From: Eduard Zingerman <eddyz87@gmail.com>
To: Amery Hung <ameryhung@gmail.com>, bpf@vger.kernel.org
Cc: alexei.starovoitov@gmail.com, andrii@kernel.org,
daniel@iogearbox.net, memxor@gmail.com, kernel-team@meta.com
Subject: Re: [PATCH bpf-next v2 10/18] bpf: Fold __szk const size handling into the scalar arg path
Date: Mon, 27 Jul 2026 15:48:27 -0700 [thread overview]
Message-ID: <efa06273caf10efacb096984b60a1d53c8eeb03b.camel@gmail.com> (raw)
In-Reply-To: <20260724190813.1458271-11-ameryhung@gmail.com>
On Fri, 2026-07-24 at 12:08 -0700, Amery Hung wrote:
> To align helper and kfunc pointer to memory argument handling, move
> kfunc constant memorry size argument handling to the kfunc scalar
> section. In addition, factor out constant scalar argument handling.
>
> The constant size argument (__szk) of a kfunc memory/size pair was
> recorded into meta->arg_constant by a dedicated block in the
> KF_ARG_PTR_TO_MEM_SIZE case, duplicating the "only one constant
> argument" and "must be a known constant" checks already in the generic
> scalar argument handling. That block also did an explicit i++ to skip
> the size argument.
>
> This also fixes a precision gap: the old dedicated block did not mark
> the size register precise, relying on check_mem_size_reg() for that. But
> check_mem_size_reg() is skipped when the buffer is a nullable arg passed
> as NULL (e.g. bpf_dynptr_slice(_rdwr) with a NULL buffer), so in that
> case the __szk value was recorded and used for regs[R0].mem_size without
> marking it precise. Routing the size through the scalar path marks it
> precise in all cases.
Could you please add a test case for this?
>
> Signed-off-by: Amery Hung <ameryhung@gmail.com>
> ---
Reviewed-by: Eduard Zingerman <eddyz87@gmail.com>
...
next prev parent reply other threads:[~2026-07-27 22:48 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-24 19:07 [PATCH bpf-next v2 00/18] Generate bpf_func_proto for kfunc Amery Hung
2026-07-24 19:07 ` [PATCH bpf-next v2 01/18] bpf: Drop process_timer_func wrappers Amery Hung
2026-07-25 1:39 ` Eduard Zingerman
2026-07-24 19:07 ` [PATCH bpf-next v2 02/18] bpf: Unify const map ptr argument checking for helpers and kfuncs Amery Hung
2026-07-24 19:28 ` sashiko-bot
2026-07-24 20:49 ` Amery Hung
2026-07-24 21:29 ` Kumar Kartikeya Dwivedi
2026-07-25 1:57 ` Eduard Zingerman
2026-07-24 19:07 ` [PATCH bpf-next v2 03/18] bpf: Split kfunc map argument into __const_map and __map Amery Hung
[not found] ` <015164cfd5ac0c3bae007313c3859fef6a583233.camel@gmail.com>
2026-07-27 16:48 ` Eduard Zingerman
2026-07-24 19:07 ` [PATCH bpf-next v2 04/18] bpf: Pass kfunc meta to mem and mem_size check Amery Hung
2026-07-27 18:37 ` Eduard Zingerman
2026-07-24 19:07 ` [PATCH bpf-next v2 05/18] bpf: Check helper and kfunc mem+size arguments identically Amery Hung
2026-07-27 20:39 ` Eduard Zingerman
2026-07-27 20:51 ` Eduard Zingerman
2026-07-24 19:08 ` [PATCH bpf-next v2 06/18] selftests/bpf: Add tests for helper and kfunc mem+size arguments Amery Hung
2026-07-24 19:25 ` sashiko-bot
2026-07-27 20:40 ` Eduard Zingerman
2026-07-24 19:08 ` [PATCH bpf-next v2 07/18] bpf: Check fixed-size mem args of helpers and kfuncs the same way Amery Hung
2026-07-24 19:32 ` sashiko-bot
2026-07-24 20:39 ` Amery Hung
2026-07-27 21:17 ` Eduard Zingerman
2026-07-24 19:08 ` [PATCH bpf-next v2 08/18] bpf: Express ARG_CONST_SIZE_OR_ZERO as ARG_CONST_SIZE | SCALAR_MAYBE_ZERO Amery Hung
2026-07-27 22:29 ` Eduard Zingerman
2026-07-24 19:08 ` [PATCH bpf-next v2 09/18] bpf: Rename ARG_CONST_SIZE{,_OR_ZERO} to ARG_MEM_SIZE{,_OR_ZERO} Amery Hung
2026-07-24 19:08 ` [PATCH bpf-next v2 10/18] bpf: Fold __szk const size handling into the scalar arg path Amery Hung
2026-07-27 22:48 ` Eduard Zingerman [this message]
2026-07-24 19:08 ` [PATCH bpf-next v2 11/18] bpf: Classify kfunc mem_size args from BTF without register state Amery Hung
2026-07-24 19:38 ` sashiko-bot
2026-07-24 22:52 ` Amery Hung
2026-07-27 22:50 ` Eduard Zingerman
2026-07-24 19:08 ` [PATCH bpf-next v2 12/18] bpf: Handle NULL kfunc pointer args without a KF_ARG_PTR_TO_NULL type Amery Hung
2026-07-27 23:15 ` Eduard Zingerman
2026-07-24 19:08 ` [PATCH bpf-next v2 13/18] bpf: Distinguish fixed- and variable-size kfunc mem args with MEM_FIXED_SIZE Amery Hung
2026-07-27 23:30 ` Eduard Zingerman
2026-07-24 19:08 ` [PATCH bpf-next v2 14/18] bpf: Check helper mem+size in ARG_PTR_TO_MEM case Amery Hung
2026-07-24 19:47 ` sashiko-bot
2026-07-24 21:10 ` Amery Hung
2026-07-27 23:39 ` Eduard Zingerman
2026-07-24 19:08 ` [PATCH bpf-next v2 15/18] bpf: Classify kfunc pointer arguments from BTF, resolve type against the register Amery Hung
2026-07-24 19:08 ` [PATCH bpf-next v2 16/18] bpf: Tag nullable kfunc pointer args with PTR_MAYBE_NULL Amery Hung
2026-07-24 19:38 ` sashiko-bot
2026-07-24 19:08 ` [PATCH bpf-next v2 17/18] bpf: Classify scalar kfunc arguments from BTF Amery Hung
2026-07-24 19:08 ` [PATCH bpf-next v2 18/18] bpf: Generate kfunc argument prototype at add-call time Amery Hung
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