From patchwork Thu Oct 13 06:22:40 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: 13005630 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 D32E5C433FE for ; Thu, 13 Oct 2022 06:23:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229665AbiJMGXZ (ORCPT ); Thu, 13 Oct 2022 02:23:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44038 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229437AbiJMGXY (ORCPT ); Thu, 13 Oct 2022 02:23:24 -0400 Received: from mail-pj1-x1043.google.com (mail-pj1-x1043.google.com [IPv6:2607:f8b0:4864:20::1043]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 16E0A125033 for ; Wed, 12 Oct 2022 23:23:22 -0700 (PDT) Received: by mail-pj1-x1043.google.com with SMTP id o9-20020a17090a0a0900b0020ad4e758b3so1069661pjo.4 for ; Wed, 12 Oct 2022 23:23:22 -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=iynB/tzG+IhB0+dH46SjaWSl87CIgpxLyW2rshmjGVI=; b=IFZCsBzBg0Ehjde6AngoNtvD1c266uWYccx+AgJnIRibcmh91PgE5Iq9jU7gDS/k1T qP1GUFvCAxDU3xiksSFwp/Ile+BpSRRXhGpG9I1HNyamvUyTXKPIZtPS3FCrhKTmgnAq VTRVc8tFkOYMihzvHKPdK7qkzxN4sgx9rvg3kOjeoANta8EEDBUwQAb4XYiMy/mcUK7V wjRgoA/cLMcoFyqswWfEP2g97Fd9pdPOulT9qJ+Vwc3yJIGJbZZjXvoiITU4a974isuD FY/RaYLpmAmUrdt4idcyV9J2QG5zk7I7x//sOs8z+Vf5/oRtCOH3rKDM4exiU+d0/awZ SIHw== 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=iynB/tzG+IhB0+dH46SjaWSl87CIgpxLyW2rshmjGVI=; b=4O7W61Z6oYoBkHZO/lKEX9FJynDUWy/KbDb+K5VnmnlJ1+aj0ttpLwk0hMl5x56wWv hH+GqpfdJ2rFW6ZQ6WBm2puExLgOY3owG87NrHA06pL7TG8YoddoIJ8263AHeZM+4Ro7 3noztMYVnLQy07x3VAsPgtf3zMlFBJ+j5ZM5fDK75lVXh24nfMe4//syOwuB6o8lGdLl KEVYL43GFJXbrr9QVqJvJZWIgSXgsn+gnB5g1GqZc5vZhC/CB1eCYYmvkDL6KkhRFvkz gJFu2b88yKQmIHjUfXMZLl+Jc9PUDgQL0fm32Ek5nKA11uOiP3v2rM4Q7+PkeCxo942s l2OQ== X-Gm-Message-State: ACrzQf0tp4eISv5YADLthwl/s9ZYv7QENkbby/JEG9kQrwouYYhtiFsf /H3miQiK3df4zQLLvfK3dzneD3+bB3k= X-Google-Smtp-Source: AMsMyM4641LCJhRXs9a24h6LLSz3cVo576A0bc17YZJ+AV4KKn6aVT4q/A1luQCqRg3Nw7X8QvUy5A== X-Received: by 2002:a17:902:ce0c:b0:185:36ce:abb6 with SMTP id k12-20020a170902ce0c00b0018536ceabb6mr1633430plg.149.1665642201702; Wed, 12 Oct 2022 23:23:21 -0700 (PDT) Received: from localhost ([14.96.13.220]) by smtp.gmail.com with ESMTPSA id c13-20020a634e0d000000b0042c0ffa0e62sm10644236pgb.47.2022.10.12.23.23.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 12 Oct 2022 23:23:21 -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 v2 02/25] bpf: Allow specifying volatile type modifier for kptrs Date: Thu, 13 Oct 2022 11:52:40 +0530 Message-Id: <20221013062303.896469-3-memxor@gmail.com> X-Mailer: git-send-email 2.38.0 In-Reply-To: <20221013062303.896469-1-memxor@gmail.com> References: <20221013062303.896469-1-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=6SUeyuyfZf//MiX/9s7h5HH7OdhEj4ml6JnfXAgYBbY=; b=owEBbQKS/ZANAwAIAUzgyIZIvxHKAcsmYgBjR67C8mT9U+PHPqdMSwsIgk2iUjJA2AVz+6qhspMm 2pPPK9KJAjMEAAEIAB0WIQRLvip+Buz51YI8YRFM4MiGSL8RygUCY0euwgAKCRBM4MiGSL8RynbTEA DBZlDObFetoUIi9zAsrPRVgm6KfU+TJtT0D3o9q5ks4UHAcXH/cDEsoXA1ZQTvqDaHiYCDy441/n/n OGezEnMJRSZRBec6sstZT5fdLjaYzbNXwGOZ5AntXco6SZuGT9tKtdIxcNbVz9s+0H43Q20IsMoJGB BfrsPOFA6PoB7j6vIYYURLaaGFVG41Qbn0zu3p09R+nztiCJlAP3sfjPlpT2EXxH95wOwM5iDs8nAs Q4tOgdaE2wxd6KWA92ueBQFEwpjHbfmmHs+wpebcBzNjL/0mFruni78/0RpBP5L8Znim2+tBBmF135 PVMVNMNoz/N0zCTy8qvwamgPbPmSMzq/Ez38ogGaOZtSjfb1bFegXDTRPrGfnV2W8hI85CJ1oBpBCH d0dnnB5IAZVPfZEcE2L8SjLl4c8Ec8yI7uZY5Bqc9gjlTtfhUs3zhqqZhQttt9IMZMEACxaEnYFGu3 GbkLJLQHPUf3N+2/eWasctdAPTefrfftf6bxl+LKzLKIx3EDHU0UDa/UmEx/7mo9puqFGpAbOndPa8 OjGoguiG+YHn//0br9ZrQ7jT9ac0tlii4tGSex5MIFzNJIIGQX/glAp/o2Tq50q4v3FCQcIqQvRC2y 8sKAI4XPwxd/0jbbzdYO9rFOEH77KNh9SaOOaAWb79PotyLw8RWUd25uwTnw== 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;