From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ot1-f41.google.com (mail-ot1-f41.google.com [209.85.210.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C9E92155C97 for ; Sat, 2 May 2026 17:03:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.41 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777741405; cv=none; b=DL3HIZaFnDzyKRrGgNLWm9XftZYjii1AXSHlgBhDJPpm6lF7Lolf7WgiQT7P4t6rlTzpuf5s3Y9NvekBgwYh4pgcQPHZ1zECibHbBS96/DTaNEnMMjTjrfUk0DF2o/CIgN0FXe8gR6zjZzEtOnTWhi0pzB7i7srd8SyaT3pu/5I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777741405; c=relaxed/simple; bh=50SaXAJ5EsO7igu7WHyWFpLAoPpVRg4nKYinvVZUGTA=; h=Mime-Version:Content-Type:Date:Message-Id:Cc:Subject:From:To: References:In-Reply-To; b=uZJi/S+sK5ELtSRWg96xj1ZBO2dUzAFhHzsYUlyRVB/JAhzyJ2T7DCINZ/uNfKcJj0h/oOEpWOHsEdfr2JZmKMYcBZbwG5LF36yi8sONIPcBHJeMr8xZLNSrxDrObIVJtz8VD4rlbYFIX3HqK+jEGL2wszLdTN8YMPmNb+i1d2A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=fg+2V8UV; arc=none smtp.client-ip=209.85.210.41 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="fg+2V8UV" Received: by mail-ot1-f41.google.com with SMTP id 46e09a7af769-7de7c57b52cso2403922a34.3 for ; Sat, 02 May 2026 10:03:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1777741403; x=1778346203; darn=vger.kernel.org; h=in-reply-to:references:to:from:subject:cc:message-id:date :content-transfer-encoding:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=gsDXyJe+iue9chJdcI7xrmbR/IebWMX+5ZCmubsnUyI=; b=fg+2V8UVzKtSnvcFccjlaeTBDEMJ7KGjv1eJCVtUSEpKpjA3+Gcmi1FJeiY28/g6dM 6PCBvfCEC/KMukpyvAaVsiK1ksilNrCHQo8v1dFOEpM7MNjt0gkt36dvrEW9on3KDBBM DUqSMEBMRg2FxwXhofxnOsQaLUeV8juHOdzaCOxJ6Y+QXLZRFk5LGLfvzDCJyu4ZKs5y zPYlmt2sRPQizON80iY9z/YcS3XCfR7OD/dQh+wi9hJG4OFtgt9ySbdzMfXF0f4r6qUP tVqKo/gsxRLskNKgvMIgFjJsBbllZemieyZeDEv6veyXo/JRAWQfieKQE8XSApXbHKFL /c1A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1777741403; x=1778346203; h=in-reply-to:references:to:from:subject:cc:message-id:date :content-transfer-encoding:mime-version:x-gm-gg:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=gsDXyJe+iue9chJdcI7xrmbR/IebWMX+5ZCmubsnUyI=; b=mImig2b/msr0/TNMdTxZ//FwldJcNCcIiH1HvlwYq1ETzrebukhSKEOu1o24zaN6oy Y0pVqsiJYAksdL63QQZGV97EDv7WCW0QAxupbpUhtOx/w4tJRkPHvu975iWY+3iFbqlG mNkZN+We1OlXGBEu/cLXdc4U1Vi9bi2eEF3l5AMHWK7RtBMzD6/IlCLQCMkXYCvBlm2o M6dDPCP5lZOX+XxLpnltm/5cI0WXIc6GeO3XMBaBdBaTJwTIV8np15L33nXorbo4DvjE 1MsGZKYrIsE04jtqvmgcoB0+iZbkoUcplqjmppnMUM4aeqShxZUKnu+V0zh+//OZ78Mk Yntg== X-Forwarded-Encrypted: i=1; AFNElJ+46/U5jcIpsKgwGLlbo8xYGOZE2/JmRZd9DodOM4C4FFjrYVB+uPOJehYyvaXKX/b0+2U=@vger.kernel.org X-Gm-Message-State: AOJu0Yz0BhrDkNwvhiaEogb6ptQJK3aO9JKqqsLCHj8KWyH7Yp+qByZc 2FEKDYdqqVpTNWCZejdOUlNrjP0pcIaKsIacxs5JLWmzUkJPKVKlur1s X-Gm-Gg: AeBDievbt8soPMtrX3u9SC7pS/ikKiAfOi0rgo0TbFk1ZRtvhbI/bwfkwwcIOgsJEju x+W2TZviCheb8gYHsZx2bEMgTCKj2m77mRIu2rvHwP2AbAqLLwc1JL2CnKuUN2LJHeE0I7eGVno I7KqWZZFJofya6jtHcpVq/XuhYTv8sqKW9z82pTj6UH5kQsni5yMEcHM3rRN3i7o+OHb4kK5oEA Gz+B4AJuWOq5Xo6nLFY9Sfks+e5HN4UfE25+ykhOrQqPFf1DBFrs57IPRINQQ9n0Hu5pkmFgoy/ Nmnjffrt4BYqRhQZ+F/2ouN9KnMHBVqiZUEd5m81DVB0nTmnfx1MtwJ9g3+cI/JaB9zbDuKLcOg hW8nn3P/eskFGQXHVKXVhlU4AVnR2sTprGzlY5RoDuVKsCuJTgJWhVdS1vVX1Ld6aox36puTx0a R4xHt6/nWnoMBSMPGjw85xleKhrNstuzy5BqILVPZm8dppTwR2OxK4zOgY3tpGoCbh/Ls4H9Vxp NBdDGYdCs2Kt9rDEECTeoDfmL4ogMfBKp2V20k= X-Received: by 2002:a05:6830:6615:b0:7d7:fb8c:3c29 with SMTP id 46e09a7af769-7dee13a715emr2337052a34.14.1777741402628; Sat, 02 May 2026 10:03:22 -0700 (PDT) Received: from localhost ([2a03:2880:10ff:49::]) by smtp.gmail.com with ESMTPSA id 46e09a7af769-7decadc350dsm4335406a34.22.2026.05.02.10.03.21 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 02 May 2026 10:03:22 -0700 (PDT) Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Sat, 02 May 2026 10:03:21 -0700 Message-Id: Cc: "Alexei Starovoitov" , "Andrii Nakryiko" , "Daniel Borkmann" , "Jose E . Marchesi" , , "Martin KaFai Lau" Subject: Re: [PATCH bpf-next 01/18] bpf: Support stack arguments for bpf functions From: "Alexei Starovoitov" To: "Yonghong Song" , X-Mailer: aerc References: <20260424171433.2034470-1-yonghong.song@linux.dev> <20260424171438.2034741-1-yonghong.song@linux.dev> In-Reply-To: <20260424171438.2034741-1-yonghong.song@linux.dev> On Fri Apr 24, 2026 at 10:14 AM PDT, Yonghong Song wrote: > @@ -1669,6 +1669,8 @@ struct bpf_prog_aux { > u32 max_pkt_offset; > u32 max_tp_access; > u32 stack_depth; > + u16 incoming_stack_arg_depth; > + u16 stack_arg_depth; /* both incoming and max outgoing of stack argumen= ts */ > u32 id; > u32 func_cnt; /* used by non-func prog as the number of func progs */ > u32 real_func_cnt; /* includes hidden progs, only used for JIT and free= ing progs */ ... > @@ -739,10 +759,13 @@ struct bpf_subprog_info { > bool keep_fastcall_stack: 1; > bool changes_pkt_data: 1; > bool might_sleep: 1; > - u8 arg_cnt:3; > + u8 arg_cnt:4; > =20 > enum priv_stack_mode priv_stack_mode; > - struct bpf_subprog_arg_info args[MAX_BPF_FUNC_REG_ARGS]; > + struct bpf_subprog_arg_info args[MAX_BPF_FUNC_ARGS]; > + u16 incoming_stack_arg_depth; > + u16 stack_arg_depth; /* incoming + max outgoing */ > + u16 max_out_stack_arg_depth; > }; I asked before but if there was an answer it got lost in all emails. So will ask again: why duplicate incoming_stack_arg_depth and stack_arg_depth in two places? One should be enough. And another question: max_out_stack_arg_depth is computed only to error like this in bpf_fixup_ca= ll_args(). + u16 outgoing =3D subprog->stack_arg_depth - subprog->incomi= ng_stack_arg_depth; + + if (subprog->max_out_stack_arg_depth > outgoing) { + verbose(env, + "func#%d writes stack arg slot at depth %u,= but calls only require %u bytes\n", + i, subprog->max_out_stack_arg_depth, outgoi= ng); + return -EINVAL; why bother? What will go wrong if it's not there?