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=-15.3 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI, 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 D0C11C433E6 for ; Fri, 5 Feb 2021 17:19:26 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 68A1064FC0 for ; Fri, 5 Feb 2021 17:19:26 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 68A1064FC0 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id D14F56B006C; Fri, 5 Feb 2021 12:19:25 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id C9E996B0073; Fri, 5 Feb 2021 12:19:25 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B66016B0074; Fri, 5 Feb 2021 12:19:25 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0168.hostedemail.com [216.40.44.168]) by kanga.kvack.org (Postfix) with ESMTP id 9DE396B006C for ; Fri, 5 Feb 2021 12:19:25 -0500 (EST) Received: from smtpin24.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 6904F181AEF0B for ; Fri, 5 Feb 2021 17:19:25 +0000 (UTC) X-FDA: 77784875490.24.53D78A2 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf04.hostedemail.com (Postfix) with ESMTP id 492FE130 for ; Fri, 5 Feb 2021 17:19:24 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id E0B5C64F2A; Fri, 5 Feb 2021 17:19:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1612545546; bh=GD1HJWPDL+WDon52gpUBIOF+4zUWtcYiATH9iQBxbMw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=fynDnKT1Ph8pNPVtE+r4TaxtbWbISD93iQOUxv4KO0WokE4jpHIDc5+QI58U3LhKQ 6MkPrX5qwJo0QSx/TsLiTb/lH+TgHhOWLnLQ/Uu2j/mWq/bEYVX1fv6dQ8OzKo2M/9 5VjkT5TSKuLvHR8rYH95fb6LkpdIkkPRq4/I6ns3Jsr1R/jR07PUHdr2AEgGpe5nva iyKGnB5Opg5bShOZX0uPaaxnqrL8msH5GOMYBCSJxP/Pl7nX2AN4ffWatBfuLs8YeR DDgJmOrpi+bmXnOSgM850qIknyAZ3nCr9dNnBTkNEU2Y2p/eOtRWJg1rln3MIhy19d 3QYZ+CtsToJFg== Date: Fri, 5 Feb 2021 17:18:59 +0000 From: Will Deacon To: Lecopzer Chen Cc: akpm@linux-foundation.org, andreyknvl@google.com, ardb@kernel.org, aryabinin@virtuozzo.com, broonie@kernel.org, catalin.marinas@arm.com, dan.j.williams@intel.com, dvyukov@google.com, glider@google.com, gustavoars@kernel.org, kasan-dev@googlegroups.com, lecopzer.chen@mediatek.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mediatek@lists.infradead.org, linux-mm@kvack.org, linux@roeck-us.net, robin.murphy@arm.com, rppt@kernel.org, tyhicks@linux.microsoft.com, vincenzo.frascino@arm.com, yj.chiang@mediatek.com Subject: Re: [PATCH v2 1/4] arm64: kasan: don't populate vmalloc area for CONFIG_KASAN_VMALLOC Message-ID: <20210205171859.GE22665@willie-the-truck> References: <20210204150100.GE20815@willie-the-truck> <20210204163721.91295-1-lecopzer@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20210204163721.91295-1-lecopzer@gmail.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Stat-Signature: 8sjc4p5nepyaxk1q7hfieycc5rjhpj1q X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 492FE130 Received-SPF: none (kernel.org>: No applicable sender policy available) receiver=imf04; identity=mailfrom; envelope-from=""; helo=mail.kernel.org; client-ip=198.145.29.99 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1612545564-17292 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, Feb 05, 2021 at 12:37:21AM +0800, Lecopzer Chen wrote: >=20 > > On Thu, Feb 04, 2021 at 10:46:12PM +0800, Lecopzer Chen wrote: > > > > On Sat, Jan 09, 2021 at 06:32:49PM +0800, Lecopzer Chen wrote: > > > > > Linux support KAsan for VMALLOC since commit 3c5c3cfb9ef4da9 > > > > > ("kasan: support backing vmalloc space with real shadow memory"= ) > > > > > > > > > > Like how the MODULES_VADDR does now, just not to early populate > > > > > the VMALLOC_START between VMALLOC_END. > > > > > similarly, the kernel code mapping is now in the VMALLOC area a= nd > > > > > should keep these area populated. > > > > > > > > > > Signed-off-by: Lecopzer Chen > > > > > --- > > > > > =A0arch/arm64/mm/kasan_init.c | 23 ++++++++++++++++++----- > > > > > =A01 file changed, 18 insertions(+), 5 deletions(-) > > > > > > > > > > diff --git a/arch/arm64/mm/kasan_init.c b/arch/arm64/mm/kasan_i= nit.c > > > > > index d8e66c78440e..39b218a64279 100644 > > > > > --- a/arch/arm64/mm/kasan_init.c > > > > > +++ b/arch/arm64/mm/kasan_init.c > > > > > @@ -214,6 +214,7 @@ static void __init kasan_init_shadow(void) > > > > > =A0{ > > > > > =A0 u64 kimg_shadow_start, kimg_shadow_end; > > > > > =A0 u64 mod_shadow_start, mod_shadow_end; > > > > > + u64 vmalloc_shadow_start, vmalloc_shadow_end; > > > > > =A0 phys_addr_t pa_start, pa_end; > > > > > =A0 u64 i; > > > > > > > > > > @@ -223,6 +224,9 @@ static void __init kasan_init_shadow(void) > > > > > =A0 mod_shadow_start =3D (u64)kasan_mem_to_shadow((void *)MODUL= ES_VADDR); > > > > > =A0 mod_shadow_end =3D (u64)kasan_mem_to_shadow((void *)MODULES= _END); > > > > > > > > > > + vmalloc_shadow_start =3D (u64)kasan_mem_to_shadow((void *)VMA= LLOC_START); > > > > > + vmalloc_shadow_end =3D (u64)kasan_mem_to_shadow((void *)VMALL= OC_END); > > > > > + > > > > > =A0 /* > > > > > =A0 =A0* We are going to perform proper setup of shadow memory. > > > > > =A0 =A0* At first we should unmap early shadow (clear_pgds() ca= ll below). > > > > > @@ -241,12 +245,21 @@ static void __init kasan_init_shadow(void= ) > > > > > > > > > > =A0 kasan_populate_early_shadow(kasan_mem_to_shadow((void *)PAG= E_END), > > > > > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0(voi= d *)mod_shadow_start); > > > > > - kasan_populate_early_shadow((void *)kimg_shadow_end, > > > > > - =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0(void = *)KASAN_SHADOW_END); > > > > > + if (IS_ENABLED(CONFIG_KASAN_VMALLOC)) { > > > > > > > > Do we really need yet another CONFIG option for KASAN? What's the= use-case > > > > for *not* enabling this if you're already enabling one of the KAS= AN > > > > backends? > > > > > > As I know, KASAN_VMALLOC now only supports KASAN_GENERIC and also > > > KASAN_VMALLOC uses more memory to map real shadow memory (1/8 of vm= alloc va). > > > > The shadow is allocated dynamically though, isn't it? >=20 > Yes, but It's still a cost. >=20 > > > There should be someone can enable KASAN_GENERIC but can't use VMAL= LOC > > > due to memory issue. > > > > That doesn't sound particularly realistic to me. The reason I'm pushi= ng here > > is because I would _really_ like to move to VMAP stack unconditionall= y, and > > that would effectively force KASAN_VMALLOC to be set if KASAN is in u= se. > > > > So unless there's a really good reason not to do that, please can we = make > > this unconditional for arm64? Pretty please? >=20 > I think it's fine since we have a good reason. > Also if someone have memory issue in KASAN_VMALLOC, > they can use SW_TAG, right? >=20 > However the SW_TAG/HW_TAG is not supported VMALLOC yet. > So the code would be like >=20 > if (IS_ENABLED(CONFIG_KASAN_GENERIC)) Just make this CONFIG_KASAN_VMALLOC, since that depends on KASAN_GENERIC. > /* explain the relationship between=20 > * KASAN_GENERIC and KASAN_VMALLOC in arm64 > * XXX: because we want VMAP stack.... > */ I don't understand the relation with SW_TAGS. The VMAP_STACK dependency i= s: depends on !KASAN || KASAN_HW_TAGS || KASAN_VMALLOC which doesn't mention SW_TAGS at all. So that seems to imply that SW_TAGS and VMAP_STACK are mutually exclusive :( Will