From patchwork Fri Sep 24 17:13:53 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christophe Leroy X-Patchwork-Id: 1532383 Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=lists.ozlabs.org (client-ip=112.213.38.117; helo=lists.ozlabs.org; envelope-from=linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org; receiver=) Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 4HGJYV50Vvz9ssP for ; Sat, 25 Sep 2021 03:14:38 +1000 (AEST) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4HGJYV4FGgz3c65 for ; Sat, 25 Sep 2021 03:14:38 +1000 (AEST) X-Original-To: linuxppc-dev@lists.ozlabs.org Delivered-To: linuxppc-dev@lists.ozlabs.org Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=csgroup.eu (client-ip=93.17.235.10; helo=pegase2.c-s.fr; envelope-from=christophe.leroy@csgroup.eu; receiver=) Received: from pegase2.c-s.fr (pegase2.c-s.fr [93.17.235.10]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4HGJY26VXWz2yHj for ; Sat, 25 Sep 2021 03:14:12 +1000 (AEST) Received: from localhost (mailhub3.si.c-s.fr [172.26.127.67]) by localhost (Postfix) with ESMTP id 4HGJXw46ttz9sW1; Fri, 24 Sep 2021 19:14:08 +0200 (CEST) X-Virus-Scanned: amavisd-new at c-s.fr Received: from pegase2.c-s.fr ([172.26.127.65]) by localhost (pegase2.c-s.fr [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id WieYpIoaJD3j; Fri, 24 Sep 2021 19:14:08 +0200 (CEST) Received: from messagerie.si.c-s.fr (messagerie.si.c-s.fr [192.168.25.192]) by pegase2.c-s.fr (Postfix) with ESMTP id 4HGJXw3234z9sW0; Fri, 24 Sep 2021 19:14:08 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 3D8BF8B77E; Fri, 24 Sep 2021 19:14:08 +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 jVw6Wv7Xqqrs; Fri, 24 Sep 2021 19:14:08 +0200 (CEST) Received: from PO20335.IDSI0.si.c-s.fr (unknown [192.168.202.215]) by messagerie.si.c-s.fr (Postfix) with ESMTP id EE74D8B763; Fri, 24 Sep 2021 19:14:07 +0200 (CEST) Received: from PO20335.IDSI0.si.c-s.fr (localhost [127.0.0.1]) by PO20335.IDSI0.si.c-s.fr (8.16.1/8.16.1) with ESMTPS id 18OHDuKh1302144 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NOT); Fri, 24 Sep 2021 19:13:57 +0200 Received: (from chleroy@localhost) by PO20335.IDSI0.si.c-s.fr (8.16.1/8.16.1/Submit) id 18OHDt7W1302143; Fri, 24 Sep 2021 19:13:55 +0200 X-Authentication-Warning: PO20335.IDSI0.si.c-s.fr: chleroy set sender to christophe.leroy@csgroup.eu using -f From: Christophe Leroy To: Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman Subject: [PATCH] powerpc: Activate CONFIG_STRICT_KERNEL_RWX by default Date: Fri, 24 Sep 2021 19:13:53 +0200 Message-Id: <057c40164084bfc7d77c0b2ff78d95dbf6a2a21b.1632503622.git.christophe.leroy@csgroup.eu> X-Mailer: git-send-email 2.31.1 MIME-Version: 1.0 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: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, Kees Cook Errors-To: linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" CONFIG_STRICT_KERNEL_RWX should be set by default on every architectures (See https://github.com/KSPP/linux/issues/4) On PPC32 we have to find a compromise between performance and/or memory wasting and selection of strict_kernel_rwx, because it implies either smaller memory chunks or larger alignment between RO memory and RW memory. For instance the 8xx maps memory with 8M pages. So either the limit between RO and RW must be 8M aligned or it falls back or 512k pages which implies more pressure on the TLB. book3s/32 maps memory with BATs as much as possible. BATS can have any power-of-two size between 128k and 256M but we have only 4 to 8 BATs so the alignment must be good enough to allow efficient use of the BATs and avoid falling back on standard page mapping which would kill performance. So let's go one step forward and make it the default but still allow users to unset it when wanted. Cc: Kees Cook Signed-off-by: Christophe Leroy --- arch/powerpc/Kconfig | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index ba5b66189358..79332f51185d 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -148,6 +148,7 @@ config PPC select ARCH_MIGHT_HAVE_PC_PARPORT select ARCH_MIGHT_HAVE_PC_SERIO select ARCH_OPTIONAL_KERNEL_RWX if ARCH_HAS_STRICT_KERNEL_RWX + select ARCH_OPTIONAL_KERNEL_RWX_DEFAULT select ARCH_STACKWALK select ARCH_SUPPORTS_ATOMIC_RMW select ARCH_SUPPORTS_DEBUG_PAGEALLOC if PPC32 || PPC_BOOK3S_64