* [PATCH bpf-next 1/2] libbpf: Introduce bpf_map__resize
2019-02-14 23:01 [PATCH bpf-next 0/2] libbpf: Add new interfaces Andrey Ignatov
@ 2019-02-14 23:01 ` Andrey Ignatov
2019-02-15 1:52 ` Yonghong Song
2019-02-14 23:01 ` [PATCH bpf-next 2/2] libbpf: Introduce bpf_object__btf Andrey Ignatov
1 sibling, 1 reply; 6+ messages in thread
From: Andrey Ignatov @ 2019-02-14 23:01 UTC (permalink / raw)
To: netdev; +Cc: Andrey Ignatov, ast, daniel, kernel-team
Add bpf_map__resize() to change max_entries for a map.
Quite often necessary map size is unknown at compile time and can be
calculated only at run time.
Currently the following approach is used to do so:
* bpf_object__open_buffer() to open Elf file from a buffer;
* bpf_object__find_map_by_name() to find relevant map;
* bpf_map__def() to get map attributes and create struct
bpf_create_map_attr from them;
* update max_entries in bpf_create_map_attr;
* bpf_create_map_xattr() to create new map with updated max_entries;
* bpf_map__reuse_fd() to replace the map in bpf_object with newly
created one.
And after all this bpf_object can finally be loaded. The map will have
new size.
It 1) is quite a lot of steps; 2) doesn't take BTF into account.
For "2)" even more steps should be made and some of them require changes
to libbpf (e.g. to get struct btf * from bpf_object).
Instead the whole problem can be solved by introducing simple
bpf_map__resize() API that checks the map and sets new max_entries if
the map is not loaded yet.
So the new steps are:
* bpf_object__open_buffer() to open Elf file from a buffer;
* bpf_object__find_map_by_name() to find relevant map;
* bpf_map__resize() to update max_entries.
That's much simpler and works with BTF.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
---
tools/lib/bpf/libbpf.c | 14 ++++++++++++++
tools/lib/bpf/libbpf.h | 1 +
tools/lib/bpf/libbpf.map | 1 +
3 files changed, 16 insertions(+)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index e3c39edfb9d3..690e7b079202 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -1114,6 +1114,20 @@ int bpf_map__reuse_fd(struct bpf_map *map, int fd)
return -errno;
}
+int bpf_map__resize(struct bpf_map *map, __u32 max_entries)
+{
+ if (!map || !max_entries)
+ return -EINVAL;
+
+ /* If map already created, its attributes can't be changed. */
+ if (map->fd >= 0)
+ return -EBUSY;
+
+ map->def.max_entries = max_entries;
+
+ return 0;
+}
+
static int
bpf_object__probe_name(struct bpf_object *obj)
{
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 69a7c25eaccc..987fd92661d6 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -294,6 +294,7 @@ LIBBPF_API int bpf_map__set_priv(struct bpf_map *map, void *priv,
bpf_map_clear_priv_t clear_priv);
LIBBPF_API void *bpf_map__priv(struct bpf_map *map);
LIBBPF_API int bpf_map__reuse_fd(struct bpf_map *map, int fd);
+LIBBPF_API int bpf_map__resize(struct bpf_map *map, __u32 max_entries);
LIBBPF_API bool bpf_map__is_offload_neutral(struct bpf_map *map);
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);
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index 5fc8222209f8..16f342c3d4bc 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -130,6 +130,7 @@ LIBBPF_0.0.2 {
bpf_probe_helper;
bpf_probe_map_type;
bpf_probe_prog_type;
+ bpf_map__resize;
bpf_map_lookup_elem_flags;
bpf_object__find_map_fd_by_name;
bpf_get_link_xdp_id;
--
2.17.1
^ permalink raw reply related [flat|nested] 6+ messages in thread* [PATCH bpf-next 2/2] libbpf: Introduce bpf_object__btf
2019-02-14 23:01 [PATCH bpf-next 0/2] libbpf: Add new interfaces Andrey Ignatov
2019-02-14 23:01 ` [PATCH bpf-next 1/2] libbpf: Introduce bpf_map__resize Andrey Ignatov
@ 2019-02-14 23:01 ` Andrey Ignatov
2019-02-15 1:53 ` Yonghong Song
1 sibling, 1 reply; 6+ messages in thread
From: Andrey Ignatov @ 2019-02-14 23:01 UTC (permalink / raw)
To: netdev; +Cc: Andrey Ignatov, ast, daniel, kernel-team
Add new accessor for bpf_object to get opaque struct btf * from it.
struct btf * is needed for all operations with BTF and it's present in
bpf_object. The only thing missing is a way to get it.
Example use-case is to get BTF key_type_id an value_type_id for a map in
bpf_object. It can be done with btf__get_map_kv_tids() but that function
requires struct btf *.
Similar API can be added for struct btf_ext but no use-case for it yet.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
---
tools/lib/bpf/libbpf.c | 5 +++++
tools/lib/bpf/libbpf.h | 3 +++
tools/lib/bpf/libbpf.map | 1 +
3 files changed, 9 insertions(+)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 690e7b079202..a77a327c2bb8 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -2332,6 +2332,11 @@ unsigned int bpf_object__kversion(struct bpf_object *obj)
return obj ? obj->kern_version : 0;
}
+struct btf *bpf_object__btf(struct bpf_object *obj)
+{
+ return obj ? obj->btf : NULL;
+}
+
int bpf_object__btf_fd(const struct bpf_object *obj)
{
return obj->btf ? btf__fd(obj->btf) : -1;
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 987fd92661d6..6c0168f8bba5 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -89,6 +89,9 @@ LIBBPF_API int bpf_object__load(struct bpf_object *obj);
LIBBPF_API int bpf_object__unload(struct bpf_object *obj);
LIBBPF_API const char *bpf_object__name(struct bpf_object *obj);
LIBBPF_API unsigned int bpf_object__kversion(struct bpf_object *obj);
+
+struct btf;
+LIBBPF_API struct btf *bpf_object__btf(struct bpf_object *obj);
LIBBPF_API int bpf_object__btf_fd(const struct bpf_object *obj);
LIBBPF_API struct bpf_program *
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index 16f342c3d4bc..99dfa710c818 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -132,6 +132,7 @@ LIBBPF_0.0.2 {
bpf_probe_prog_type;
bpf_map__resize;
bpf_map_lookup_elem_flags;
+ bpf_object__btf;
bpf_object__find_map_fd_by_name;
bpf_get_link_xdp_id;
btf__dedup;
--
2.17.1
^ permalink raw reply related [flat|nested] 6+ messages in thread