From patchwork Thu Nov 3 19:09:51 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kumar Kartikeya Dwivedi X-Patchwork-Id: 13030869 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 42DE7C433FE for ; Thu, 3 Nov 2022 19:10:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229493AbiKCTKn (ORCPT ); Thu, 3 Nov 2022 15:10:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52602 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231273AbiKCTKl (ORCPT ); Thu, 3 Nov 2022 15:10:41 -0400 Received: from mail-pj1-x1044.google.com (mail-pj1-x1044.google.com [IPv6:2607:f8b0:4864:20::1044]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DF45A12AB2 for ; Thu, 3 Nov 2022 12:10:40 -0700 (PDT) Received: by mail-pj1-x1044.google.com with SMTP id k5so2562169pjo.5 for ; Thu, 03 Nov 2022 12:10:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=2Lc706GwNapjFquiXyWB+lyzui/fdMPG+KzVG5uKH9M=; b=hLmpohcGeb3rupAWnsIS94fUs44DgeK3+73xtRqPX9kXCFxiaXEDrXXfjVip3qiRAv MxurJEcgRCcm2HFnhbpsAHhT0T2Y7D9yWjYWVNJwWAMagf8tVWlZMmJZApqb69lym4+6 XeH78wzM1n9TkxV+Z7qCmXVKWLOrAinAD7odFDZYyh20WdohE9z+LJwiNOtDC76SmLxz q9munmipu+6wl6ZC1AVZBGqGaBRYFT6T4eZrJyEtqJNG49Q9o1Q4+qlB2jL/lS7hdluY HK6OlU6W69Lsk6LKujrMD+3FrdbObZI24tQ5gL7eIYMPLPhXXdHYfqo5pECFlIsyeft6 6QXw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=2Lc706GwNapjFquiXyWB+lyzui/fdMPG+KzVG5uKH9M=; b=k+7HQujxE3GK5cdAF78lZD/wfAH7lE8abYfk8+Pr9ia4LyqsLKRxmVavtCNa+OcitU mFEo50rQQ3GUE5XwSBjO6w3/O1qlkLS0VSMYpJPBqM2g4dTzzGW8T3j60YQLDuiYbxnd efdJyc2giiirV++W7PIYYQ3/yvSwDWGqS7yVKpEsQv28+V1ilRVJeN8Y6ZmRhh82GRJ6 LUCpU6nhlaBMnyrLgVyLuIZ1rpEFUcCUjV8N4JjXq/jScqo3Ol1jVsCr0yC21gcvJwHG aFJcE3LYIZSOfAl50Y33YeBpp2OuNeU632JS2L9qbC1CMaOTDUDqW2mnk92njM+5IptI mSNQ== X-Gm-Message-State: ACrzQf1/XMEX+zoFkglKjLKQQ2KjEPBYtWjJijga8CFB+QvSipXurR/n JfHA2pt6C0wDWSsqSOEm0sCopT5/XdV79Q== X-Google-Smtp-Source: AMsMyM5tsgT+wKItfDA1wbeA8/m0QU77gQ762UTIuvN4gkHYgGHdP0UvT2/PPevkxFMX2xNumsv5aw== X-Received: by 2002:a17:903:11c8:b0:179:de93:bd7e with SMTP id q8-20020a17090311c800b00179de93bd7emr31693553plh.95.1667502639877; Thu, 03 Nov 2022 12:10:39 -0700 (PDT) Received: from localhost ([103.4.222.252]) by smtp.gmail.com with ESMTPSA id p20-20020a170902e35400b0016be834d54asm932184plc.306.2022.11.03.12.10.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 03 Nov 2022 12:10:39 -0700 (PDT) From: Kumar Kartikeya Dwivedi To: bpf@vger.kernel.org Cc: Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , Martin KaFai Lau , Dave Marchevsky , Delyan Kratunov Subject: [PATCH bpf-next v4 02/24] bpf: Allow specifying volatile type modifier for kptrs Date: Fri, 4 Nov 2022 00:39:51 +0530 Message-Id: <20221103191013.1236066-3-memxor@gmail.com> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20221103191013.1236066-1-memxor@gmail.com> References: <20221103191013.1236066-1-memxor@gmail.com> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=1457; i=memxor@gmail.com; h=from:subject; bh=UE8V6yvdXZF76Mps6QpQeIy8MEWTIpPT5HrXdPOKfh0=; b=owEBbQKS/ZANAwAIAUzgyIZIvxHKAcsmYgBjZBIAnT9XFt3DkDeOqLgO/iWSMVxRkePd4mVpqHnS G4FfOCKJAjMEAAEIAB0WIQRLvip+Buz51YI8YRFM4MiGSL8RygUCY2QSAAAKCRBM4MiGSL8RyoohD/ 9BCXS/aT5Wz9Na7pFXMMrEdb9NikkgrbocB0IYZ54Lj+3pEsIEpjbe9U1qx9rKclAonMZZqtrQ4GcT FoP68vChY8zooXbYofa5wlqxWcYhILETd+8+QvcUnEwkSv7w5dnCecHhOyTr91WAzoyJo4owqt5sWd HiWfQyDeLBBpDqI6u29A9qt2aYTm1w41VPGo40OrB8BvVXWHLcUjGoYUDVhv54E0LZlBFSQT8YdGx0 E/wUOJLN9UioKYiEpeafzG62zDLgXH0AuWA0/daid5mQAXuBDtoT5UnWKwdo4JaOvrj3nPeQPc5su2 bvutMGmbNoMonU0NEgpRx4aIormVBqlUzcCaepzp7AilDQ870bzUOjrA03F7D1GUPKCOFKOuqoBhV6 qG3CvDHaGMFH+xpd9ovH7sn9ZgUf59MRa+CDhhdxRsDr3NgSLU46u0hny9KINcrn77n4ye2D+hSWp6 aQwiePFibGYiTp3b13vCLXG+zMpzrMxI7c7FDPNSN7gk6WFKZT2FY/vFzqwhvKBYhhMo5zmKcT7q9P zy7iMfjaZClMpbsDwZgxHBoLMKloUVtnFJeGNV4iTbBgbelxz88IV3CekBu2RCYvd42OzDiEQAj3Kd sGuIwN+xc3wQryj5Jm0CRXS7HXNjfgknEFq0fgqDBtQCxXVBX1stojlA4GCw== X-Developer-Key: i=memxor@gmail.com; a=openpgp; fpr=4BBE2A7E06ECF9D5823C61114CE0C88648BF11CA Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net This is useful in particular to mark the pointer as volatile, so that compiler treats each load and store to the field as a volatile access. The alternative is having to define and use READ_ONCE and WRITE_ONCE in the BPF program. Signed-off-by: Kumar Kartikeya Dwivedi Acked-by: David Vernet --- include/linux/btf.h | 5 +++++ kernel/bpf/btf.c | 3 +++ 2 files changed, 8 insertions(+) diff --git a/include/linux/btf.h b/include/linux/btf.h index f9aababc5d78..86aad9b2ce02 100644 --- a/include/linux/btf.h +++ b/include/linux/btf.h @@ -288,6 +288,11 @@ static inline bool btf_type_is_typedef(const struct btf_type *t) return BTF_INFO_KIND(t->info) == BTF_KIND_TYPEDEF; } +static inline bool btf_type_is_volatile(const struct btf_type *t) +{ + return BTF_INFO_KIND(t->info) == BTF_KIND_VOLATILE; +} + static inline bool btf_type_is_func(const struct btf_type *t) { return BTF_INFO_KIND(t->info) == BTF_KIND_FUNC; diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 35c07afac924..f4d21eef6ebd 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -3225,6 +3225,9 @@ static int btf_find_kptr(const struct btf *btf, const struct btf_type *t, enum bpf_kptr_type type; u32 res_id; + /* Permit modifiers on the pointer itself */ + if (btf_type_is_volatile(t)) + t = btf_type_by_id(btf, t->type); /* For PTR, sz is always == 8 */ if (!btf_type_is_ptr(t)) return BTF_FIELD_IGNORE;