From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pd0-f170.google.com (mail-pd0-f170.google.com [209.85.192.170]) by kanga.kvack.org (Postfix) with ESMTP id 6D2109003C7 for ; Mon, 27 Jul 2015 13:53:33 -0400 (EDT) Received: by pdbnt7 with SMTP id nt7so55547122pdb.0 for ; Mon, 27 Jul 2015 10:53:33 -0700 (PDT) Received: from mailout3.w1.samsung.com (mailout3.w1.samsung.com. [210.118.77.13]) by mx.google.com with ESMTPS id y5si45738558pas.76.2015.07.27.10.53.32 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Mon, 27 Jul 2015 10:53:32 -0700 (PDT) Received: from eucpsbgm1.samsung.com (unknown [203.254.199.244]) by mailout3.w1.samsung.com (Oracle Communications Messaging Server 7.0.5.31.0 64bit (built May 5 2014)) with ESMTP id <0NS500K2HR149N50@mailout3.w1.samsung.com> for linux-mm@kvack.org; Mon, 27 Jul 2015 18:53:28 +0100 (BST) Message-id: <55B67016.6090402@samsung.com> Date: Mon, 27 Jul 2015 20:53:26 +0300 From: Andrey Ryabinin MIME-version: 1.0 Subject: Re: [PATCH v4 5/7] arm64: add KASAN support References: <1437756119-12817-1-git-send-email-a.ryabinin@samsung.com> <1437756119-12817-6-git-send-email-a.ryabinin@samsung.com> <20150727155922.GB350@e104818-lin.cambridge.arm.com> In-reply-to: <20150727155922.GB350@e104818-lin.cambridge.arm.com> Content-type: text/plain; charset=windows-1252 Content-transfer-encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Catalin Marinas Cc: Will Deacon , linux-arm-kernel@lists.infradead.org, Alexey Klimov , Arnd Bergmann , linux-mm@kvack.org, Linus Walleij , linux-kernel@vger.kernel.org, David Keitel , Alexander Potapenko , Andrew Morton , Dmitry Vyukov On 07/27/2015 06:59 PM, Catalin Marinas wrote: > On Fri, Jul 24, 2015 at 07:41:57PM +0300, Andrey Ryabinin wrote: >> diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile >> index 4d2a925..2cacf55 100644 >> --- a/arch/arm64/Makefile >> +++ b/arch/arm64/Makefile >> @@ -40,6 +40,12 @@ else >> TEXT_OFFSET := 0x00080000 >> endif >> >> +# KASAN_SHADOW_OFFSET = VA_START + (1 << (VA_BITS - 3)) - (1 << 61) >> +KASAN_SHADOW_OFFSET := $(shell printf "0x%x\n" $$(( \ >> + (-1 << $(CONFIG_ARM64_VA_BITS)) \ >> + + (1 << ($(CONFIG_ARM64_VA_BITS) - 3)) \ >> + - (1 << (64 - 3)) )) ) > > Does this work with any POSIX shell? Do we always have a 64-bit type? > As I wasn't sure about this, I suggested awk (or perl). > Ok, It will be safer to use 32-bit arithmetic. I've checked this on 32-bit bash, however this doesn't guarantee that it works with any other version of bash or another shell. >> +static void __init clear_pgds(unsigned long start, >> + unsigned long end) >> +{ >> + /* >> + * Remove references to kasan page tables from >> + * swapper_pg_dir. pgd_clear() can't be used >> + * here because it's nop on 2,3-level pagetable setups >> + */ >> + for (; start && start < end; start += PGDIR_SIZE) >> + set_pgd(pgd_offset_k(start), __pgd(0)); >> +} > > I don't think we need the "start" check, just "start < end". Do you > expect a start == 0 (or overflow)? Right, we don't need this. -- 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