Message ID | 20181126.134241.1241912335032719237.davem@redhat.com |
---|---|
State | Accepted, archived |
Delegated to: | BPF Maintainers |
Headers | show |
Series | [bpf-next] bpf: Avoid unnecessary instruction in conver_bpf_ld_abs() | expand |
On 11/26/2018 10:42 PM, David Miller wrote: > > 'offset' is constant and if it is zero, no need to subtract it > from BPF_REG_TMP. > > Signed-off-by: David S. Miller <davem@davemloft.net> Applied to bpf-next, thanks!
diff --git a/net/core/filter.c b/net/core/filter.c index aa274679965d..f50ea971f7a9 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -463,7 +463,8 @@ static bool convert_bpf_ld_abs(struct sock_filter *fp, struct bpf_insn **insnp) bool ldx_off_ok = offset <= S16_MAX; *insn++ = BPF_MOV64_REG(BPF_REG_TMP, BPF_REG_H); - *insn++ = BPF_ALU64_IMM(BPF_SUB, BPF_REG_TMP, offset); + if (offset) + *insn++ = BPF_ALU64_IMM(BPF_SUB, BPF_REG_TMP, offset); *insn++ = BPF_JMP_IMM(BPF_JSLT, BPF_REG_TMP, size, 2 + endian + (!ldx_off_ok * 2)); if (ldx_off_ok) {
'offset' is constant and if it is zero, no need to subtract it from BPF_REG_TMP. Signed-off-by: David S. Miller <davem@davemloft.net>