Re: Re: [PATCH bpf 2/2] selftests/bpf: Cover fastcall helper stack reads

[Nuoqi Gui]

> -----Original Messages-----
> From: "Eduard Zingerman" <eddyz87@xxxxxxxxx>
> Send time:Friday, 26/06/2026 02:35:39
> To: "Nuoqi Gui" <gnq25@xxxxxxxxxxxxxxxxxxxxx>, "Alexei Starovoitov" <ast@xxxxxxxxxx>, "Daniel Borkmann" <daniel@xxxxxxxxxxxxx>, "Andrii Nakryiko" <andrii@xxxxxxxxxx>, "Kumar Kartikeya Dwivedi" <memxor@xxxxxxxxx>
> Cc: "John Fastabend" <john.fastabend@xxxxxxxxx>, "Martin KaFai Lau" <martin.lau@xxxxxxxxx>, "Shuah Khan" <shuah@xxxxxxxxxx>, bpf@xxxxxxxxxxxxxxx, linux-kselftest@xxxxxxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH bpf 2/2] selftests/bpf: Cover fastcall helper stack reads
> 
> On Wed, 2026-06-24 at 16:39 +0800, Nuoqi Gui wrote:
> > Add verifier_bpf_fastcall test where a spill/fill pair initializes a stack
> > slot. bpf_csum_diff() later reads it through ARG_PTR_TO_MEM | MEM_RDONLY.
> > 
> > The translated program must keep the spill and fill materialized. Otherwise
> > the helper reads stack bytes that no longer match the verifier model.
> > 
> > Signed-off-by: Nuoqi Gui <gnq25@xxxxxxxxxxxxxxxxxxxxx>
> > ---
> 
> Could you please add a kfunc based test case as well?
> 
> [...]
Sure, I'll add a kfunc-based verifier test as well.