linux-kernel - Re: [PATCH bpf-next v3 0/2] bpf: Allow access to const void pointer arguments in tracing programs

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Message-ID: <aAdqorjuW68ld6ps@krava>
Date: Tue, 22 Apr 2025 12:08:34 +0200
From: Jiri Olsa <olsajiri@...il.com>
To: KaFai Wan <mannkafai@...il.com>
Cc: martin.lau@...ux.dev, ast@...nel.org, daniel@...earbox.net,
	andrii@...nel.org, eddyz87@...il.com, song@...nel.org,
	yonghong.song@...ux.dev, john.fastabend@...il.com,
	kpsingh@...nel.org, sdf@...ichev.me, haoluo@...gle.com,
	davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
	pabeni@...hat.com, horms@...nel.org, mykolal@...com,
	shuah@...nel.org, memxor@...il.com, bpf@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org,
	kafai.wan@...mail.com, leon.hwang@...ux.dev
Subject: Re: [PATCH bpf-next v3 0/2] bpf: Allow access to const void pointer
 arguments in tracing programs

On Thu, Apr 17, 2025 at 11:15:46PM +0800, KaFai Wan wrote:
> If we try to access argument which is pointer to const void, it's an 
> UNKNOWN type, verifier will fail to load.
> 
> Use is_void_or_int_ptr to check if type is void or int pointer. 
> Add a selftest to check it.
> 
> ---
> KaFai Wan (2):
>   bpf: Allow access to const void pointer arguments in tracing programs
>   selftests/bpf: Add test to access const void pointer argument in
>     tracing program
> 
>  kernel/bpf/btf.c                                    | 13 +++----------
>  net/bpf/test_run.c                                  |  8 +++++++-
>  .../selftests/bpf/progs/verifier_btf_ctx_access.c   | 12 ++++++++++++
>  3 files changed, 22 insertions(+), 11 deletions(-)
> 
> Changelog:
> v2->v3: Addressed comments from jirka
> - remove duplicate checks for void pointer
> Details in here:
> https://lore.kernel.org/bpf/20250416161756.1079178-1-kafai.wan@hotmail.com/

Acked-by: Jiri Olsa <jolsa@...nel.org>

thanks,
jirka


> 
> v1->v2: Addressed comments from jirka
> - use btf_type_is_void to check if type is void
> - merge is_void_ptr and is_int_ptr to is_void_or_int_ptr
> - fix selftests
> Details in here:
> https://lore.kernel.org/all/20250412170626.3638516-1-kafai.wan@hotmail.com/
> 
> -- 
> 2.43.0
>