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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 785D3C433EF for ; Tue, 12 Apr 2022 17:18:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1358066AbiDLRUW (ORCPT ); Tue, 12 Apr 2022 13:20:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43736 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243106AbiDLRUU (ORCPT ); Tue, 12 Apr 2022 13:20:20 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 0598051E70 for ; Tue, 12 Apr 2022 10:18:01 -0700 (PDT) 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 9EBE71424; Tue, 12 Apr 2022 10:18:01 -0700 (PDT) Received: from [10.1.196.40] (e121345-lin.cambridge.arm.com [10.1.196.40]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 86DC33F5A1; Tue, 12 Apr 2022 10:17:59 -0700 (PDT) Message-ID: <306b1b09-487a-9ccd-4a63-8c78889492c6@arm.com> Date: Tue, 12 Apr 2022 18:17:58 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux aarch64; rv:91.0) Gecko/20100101 Thunderbird/91.7.0 Subject: Re: [RFC PATCH -next V3 4/6] arm64: add copy_{to, from}_user to machine check safe Content-Language: en-GB From: Robin Murphy To: Tong Tiangen , Mark Rutland , James Morse , Andrew Morton , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , Catalin Marinas , Will Deacon , Alexander Viro , x86@kernel.org, "H . Peter Anvin" Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Kefeng Wang , Xie XiuQi References: <20220412072552.2526871-1-tongtiangen@huawei.com> <20220412072552.2526871-5-tongtiangen@huawei.com> <38c6d4b5-a3db-5c3e-02e7-39875edb3476@arm.com> In-Reply-To: <38c6d4b5-a3db-5c3e-02e7-39875edb3476@arm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/04/2022 6:08 pm, Robin Murphy wrote: [...] >> @@ -62,7 +63,11 @@ SYM_FUNC_START(__arch_copy_from_user) >>       ret >>       // Exception fixups >> -9997:    cmp    dst, dstin >> +9997:    mrs esr, esr_el1            // Check exception first >> +    and esr, esr, #ESR_ELx_FSC >> +    cmp esr, #ESR_ELx_FSC_EXTABT > > Should we be checking EC to make sure it's a data abort - and thus FSC > is valid - in the first place? I'm a little fuzzy on all the possible > paths into fixup_exception(), and it's not entirely obvious whether this > is actually safe or not. In fact, thinking some more about that, I don't think there should be any need for this sort of logic in these handlers at all. The fixup_exception() machinery should already know enough about the exception that's happened and the extable entry to figure this out and not bother calling the handler at all. Thanks, Robin. 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id B94B7C433EF for ; Tue, 12 Apr 2022 17:19:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Content-Type: Content-Transfer-Encoding:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:References:Cc:To:From:Subject: MIME-Version:Date:Message-ID:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=jgqJ/5xPrnM2F+oCVPB6os6DxtxuzU+gxqvpCpXPkJU=; b=RtDTiaFKAJeSgn M34M9bxZwPRaUOL+X66mOOmKvleZ0shXWJxdUVxWjGtj4kYnbkbJgBjixffxWvmoobFhexoJ1YVxN bdMrf4bahL50WLhqj8gTC4SZ1AUTysHrn2H3Z9v7VE7gyPJz8r6umQ35U2zFp3gpUgPcJPniECSSR 8J0WaWFIe5mZOVAiGmxLffbV24SSDsbRrezzU+MGzjBnL7xGPQfT19D+2PQ8Lx0GmvcRlbaXJmjLP B8LyWogrs0mkACzaB4pN7GexskDLtpgCvzDRB7jCW4o3EDwICNOFo0v4rAhBqwFR/hN2Tc0L5Inrs Rrgr4jWqjhahgS73jGDA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1neK9W-00FCTN-8R; Tue, 12 Apr 2022 17:18:06 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1neK9S-00FCSb-Of for linux-arm-kernel@lists.infradead.org; Tue, 12 Apr 2022 17:18:04 +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 9EBE71424; Tue, 12 Apr 2022 10:18:01 -0700 (PDT) Received: from [10.1.196.40] (e121345-lin.cambridge.arm.com [10.1.196.40]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 86DC33F5A1; Tue, 12 Apr 2022 10:17:59 -0700 (PDT) Message-ID: <306b1b09-487a-9ccd-4a63-8c78889492c6@arm.com> Date: Tue, 12 Apr 2022 18:17:58 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux aarch64; rv:91.0) Gecko/20100101 Thunderbird/91.7.0 Subject: Re: [RFC PATCH -next V3 4/6] arm64: add copy_{to, from}_user to machine check safe Content-Language: en-GB From: Robin Murphy To: Tong Tiangen , Mark Rutland , James Morse , Andrew Morton , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , Catalin Marinas , Will Deacon , Alexander Viro , x86@kernel.org, "H . Peter Anvin" Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Kefeng Wang , Xie XiuQi References: <20220412072552.2526871-1-tongtiangen@huawei.com> <20220412072552.2526871-5-tongtiangen@huawei.com> <38c6d4b5-a3db-5c3e-02e7-39875edb3476@arm.com> In-Reply-To: <38c6d4b5-a3db-5c3e-02e7-39875edb3476@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220412_101802_883105_49BDAC46 X-CRM114-Status: GOOD ( 12.81 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: base64 Content-Type: text/plain; charset="utf-8"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org T24gMTIvMDQvMjAyMiA2OjA4IHBtLCBSb2JpbiBNdXJwaHkgd3JvdGU6ClsuLi5dCj4+IEBAIC02 Miw3ICs2MywxMSBAQCBTWU1fRlVOQ19TVEFSVChfX2FyY2hfY29weV9mcm9tX3VzZXIpCj4+IMKg wqDCoMKgwqAgcmV0Cj4+IMKgwqDCoMKgwqAgLy8gRXhjZXB0aW9uIGZpeHVwcwo+PiAtOTk5NzrC oMKgwqAgY21wwqDCoMKgIGRzdCwgZHN0aW4KPj4gKzk5OTc6wqDCoMKgIG1ycyBlc3IsIGVzcl9l bDHCoMKgwqDCoMKgwqDCoMKgwqDCoMKgIC8vIENoZWNrIGV4Y2VwdGlvbiBmaXJzdAo+PiArwqDC oMKgIGFuZCBlc3IsIGVzciwgI0VTUl9FTHhfRlNDCj4+ICvCoMKgwqAgY21wIGVzciwgI0VTUl9F THhfRlNDX0VYVEFCVAo+IAo+IFNob3VsZCB3ZSBiZSBjaGVja2luZyBFQyB0byBtYWtlIHN1cmUg aXQncyBhIGRhdGEgYWJvcnQgLSBhbmQgdGh1cyBGU0MgCj4gaXMgdmFsaWQgLSBpbiB0aGUgZmly c3QgcGxhY2U/IEknbSBhIGxpdHRsZSBmdXp6eSBvbiBhbGwgdGhlIHBvc3NpYmxlIAo+IHBhdGhz IGludG8gZml4dXBfZXhjZXB0aW9uKCksIGFuZCBpdCdzIG5vdCBlbnRpcmVseSBvYnZpb3VzIHdo ZXRoZXIgdGhpcyAKPiBpcyBhY3R1YWxseSBzYWZlIG9yIG5vdC4KCkluIGZhY3QsIHRoaW5raW5n IHNvbWUgbW9yZSBhYm91dCB0aGF0LCBJIGRvbid0IHRoaW5rIHRoZXJlIHNob3VsZCBiZSAKYW55 IG5lZWQgZm9yIHRoaXMgc29ydCBvZiBsb2dpYyBpbiB0aGVzZSBoYW5kbGVycyBhdCBhbGwuIFRo ZSAKZml4dXBfZXhjZXB0aW9uKCkgbWFjaGluZXJ5IHNob3VsZCBhbHJlYWR5IGtub3cgZW5vdWdo IGFib3V0IHRoZSAKZXhjZXB0aW9uIHRoYXQncyBoYXBwZW5lZCBhbmQgdGhlIGV4dGFibGUgZW50 cnkgdG8gZmlndXJlIHRoaXMgb3V0IGFuZCAKbm90IGJvdGhlciBjYWxsaW5nIHRoZSBoYW5kbGVy IGF0IGFsbC4KClRoYW5rcywKUm9iaW4uCgpfX19fX19fX19fX19fX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fXwpsaW51eC1hcm0ta2VybmVsIG1haWxpbmcgbGlzdApsaW51eC1hcm0t a2VybmVsQGxpc3RzLmluZnJhZGVhZC5vcmcKaHR0cDovL2xpc3RzLmluZnJhZGVhZC5vcmcvbWFp bG1hbi9saXN0aW5mby9saW51eC1hcm0ta2VybmVsCg==