From patchwork Tue Oct 11 01:22:17 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: 13003520 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 7DBABC433FE for ; Tue, 11 Oct 2022 01:23:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229911AbiJKBXp (ORCPT ); Mon, 10 Oct 2022 21:23:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49852 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230237AbiJKBXR (ORCPT ); Mon, 10 Oct 2022 21:23:17 -0400 Received: from mail-pl1-x644.google.com (mail-pl1-x644.google.com [IPv6:2607:f8b0:4864:20::644]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4383782D04 for ; Mon, 10 Oct 2022 18:22:52 -0700 (PDT) Received: by mail-pl1-x644.google.com with SMTP id c20so2251142plc.5 for ; Mon, 10 Oct 2022 18:22:52 -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=hv2RM/Gc/5fxkeVrZbmO9zQwxyDDXIFkyfCJKBgP+jQ=; b=BSlOcwJrFWR4lL1tNDXIcQuTNV0FPuZBfUUiFzA8P8mJrhseLVXRKXUw3N591DWmcL 496p3SNm3tfZmXAPi6qA8hoNCjsL/4S/QvGAGZ0Ho0f/7PkO34vjO7N4Hxv4j+iTLHNN 6sNI9gS2HmpWQqTad2GWRe/hO9v0iLQZPlSJh7id7wcGn/1UVnTZizZsNjQSCMIIRuVM jESCcVlxp2ASaR+v56GQz8j8N3GCPqnKQUj0za5BG6eW2TBXD1HN05gEuZD1zS1lm2zc +ScQ9urUkYtXnKhHp9owRtU6aKU2KJzSi7jj1XngIVxd2GjPQNyYBwFUPQKj8tK3gnbb PCGw== 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=hv2RM/Gc/5fxkeVrZbmO9zQwxyDDXIFkyfCJKBgP+jQ=; b=wItKIzGdyXvLw/B+bihIpn4dHhgz0/zb7AxOwuTqP2S5btNe8Cc690JlFIxzVbE5yi u99QsnFOoipYRdq+T+L9OhVB2xO8s2lwjZatrmkpJROe2Kz3MPpxskl38WAG/d/Smpcl fdX+7hoFkk2AxI9th6CFXQeYaoKQFx95hmeuo6UtKnCh1eiy7cT75aRbTfP1Dv8uNxB8 TwMd4EP+ytntppq+uIESmc1JlePDYxcFG6p948DzT7eHfSTNkk3wXjcixeJywGz+gr94 ByAMo4B9E6/umEvUh7fzDT9w9e448hyhl4U0/pF0M8dXi7+0Hq1hUs2+P6pZlj1BKWV0 iFhA== X-Gm-Message-State: ACrzQf37pR5CvWJEGPWgsj/ourDeTcHQwFKNO0XszExaXAExSGrzBqLK DxrZJs9kYwmnBxwmpw+oUCZzF7cmh1eUyw== X-Google-Smtp-Source: AMsMyM6TQFkA7I8pLLuk+0ImY3y5NYdRxgrSy4vVSGYyIo/1W7z6k1hAVyl6INnTZtJXRC+8LipFtQ== X-Received: by 2002:a17:902:d4ce:b0:178:1e39:3218 with SMTP id o14-20020a170902d4ce00b001781e393218mr21707318plg.144.1665451370890; Mon, 10 Oct 2022 18:22:50 -0700 (PDT) Received: from localhost ([103.4.221.252]) by smtp.gmail.com with ESMTPSA id q9-20020aa78429000000b0053e4baecc14sm7544886pfn.108.2022.10.10.18.22.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 10 Oct 2022 18:22:50 -0700 (PDT) From: Kumar Kartikeya Dwivedi To: bpf@vger.kernel.org Cc: Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , Dave Marchevsky , Delyan Kratunov Subject: [PATCH bpf-next v1 02/25] bpf: Allow specifying volatile type modifier for kptrs Date: Tue, 11 Oct 2022 06:52:17 +0530 Message-Id: <20221011012240.3149-3-memxor@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20221011012240.3149-1-memxor@gmail.com> References: <20221011012240.3149-1-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=yyO+aCTALZegtvRf3fQf0a5NZMFkaIgWLpfML2P9IPU=; b=owEBbQKS/ZANAwAKAUzgyIZIvxHKAcsmYgBjRMUa1ODWu0lBULS8TM+tAzzVDTt9Dv0f7q7r2jiJ O3cbKsKJAjMEAAEKAB0WIQRLvip+Buz51YI8YRFM4MiGSL8RygUCY0TFGgAKCRBM4MiGSL8Rynn3D/ 4nzwdFcbeUfc79CejV7WuAOPCLZjXU26+ckOGpGIR1sUxgioz8deIHjMsaw7aeg5b6wwNlvjKTOtdO suDvvvUOj1VnAe67dUQAtnDo3pEI4GV8VKP9NwdhPA9XpuxlogRraC1wCmxO5ydAP6xFCe/BDqTTOh NJhv9y8Xe1V30dMS8a2n3l8UG6Qc1JNCWTEJpTrcV27lvms0n7ksq8UMBAq+gbRZ44TKb4f5Q/MOlS 1ONq9Bao/LadeWvBy/YQhDldtE0Je4DrAMs/i2706y8ugHaKBHGcd3aZVP6Er0sZEJ0aao6TmsVCf9 y0reTrtWeclI59VNL31GGHLngQojEzKdPU2SlQZsGFKE+r9aNY0p9Sq/XOqyPDUxzVRxc3GEMlOqiq Pslb8gKhL9BYfV4dtBHMbn3W0SrKFMKTosTdD2enE6BeB4QyurAE4xIRpIA66iO3GRvxsAEYzfebcd GRorDOWT6Ws8hDfKQDvs6O8smfyWL0pnP5w1HWNxL/TgrRTnhl/Aw4n0n41aVH5whNi79DUYc/qP5q aT82nWW6nS4JwD4vFCTifg7YJDfJq28e8b2aSx81d2hI0455bNOszKEYfphFKnIumaD6mA/vLPx2Mu hnmHr2/ZjAXRmsPpJoWeBVVIvpJ/AqsDnQ5GFtnDYWMaSe5EP3rnR8zGyHPw== 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 --- 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 eba603cec2c5..ad301e78f7ee 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;