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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham 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 EFD41C3A5A4 for ; Fri, 30 Aug 2019 09:41:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D04B321670 for ; Fri, 30 Aug 2019 09:41:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727620AbfH3JlH (ORCPT ); Fri, 30 Aug 2019 05:41:07 -0400 Received: from foss.arm.com ([217.140.110.172]:57356 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726480AbfH3JlG (ORCPT ); Fri, 30 Aug 2019 05:41:06 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 39120344; Fri, 30 Aug 2019 02:41:06 -0700 (PDT) Received: from lakrids.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id D989D3F718; Fri, 30 Aug 2019 02:41:04 -0700 (PDT) Date: Fri, 30 Aug 2019 10:41:02 +0100 From: Mark Rutland To: Viresh Kumar Cc: stable@vger.kernel.org, Julien Thierry , linux-arm-kernel@lists.infradead.org, Catalin Marinas , Marc Zyngier , Will Deacon , Russell King , Vincent Guittot , mark.brown@arm.com Subject: Re: [PATCH ARM64 v4.4 V3 08/44] arm64: uaccess: Don't bother eliding access_ok checks in __{get, put}_user Message-ID: <20190830094102.GH46475@lakrids.cambridge.arm.com> References: <40fe1d91c9cd8d78ae952b821185681621f92b10.1567077734.git.viresh.kumar@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <40fe1d91c9cd8d78ae952b821185681621f92b10.1567077734.git.viresh.kumar@linaro.org> User-Agent: Mutt/1.11.1+11 (2f07cb52) (2018-12-01) Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Thu, Aug 29, 2019 at 05:03:53PM +0530, Viresh Kumar wrote: > From: Will Deacon > > commit 84624087dd7e3b482b7b11c170ebc1f329b3a218 upstream. > > access_ok isn't an expensive operation once the addr_limit for the current > thread has been loaded into the cache. Given that the initial access_ok > check preceding a sequence of __{get,put}_user operations will take > the brunt of the miss, we can make the __* variants identical to the > full-fat versions, which brings with it the benefits of address masking. > > The likely cost in these sequences will be from toggling PAN/UAO, which > we can address later by implementing the *_unsafe versions. > > Reviewed-by: Robin Murphy > Signed-off-by: Will Deacon > Signed-off-by: Catalin Marinas > [ v4.4: Fixed conflicts around {__get_user|__put_user}_unaligned macros ] > Signed-off-by: Viresh Kumar > --- Reviewed-by: Mark Rutland [v4.4 backport] Mark. > arch/arm64/include/asm/uaccess.h | 62 ++++++++++++++++++-------------- > 1 file changed, 36 insertions(+), 26 deletions(-) > > diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h > index fc11c50af558..a34324436ce1 100644 > --- a/arch/arm64/include/asm/uaccess.h > +++ b/arch/arm64/include/asm/uaccess.h > @@ -200,30 +200,35 @@ do { \ > CONFIG_ARM64_PAN)); \ > } while (0) > > -#define __get_user(x, ptr) \ > +#define __get_user_check(x, ptr, err) \ > ({ \ > - int __gu_err = 0; \ > - __get_user_err((x), (ptr), __gu_err); \ > - __gu_err; \ > + __typeof__(*(ptr)) __user *__p = (ptr); \ > + might_fault(); \ > + if (access_ok(VERIFY_READ, __p, sizeof(*__p))) { \ > + __p = uaccess_mask_ptr(__p); \ > + __get_user_err((x), __p, (err)); \ > + } else { \ > + (x) = 0; (err) = -EFAULT; \ > + } \ > }) > > #define __get_user_error(x, ptr, err) \ > ({ \ > - __get_user_err((x), (ptr), (err)); \ > + __get_user_check((x), (ptr), (err)); \ > (void)0; \ > }) > > -#define __get_user_unaligned __get_user > - > -#define get_user(x, ptr) \ > +#define __get_user(x, ptr) \ > ({ \ > - __typeof__(*(ptr)) __user *__p = (ptr); \ > - might_fault(); \ > - access_ok(VERIFY_READ, __p, sizeof(*__p)) ? \ > - __p = uaccess_mask_ptr(__p), __get_user((x), __p) : \ > - ((x) = 0, -EFAULT); \ > + int __gu_err = 0; \ > + __get_user_check((x), (ptr), __gu_err); \ > + __gu_err; \ > }) > > +#define __get_user_unaligned __get_user > + > +#define get_user __get_user > + > #define __put_user_asm(instr, reg, x, addr, err) \ > asm volatile( \ > "1: " instr " " reg "1, [%2]\n" \ > @@ -266,30 +271,35 @@ do { \ > CONFIG_ARM64_PAN)); \ > } while (0) > > -#define __put_user(x, ptr) \ > +#define __put_user_check(x, ptr, err) \ > ({ \ > - int __pu_err = 0; \ > - __put_user_err((x), (ptr), __pu_err); \ > - __pu_err; \ > + __typeof__(*(ptr)) __user *__p = (ptr); \ > + might_fault(); \ > + if (access_ok(VERIFY_WRITE, __p, sizeof(*__p))) { \ > + __p = uaccess_mask_ptr(__p); \ > + __put_user_err((x), __p, (err)); \ > + } else { \ > + (err) = -EFAULT; \ > + } \ > }) > > #define __put_user_error(x, ptr, err) \ > ({ \ > - __put_user_err((x), (ptr), (err)); \ > + __put_user_check((x), (ptr), (err)); \ > (void)0; \ > }) > > -#define __put_user_unaligned __put_user > - > -#define put_user(x, ptr) \ > +#define __put_user(x, ptr) \ > ({ \ > - __typeof__(*(ptr)) __user *__p = (ptr); \ > - might_fault(); \ > - access_ok(VERIFY_WRITE, __p, sizeof(*__p)) ? \ > - __p = uaccess_mask_ptr(__p), __put_user((x), __p) : \ > - -EFAULT; \ > + int __pu_err = 0; \ > + __put_user_check((x), (ptr), __pu_err); \ > + __pu_err; \ > }) > > +#define __put_user_unaligned __put_user > + > +#define put_user __put_user > + > extern unsigned long __must_check __copy_from_user(void *to, const void __user *from, unsigned long n); > extern unsigned long __must_check __copy_to_user(void __user *to, const void *from, unsigned long n); > extern unsigned long __must_check __copy_in_user(void __user *to, const void __user *from, unsigned long n); > -- > 2.21.0.rc0.269.g1a574e7a288b >