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| author | Daniel Borkmann <daniel@iogearbox.net> | 2015-12-17 23:51:56 +0100 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2015-12-18 22:04:51 +0100 |
| commit | 606c88a86c77fa27cb4eac899ddced9092825bea (patch) | |
| tree | 6912e097e8e74ca15f8567739eb4b215845f6bc7 /lib/test_bpf.c | |
| parent | bpf: fix misleading comment in bpf_convert_filter (diff) | |
| download | linux-606c88a86c77fa27cb4eac899ddced9092825bea.tar.xz linux-606c88a86c77fa27cb4eac899ddced9092825bea.zip | |
bpf, x86: detect/optimize loading 0 immediates
When sometimes structs or variables need to be initialized/'memset' to 0 in
an eBPF C program, the x86 BPF JIT converts this to use immediates. We can
however save a couple of bytes (f.e. even up to 7 bytes on a single emmission
of BPF_LD | BPF_IMM | BPF_DW) in the image by detecting such case and use xor
on the dst register instead.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'lib/test_bpf.c')
0 files changed, 0 insertions, 0 deletions