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| author |   David Miller <davem@redhat.com> | 2018-11-26 13:42:41 -0800 |
|---|---|---|
| committer |   Daniel Borkmann <daniel@iogearbox.net> | 2018-11-26 23:10:27 +0100 |
| commit | d8f3e978bd30014081c599456285ca1d58c2aae1 (patch) | |
| tree | 16031a2c1fc047a49c38fb4a3024e9cc3797e1eb /net/core/filter.c | |
| parent | Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next (diff) | |
| download | linux-dev-d8f3e978bd30014081c599456285ca1d58c2aae1.tar.xz linux-dev-d8f3e978bd30014081c599456285ca1d58c2aae1.zip | |
bpf: Avoid unnecessary instruction in convert_bpf_ld_abs()
'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>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Diffstat (limited to 'net/core/filter.c')
| -rw-r--r-- | net/core/filter.c | 3 |
1 files changed, 2 insertions, 1 deletions
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) { |