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| author | Daniel Borkmann <daniel@iogearbox.net> | 2018-01-26 23:33:36 +0100 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2018-01-26 16:42:05 -0800 |
| commit | 1d621674d923790d09cab9e2c7da7da6446a6257 (patch) | |
| tree | 77e833adb01837abf0edc3421b403e9244c9e9b0 /net/core | |
| parent | c25ef6a5e62fa212d298ce24995ce239f29b5f96 (diff) | |
| download | linux-stable-1d621674d923790d09cab9e2c7da7da6446a6257.tar.gz linux-stable-1d621674d923790d09cab9e2c7da7da6446a6257.tar.bz2 linux-stable-1d621674d923790d09cab9e2c7da7da6446a6257.zip | |
bpf: xor of a/x in cbpf can be done in 32 bit alu
Very minor optimization; saves 1 byte per program in x86_64
JIT in cBPF prologue.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'net/core')
| -rw-r--r-- | net/core/filter.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/net/core/filter.c b/net/core/filter.c index fe2c7937351f..60d8c8712652 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -401,8 +401,8 @@ do_pass: /* Classic BPF expects A and X to be reset first. These need * to be guaranteed to be the first two instructions. */ - *new_insn++ = BPF_ALU64_REG(BPF_XOR, BPF_REG_A, BPF_REG_A); - *new_insn++ = BPF_ALU64_REG(BPF_XOR, BPF_REG_X, BPF_REG_X); + *new_insn++ = BPF_ALU32_REG(BPF_XOR, BPF_REG_A, BPF_REG_A); + *new_insn++ = BPF_ALU32_REG(BPF_XOR, BPF_REG_X, BPF_REG_X); /* All programs must keep CTX in callee saved BPF_REG_CTX. * In eBPF case it's done by the compiler, here we need to |