[PATCH bpf-next 01/13] bpf: xor of a/x in cbpf can be done in 32 bit alu

[Daniel Borkmann]

Very minor optimization; saves 1 byte per program in x86_64
JIT in cBPF prologue.

Signed-off-by: Daniel Borkmann <dan...@iogearbox.net>
Acked-by: Alexei Starovoitov <a...@kernel.org>
---
 net/core/filter.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/core/filter.c b/net/core/filter.c
index 18da42a..cba2f73 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -401,8 +401,8 @@ static int bpf_convert_filter(struct sock_filter *prog, int 
len,
                /* 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
-- 
2.9.5