk_lookup_kern.o test_xdp_vlan.o test_queue_map.o test_stack_map.o \
+	test_mapinmap.o
 
 # Order correspond to 'make run_tests' order
 TEST_PROGS := test_kmod.sh \
diff --git a/tools/testing/selftests/bpf/test_mapinmap.c b/tools/testing/selftests/bpf/test_mapinmap.c
new file mode 100644
index 000000000000..8aef6c652c9c
--- /dev/null
+++ b/tools/testing/selftests/bpf/test_mapinmap.c
@@ -0,0 +1,53 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2018 Facebook */
+#include <stddef.h>
+#include <linux/bpf.h>
+#include <linux/types.h>
+#include "bpf_helpers.h"
+
+
+struct bpf_map_def SEC("maps") mim_array = {
+	.type = BPF_MAP_TYPE_ARRAY_OF_MAPS,
+	.key_size = sizeof(int),
+	/* must be sizeof(__u32) for map in map */
+	.value_size = sizeof(__u32),
+	.max_entries = 1,
+	.map_flags = 0,
+};
+
+struct bpf_map_def SEC("maps") mim_hash = {
+	.type = BPF_MAP_TYPE_HASH_OF_MAPS,
+	.key_size = sizeof(int),
+	/* must be sizeof(__u32) for map in map */
+	.value_size = sizeof(__u32),
+	.max_entries = 1,
+	.map_flags = 0,
+};
+
+
+
+SEC("xdp_mimtest")
+int xdp_mimtest0(struct xdp_md *ctx)
+{
+	int value = 123;
+	int key = 0;
+	void *map;
+
+	map = bpf_map_lookup_elem(&mim_array, &key);
+	if (!map)
+		return XDP_DROP;
+
+	bpf_map_update_elem(map, &key, &value, 0);
+
+	map = bpf_map_lookup_elem(&mim_hash, &key);
+	if (!map)
+		return XDP_DROP;
+
+	bpf_map_update_elem(map, &key, &value, 0);
+
+	return XDP_PASS;
+}
+
+
+int _version SEC("version") = 1;
+char _license[] SEC("license") = "GPL";
diff --git a/tools/testing/selftests/bpf/test_maps.c b/tools/testing/selftests/bpf/test_maps.c
index 4db2116e52be..a49ab294971d 100644
--- a/tools/testing/selftests/bpf/test_maps.c
+++ b/tools/testing/selftests/bpf/test_maps.c
@@ -1080,6 +1080,80 @@ static void test_sockmap(int tasks, void *data)
 	exit(1);
 }
 
+#define MAPINMAP_PROG "./test_mapinmap.o"
+static void test_mapinmap(void)
+{
+	struct bpf_program *prog;
+	struct bpf_object *obj;
+	struct bpf_map *map;
+	int mim_fd, fd;
+	int pos = 0;
+
+	obj = bpf_object__open(MAPINMAP_PROG);
+
+	fd = bpf_create_map(BPF_MAP_TYPE_HASH, sizeof(int), sizeof(int),
+			    2, 0);
+	if (fd < 0) {
+		printf("Failed to create hashmap '%s'!\n", strerror(errno));
+		exit(1);
+	}
+	printf("fd is %d\n", fd);
+
+	map = bpf_object__find_map_by_name(obj, "mim_array");
+	if (IS_ERR(map)) {
+		printf("Failed to load array of maps from test prog\n");
+		goto out_mapinmap;
+	}
+	bpf_map__add_inner_map_fd(map, fd);
+
+	map = bpf_object__find_map_by_name(obj, "mim_hash");
+	if (IS_ERR(map)) {
+		printf("Failed to load hash of maps from test prog\n");
+		goto out_mapinmap;
+	}
+	bpf_map__add_inner_map_fd(map, fd);
+
+
+	bpf_object__for_each_program(prog, obj) {
+		bpf_program__set_xdp(prog);
+	}
+	bpf_object__load(obj);
+
+	map = bpf_object__find_map_by_name(obj, "mim_array");
+	if (IS_ERR(map)) {
+		printf("Failed to load array of maps from test prog\n");
+		goto out_mapinmap;
+	}
+	mim_fd = bpf_map__fd(map);
+	if (mim_fd < 0) {
+		printf("Failed to get descriptor for array of maps\n");
+		goto out_mapinmap;
+	}
+
+	bpf_map_update_elem(mim_fd, &pos, &fd, 0);
+
+	map = bpf_object__find_map_by_name(obj, "mim_hash");
+	if (IS_ERR(map)) {
+		printf("Failed to load hash of maps from test prog\n");
+		goto out_mapinmap;
+	}
+	mim_fd = bpf_map__fd(map);
+	if (mim_fd < 0) {
+		printf("Failed to get descriptor for hash of maps\n");
+		goto out_mapinmap;
+	}
+	bpf_map_update_elem(mim_fd, &pos, &fd, 0);
+
+
+	close(fd);
+	bpf_object__close(obj);
+	return;
+
+out_mapinmap:
+	close(fd);
+	exit(1);
+}
+
 #define MAP_SIZE (32 * 1024)
 
 static void test_map_large(void)
@@ -1554,6 +1628,8 @@ static void run_all_tests(void)
 
 	test_queuemap(0, NULL);
 	test_stackmap(0, NULL);
+
+	test_mapinmap();
 }
 
 int main(void)
-- 
2.15.1

Re: [PATCH bpf-next 1/2] bpf: adding support for map in map in libbpf

[Y Song]

On Mon, Nov 19, 2018 at 4:13 PM Nikita V. Shirokov <tehnerd@tehnerd.com> wrote:
>
> idea is pretty simple. for specified map (pointed by struct bpf_map)
> we would provide descriptor of already loaded map, which is going to be
> used as a prototype for inner map. proposed workflow:
> 1) open bpf's object (bpf_object__open)
> 2) create bpf's map which is going to be used as a prototype
> 3) find (by name) map-in-map which you want to load and update w/
> descriptor of inner map w/ a new helper from this patch
> 4) load bpf program w/ bpf_object__load
>
> inner_map_fd is ignored by any other maps asidef from (hash|array) of
> maps
>
> Signed-off-by: Nikita V. Shirokov <tehnerd@tehnerd.com>
> ---
>  tools/lib/bpf/libbpf.c | 7 +++++++
>  tools/lib/bpf/libbpf.h | 2 ++
>  2 files changed, 9 insertions(+)
>
> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index a01eb9584e52..a2ee1b1a93b6 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -163,6 +163,7 @@ struct bpf_map {
>         char *name;
>         size_t offset;
>         int map_ifindex;
> +       int inner_map_fd;
>         struct bpf_map_def def;
>         __u32 btf_key_type_id;
>         __u32 btf_value_type_id;
> @@ -1146,6 +1147,7 @@ bpf_object__create_maps(struct bpf_object *obj)
>                 create_attr.btf_fd = 0;
>                 create_attr.btf_key_type_id = 0;
>                 create_attr.btf_value_type_id = 0;
> +               create_attr.inner_map_fd = map->inner_map_fd;
>
>                 if (obj->btf && !bpf_map_find_btf_info(map, obj->btf)) {
>                         create_attr.btf_fd = btf__fd(obj->btf);
> @@ -2562,6 +2564,11 @@ void bpf_map__set_ifindex(struct bpf_map *map, __u32 ifindex)
>         map->map_ifindex = ifindex;
>  }
>
> +void bpf_map__add_inner_map_fd(struct bpf_map *map, const int fd)

Do we need "const" attribute here?

> +{
> +       map->inner_map_fd = fd;
> +}
> +
>  static struct bpf_map *
>  __bpf_map__iter(struct bpf_map *m, struct bpf_object *obj, int i)
>  {
> diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
> index b1686a787102..7cb00cd41789 100644
> --- a/tools/lib/bpf/libbpf.h
> +++ b/tools/lib/bpf/libbpf.h
> @@ -293,6 +293,8 @@ LIBBPF_API void bpf_map__set_ifindex(struct bpf_map *map, __u32 ifindex);
>  LIBBPF_API int bpf_map__pin(struct bpf_map *map, const char *path);
>  LIBBPF_API int bpf_map__unpin(struct bpf_map *map, const char *path);
>
> +LIBBPF_API void bpf_map__add_inner_map_fd(struct bpf_map *map, const int fd);
> +
>  LIBBPF_API long libbpf_get_error(const void *ptr);
>
>  struct bpf_prog_load_attr {
> --
> 2.15.1
>

Re: [PATCH bpf-next 2/2] bpf: adding tests for mapinmap helpber in libbpf

[Y Song]

On Mon, Nov 19, 2018 at 4:13 PM Nikita V. Shirokov <tehnerd@tehnerd.com> wrote:
>
> adding test/example of bpf_map__add_inner_map_fd usage
>
> Signed-off-by: Nikita V. Shirokov <tehnerd@tehnerd.com>
> ---
>  tools/testing/selftests/bpf/Makefile        |  3 +-
>  tools/testing/selftests/bpf/test_mapinmap.c | 53 ++++++++++++++++++++
>  tools/testing/selftests/bpf/test_maps.c     | 76 +++++++++++++++++++++++++++++
>  3 files changed, 131 insertions(+), 1 deletion(-)
>  create mode 100644 tools/testing/selftests/bpf/test_mapinmap.c
>
> diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
> index 57b4712a6276..a3ea69dc9bdf 100644
> --- a/tools/testing/selftests/bpf/Makefile
> +++ b/tools/testing/selftests/bpf/Makefile
> @@ -38,7 +38,8 @@ TEST_GEN_FILES = test_pkt_access.o test_xdp.o test_l4lb.o test_tcp_estats.o test
>         test_lwt_seg6local.o sendmsg4_prog.o sendmsg6_prog.o test_lirc_mode2_kern.o \
>         get_cgroup_id_kern.o socket_cookie_prog.o test_select_reuseport_kern.o \
>         test_skb_cgroup_id_kern.o bpf_flow.o netcnt_prog.o \
> -       test_sk_lookup_kern.o test_xdp_vlan.o test_queue_map.o test_stack_map.o
> +       test_sk_lookup_kern.o test_xdp_vlan.o test_queue_map.o test_stack_map.o \
> +       test_mapinmap.o
>
>  # Order correspond to 'make run_tests' order
>  TEST_PROGS := test_kmod.sh \
> diff --git a/tools/testing/selftests/bpf/test_mapinmap.c b/tools/testing/selftests/bpf/test_mapinmap.c
> new file mode 100644
> index 000000000000..8aef6c652c9c
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/test_mapinmap.c
> @@ -0,0 +1,53 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright (c) 2018 Facebook */
> +#include <stddef.h>
> +#include <linux/bpf.h>
> +#include <linux/types.h>
> +#include "bpf_helpers.h"
> +
> +
nit: extra new line

> +struct bpf_map_def SEC("maps") mim_array = {
> +       .type = BPF_MAP_TYPE_ARRAY_OF_MAPS,
> +       .key_size = sizeof(int),
> +       /* must be sizeof(__u32) for map in map */
> +       .value_size = sizeof(__u32),
> +       .max_entries = 1,
> +       .map_flags = 0,
> +};
> +
> +struct bpf_map_def SEC("maps") mim_hash = {
> +       .type = BPF_MAP_TYPE_HASH_OF_MAPS,
> +       .key_size = sizeof(int),
> +       /* must be sizeof(__u32) for map in map */
> +       .value_size = sizeof(__u32),
> +       .max_entries = 1,
> +       .map_flags = 0,
> +};
> +
> +
> +
nit: extra new lines.
> +SEC("xdp_mimtest")
> +int xdp_mimtest0(struct xdp_md *ctx)
> +{
> +       int value = 123;
> +       int key = 0;
> +       void *map;
> +
> +       map = bpf_map_lookup_elem(&mim_array, &key);
> +       if (!map)
> +               return XDP_DROP;
> +
> +       bpf_map_update_elem(map, &key, &value, 0);
> +
> +       map = bpf_map_lookup_elem(&mim_hash, &key);
> +       if (!map)
> +               return XDP_DROP;
> +
> +       bpf_map_update_elem(map, &key, &value, 0);
> +
> +       return XDP_PASS;
> +}
> +
> +
nit: extra new line
> +int _version SEC("version") = 1;
> +char _license[] SEC("license") = "GPL";
> diff --git a/tools/testing/selftests/bpf/test_maps.c b/tools/testing/selftests/bpf/test_maps.c
> index 4db2116e52be..a49ab294971d 100644
> --- a/tools/testing/selftests/bpf/test_maps.c
> +++ b/tools/testing/selftests/bpf/test_maps.c
> @@ -1080,6 +1080,80 @@ static void test_sockmap(int tasks, void *data)
>         exit(1);
>  }
>
> +#define MAPINMAP_PROG "./test_mapinmap.o"
> +static void test_mapinmap(void)
> +{
> +       struct bpf_program *prog;
> +       struct bpf_object *obj;
> +       struct bpf_map *map;
> +       int mim_fd, fd;
> +       int pos = 0;
> +
> +       obj = bpf_object__open(MAPINMAP_PROG);
> +
> +       fd = bpf_create_map(BPF_MAP_TYPE_HASH, sizeof(int), sizeof(int),
> +                           2, 0);
> +       if (fd < 0) {
> +               printf("Failed to create hashmap '%s'!\n", strerror(errno));
> +               exit(1);
> +       }
> +       printf("fd is %d\n", fd);
not sure whether you need to print fd in the console or not. Any particular
reason?
> +
> +       map = bpf_object__find_map_by_name(obj, "mim_array");
> +       if (IS_ERR(map)) {
> +               printf("Failed to load array of maps from test prog\n");
> +               goto out_mapinmap;
> +       }
> +       bpf_map__add_inner_map_fd(map, fd);
> +
> +       map = bpf_object__find_map_by_name(obj, "mim_hash");
> +       if (IS_ERR(map)) {
> +               printf("Failed to load hash of maps from test prog\n");
> +               goto out_mapinmap;
> +       }
> +       bpf_map__add_inner_map_fd(map, fd);
> +
> +
nit: extra new line
> +       bpf_object__for_each_program(prog, obj) {
> +               bpf_program__set_xdp(prog);
> +       }
> +       bpf_object__load(obj);
> +
> +       map = bpf_object__find_map_by_name(obj, "mim_array");
> +       if (IS_ERR(map)) {
> +               printf("Failed to load array of maps from test prog\n");
> +               goto out_mapinmap;
> +       }
> +       mim_fd = bpf_map__fd(map);
> +       if (mim_fd < 0) {
> +               printf("Failed to get descriptor for array of maps\n");
> +               goto out_mapinmap;
> +       }
> +
> +       bpf_map_update_elem(mim_fd, &pos, &fd, 0);
do you want to test return value of bpf_map_update_elem() to make sure
update is successful?
> +
> +       map = bpf_object__find_map_by_name(obj, "mim_hash");
> +       if (IS_ERR(map)) {
> +               printf("Failed to load hash of maps from test prog\n");
> +               goto out_mapinmap;
> +       }
> +       mim_fd = bpf_map__fd(map);
> +       if (mim_fd < 0) {
> +               printf("Failed to get descriptor for hash of maps\n");
> +               goto out_mapinmap;
> +       }
> +       bpf_map_update_elem(mim_fd, &pos, &fd, 0);
do you want to test return value of bpf_map_update_elem()?
> +
> +
nit: extra new line
> +       close(fd);
> +       bpf_object__close(obj);
> +       return;
> +
> +out_mapinmap:
> +       close(fd);
> +       exit(1);
> +}
> +
>  #define MAP_SIZE (32 * 1024)
>
>  static void test_map_large(void)
> @@ -1554,6 +1628,8 @@ static void run_all_tests(void)
>
>         test_queuemap(0, NULL);
>         test_stackmap(0, NULL);
> +
> +       test_mapinmap();
>  }
>
>  int main(void)
> --
> 2.15.1
>

Re: [PATCH bpf-next 2/2] bpf: adding tests for mapinmap helpber in libbpf

[Nikita V. Shirokov]

O Mon, Nov 19, 2018 at 05:18:46PM -0800, Y Song wrote:
> On Mon, Nov 19, 2018 at 4:13 PM Nikita V. Shirokov <tehnerd@tehnerd.com> wrote:
> >
> > adding test/example of bpf_map__add_inner_map_fd usage
> >
> > Signed-off-by: Nikita V. Shirokov <tehnerd@tehnerd.com>
> > ---
> >  tools/testing/selftests/bpf/Makefile        |  3 +-
> >  tools/testing/selftests/bpf/test_mapinmap.c | 53 ++++++++++++++++++++
> >  tools/testing/selftests/bpf/test_maps.c     | 76 +++++++++++++++++++++++++++++
> >  3 files changed, 131 insertions(+), 1 deletion(-)
> >  create mode 100644 tools/testing/selftests/bpf/test_mapinmap.c
> >
> > diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
> > index 57b4712a6276..a3ea69dc9bdf 100644
> > --- a/tools/testing/selftests/bpf/Makefile
> > +++ b/tools/testing/selftests/bpf/Makefile
> > @@ -38,7 +38,8 @@ TEST_GEN_FILES = test_pkt_access.o test_xdp.o test_l4lb.o test_tcp_estats.o test
> >         test_lwt_seg6local.o sendmsg4_prog.o sendmsg6_prog.o test_lirc_mode2_kern.o \
> >         get_cgroup_id_kern.o socket_cookie_prog.o test_select_reuseport_kern.o \
> >         test_skb_cgroup_id_kern.o bpf_flow.o netcnt_prog.o \
> > -       test_sk_lookup_kern.o test_xdp_vlan.o test_queue_map.o test_stack_map.o
> > +       test_sk_lookup_kern.o test_xdp_vlan.o test_queue_map.o test_stack_map.o \
> > +       test_mapinmap.o
> >
> >  # Order correspond to 'make run_tests' order
> >  TEST_PROGS := test_kmod.sh \
> > diff --git a/tools/testing/selftests/bpf/test_mapinmap.c b/tools/testing/selftests/bpf/test_mapinmap.c
> > new file mode 100644
> > index 000000000000..8aef6c652c9c
> > --- /dev/null
> > +++ b/tools/testing/selftests/bpf/test_mapinmap.c
> > @@ -0,0 +1,53 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/* Copyright (c) 2018 Facebook */
> > +#include <stddef.h>
> > +#include <linux/bpf.h>
> > +#include <linux/types.h>
> > +#include "bpf_helpers.h"
> > +
> > +
> nit: extra new line
> 
> > +struct bpf_map_def SEC("maps") mim_array = {
> > +       .type = BPF_MAP_TYPE_ARRAY_OF_MAPS,
> > +       .key_size = sizeof(int),
> > +       /* must be sizeof(__u32) for map in map */
> > +       .value_size = sizeof(__u32),
> > +       .max_entries = 1,
> > +       .map_flags = 0,
> > +};
> > +
> > +struct bpf_map_def SEC("maps") mim_hash = {
> > +       .type = BPF_MAP_TYPE_HASH_OF_MAPS,
> > +       .key_size = sizeof(int),
> > +       /* must be sizeof(__u32) for map in map */
> > +       .value_size = sizeof(__u32),
> > +       .max_entries = 1,
> > +       .map_flags = 0,
> > +};
> > +
> > +
> > +
> nit: extra new lines.
> > +SEC("xdp_mimtest")
> > +int xdp_mimtest0(struct xdp_md *ctx)
> > +{
> > +       int value = 123;
> > +       int key = 0;
> > +       void *map;
> > +
> > +       map = bpf_map_lookup_elem(&mim_array, &key);
> > +       if (!map)
> > +               return XDP_DROP;
> > +
> > +       bpf_map_update_elem(map, &key, &value, 0);
> > +
> > +       map = bpf_map_lookup_elem(&mim_hash, &key);
> > +       if (!map)
> > +               return XDP_DROP;
> > +
> > +       bpf_map_update_elem(map, &key, &value, 0);
> > +
> > +       return XDP_PASS;
> > +}
> > +
> > +
> nit: extra new line
> > +int _version SEC("version") = 1;
> > +char _license[] SEC("license") = "GPL";
> > diff --git a/tools/testing/selftests/bpf/test_maps.c b/tools/testing/selftests/bpf/test_maps.c
> > index 4db2116e52be..a49ab294971d 100644
> > --- a/tools/testing/selftests/bpf/test_maps.c
> > +++ b/tools/testing/selftests/bpf/test_maps.c
> > @@ -1080,6 +1080,80 @@ static void test_sockmap(int tasks, void *data)
> >         exit(1);
> >  }
> >
> > +#define MAPINMAP_PROG "./test_mapinmap.o"
> > +static void test_mapinmap(void)
> > +{
> > +       struct bpf_program *prog;
> > +       struct bpf_object *obj;
> > +       struct bpf_map *map;
> > +       int mim_fd, fd;
> > +       int pos = 0;
> > +
> > +       obj = bpf_object__open(MAPINMAP_PROG);
> > +
> > +       fd = bpf_create_map(BPF_MAP_TYPE_HASH, sizeof(int), sizeof(int),
> > +                           2, 0);
> > +       if (fd < 0) {
> > +               printf("Failed to create hashmap '%s'!\n", strerror(errno));
> > +               exit(1);
> > +       }
> > +       printf("fd is %d\n", fd);
> not sure whether you need to print fd in the console or not. Any particular
> reason?

was using for debugging. forget to remove.

> > +
> > +       map = bpf_object__find_map_by_name(obj, "mim_array");
> > +       if (IS_ERR(map)) {
> > +               printf("Failed to load array of maps from test prog\n");
> > +               goto out_mapinmap;
> > +       }
> > +       bpf_map__add_inner_map_fd(map, fd);
> > +
> > +       map = bpf_object__find_map_by_name(obj, "mim_hash");
> > +       if (IS_ERR(map)) {
> > +               printf("Failed to load hash of maps from test prog\n");
> > +               goto out_mapinmap;
> > +       }
> > +       bpf_map__add_inner_map_fd(map, fd);
> > +
> > +
> nit: extra new line
> > +       bpf_object__for_each_program(prog, obj) {
> > +               bpf_program__set_xdp(prog);
> > +       }
> > +       bpf_object__load(obj);
> > +
> > +       map = bpf_object__find_map_by_name(obj, "mim_array");
> > +       if (IS_ERR(map)) {
> > +               printf("Failed to load array of maps from test prog\n");
> > +               goto out_mapinmap;
> > +       }
> > +       mim_fd = bpf_map__fd(map);
> > +       if (mim_fd < 0) {
> > +               printf("Failed to get descriptor for array of maps\n");
> > +               goto out_mapinmap;
> > +       }
> > +
> > +       bpf_map_update_elem(mim_fd, &pos, &fd, 0);
> do you want to test return value of bpf_map_update_elem() to make sure
> update is successful?

sure.

> > +
> > +       map = bpf_object__find_map_by_name(obj, "mim_hash");
> > +       if (IS_ERR(map)) {
> > +               printf("Failed to load hash of maps from test prog\n");
> > +               goto out_mapinmap;
> > +       }
> > +       mim_fd = bpf_map__fd(map);
> > +       if (mim_fd < 0) {
> > +               printf("Failed to get descriptor for hash of maps\n");
> > +               goto out_mapinmap;
> > +       }
> > +       bpf_map_update_elem(mim_fd, &pos, &fd, 0);
> do you want to test return value of bpf_map_update_elem()?
> > +
> > +
> nit: extra new line
> > +       close(fd);
> > +       bpf_object__close(obj);
> > +       return;
> > +
> > +out_mapinmap:
> > +       close(fd);
> > +       exit(1);
> > +}
> > +
> >  #define MAP_SIZE (32 * 1024)
> >
> >  static void test_map_large(void)
> > @@ -1554,6 +1628,8 @@ static void run_all_tests(void)
> >
> >         test_queuemap(0, NULL);
> >         test_stackmap(0, NULL);
> > +
> > +       test_mapinmap();
> >  }
> >
> >  int main(void)
> > --
> > 2.15.1
> >

Re: [PATCH bpf-next 1/2] bpf: adding support for map in map in libbpf

[Nikita V. Shirokov]

On Mon, Nov 19, 2018 at 05:12:43PM -0800, Y Song wrote:
> On Mon, Nov 19, 2018 at 4:13 PM Nikita V. Shirokov <tehnerd@tehnerd.com> wrote:
> >
> > idea is pretty simple. for specified map (pointed by struct bpf_map)
> > we would provide descriptor of already loaded map, which is going to be
> > used as a prototype for inner map. proposed workflow:
> > 1) open bpf's object (bpf_object__open)
> > 2) create bpf's map which is going to be used as a prototype
> > 3) find (by name) map-in-map which you want to load and update w/
> > descriptor of inner map w/ a new helper from this patch
> > 4) load bpf program w/ bpf_object__load
> >
> > inner_map_fd is ignored by any other maps asidef from (hash|array) of
> > maps
> >
> > Signed-off-by: Nikita V. Shirokov <tehnerd@tehnerd.com>
> > ---
> >  tools/lib/bpf/libbpf.c | 7 +++++++
> >  tools/lib/bpf/libbpf.h | 2 ++
> >  2 files changed, 9 insertions(+)
> >
> > diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> > index a01eb9584e52..a2ee1b1a93b6 100644
> > --- a/tools/lib/bpf/libbpf.c
> > +++ b/tools/lib/bpf/libbpf.c
> > @@ -163,6 +163,7 @@ struct bpf_map {
> >         char *name;
> >         size_t offset;
> >         int map_ifindex;
> > +       int inner_map_fd;
> >         struct bpf_map_def def;
> >         __u32 btf_key_type_id;
> >         __u32 btf_value_type_id;
> > @@ -1146,6 +1147,7 @@ bpf_object__create_maps(struct bpf_object *obj)
> >                 create_attr.btf_fd = 0;
> >                 create_attr.btf_key_type_id = 0;
> >                 create_attr.btf_value_type_id = 0;
> > +               create_attr.inner_map_fd = map->inner_map_fd;
> >
> >                 if (obj->btf && !bpf_map_find_btf_info(map, obj->btf)) {
> >                         create_attr.btf_fd = btf__fd(obj->btf);
> > @@ -2562,6 +2564,11 @@ void bpf_map__set_ifindex(struct bpf_map *map, __u32 ifindex)
> >         map->map_ifindex = ifindex;
> >  }
> >
> > +void bpf_map__add_inner_map_fd(struct bpf_map *map, const int fd)
> 
> Do we need "const" attribute here?
>

i can drop it in v2
 
> > +{
> > +       map->inner_map_fd = fd;
> > +}
> > +
> >  static struct bpf_map *
> >  __bpf_map__iter(struct bpf_map *m, struct bpf_object *obj, int i)
> >  {
> > diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
> > index b1686a787102..7cb00cd41789 100644
> > --- a/tools/lib/bpf/libbpf.h
> > +++ b/tools/lib/bpf/libbpf.h
> > @@ -293,6 +293,8 @@ LIBBPF_API void bpf_map__set_ifindex(struct bpf_map *map, __u32 ifindex);
> >  LIBBPF_API int bpf_map__pin(struct bpf_map *map, const char *path);
> >  LIBBPF_API int bpf_map__unpin(struct bpf_map *map, const char *path);
> >
> > +LIBBPF_API void bpf_map__add_inner_map_fd(struct bpf_map *map, const int fd);
> > +
> >  LIBBPF_API long libbpf_get_error(const void *ptr);
> >
> >  struct bpf_prog_load_attr {
> > --
> > 2.15.1
> >

Re: [PATCH bpf-next 1/2] bpf: adding support for map in map in libbpf

[Edward Cree]

On 20/11/18 00:06, Nikita V. Shirokov wrote:
> idea is pretty simple. for specified map (pointed by struct bpf_map)
> we would provide descriptor of already loaded map, which is going to be
> used as a prototype for inner map. proposed workflow:
> 1) open bpf's object (bpf_object__open)
> 2) create bpf's map which is going to be used as a prototype
> 3) find (by name) map-in-map which you want to load and update w/
> descriptor of inner map w/ a new helper from this patch
> 4) load bpf program w/ bpf_object__load
>
> inner_map_fd is ignored by any other maps asidef from (hash|array) of
"asidef" -> "aside"