]> git.proxmox.com Git - mirror_ubuntu-kernels.git/commit
bpf: do not use reciprocal divide
authorEric Dumazet <edumazet@google.com>
Wed, 15 Jan 2014 14:50:07 +0000 (06:50 -0800)
committerDavid S. Miller <davem@davemloft.net>
Thu, 16 Jan 2014 01:02:08 +0000 (17:02 -0800)
commitaee636c4809fa54848ff07a899b326eb1f9987a2
tree8f0c327f82dd7d5056dc487064f05f3f804f2fea
parentba42fad0964a41f0830e80c1b6be49c1e6bfcc01
bpf: do not use reciprocal divide

At first Jakub Zawadzki noticed that some divisions by reciprocal_divide
were not correct. (off by one in some cases)
http://www.wireshark.org/~darkjames/reciprocal-buggy.c

He could also show this with BPF:
http://www.wireshark.org/~darkjames/set-and-dump-filter-k-bug.c

The reciprocal divide in linux kernel is not generic enough,
lets remove its use in BPF, as it is not worth the pain with
current cpus.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Jakub Zawadzki <darkjames-ws@darkjames.pl>
Cc: Mircea Gherzan <mgherzan@gmail.com>
Cc: Daniel Borkmann <dxchgb@gmail.com>
Cc: Hannes Frederic Sowa <hannes@stressinduktion.org>
Cc: Matt Evans <matt@ozlabs.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
arch/arm/net/bpf_jit_32.c
arch/powerpc/net/bpf_jit_comp.c
arch/s390/net/bpf_jit_comp.c
arch/sparc/net/bpf_jit_comp.c
arch/x86/net/bpf_jit_comp.c
net/core/filter.c