From: Alexei Starovoitov <ast@plumgrid.com>
Date: Fri, 26 Sep 2014 07:16:57 +0000 (-0700)
Subject: bpf: introduce BPF syscall and maps
X-Git-Tag: fixes-against-v3.18-rc2~81^2~1^2~10
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=99c55f7d47c0dc6fc64729f37bf435abf43f4c60;p=pandora-kernel.git

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 <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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