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Sun, 16 Jun 2019 10:21:08 +0200 (CEST) X-Virus-Scanned: amavisd-new at c-s.fr Received: from messagerie.si.c-s.fr ([127.0.0.1]) by localhost (messagerie.si.c-s.fr [127.0.0.1]) (amavisd-new, port 10023) with ESMTP id QnD6C3CT-bfe; Sun, 16 Jun 2019 10:21:08 +0200 (CEST) Received: from [192.168.232.53] (unknown [192.168.232.53]) by messagerie.si.c-s.fr (Postfix) with ESMTP id E9A958B7CD; Sun, 16 Jun 2019 10:21:07 +0200 (CEST) Subject: Re: [PATCH] powerpc/mm/32s: only use MMU to mark initmem NX if STRICT_KERNEL_RWX To: Andreas Schwab References: <1e412310cc18ea654fb2ce4c935654d8d1069f27.1550775950.git.christophe.leroy@c-s.fr> <8736kb9fry.fsf_-_@igel.home> <20190615152559.Horde.0lTFIZALxZ-RI75z94G3jA8@messagerie.si.c-s.fr> <87pnne9aqo.fsf@igel.home> From: christophe leroy Message-ID: <7dd94b1c-08cb-c6ac-83c1-5b67a3dad2d8@c-s.fr> Date: Sun, 16 Jun 2019 10:06:14 +0200 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.7.1 MIME-Version: 1.0 In-Reply-To: <87pnne9aqo.fsf@igel.home> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: fr Content-Transfer-Encoding: 8bit X-Antivirus: Avast (VPS 190616-0, 16/06/2019), Outbound message X-Antivirus-Status: Clean X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-kernel@vger.kernel.org, j.neuschaefer@gmx.net, Paul Mackerras , linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Le 15/06/2019 à 16:36, Andreas Schwab a écrit : > On Jun 15 2019, Christophe Leroy wrote: > >> Andreas Schwab a écrit : >> >>> If STRICT_KERNEL_RWX is disabled, never use the MMU to mark initmen >>> nonexecutable. >> >> I dont understand, can you elaborate ? > > It breaks suspend. Ok, but we need to explain why it breaks suspend, and again your patch is wrong anyway because that area of memory is mapped with BATs so you can't use change_page_attr() > >> This area is mapped with BATs so using change_page_attr() is pointless. > > There must be a reason STRICT_KERNEL_RWX is not available with > HIBERNATE. Yes but HIBERNATE and suspend are not the same thing. I guess HIBERNATE is not available with STRICT_KERNEL_RWX because HIBERNATE have to write back saved state into read-only memory as well. Christophe --- L'absence de virus dans ce courrier électronique a été vérifiée par le logiciel antivirus Avast. https://www.avast.com/antivirus