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,NICE_REPLY_A,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 43B81C433E0 for ; Mon, 25 Jan 2021 16:07:43 +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 0118B221EB for ; Mon, 25 Jan 2021 16:07:42 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0118B221EB 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:Date:Message-ID:From: References:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=b7gn6KGvhOmcCCZ/9vrh33e8UxPnLKt3B8/a8EhQ0ek=; b=hBbO+cwVjDbDVq/d0hdiMqGil Q5GtPrNDgL6Go/ZBGi/IlpWWw/+MDz1M9S6hj+GPWDI0riLMuWB2+Y8rrr2UKGRtxd2vKzfBdTSKg hM2TyzeuFY06mnIF23LauDv7o7WqP/6oOu9BbVh1XTRDcMMb8sG30JhKaJdT0uC6nMuzpLfmq5+oK 1lcnIvXCV9tCZ7B7Wj9U96Aqyl7WNSrdyd6X/OvoeJTqsNwhjcQeJRJzPPdO52OjV4Fr3ji8fOmf1 O1jN6jo+GsiQi7x4xEwBYdOr4WoOYjt331XaEflICUSM8k0xV8cPtTGN1xg2IevLnMU4fdB6dqBAn lX+x6KYAQ==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1l44NX-0008Qv-1f; Mon, 25 Jan 2021 16:06:11 +0000 Received: from foss.arm.com ([217.140.110.172]) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1l44NV-0008Q7-5o for linux-arm-kernel@lists.infradead.org; Mon, 25 Jan 2021 16:06:10 +0000 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 22511139F; Mon, 25 Jan 2021 08:06:07 -0800 (PST) Received: from [10.37.8.33] (unknown [10.37.8.33]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 68E893F68F; Mon, 25 Jan 2021 08:06:04 -0800 (PST) Subject: Re: [PATCH v4 1/3] arm64: Improve kernel address detection of __is_lm_address() To: Catalin Marinas References: <20210122155642.23187-1-vincenzo.frascino@arm.com> <20210122155642.23187-2-vincenzo.frascino@arm.com> <20210125130204.GA4565@C02TD0UTHF1T.local> <20210125145911.GG25360@gaia> From: Vincenzo Frascino Message-ID: <4bd1c01b-613c-787f-4363-c55a071f14ae@arm.com> Date: Mon, 25 Jan 2021 16:09:57 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20210125145911.GG25360@gaia> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210125_110609_311671_BB591A0E X-CRM114-Status: GOOD ( 26.16 ) 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 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. Tomorrow I will post a new version of the series that includes what you are suggesting. -- Regards, Vincenzo _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel