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| author | Alexei Starovoitov <ast@fb.com> | 2017-11-30 21:31:39 -0800 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2017-12-01 11:25:10 +0100 |
| commit | 3bf15921c58df982f9b15d64754c483785bf66f3 (patch) | |
| tree | e1cd41a7e3540de48e922412481a58451188fcbf /kernel | |
| parent | 2f18f62ee1648b2c93e6ab4a58d548010b0a67e4 (diff) | |
| download | linux-stable-3bf15921c58df982f9b15d64754c483785bf66f3.tar.gz linux-stable-3bf15921c58df982f9b15d64754c483785bf66f3.tar.bz2 linux-stable-3bf15921c58df982f9b15d64754c483785bf66f3.zip | |
bpf: improve JEQ/JNE path walking
verifier knows how to trim paths that are known not to be
taken at run-time when register containing run-time constant
is compared with another constant.
It was done only for JEQ comparison.
Extend it to include JNE as well.
More cases can be added in the future.
before after
bpf_lb-DLB_L3.o 2270 2051
bpf_lb-DLB_L4.o 3682 3287
bpf_lb-DUNKNOWN.o 1110 1080
bpf_lxc-DDROP_ALL.o 27876 24980
bpf_lxc-DUNKNOWN.o 38780 34308
bpf_netdev.o 16937 15404
bpf_overlay.o 7929 7191
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/bpf/verifier.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 46ff4e5b3fb7..afe9a1a0a5fe 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -2955,8 +2955,9 @@ static int check_cond_jmp_op(struct bpf_verifier_env *env, if (BPF_SRC(insn->code) == BPF_K && (opcode == BPF_JEQ || opcode == BPF_JNE) && dst_reg->type == SCALAR_VALUE && - tnum_equals_const(dst_reg->var_off, insn->imm)) { - if (opcode == BPF_JEQ) { + tnum_is_const(dst_reg->var_off)) { + if ((opcode == BPF_JEQ && dst_reg->var_off.value == insn->imm) || + (opcode == BPF_JNE && dst_reg->var_off.value != insn->imm)) { /* if (imm == imm) goto pc+off; * only follow the goto, ignore fall-through */ |