From 99c55f7d47c0dc6fc64729f37bf435abf43f4c60 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Fri, 26 Sep 2014 00:16:57 -0700 Subject: bpf: introduce BPF syscall and maps BPF syscall is a multiplexor for a range of different operations on eBPF. This patch introduces syscall with single command to create a map. Next patch adds commands to access maps. 'maps' is a generic storage of different types for sharing data between kernel and userspace. Userspace example: /* this syscall wrapper creates a map with given type and attributes * and returns map_fd on success. * use close(map_fd) to delete the map */ int bpf_create_map(enum bpf_map_type map_type, int key_size, int value_size, int max_entries) { union bpf_attr attr = { .map_type = map_type, .key_size = key_size, .value_size = value_size, .max_entries = max_entries }; return bpf(BPF_MAP_CREATE, &attr, sizeof(attr)); } 'union bpf_attr' is backwards compatible with future extensions. More details in Documentation/networking/filter.txt and in manpage Signed-off-by: Alexei Starovoitov Signed-off-by: David S. Miller --- include/uapi/linux/bpf.h | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) (limited to 'include/uapi/linux/bpf.h') diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 479ed0b6be16..f58a10f9670c 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -62,4 +62,27 @@ struct bpf_insn { __s32 imm; /* signed immediate constant */ }; +/* BPF syscall commands */ +enum bpf_cmd { + /* create a map with given type and attributes + * fd = bpf(BPF_MAP_CREATE, union bpf_attr *, u32 size) + * returns fd or negative error + * map is deleted when fd is closed + */ + BPF_MAP_CREATE, +}; + +enum bpf_map_type { + BPF_MAP_TYPE_UNSPEC, +}; + +union bpf_attr { + struct { /* anonymous struct used by BPF_MAP_CREATE command */ + __u32 map_type; /* one of enum bpf_map_type */ + __u32 key_size; /* size of key in bytes */ + __u32 value_size; /* size of value in bytes */ + __u32 max_entries; /* max number of entries in a map */ + }; +} __attribute__((aligned(8))); + #endif /* _UAPI__LINUX_BPF_H__ */ -- cgit v1.2.3