Re: [PATCH bpf-next v4 08/20] bpf: Walk the exception unwind in the verifier

[Yonghong Song <yonghong.song@linux.dev>]

On 9/21/26 9:08 PM, Alexei Starovoitov wrote:
> On Mon Sep 21, 2026 at 9:01 PM UTC, Yonghong Song wrote:
>> --- /dev/null
>> +++ b/include/linux/bpf_cleanup_abi.h
>> @@ -0,0 +1,16 @@
>> +/* SPDX-License-Identifier: GPL-2.0-only */
>> +/* Copyright (c) 2026 Meta Platforms, Inc. and affiliates. */
>> +#ifndef _LINUX_BPF_CLEANUP_ABI_H
>> +#define _LINUX_BPF_CLEANUP_ABI_H
>> +
>> +/*
>> + * Value arch_bpf_run_cleanup_pad() leaves in r0 on the way into a landing pad.
>> + * It has to be a constant the verifier knows: LLVM names r0 as both the
>> + * exception pointer and the exception selector register, so every pad reads it
>> + * before anything else and is free to store what it read. It gets a header of
>> + * its own because the two sides that have to agree on it are the verifier and
>> + * the arch dispatchers, which are assembly.
>> + */
>> +#define BPF_PAD_ENTRY_R0	1
>> +
>> +#endif /* _LINUX_BPF_CLEANUP_ABI_H */
> I'm not going to read the AI reasons in commit log that it came up with
> to justify new .h.
> I bet it doesn't need new .h. If it does, please spell it out with human voice.
> And, in general, pls tell AI to be terse. and remember it forever.
>
> I told my clanker to be like me. Terse and to the point.

Okay, I added this file to be shared in x86/net/bpf_cleanup_pad.S,
arm64/net/bpf_cleanup_pad.S and verifier.c.  Yes, we can remove it
with single line comment in their respective files.