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=-10.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 C0658C433E0 for ; Tue, 26 Jan 2021 12:09:24 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 8EAF72311D for ; Tue, 26 Jan 2021 12:09:24 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8EAF72311D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References:Message-ID: Subject:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=J4xSYHiAd65KQ8B1l8P1kWti0UhTg3rtvnVYJJGTICc=; b=ZHfkayMI59q5N6ZMRg5FKqm2o qGtqLKMxGDi3nnb6OWXlZdhJolB4u5QMEamsS8J7po9CKrWYATPCtCHPznMr78RwBtCA8Kz2lIDl+ Wi5IGf6NRweL2SuAPsjjD8vQUb7SQoMM3eX0gDl+OGRYo8yoIa4QReR2YLH3d8q1yh5XyGfBu5Llh bQkpj/VMGmQW5AqaDEZZKIhIk3YetLzm1Jolx5adUbwEcyidKkIV6dB1fzWF6F1iqzCVgRRCKXBdT iVrDLscsJs3hgTdfWVoDNft3pccpC8VNLAe6W/fM6AxBi3rDD9Qb7OYxdYoymelztRptI8ip+1ye1 CwRSBVn9Q==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1l4N8d-00039R-6l; Tue, 26 Jan 2021 12:08:03 +0000 Received: from mail.kernel.org ([198.145.29.99]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1l4N8a-00038l-55 for linux-arm-kernel@lists.infradead.org; Tue, 26 Jan 2021 12:08:01 +0000 Received: by mail.kernel.org (Postfix) with ESMTPSA id D34212311D; Tue, 26 Jan 2021 12:07:56 +0000 (UTC) Date: Tue, 26 Jan 2021 12:07:54 +0000 From: Catalin Marinas To: Vincenzo Frascino Subject: Re: [PATCH v4 1/3] arm64: Improve kernel address detection of __is_lm_address() Message-ID: <20210126120754.GB20158@gaia> References: <20210122155642.23187-1-vincenzo.frascino@arm.com> <20210122155642.23187-2-vincenzo.frascino@arm.com> <20210125130204.GA4565@C02TD0UTHF1T.local> <20210125145911.GG25360@gaia> <4bd1c01b-613c-787f-4363-c55a071f14ae@arm.com> <20210125175630.GK25360@gaia> <62348cb4-0b2e-e17a-d930-8d41dc4200d3@arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <62348cb4-0b2e-e17a-d930-8d41dc4200d3@arm.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210126_070800_365977_441EE59D X-CRM114-Status: GOOD ( 29.68 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , "Paul E . McKenney" , Andrey Konovalov , Naresh Kamboju , linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, Leon Romanovsky , Alexander Potapenko , Dmitry Vyukov , Andrey Ryabinin , Will Deacon , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Jan 26, 2021 at 11:58:13AM +0000, Vincenzo Frascino wrote: > On 1/25/21 5:56 PM, Catalin Marinas wrote: > > On Mon, Jan 25, 2021 at 04:09:57PM +0000, Vincenzo Frascino wrote: > >> On 1/25/21 2:59 PM, Catalin Marinas wrote: > >>> On Mon, Jan 25, 2021 at 02:36:34PM +0000, Vincenzo Frascino wrote: > >>>> On 1/25/21 1:02 PM, Mark Rutland wrote: > >>>>> On Fri, Jan 22, 2021 at 03:56:40PM +0000, Vincenzo Frascino wrote: > >>>>>> Currently, the __is_lm_address() check just masks out the top 12 bits > >>>>>> of the address, but if they are 0, it still yields a true result. > >>>>>> This has as a side effect that virt_addr_valid() returns true even for > >>>>>> invalid virtual addresses (e.g. 0x0). > >>>>>> > >>>>>> Improve the detection checking that it's actually a kernel address > >>>>>> starting at PAGE_OFFSET. > >>>>>> > >>>>>> Cc: Catalin Marinas > >>>>>> Cc: Will Deacon > >>>>>> Suggested-by: Catalin Marinas > >>>>>> Reviewed-by: Catalin Marinas > >>>>>> Signed-off-by: Vincenzo Frascino > >>>>> > >>>>> Looking around, it seems that there are some existing uses of > >>>>> virt_addr_valid() that expect it to reject addresses outside of the > >>>>> TTBR1 range. For example, check_mem_type() in drivers/tee/optee/call.c. > >>>>> > >>>>> Given that, I think we need something that's easy to backport to stable. > >>>>> > >>>> > >>>> I agree, I started looking at it this morning and I found cases even in the main > >>>> allocators (slub and page_alloc) either then the one you mentioned. > >>>> > >>>>> This patch itself looks fine, but it's not going to backport very far, > >>>>> so I suspect we might need to write a preparatory patch that adds an > >>>>> explicit range check to virt_addr_valid() which can be trivially > >>>>> backported. > >>>>> > >>>> > >>>> I checked the old releases and I agree this is not back-portable as it stands. > >>>> I propose therefore to add a preparatory patch with the check below: > >>>> > >>>> #define __is_ttrb1_address(addr) ((u64)(addr) >= PAGE_OFFSET && \ > >>>> (u64)(addr) < PAGE_END) > >>>> > >>>> If it works for you I am happy to take care of it and post a new version of my > >>>> patches. > >>> > >>> I'm not entirely sure we need a preparatory patch. IIUC (it needs > >>> checking), virt_addr_valid() was fine until 5.4, broken by commit > >>> 14c127c957c1 ("arm64: mm: Flip kernel VA space"). Will addressed the > >>> flip case in 68dd8ef32162 ("arm64: memory: Fix virt_addr_valid() using > >>> __is_lm_address()") but this broke the >>> NULL address is considered valid. > >>> > >>> Ard's commit f4693c2716b3 ("arm64: mm: extend linear region for 52-bit > >>> VA configurations") changed the test to no longer rely on va_bits but > >>> did not change the broken semantics. > >>> > >>> If Ard's change plus the fix proposed in this test works on 5.4, I'd say > >>> we just merge this patch with the corresponding Cc stable and Fixes tags > >>> and tweak it slightly when doing the backports as it wouldn't apply > >>> cleanly. IOW, I wouldn't add another check to virt_addr_valid() as we > >>> did not need one prior to 5.4. > >> > >> Thank you for the detailed analysis. I checked on 5.4 and it seems that Ard > >> patch (not a clean backport) plus my proposed fix works correctly and solves the > >> issue. > > > > I didn't mean the backport of the whole commit f4693c2716b3 as it > > probably has other dependencies, just the __is_lm_address() change in > > that patch. > > Then call it preparatory patch ;) It's preparatory only for the stable backports, not for current mainline. But I'd rather change the upstream patch when backporting to apply cleanly, no need for a preparatory stable patch. -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel