From patchwork Wed Feb 16 13:13:25 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Arnd Bergmann X-Patchwork-Id: 12748545 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 85211C433EF for ; Wed, 16 Feb 2022 13:17:56 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 1A1856B007B; Wed, 16 Feb 2022 08:17:56 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 1527C6B0083; Wed, 16 Feb 2022 08:17:56 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id F0D516B0085; Wed, 16 Feb 2022 08:17:55 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0102.hostedemail.com [216.40.44.102]) by kanga.kvack.org (Postfix) with ESMTP id E2D996B007B for ; Wed, 16 Feb 2022 08:17:55 -0500 (EST) Received: from smtpin08.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id AC166884B9 for ; Wed, 16 Feb 2022 13:17:55 +0000 (UTC) X-FDA: 79148695710.08.A7BD3C7 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf08.hostedemail.com (Postfix) with ESMTP id 4FAE2160003 for ; Wed, 16 Feb 2022 13:17:35 +0000 (UTC) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 9BE186165A; Wed, 16 Feb 2022 13:17:34 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 29850C36AEA; Wed, 16 Feb 2022 13:17:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1645017454; bh=vo9dsIEQPQMwDE1F9151Sj8jUgLpMoSWAhLaZqQrPZo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=lBOJyeVG43t32e6bfIFQr2JNVmm/3CNnrSPgqp1aywEBs/TnQkH6UoCiuwvYMO5MT lwj96h6bIunw0aUrOBHuzAKda33BuKaGijgF6GnixzSz0Sdjj9nkHeXMHqnuG3V0jx 44u9TnpCcEvGf+Vd6ksaKYU1m1gu9FHVMuqt7U7Z/oHjVq7rSyW4eH2Jx7Z461guOE mcS1xOazBw3oe3viFMv1lFKhgYJQk0K4Po3WN6QX2wQnkyybT7djomYdy6S5JuLuay gvNVGTV6/HrfYqwdbeOKnPWvh89RBj9KN27iwj3K2hOs52sURTV04KxU5EHc02P7Ol oUX9kkXIU5HPQ== From: Arnd Bergmann To: Linus Torvalds , Christoph Hellwig , linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-api@vger.kernel.org, arnd@arndb.de, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk Cc: linux@armlinux.org.uk, will@kernel.org, guoren@kernel.org, bcain@codeaurora.org, geert@linux-m68k.org, monstr@monstr.eu, tsbogend@alpha.franken.de, nickhu@andestech.com, green.hu@gmail.com, dinguyen@kernel.org, shorne@gmail.com, deller@gmx.de, mpe@ellerman.id.au, peterz@infradead.org, mingo@redhat.com, mark.rutland@arm.com, hca@linux.ibm.com, dalias@libc.org, davem@davemloft.net, richard@nod.at, x86@kernel.org, jcmvbkbc@gmail.com, ebiederm@xmission.com, akpm@linux-foundation.org, ardb@kernel.org, linux-alpha@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-csky@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, openrisc@lists.librecores.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-um@lists.infradead.org, linux-xtensa@linux-xtensa.org, Robin Murphy Subject: [PATCH v2 11/18] arm64: simplify access_ok() Date: Wed, 16 Feb 2022 14:13:25 +0100 Message-Id: <20220216131332.1489939-12-arnd@kernel.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20220216131332.1489939-1-arnd@kernel.org> References: <20220216131332.1489939-1-arnd@kernel.org> MIME-Version: 1.0 X-Stat-Signature: 4cniakerjt8xutmuikhocm38aw5tsxak X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 4FAE2160003 Authentication-Results: imf08.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=lBOJyeVG; dmarc=pass (policy=none) header.from=kernel.org; spf=pass (imf08.hostedemail.com: domain of arnd@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=arnd@kernel.org X-Rspam-User: X-HE-Tag: 1645017455-381301 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: From: Arnd Bergmann arm64 has an inline asm implementation of access_ok() that is derived from the 32-bit arm version and optimized for the case that both the limit and the size are variable. With set_fs() gone, the limit is always constant, and the size usually is as well, so just using the default implementation reduces the check into a comparison against a constant that can be scheduled by the compiler. On a defconfig build, this saves over 28KB of .text. Acked-by: Robin Murphy Acked-by: Mark Rutland Signed-off-by: Arnd Bergmann --- arch/arm64/include/asm/uaccess.h | 34 ++++++++++---------------------- 1 file changed, 10 insertions(+), 24 deletions(-) diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h index 2e20879fe3cf..199c553b740a 100644 --- a/arch/arm64/include/asm/uaccess.h +++ b/arch/arm64/include/asm/uaccess.h @@ -26,6 +26,14 @@ #include #include +static inline int __access_ok(const void __user *ptr, unsigned long size) +{ + unsigned long limit = TASK_SIZE_MAX; + unsigned long addr = (unsigned long)ptr; + + return (size <= limit) && (addr <= (limit - size)); +} + /* * Test whether a block of memory is a valid user space address. * Returns 1 if the range is valid, 0 otherwise. @@ -33,10 +41,8 @@ * This is equivalent to the following test: * (u65)addr + (u65)size <= (u65)TASK_SIZE_MAX */ -static inline unsigned long __range_ok(const void __user *addr, unsigned long size) +static inline int access_ok(const void __user *addr, unsigned long size) { - unsigned long ret, limit = TASK_SIZE_MAX - 1; - /* * Asynchronous I/O running in a kernel thread does not have the * TIF_TAGGED_ADDR flag of the process owning the mm, so always untag @@ -46,29 +52,9 @@ static inline unsigned long __range_ok(const void __user *addr, unsigned long si (current->flags & PF_KTHREAD || test_thread_flag(TIF_TAGGED_ADDR))) addr = untagged_addr(addr); - __chk_user_ptr(addr); - asm volatile( - // A + B <= C + 1 for all A,B,C, in four easy steps: - // 1: X = A + B; X' = X % 2^64 - " adds %0, %3, %2\n" - // 2: Set C = 0 if X > 2^64, to guarantee X' > C in step 4 - " csel %1, xzr, %1, hi\n" - // 3: Set X' = ~0 if X >= 2^64. For X == 2^64, this decrements X' - // to compensate for the carry flag being set in step 4. For - // X > 2^64, X' merely has to remain nonzero, which it does. - " csinv %0, %0, xzr, cc\n" - // 4: For X < 2^64, this gives us X' - C - 1 <= 0, where the -1 - // comes from the carry in being clear. Otherwise, we are - // testing X' - C == 0, subject to the previous adjustments. - " sbcs xzr, %0, %1\n" - " cset %0, ls\n" - : "=&r" (ret), "+r" (limit) : "Ir" (size), "0" (addr) : "cc"); - - return ret; + return likely(__access_ok(addr, size)); } -#define access_ok(addr, size) __range_ok(addr, size) - /* * User access enabling/disabling. */