From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DDDC5C10F14 for ; Sun, 21 Apr 2019 15:07:21 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 943B420693 for ; Sun, 21 Apr 2019 15:07:21 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 943B420693 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ellerman.id.au Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 44nCjz5Ng4zDqHv for ; Mon, 22 Apr 2019 01:07:19 +1000 (AEST) Received: from ozlabs.org (bilbo.ozlabs.org [IPv6:2401:3900:2:1::2]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 44nBfX1nWmzDqFL for ; Mon, 22 Apr 2019 00:19:16 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=ellerman.id.au Received: by ozlabs.org (Postfix) id 44nBfW4Hbdz9sB3; Mon, 22 Apr 2019 00:19:15 +1000 (AEST) Received: by ozlabs.org (Postfix, from userid 1034) id 44nBfV60dTz9sNF; Mon, 22 Apr 2019 00:19:14 +1000 (AEST) X-powerpc-patch-notification: thanks X-powerpc-patch-commit: a3f3072db6cad40895c585dce65e36aab997f042 X-Patchwork-Hint: ignore In-Reply-To: <20190418065125.2687-1-mpe@ellerman.id.au> To: Michael Ellerman , linuxppc-dev@ozlabs.org From: Michael Ellerman Subject: Re: [v6,01/10] powerpc/powernv/idle: Restore IAMR after idle Message-Id: <44nBfV60dTz9sNF@ozlabs.org> Date: Mon, 22 Apr 2019 00:19:14 +1000 (AEST) 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: , Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Thu, 2019-04-18 at 06:51:16 UTC, Michael Ellerman wrote: > From: Russell Currey > > Without restoring the IAMR after idle, execution prevention on POWER9 > with Radix MMU is overwritten and the kernel can freely execute > userspace without faulting. > > This is necessary when returning from any stop state that modifies > user state, as well as hypervisor state. > > To test how this fails without this patch, load the lkdtm driver and > do the following: > > $ echo EXEC_USERSPACE > /sys/kernel/debug/provoke-crash/DIRECT > > which won't fault, then boot the kernel with powersave=off, where it > will fault. Applying this patch will fix this. > > Fixes: 3b10d0095a1e ("powerpc/mm/radix: Prevent kernel execution of user space") > Cc: stable@vger.kernel.org # v4.10+ > Signed-off-by: Russell Currey > Reviewed-by: Akshay Adiga > Reviewed-by: Nicholas Piggin > Signed-off-by: Michael Ellerman Series applied to powerpc next. https://git.kernel.org/powerpc/c/a3f3072db6cad40895c585dce65e36aa cheers