netdev - Re: [PATCH bpf-next 1/4] bpf, verifier: Support direct helper calls from prologue/epilogue

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Message-ID: <0ea85474-d3ce-42c3-8360-1a53eb456879@linux.dev>
Date: Tue, 20 Jan 2026 15:44:15 -0800
From: Martin KaFai Lau <martin.lau@...ux.dev>
To: Jakub Sitnicki <jakub@...udflare.com>
Cc: Alexei Starovoitov <ast@...nel.org>,
 Daniel Borkmann <daniel@...earbox.net>,
 John Fastabend <john.fastabend@...il.com>,
 Andrii Nakryiko <andrii@...nel.org>, Eduard Zingerman <eddyz87@...il.com>,
 Song Liu <song@...nel.org>, Yonghong Song <yonghong.song@...ux.dev>,
 KP Singh <kpsingh@...nel.org>, Stanislav Fomichev <sdf@...ichev.me>,
 Hao Luo <haoluo@...gle.com>, Jiri Olsa <jolsa@...nel.org>,
 Amery Hung <ameryhung@...il.com>, netdev@...r.kernel.org,
 kernel-team@...udflare.com, bpf@...r.kernel.org
Subject: Re: [PATCH bpf-next 1/4] bpf, verifier: Support direct helper calls
 from prologue/epilogue

On 1/19/26 11:53 AM, Jakub Sitnicki wrote:
> Prepare to remove support for calling kfuncs from prologue & epilogue.
> 
> Instead allow direct helpers calls using BPF_EMIT_CALL. Such calls already
> contain helper offset relative to __bpf_call_base and must bypass the
> verifier's patch_call_imm fixup, which expects BPF helper IDs rather than a
> pre-resolved offsets.
> 
> Add a finalized_call flag to bpf_insn_aux_data to mark call instructions
> with resolved offsets so the verifier can skip patch_call_imm fixup for
> these calls.
> 
> Note that the target of BPF_EMIT_CALL should be wrapped with BPF_CALL_x to
> prevent an ABI mismatch between BPF and C on 32-bit architectures.

Acked-by: Martin KaFai Lau <martin.lau@...nel.org>