Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753093AbbKPQvJ (ORCPT ); Mon, 16 Nov 2015 11:51:09 -0500 Received: from foss.arm.com ([217.140.101.70]:51209 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751939AbbKPQvG (ORCPT ); Mon, 16 Nov 2015 11:51:06 -0500 Date: Mon, 16 Nov 2015 16:51:00 +0000 From: Catalin Marinas To: Andrey Ryabinin Cc: "Suzuki K. Poulose" , Yury , Arnd Bergmann , linux-mm@kvack.org, Linus Walleij , Ard Biesheuvel , Will Deacon , linux-kernel@vger.kernel.org, kasan-dev , Alexey Klimov , Alexander Potapenko , Dmitry Vyukov , Andrey Konovalov , David Keitel , linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v7 0/4] KASAN for arm64 Message-ID: <20151116165100.GE6556@e104818-lin.cambridge.arm.com> References: <1444665180-301-1-git-send-email-ryabinin.a.a@gmail.com> <20151013083432.GG6320@e104818-lin.cambridge.arm.com> <5649BAFD.6030005@arm.com> <5649F783.40109@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <5649F783.40109@gmail.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2742 Lines: 55 On Mon, Nov 16, 2015 at 06:34:27PM +0300, Andrey Ryabinin wrote: > On 11/16/2015 02:16 PM, Suzuki K. Poulose wrote: > > On 13/10/15 09:34, Catalin Marinas wrote: > >> On Mon, Oct 12, 2015 at 06:52:56PM +0300, Andrey Ryabinin wrote: > >>> Andrey Ryabinin (3): > >>> arm64: move PGD_SIZE definition to pgalloc.h > >>> arm64: add KASAN support > >>> Documentation/features/KASAN: arm64 supports KASAN now > >>> > >>> Linus Walleij (1): > >>> ARM64: kasan: print memory assignment > >> > >> Patches queued for 4.4. Thanks. > > > > I get the following failure with KASAN + 16K_PAGES + 48BIT_VA, with 4.4-rc1: > > > > arch/arm64/mm/kasan_init.c: In function ‘kasan_early_init’: > > include/linux/compiler.h:484:38: error: call to ‘__compiletime_assert_95’ declared with attribute error: BUILD_BUG_ON failed: !IS_ALIGNED(KASAN_SHADOW_END, PGDIR_SIZE) > > _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__) > > ^ > > include/linux/compiler.h:467:4: note: in definition of macro ‘__compiletime_assert’ > > prefix ## suffix(); \ > > ^ > > include/linux/compiler.h:484:2: note: in expansion of macro ‘_compiletime_assert’ > > _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__) > > ^ > > include/linux/bug.h:50:37: note: in expansion of macro ‘compiletime_assert’ > > #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg) > > ^ > > include/linux/bug.h:74:2: note: in expansion of macro ‘BUILD_BUG_ON_MSG’ > > BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition) > > ^ > > arch/arm64/mm/kasan_init.c:95:2: note: in expansion of macro ‘BUILD_BUG_ON’ > > BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, PGDIR_SIZE)); > > > > The problem is that the PGDIR_SIZE is (1UL << 47) with 16K+48bit, which makes > > the KASAN_SHADOW_END unaligned(which is aligned to (1UL << (48 - 3)) ). Is the > > alignment really needed ? Thoughts on how best we could fix this ? > > Yes, it's really needed, because some code relies on this (e.g. > clear_pgs() and kasan_init()). But it should be possible to get rid of > this requirement. I don't think clear_pgds() and kasan_init() are the only problems. IIUC, kasan_populate_zero_shadow() also assumes that KASan shadow covers multiple pgds. You need some kind of recursive writing which avoids populating an entry which is not empty (like kasan_early_pud_populate). -- Catalin -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/