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, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT 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 7DE20C10F0B for ; Thu, 18 Apr 2019 06:54:31 +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 EFB9920643 for ; Thu, 18 Apr 2019 06:54:30 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EFB9920643 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 44l8wj0K3jzDqPP for ; Thu, 18 Apr 2019 16:54:29 +1000 (AEST) Received: from ozlabs.org (bilbo.ozlabs.org [203.11.71.1]) (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 44l8sJ5v76zDqHm for ; Thu, 18 Apr 2019 16:51:32 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=ellerman.id.au Received: by ozlabs.org (Postfix) id 44l8sJ01dtz9s3l; Thu, 18 Apr 2019 16:51:32 +1000 (AEST) Received: by ozlabs.org (Postfix, from userid 1034) id 44l8sH6gnKz9s4V; Thu, 18 Apr 2019 16:51:31 +1000 (AEST) From: Michael Ellerman To: linuxppc-dev@ozlabs.org Subject: [PATCH v6 01/10] powerpc/powernv/idle: Restore IAMR after idle Date: Thu, 18 Apr 2019 16:51:16 +1000 Message-Id: <20190418065125.2687-1-mpe@ellerman.id.au> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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" 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 --- v6: Unchanged. v5: Unchanged. v4: mpe: Use a #define for the stack slot. --- arch/powerpc/kernel/idle_book3s.S | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/arch/powerpc/kernel/idle_book3s.S b/arch/powerpc/kernel/idle_book3s.S index 7f5ac2e8581b..36178000a2f2 100644 --- a/arch/powerpc/kernel/idle_book3s.S +++ b/arch/powerpc/kernel/idle_book3s.S @@ -170,6 +170,9 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_300) bne- core_idle_lock_held blr +/* Reuse an unused pt_regs slot for IAMR */ +#define PNV_POWERSAVE_IAMR _DAR + /* * Pass requested state in r3: * r3 - PNV_THREAD_NAP/SLEEP/WINKLE in POWER8 @@ -200,6 +203,12 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_300) /* Continue saving state */ SAVE_GPR(2, r1) SAVE_NVGPRS(r1) + +BEGIN_FTR_SECTION + mfspr r5, SPRN_IAMR + std r5, PNV_POWERSAVE_IAMR(r1) +END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S) + mfcr r5 std r5,_CCR(r1) std r1,PACAR1(r13) @@ -924,6 +933,17 @@ BEGIN_FTR_SECTION END_FTR_SECTION_IFSET(CPU_FTR_HVMODE) REST_NVGPRS(r1) REST_GPR(2, r1) + +BEGIN_FTR_SECTION + /* IAMR was saved in pnv_powersave_common() */ + ld r5, PNV_POWERSAVE_IAMR(r1) + mtspr SPRN_IAMR, r5 + /* + * We don't need an isync here because the upcoming mtmsrd is + * execution synchronizing. + */ +END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S) + ld r4,PACAKMSR(r13) ld r5,_LINK(r1) ld r6,_CCR(r1) -- 2.20.1