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Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hufzG-0000SW-A3; Mon, 05 Aug 2019 16:37:30 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hufzB-0000PO-0Y for linux-arm-kernel@lists.infradead.org; Mon, 05 Aug 2019 16:37:27 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 314C8344; Mon, 5 Aug 2019 09:37:24 -0700 (PDT) Received: from arrakis.emea.arm.com (arrakis.cambridge.arm.com [10.1.196.78]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 2E1F63F694; Mon, 5 Aug 2019 09:37:23 -0700 (PDT) Date: Mon, 5 Aug 2019 17:37:21 +0100 From: Catalin Marinas To: Steve Capper Subject: Re: [PATCH V4 03/11] arm64: kasan: Switch to using KASAN_SHADOW_OFFSET Message-ID: <20190805163720.GF4175@arrakis.emea.arm.com> References: <20190729162117.832-1-steve.capper@arm.com> <20190729162117.832-4-steve.capper@arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190729162117.832-4-steve.capper@arm.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190805_093725_643413_5D4E81D0 X-CRM114-Status: GOOD ( 14.23 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: crecklin@redhat.com, ard.biesheuvel@linaro.org, maz@kernel.org, bhsharma@redhat.com, will@kernel.org, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Jul 29, 2019 at 05:21:09PM +0100, Steve Capper wrote: > diff --git a/Documentation/arm64/kasan-offsets.sh b/Documentation/arm64/kasan-offsets.sh > new file mode 100644 > index 000000000000..2b7a021db363 > --- /dev/null > +++ b/Documentation/arm64/kasan-offsets.sh > @@ -0,0 +1,27 @@ > +#!/bin/sh > + > +# Print out the KASAN_SHADOW_OFFSETS required to place the KASAN SHADOW > +# start address at the mid-point of the kernel VA space > + > +print_kasan_offset () { > + printf "%02d\t" $1 > + printf "0x%08x00000000\n" $(( (0xffffffff & (-1 << ($1 - 1 - 32))) \ > + + (1 << ($1 - 32 - $2)) \ > + - (1 << (64 - 32 - $2)) )) > +} > + > +echo KASAN_SHADOW_SCALE_SHIFT = 3 > +printf "VABITS\tKASAN_SHADOW_OFFSET\n" > +print_kasan_offset 48 3 > +print_kasan_offset 47 3 > +print_kasan_offset 42 3 > +print_kasan_offset 39 3 > +print_kasan_offset 36 3 > +echo > +echo KASAN_SHADOW_SCALE_SHIFT = 4 > +printf "VABITS\tKASAN_SHADOW_OFFSET\n" > +print_kasan_offset 48 4 > +print_kasan_offset 47 4 > +print_kasan_offset 42 4 > +print_kasan_offset 39 4 > +print_kasan_offset 36 4 Even better if this generated the Kconfig entry directly ;). Anyway, it's fine as it is. > diff --git a/arch/arm64/mm/kasan_init.c b/arch/arm64/mm/kasan_init.c > index 05edfe9b02e4..9e68e3d12956 100644 > --- a/arch/arm64/mm/kasan_init.c > +++ b/arch/arm64/mm/kasan_init.c > @@ -154,8 +154,6 @@ static void __init kasan_pgd_populate(unsigned long addr, unsigned long end, > /* The early shadow maps everything to a single page of zeroes */ > asmlinkage void __init kasan_early_init(void) > { > - BUILD_BUG_ON(KASAN_SHADOW_OFFSET != > - KASAN_SHADOW_END - (1UL << (64 - KASAN_SHADOW_SCALE_SHIFT))); Can we not still keep a BUILD_BUG_ON() for KASAN_SHADOW_OFFSET around, even if it does the same calculation as the script? -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel