[RFC PATCH 01/13] bpf tools: Add map related BPF helper

[Wang Nan <wangnan0@huawei.com>]

Add BPF map helpers so user can read from bpf map in user space.
Following commits will introduce user space BPF, bpf_map will be
used to pass information between kernel and user BPF programs.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Li Zefan <lizefan@huawei.com>
---
 tools/lib/bpf/bpf.c | 24 ++++++++++++++++++++++++
 tools/lib/bpf/bpf.h |  2 ++
 2 files changed, 26 insertions(+)

diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index 1f91cc9..337d9dc 100644
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c
@@ -97,3 +97,27 @@ int bpf_map_update_elem(int fd, void *key, void *value,
 
 	return sys_bpf(BPF_MAP_UPDATE_ELEM, &attr, sizeof(attr));
 }
+
+int bpf_map_lookup_elem(int fd, void *key, void *value)
+{
+	union bpf_attr attr;
+
+	bzero(&attr, sizeof(attr));
+	attr.map_fd = fd;
+	attr.key = ptr_to_u64(key);
+	attr.value = ptr_to_u64(value);
+
+	return sys_bpf(BPF_MAP_LOOKUP_ELEM, &attr, sizeof(attr));
+}
+
+int bpf_map_get_next_key(int fd, void *key, void *next_key)
+{
+	union bpf_attr attr;
+
+	bzero(&attr, sizeof(attr));
+	attr.map_fd = fd;
+	attr.key = ptr_to_u64(key);
+	attr.next_key = ptr_to_u64(next_key);
+
+	return sys_bpf(BPF_MAP_GET_NEXT_KEY, &attr, sizeof(attr));
+}
diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
index a764655..c06ea21 100644
--- a/tools/lib/bpf/bpf.h
+++ b/tools/lib/bpf/bpf.h
@@ -22,4 +22,6 @@ int bpf_load_program(enum bpf_prog_type type, struct bpf_insn *insns,
 
 int bpf_map_update_elem(int fd, void *key, void *value,
 			u64 flags);
+int bpf_map_lookup_elem(int fd, void *key, void *value);
+int bpf_map_get_next_key(int fd, void *key, void *next_key);
 #endif
-- 
1.8.3.4