On Tue, 2025-09-09 at 22:46 +0800, KaFai Wan wrote: > OpenWRT users reported regression on ARMv6 devices after updating to latest > HEAD, where tcpdump filter: > > tcpdump "not ether host 3c37121a2b3c and not ether host 184ecbca2a3a \ > and not ether host 14130b4d3f47 and not ether host f0f61cf440b7 \ > and not ether host a84b4dedf471 and not ether host d022be17e1d7 \ > and not ether host 5c497967208b and not ether host 706655784d5b" > > fails with warning: "Kernel filter failed: No error information" > when using config: > # CONFIG_BPF_JIT_ALWAYS_ON is not set > CONFIG_BPF_JIT_DEFAULT_ON=y > > The issue arises because commits: > 1. "bpf: Fix array bounds error with may_goto" changed default runtime to > __bpf_prog_ret0_warn when jit_requested = 1 > 2. "bpf: Avoid __bpf_prog_ret0_warn when jit fails" returns error when > jit_requested = 1 but jit fails > > This change restores interpreter fallback capability for BPF programs with > stack size <= 512 bytes when jit fails. > > Reported-by: Felix Fietkau <nbd@xxxxxxxx> > Closes: https://lore.kernel.org/bpf/2e267b4b-0540-45d8-9310-e127bf95fc63@xxxxxxxx/ > Fixes: 6ebc5030e0c5 ("bpf: Fix array bounds error with may_goto") > Signed-off-by: KaFai Wan <kafai.wan@xxxxxxxxx> > --- > changes: > v3: > - Remove the selftest (Puranjay and Eduard) > > v2: > - Addressed comments from Alexei > - Add selftest > https://lore.kernel.org/all/20250813152958.3107403-1-kafai.wan@xxxxxxxxx/ > > v1: > https://lore.kernel.org/all/20250805115513.4018532-1-kafai.wan@xxxxxxxxx/ > --- Acked-by: Eduard Zingerman <eddyz87@xxxxxxxxx> [...]
