• Eric Dumazet's avatar
    filter: optimize accesses to ancillary data · 12b16dad
    Eric Dumazet authored
    
    
    We can translate pseudo load instructions at filter check time to
    dedicated instructions to speed up filtering and avoid one switch().
    libpcap currently uses SKF_AD_PROTOCOL, but custom filters probably use
    other ancillary accesses.
    
    Note : I made the assertion that ancillary data was always accessed with
    BPF_LD|BPF_?|BPF_ABS instructions, not with BPF_LD|BPF_?|BPF_IND ones
    (offset given by K constant, not by K + X register)
    
    On x86_64, this saves a few bytes of text :
    
    # size net/core/filter.o.*
       text	   data	    bss	    dec	    hex	filename
       4864	      0	      0	   4864	   1300	net/core/filter.o.new
       4944	      0	      0	   4944	   1350	net/core/filter.o.old
    Signed-off-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    12b16dad