Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933126AbbKROdQ (ORCPT ); Wed, 18 Nov 2015 09:33:16 -0500 Received: from mail-lb0-f180.google.com ([209.85.217.180]:33130 "EHLO mail-lb0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932085AbbKROdO (ORCPT ); Wed, 18 Nov 2015 09:33:14 -0500 Subject: Re: [PATCH v7 0/4] KASAN for arm64 To: Catalin Marinas 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> <20151116165100.GE6556@e104818-lin.cambridge.arm.com> 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 From: Andrey Ryabinin Message-ID: <564C8C47.1080904@gmail.com> Date: Wed, 18 Nov 2015 17:33:43 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: <20151116165100.GE6556@e104818-lin.cambridge.arm.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3404 Lines: 81 On 11/16/2015 07:51 PM, Catalin Marinas wrote: > 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). > I think kasan_populate_zero_shadow() should be fine. We call pgd_populate() only if address range covers the entire pgd: if (IS_ALIGNED(addr, PGDIR_SIZE) && end - addr >= PGDIR_SIZE) { .... pgd_populate(&init_mm, pgd, kasan_zero_pud); .... and otherwise we check for pgd_none(*pgd): if (pgd_none(*pgd)) { pgd_populate(&init_mm, pgd, early_alloc(PAGE_SIZE, NUMA_NO_NODE)); } Is there any way to run 16K pages on emulated environment? I've tried: - ARM V8 Foundation Platformr0p0 (platform build 9.4.59) - QEMU 2.4.0 and both just doesn't boot for me on 4.4-rc1 with 16k pages config. -- 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/