From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752303AbdFAQfj (ORCPT ); Thu, 1 Jun 2017 12:35:39 -0400 Received: from mail-db5eur01on0083.outbound.protection.outlook.com ([104.47.2.83]:20896 "EHLO EUR01-DB5-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751997AbdFAQff (ORCPT ); Thu, 1 Jun 2017 12:35:35 -0400 Authentication-Results: virtuozzo.com; dkim=none (message not signed) header.d=none;virtuozzo.com; dmarc=none action=none header.from=arm.com; Date: Thu, 1 Jun 2017 17:34:43 +0100 From: Mark Rutland To: Andrey Ryabinin CC: Andrew Morton , Catalin Marinas , Will Deacon , , , , Alexander Potapenko , , Dmitry Vyukov Subject: Re: [PATCH 3/4] arm64/kasan: don't allocate extra shadow memory Message-ID: <20170601163442.GC17711@leverpostej> References: <20170601162338.23540-1-aryabinin@virtuozzo.com> <20170601162338.23540-3-aryabinin@virtuozzo.com> MIME-Version: 1.0 Content-Type: text/plain; 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I see that patch 1 fixed up the Linux helpers for outline instrumentation. Just to check, is it also true that the inline instrumentation never performs unaligned accesses to the shadow memory? If so, this looks good to me; it also avoids a potential fencepost issue when memory exists right at the end of the linear map. Assuming that holds: Acked-by: Mark Rutland Thanks, Mark. > > Signed-off-by: Andrey Ryabinin > Cc: Catalin Marinas > Cc: Will Deacon > Cc: linux-arm-kernel@lists.infradead.org > --- > arch/arm64/mm/kasan_init.c | 8 +------- > 1 file changed, 1 insertion(+), 7 deletions(-) > > diff --git a/arch/arm64/mm/kasan_init.c b/arch/arm64/mm/kasan_init.c > index 687a358a3733..81f03959a4ab 100644 > --- a/arch/arm64/mm/kasan_init.c > +++ b/arch/arm64/mm/kasan_init.c > @@ -191,14 +191,8 @@ void __init kasan_init(void) > if (start >= end) > break; > > - /* > - * end + 1 here is intentional. We check several shadow bytes in > - * advance to slightly speed up fastpath. In some rare cases > - * we could cross boundary of mapped shadow, so we just map > - * some more here. > - */ > vmemmap_populate((unsigned long)kasan_mem_to_shadow(start), > - (unsigned long)kasan_mem_to_shadow(end) + 1, > + (unsigned long)kasan_mem_to_shadow(end), > pfn_to_nid(virt_to_pfn(start))); > } > > -- > 2.13.0 > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f200.google.com (mail-pf0-f200.google.com [209.85.192.200]) by kanga.kvack.org (Postfix) with ESMTP id C82F16B0292 for ; Thu, 1 Jun 2017 12:35:26 -0400 (EDT) Received: by mail-pf0-f200.google.com with SMTP id q27so48214327pfi.8 for ; Thu, 01 Jun 2017 09:35:26 -0700 (PDT) Received: from EUR01-DB5-obe.outbound.protection.outlook.com (mail-db5eur01on0064.outbound.protection.outlook.com. [104.47.2.64]) by mx.google.com with ESMTPS id 65si2296166pfi.240.2017.06.01.09.35.25 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Thu, 01 Jun 2017 09:35:25 -0700 (PDT) Date: Thu, 1 Jun 2017 17:34:43 +0100 From: Mark Rutland Subject: Re: [PATCH 3/4] arm64/kasan: don't allocate extra shadow memory Message-ID: <20170601163442.GC17711@leverpostej> References: <20170601162338.23540-1-aryabinin@virtuozzo.com> <20170601162338.23540-3-aryabinin@virtuozzo.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20170601162338.23540-3-aryabinin@virtuozzo.com> Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org List-ID: To: Andrey Ryabinin Cc: Andrew Morton , Catalin Marinas , Will Deacon , linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, linux-mm@kvack.org, Alexander Potapenko , linux-arm-kernel@lists.infradead.org, Dmitry Vyukov On Thu, Jun 01, 2017 at 07:23:37PM +0300, Andrey Ryabinin wrote: > We used to read several bytes of the shadow memory in advance. > Therefore additional shadow memory mapped to prevent crash if > speculative load would happen near the end of the mapped shadow memory. > > Now we don't have such speculative loads, so we no longer need to map > additional shadow memory. I see that patch 1 fixed up the Linux helpers for outline instrumentation. Just to check, is it also true that the inline instrumentation never performs unaligned accesses to the shadow memory? If so, this looks good to me; it also avoids a potential fencepost issue when memory exists right at the end of the linear map. Assuming that holds: Acked-by: Mark Rutland Thanks, Mark. > > Signed-off-by: Andrey Ryabinin > Cc: Catalin Marinas > Cc: Will Deacon > Cc: linux-arm-kernel@lists.infradead.org > --- > arch/arm64/mm/kasan_init.c | 8 +------- > 1 file changed, 1 insertion(+), 7 deletions(-) > > diff --git a/arch/arm64/mm/kasan_init.c b/arch/arm64/mm/kasan_init.c > index 687a358a3733..81f03959a4ab 100644 > --- a/arch/arm64/mm/kasan_init.c > +++ b/arch/arm64/mm/kasan_init.c > @@ -191,14 +191,8 @@ void __init kasan_init(void) > if (start >=3D end) > break; > > - /* > - * end + 1 here is intentional. We check several shadow byt= es in > - * advance to slightly speed up fastpath. In some rare case= s > - * we could cross boundary of mapped shadow, so we just map > - * some more here. > - */ > vmemmap_populate((unsigned long)kasan_mem_to_shadow(start), > - (unsigned long)kasan_mem_to_shadow(end) + 1= , > + (unsigned long)kasan_mem_to_shadow(end), > pfn_to_nid(virt_to_pfn(start))); > } > > -- > 2.13.0 > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel IMPORTANT NOTICE: The contents of this email and any attachments are confid= ential and may also be privileged. If you are not the intended recipient, p= lease notify the sender immediately and do not disclose the contents to any= other person, use it for any purpose, or store or copy the information in = any medium. Thank you. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org From mboxrd@z Thu Jan 1 00:00:00 1970 From: mark.rutland@arm.com (Mark Rutland) Date: Thu, 1 Jun 2017 17:34:43 +0100 Subject: [PATCH 3/4] arm64/kasan: don't allocate extra shadow memory In-Reply-To: <20170601162338.23540-3-aryabinin@virtuozzo.com> References: <20170601162338.23540-1-aryabinin@virtuozzo.com> <20170601162338.23540-3-aryabinin@virtuozzo.com> Message-ID: <20170601163442.GC17711@leverpostej> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Thu, Jun 01, 2017 at 07:23:37PM +0300, Andrey Ryabinin wrote: > We used to read several bytes of the shadow memory in advance. > Therefore additional shadow memory mapped to prevent crash if > speculative load would happen near the end of the mapped shadow memory. > > Now we don't have such speculative loads, so we no longer need to map > additional shadow memory. I see that patch 1 fixed up the Linux helpers for outline instrumentation. Just to check, is it also true that the inline instrumentation never performs unaligned accesses to the shadow memory? If so, this looks good to me; it also avoids a potential fencepost issue when memory exists right at the end of the linear map. Assuming that holds: Acked-by: Mark Rutland Thanks, Mark. > > Signed-off-by: Andrey Ryabinin > Cc: Catalin Marinas > Cc: Will Deacon > Cc: linux-arm-kernel at lists.infradead.org > --- > arch/arm64/mm/kasan_init.c | 8 +------- > 1 file changed, 1 insertion(+), 7 deletions(-) > > diff --git a/arch/arm64/mm/kasan_init.c b/arch/arm64/mm/kasan_init.c > index 687a358a3733..81f03959a4ab 100644 > --- a/arch/arm64/mm/kasan_init.c > +++ b/arch/arm64/mm/kasan_init.c > @@ -191,14 +191,8 @@ void __init kasan_init(void) > if (start >= end) > break; > > - /* > - * end + 1 here is intentional. We check several shadow bytes in > - * advance to slightly speed up fastpath. In some rare cases > - * we could cross boundary of mapped shadow, so we just map > - * some more here. > - */ > vmemmap_populate((unsigned long)kasan_mem_to_shadow(start), > - (unsigned long)kasan_mem_to_shadow(end) + 1, > + (unsigned long)kasan_mem_to_shadow(end), > pfn_to_nid(virt_to_pfn(start))); > } > > -- > 2.13.0 > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel at lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you.