[PATCH v4 bpf-next 17/22] libbpf: Introduce bpf_map__get_initial_value().

[Alexei Starovoitov <alexei.starovoitov@gmail.com>]

From: Alexei Starovoitov <ast@kernel.org>

Introduce bpf_map__get_initial_value() to read initial contents
of rodata/bss maps. Note only mmaped maps qualify.
Just as bpf_map__set_initial_value() works only for mmaped kconfig.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
---
 tools/lib/bpf/libbpf.c   | 10 ++++++++++
 tools/lib/bpf/libbpf.h   |  2 ++
 tools/lib/bpf/libbpf.map |  1 +
 3 files changed, 13 insertions(+)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 24a659448782..f7cdbb0e1faf 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -9763,6 +9763,16 @@ int bpf_map__set_initial_value(struct bpf_map *map,
 	return 0;
 }
 
+int bpf_map__get_initial_value(struct bpf_map *map,
+			       const void **pdata, size_t *psize)
+{
+	if (!map->mmaped)
+		return -EINVAL;
+	*psize = map->def.value_size;
+	*pdata = map->mmaped;
+	return 0;
+}
+
 bool bpf_map__is_offload_neutral(const struct bpf_map *map)
 {
 	return map->def.type == BPF_MAP_TYPE_PERF_EVENT_ARRAY;
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index fb291b4529e8..f8976a30586f 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -471,6 +471,8 @@ LIBBPF_API int bpf_map__set_priv(struct bpf_map *map, void *priv,
 LIBBPF_API void *bpf_map__priv(const struct bpf_map *map);
 LIBBPF_API int bpf_map__set_initial_value(struct bpf_map *map,
 					  const void *data, size_t size);
+LIBBPF_API int bpf_map__get_initial_value(struct bpf_map *map,
+					  const void **pdata, size_t *psize);
 LIBBPF_API bool bpf_map__is_offload_neutral(const struct bpf_map *map);
 LIBBPF_API bool bpf_map__is_internal(const struct bpf_map *map);
 LIBBPF_API int bpf_map__set_pin_path(struct bpf_map *map, const char *path);
diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
index 889ee2f3611c..44285045ddf4 100644
--- a/tools/lib/bpf/libbpf.map
+++ b/tools/lib/bpf/libbpf.map
@@ -360,6 +360,7 @@ LIBBPF_0.4.0 {
 		bpf_linker__free;
 		bpf_linker__new;
 		bpf_map__inner_map;
+		bpf_map__get_initial_value;
 		bpf_object__gen_loader;
 		bpf_object__set_kversion;
 } LIBBPF_0.3.0;
-- 
2.30.2