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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id AFCD2C04FFE for ; Tue, 14 May 2024 17:28:08 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 48A0A8D0035; Tue, 14 May 2024 13:28:08 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 4126D8D000D; Tue, 14 May 2024 13:28:08 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 2B3798D0035; Tue, 14 May 2024 13:28:08 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id F2D858D000D for ; Tue, 14 May 2024 13:28:07 -0400 (EDT) Received: from smtpin12.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 9E1C11201BB for ; Tue, 14 May 2024 17:28:07 +0000 (UTC) X-FDA: 82117684614.12.F832471 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf14.hostedemail.com (Postfix) with ESMTP id D7D26100009 for ; Tue, 14 May 2024 17:28:05 +0000 (UTC) Authentication-Results: imf14.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b="1/qr7dii"; dmarc=none; spf=pass (imf14.hostedemail.com: domain of akpm@linux-foundation.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1715707686; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=nnX0R/TI2GhzGB/I6J3h0hAMTwZ7xbcibP7Acu3/QWA=; b=ehI2P+DgPDZBoGIkdcHQdo89nVRDqhp13g6r6NlkPPyWWCL4IHB+yjOe+aunhWancsua+I LerN8l/nkhErmBY754j2Yz82/+sFWKbI2mG33UjfnitM9MAXQ+S1aOwVwtwgxTgyRcCPgc iaCxO5lB4C+X+YTbjYGvY/oGr0/hA/c= ARC-Authentication-Results: i=1; imf14.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b="1/qr7dii"; dmarc=none; spf=pass (imf14.hostedemail.com: domain of akpm@linux-foundation.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1715707686; a=rsa-sha256; cv=none; b=4SQ2d3YOHp6fG2rGDoo8jit0ZWu0cThUxcH683UrKzYp9C152VytS5V06Es3eYeDBl9eMX h1UFa54p6T80pfJGLXn5eLWFou+NYGohBgTago3q6SUa0cGWMT/WSXcopCfNfEQqOdRAJu kMvlgG4d/lrp7vFgJYcIDFzsMrG/+T4= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id B03FB611A8; Tue, 14 May 2024 17:28:04 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 646BCC2BD10; Tue, 14 May 2024 17:28:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1715707684; bh=Ex1jECYg9YCi18DK+c5M5YI2kVJQ/OqqOZjhQriYWAA=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=1/qr7diiZFoMOkRRQAHecS9twVK6/XddQVf6LcYQfZ8frrVMFvQPtesA7vPTTbTlS b6lXYLnfiexNKGDEEeSSHJNv82F9Xc9xqceX5XyBR/td70xNUY8HsYwTZHF9+ceK3T eeiBtwEtzFdoNRXSrh9s41596Job3PtivO6KBaXw= Date: Tue, 14 May 2024 10:27:57 -0700 From: Andrew Morton To: Alice Ryhl Cc: Miguel Ojeda , Matthew Wilcox , Al Viro , Kees Cook , Alex Gaynor , Wedson Almeida Filho , Boqun Feng , Gary Guo , =?ISO-8859-1?Q?"Bj=F6rn_Roy_Baron"?= , Benno Lossin , Andreas Hindborg , Greg Kroah-Hartman , =?ISO-8859-1?Q?"Arve_Hj?= =?ISO-8859-1?Q?=F8nnev=E5g"?= , Todd Kjos , Martijn Coenen , Joel Fernandes , Carlos Llamas , Suren Baghdasaryan , Arnd Bergmann , Trevor Gross , linux-mm@kvack.org, linux-kernel@vger.kernel.org, rust-for-linux@vger.kernel.org, Christian Brauner Subject: Re: [PATCH v6 2/4] uaccess: always export _copy_[from|to]_user with CONFIG_RUST Message-Id: <20240514102757.b7034966a58e6cf44d75dc7d@linux-foundation.org> In-Reply-To: <20240418-alice-mm-v6-2-cb8f3e5d688f@google.com> References: <20240418-alice-mm-v6-0-cb8f3e5d688f@google.com> <20240418-alice-mm-v6-2-cb8f3e5d688f@google.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: D7D26100009 X-Stat-Signature: p7ydyz6gc6io9tyupt76sdwxkth3d37m X-Rspam-User: X-Rspamd-Server: rspam04 X-HE-Tag: 1715707685-297001 X-HE-Meta: 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 xPzhNsor eRBB08XtPtPWl27HKctPEJs7xcx1a/+pmhh6Qr3u8Zx85u86nJXqp4oYWddOaduglvyGrBu16UQdbk+h1Aquhq7fCQhD6OI3PxDFwesrwDjf3mezFD71k8NCkLI622anZVbXDudzwL/EvWCdPwwnK2q2amWDQ1V9Un+Jvp6zkWTsxcMyGE1/eXZ87bgz1vkd7o3c4jkTbr5SSIOzJj+jwigMuaF/jBwFNgNVHy0bQl+ykV4KNGqkhqOYVy+1mufMNGCw9keM3K58IatXRDPEWJaY/ET/4VaQjz9chiy3gzfd6p6OskRVAHjkvOHaeJbpb1sG9AAh/bmNXCDdI9oGs0V4l24OR3BJil4Ex3z22J+jo1qACwClu6GMVN7mB1eLxWRSWhRZgyW7E+UE= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, 18 Apr 2024 08:59:18 +0000 Alice Ryhl wrote: > From: Arnd Bergmann > > Rust code needs to be able to access _copy_from_user and _copy_to_user > so that it can skip the check_copy_size check in cases where the length > is known at compile-time, mirroring the logic for when C code will skip > check_copy_size. To do this, we ensure that exported versions of these > methods are available when CONFIG_RUST is enabled. > > Alice has verified that this patch passes the CONFIG_TEST_USER_COPY test > on x86 using the Android cuttlefish emulator. > > ... > > -#ifdef INLINE_COPY_TO_USER > static inline __must_check unsigned long > -_copy_to_user(void __user *to, const void *from, unsigned long n) > +_inline_copy_to_user(void __user *to, const void *from, unsigned long n) > { I think it would be helpful to have some comments in here describing why we're doing this _inline_* thing. What problem is it avoiding?