From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-11.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A007AC00143 for ; Sat, 31 Jul 2021 02:59:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8891860FED for ; Sat, 31 Jul 2021 02:59:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235360AbhGaC7O (ORCPT ); Fri, 30 Jul 2021 22:59:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57676 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231395AbhGaC7N (ORCPT ); Fri, 30 Jul 2021 22:59:13 -0400 Received: from mail-pl1-x630.google.com (mail-pl1-x630.google.com [IPv6:2607:f8b0:4864:20::630]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BEC0DC061796 for ; Fri, 30 Jul 2021 19:59:06 -0700 (PDT) Received: by mail-pl1-x630.google.com with SMTP id u16so4728806ple.2 for ; Fri, 30 Jul 2021 19:59:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:content-transfer-encoding:in-reply-to; bh=9Aa9q+ZgPH94d4mui+MhDlRe9awiZiZZrbzXI3QwflQ=; b=K/AnMh6xbreh13akr8KlRWX933KG/LVSiOukQOOU02w9zDvPcZa/3brhzVIyI/b/3I 8MwYX4XWyDe4L8DaHTAAOwEDtNaP6NmQ6MxmN2PhdWVt37y0G/ZLykupXyKWHjpiieLb dX8vGbaeXhGoISkRuWXLfYmOV+Mfm2EZz2F7A= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to; bh=9Aa9q+ZgPH94d4mui+MhDlRe9awiZiZZrbzXI3QwflQ=; b=lE0hiNoip/Bprbls/M5WJ5vJWSdmfKdkgWRMEQ2M2pZT23lrmIk41xvvDIw/c2KhRT F1G1MIGefdhqZCzf7nfLLBeHr5oOTrYDsZp0YRmUmkkWU+T7M/O+07/qQnUU8zi00G23 cTjprqZziySxwhzpm4ZONGLZqPRzBeVTbZAhC7n6sQKYAPVms6eg5bjhZz6ZbRhcAbBa wOpuE3WEb8Qc9moC6TnbKsubEQ156OBmLvJ8eOYMMYgaQ+B6Ocp4j/q4QA3BaTRPfCi1 DgNxpOedV1DUEQ28yusrKoe8T5zKK+W4ZXEp173/w6e3hGvKICfcCBUV2tdqdkqGFLxm C5lw== X-Gm-Message-State: AOAM532FSga+YB4LHZs2piTECQVc+qTK9cy4WU1kQQhsi4EY3c2lcoCs NEjETfFeCVXqzJyvxsjS7YQNNQ== X-Google-Smtp-Source: ABdhPJxTfKt3gvdchGd16NukW5boDEwoaheumkJt6I1FzMy8GwJfQpRQICiNX//vocu1zdwGzNo0jA== X-Received: by 2002:a63:5505:: with SMTP id j5mr1362082pgb.250.1627700346188; Fri, 30 Jul 2021 19:59:06 -0700 (PDT) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id c7sm4280329pgq.22.2021.07.30.19.59.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 30 Jul 2021 19:59:05 -0700 (PDT) Date: Fri, 30 Jul 2021 19:59:04 -0700 From: Kees Cook To: "Williams, Dan J" Cc: "linux@rasmusvillemoes.dk" , "keithpac@amazon.com" , "clang-built-linux@googlegroups.com" , "linux-kbuild@vger.kernel.org" , "akpm@linux-foundation.org" , "gregkh@linuxfoundation.org" , "dri-devel@lists.freedesktop.org" , "linux-cxl@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-wireless@vger.kernel.org" , "netdev@vger.kernel.org" , "linux-hardening@vger.kernel.org" , "gustavoars@kernel.org" , "linux-staging@lists.linux.dev" , "linux-block@vger.kernel.org" Subject: Re: [PATCH 04/64] stddef: Introduce struct_group() helper macro Message-ID: <202107301952.B484563@keescook> References: <20210727205855.411487-1-keescook@chromium.org> <20210727205855.411487-5-keescook@chromium.org> <41183a98-bdb9-4ad6-7eab-5a7292a6df84@rasmusvillemoes.dk> <202107281456.1A3A5C18@keescook> <1d9a2e6df2a9a35b2cdd50a9a68cac5991e7e5f0.camel@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1d9a2e6df2a9a35b2cdd50a9a68cac5991e7e5f0.camel@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org On Fri, Jul 30, 2021 at 10:19:20PM +0000, Williams, Dan J wrote: > On Wed, 2021-07-28 at 14:59 -0700, Kees Cook wrote: > > On Wed, Jul 28, 2021 at 12:54:18PM +0200, Rasmus Villemoes wrote: > > > On 27/07/2021 22.57, Kees Cook wrote: > > > > > > > In order to have a regular programmatic way to describe a struct > > > > region that can be used for references and sizing, can be examined for > > > > bounds checking, avoids forcing the use of intermediate identifiers, > > > > and avoids polluting the global namespace, introduce the struct_group() > > > > macro. This macro wraps the member declarations to create an anonymous > > > > union of an anonymous struct (no intermediate name) and a named struct > > > > (for references and sizing): > > > > > > > >         struct foo { > > > >                 int one; > > > >                 struct_group(thing, > > > >                         int two, > > > >                         int three, > > > >                 ); > > > >                 int four; > > > >         }; > > > > > > That example won't compile, the commas after two and three should be > > > semicolons. > > > > Oops, yes, thanks. This is why I shouldn't write code that doesn't first > > go through a compiler. ;) > > > > > And your implementation relies on MEMBERS not containing any comma > > > tokens, but as > > > > > >   int a, b, c, d; > > > > > > is a valid way to declare multiple members, consider making MEMBERS > > > variadic > > > > > > #define struct_group(NAME, MEMBERS...) > > > > > > to have it slurp up every subsequent argument and make that work. > > > > Ah! Perfect, thank you. I totally forgot I could do it that way. > > This is great Kees. It just so happens it would clean-up what we are > already doing in drivers/cxl/cxl.h for anonymous + named register block > pointers. However in the cxl case it also needs the named structure to > be typed. Any appetite for a typed version of this? Oh cool! Yeah, totally I can expand it. Thanks for the suggestion! > > Here is a rough idea of the cleanup it would induce in drivers/cxl/: > > diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h > index 53927f9fa77e..a2308c995654 100644 > --- a/drivers/cxl/cxl.h > +++ b/drivers/cxl/cxl.h > @@ -75,52 +75,19 @@ static inline int cxl_hdm_decoder_count(u32 cap_hdr) > #define CXLDEV_MBOX_BG_CMD_STATUS_OFFSET 0x18 > #define CXLDEV_MBOX_PAYLOAD_OFFSET 0x20 > > -#define CXL_COMPONENT_REGS() \ > - void __iomem *hdm_decoder > - > -#define CXL_DEVICE_REGS() \ > - void __iomem *status; \ > - void __iomem *mbox; \ > - void __iomem *memdev > - > -/* See note for 'struct cxl_regs' for the rationale of this organization */ > /* > - * CXL_COMPONENT_REGS - Common set of CXL Component register block base pointers > * @hdm_decoder: CXL 2.0 8.2.5.12 CXL HDM Decoder Capability Structure > - */ > -struct cxl_component_regs { > - CXL_COMPONENT_REGS(); > -}; > - > -/* See note for 'struct cxl_regs' for the rationale of this organization */ > -/* > - * CXL_DEVICE_REGS - Common set of CXL Device register block base pointers > * @status: CXL 2.0 8.2.8.3 Device Status Registers > * @mbox: CXL 2.0 8.2.8.4 Mailbox Registers > * @memdev: CXL 2.0 8.2.8.5 Memory Device Registers > */ > -struct cxl_device_regs { > - CXL_DEVICE_REGS(); > -}; > - > -/* > - * Note, the anonymous union organization allows for per > - * register-block-type helper routines, without requiring block-type > - * agnostic code to include the prefix. > - */ > struct cxl_regs { > - union { > - struct { > - CXL_COMPONENT_REGS(); > - }; > - struct cxl_component_regs component; > - }; > - union { > - struct { > - CXL_DEVICE_REGS(); > - }; > - struct cxl_device_regs device_regs; > - }; > + struct_group_typed(cxl_component_regs, component, > + void __iomem *hdm_decoder; > + ); > + struct_group_typed(cxl_device_regs, device_regs, > + void __iomem *status, *mbox, *memdev; > + ); > }; > > struct cxl_reg_map { > diff --git a/include/linux/stddef.h b/include/linux/stddef.h > index cf7f866944f9..84b7de24ffb5 100644 > --- a/include/linux/stddef.h > +++ b/include/linux/stddef.h > @@ -49,12 +49,18 @@ enum { > * @ATTRS: Any struct attributes (normally empty) > * @MEMBERS: The member declarations for the mirrored structs > */ > -#define struct_group_attr(NAME, ATTRS, MEMBERS) \ > +#define struct_group_attr(NAME, ATTRS, MEMBERS...) \ > union { \ > struct { MEMBERS } ATTRS; \ > struct { MEMBERS } ATTRS NAME; \ > } > > +#define struct_group_attr_typed(TYPE, NAME, ATTRS, MEMBERS...) \ > + union { \ > + struct { MEMBERS } ATTRS; \ > + struct TYPE { MEMBERS } ATTRS NAME; \ > + } > + > /** > * struct_group(NAME, MEMBERS) > * > @@ -67,7 +73,10 @@ enum { > * @NAME: The name of the mirrored sub-struct > * @MEMBERS: The member declarations for the mirrored structs > */ > -#define struct_group(NAME, MEMBERS) \ > +#define struct_group(NAME, MEMBERS...) \ > struct_group_attr(NAME, /* no attrs */, MEMBERS) > > +#define struct_group_typed(TYPE, NAME, MEMBERS...) \ > + struct_group_attr_typed(TYPE, NAME, /* no attrs */, MEMBERS) > + > #endif Awesome! My instinct is to expose the resulting API as: __struct_group(type, name, attrs, members...) struct_group(name, members...) struct_group_attr(name, attrs, members...) struct_group_typed(type, name, members...) -- Kees Cook