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author | Alexei Starovoitov | 2017-12-01 06:31:38 +0100 |
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committer | Daniel Borkmann | 2017-12-01 11:25:10 +0100 |
commit | 2f18f62ee1648b2c93e6ab4a58d548010b0a67e4 (patch) | |
tree | cf7f96af09a7601e9b82701a720b24e3e19a36c9 /kernel | |
parent | bpf: don't mark FP reg as uninit (diff) | |
download | kernel-qcow2-linux-2f18f62ee1648b2c93e6ab4a58d548010b0a67e4.tar.gz kernel-qcow2-linux-2f18f62ee1648b2c93e6ab4a58d548010b0a67e4.tar.xz kernel-qcow2-linux-2f18f62ee1648b2c93e6ab4a58d548010b0a67e4.zip |
bpf: improve verifier liveness marks
registers with pointers filled from stack were missing live_written marks
which caused liveness propagation to unnecessary mark more registers as
live_read and miss state pruning opportunities later on.
before after
bpf_lb-DLB_L3.o 2285 2270
bpf_lb-DLB_L4.o 3723 3682
bpf_lb-DUNKNOWN.o 1110 1110
bpf_lxc-DDROP_ALL.o 27954 27876
bpf_lxc-DUNKNOWN.o 38954 38780
bpf_netdev.o 16943 16937
bpf_overlay.o 7929 7929
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, 5 insertions, 0 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 14ad7c6e806a..46ff4e5b3fb7 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -795,6 +795,11 @@ static int check_stack_read(struct bpf_verifier_env *env, if (value_regno >= 0) { /* restore register state from stack */ state->regs[value_regno] = state->stack[spi].spilled_ptr; + /* mark reg as written since spilled pointer state likely + * has its liveness marks cleared by is_state_visited() + * which resets stack/reg liveness for state transitions + */ + state->regs[value_regno].live |= REG_LIVE_WRITTEN; mark_stack_slot_read(state, spi); } return 0; |