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Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1hBLOY-0005J2-9W; Tue, 02 Apr 2019 15:32:14 +0000 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70] helo=foss.arm.com) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1hBLOT-0005Ib-Cd for linux-arm-kernel@lists.infradead.org; Tue, 02 Apr 2019 15:32:10 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 82BEC374; Tue, 2 Apr 2019 08:32:08 -0700 (PDT) Received: from fuggles.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 4DD893F721; Tue, 2 Apr 2019 08:32:07 -0700 (PDT) Date: Tue, 2 Apr 2019 16:32:01 +0100 From: Will Deacon To: Vincenzo Frascino Subject: Re: [PATCH v2] arm64: compat: Reduce address limit Message-ID: <20190402153201.GA18557@fuggles.cambridge.arm.com> References: <20190401113014.20866-1-vincenzo.frascino@arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190401113014.20866-1-vincenzo.frascino@arm.com> User-Agent: Mutt/1.11.1+86 (6f28e57d73f2) () X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190402_083209_434071_C0B5EF6A X-CRM114-Status: GOOD ( 16.77 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-arch@vger.kernel.org, Catalin Marinas , stable@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Jann Horn 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, Apr 01, 2019 at 12:30:14PM +0100, Vincenzo Frascino wrote: > Currently, compat tasks running on arm64 can allocate memory up to > TASK_SIZE_32 (UL(0x100000000)). > > This means that mmap() allocations, if we treat them as returning an > array, are not compliant with the sections 6.5.8 of the C standard > (C99) which states that: "If the expression P points to an element of > an array object and the expression Q points to the last element of the > same array object, the pointer expression Q+1 compares greater than P". > > Redefine TASK_SIZE_32 to address the issue. > > Cc: Catalin Marinas > Cc: Will Deacon > Cc: Jann Horn > Cc: > Reported-by: Jann Horn > Signed-off-by: Vincenzo Frascino > --- > arch/arm64/include/asm/processor.h | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h > index 5d9ce62bdebd..9c831d9d3cd2 100644 > --- a/arch/arm64/include/asm/processor.h > +++ b/arch/arm64/include/asm/processor.h > @@ -57,7 +57,15 @@ > #define TASK_SIZE_64 (UL(1) << vabits_user) > > #ifdef CONFIG_COMPAT > +#ifdef CONFIG_ARM64_64K_PAGES > +/* > + * With CONFIG_ARM64_64K_PAGES enabled, the last page is occupied > + * by the compact vectors page. s/compact/compat/ Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel