From: Eduard Zingerman <eddyz87@gmail.com>
To: KaFai Wan <kafai.wan@linux.dev>,
ast@kernel.org, daniel@iogearbox.net, john.fastabend@gmail.com,
andrii@kernel.org, martin.lau@linux.dev, song@kernel.org,
yonghong.song@linux.dev, kpsingh@kernel.org, sdf@fomichev.me,
haoluo@google.com, jolsa@kernel.org, mrpre@163.com,
bpf@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: Felix Fietkau <nbd@nbd.name>
Subject: Re: [PATCH bpf v3 1/1] bpf: Allow fall back to interpreter for programs with stack size <= 512
Date: Tue, 09 Sep 2025 14:05:31 -0700 [thread overview]
Message-ID: <9669e2334e7292d2522b4367703c25a6338b3280.camel@gmail.com> (raw)
In-Reply-To: <20250909144614.2991253-1-kafai.wan@linux.dev>
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@nbd.name>
> Closes: https://lore.kernel.org/bpf/2e267b4b-0540-45d8-9310-e127bf95fc63@nbd.name/
> Fixes: 6ebc5030e0c5 ("bpf: Fix array bounds error with may_goto")
> Signed-off-by: KaFai Wan <kafai.wan@linux.dev>
> ---
> 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@linux.dev/
>
> v1:
> https://lore.kernel.org/all/20250805115513.4018532-1-kafai.wan@linux.dev/
> ---
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
[...]
next prev parent reply other threads:[~2025-09-09 21:05 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-09 14:46 [PATCH bpf v3 1/1] bpf: Allow fall back to interpreter for programs with stack size <= 512 KaFai Wan
2025-09-09 21:05 ` Eduard Zingerman [this message]
2025-09-09 22:20 ` patchwork-bot+netdevbpf
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