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| author |   Jakub Kicinski <jakub.kicinski@netronome.com> | 2019-01-22 22:45:20 -0800 |
|---|---|---|
| committer |   Alexei Starovoitov <ast@kernel.org> | 2019-01-23 17:35:31 -0800 |
| commit | 52875a04f4b26e7ef30a288ea096f7cfec0e93cd (patch) | |
| tree | ef2b72219c9eae090adb9a35d75bc64b2b9ed50c /kernel/bpf/core.c | |
| parent | bpf: verifier: hard wire branches to dead code (diff) | |
| download | linux-dev-52875a04f4b26e7ef30a288ea096f7cfec0e93cd.tar.xz linux-dev-52875a04f4b26e7ef30a288ea096f7cfec0e93cd.zip | |
bpf: verifier: remove dead code
Instead of overwriting dead code with jmp -1 instructions
remove it completely for root. Adjust verifier state and
line info appropriately.
v2:
- adjust func_info (Alexei);
- make sure first instruction retains line info (Alexei).
v4: (Yonghong)
- remove unnecessary if (!insn to remove) checks;
- always keep last line info if first live instruction lacks one.
v5: (Martin Lau)
- improve and clarify comments.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'kernel/bpf/core.c')
| -rw-r--r-- | kernel/bpf/core.c | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index ad08ba341197..2a81b8af3748 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -462,6 +462,18 @@ struct bpf_prog *bpf_patch_insn_single(struct bpf_prog *prog, u32 off, return prog_adj; } +int bpf_remove_insns(struct bpf_prog *prog, u32 off, u32 cnt) +{ + /* Branch offsets can't overflow when program is shrinking, no need + * to call bpf_adj_branches(..., true) here + */ + memmove(prog->insnsi + off, prog->insnsi + off + cnt, + sizeof(struct bpf_insn) * (prog->len - off - cnt)); + prog->len -= cnt; + + return WARN_ON_ONCE(bpf_adj_branches(prog, off, off + cnt, off, false)); +} + void bpf_prog_kallsyms_del_subprogs(struct bpf_prog *fp) { int i; |