From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:37014 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752759AbeDFNma (ORCPT ); Fri, 6 Apr 2018 09:42:30 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Nicholas Piggin , Michael Ellerman Subject: [PATCH 4.15 18/72] powerpc/64s: Fix i-side SLB miss bad address handler saving nonvolatile GPRs Date: Fri, 6 Apr 2018 15:23:53 +0200 Message-Id: <20180406084350.948403208@linuxfoundation.org> In-Reply-To: <20180406084349.367583460@linuxfoundation.org> References: <20180406084349.367583460@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Nicholas Piggin commit 52396500f97c53860164debc7d4f759077853423 upstream. The SLB bad address handler's trap number fixup does not preserve the low bit that indicates nonvolatile GPRs have not been saved. This leads save_nvgprs to skip saving them, and subsequent functions and return from interrupt will think they are saved. This causes kernel branch-to-garbage debugging to not have correct registers, can also cause userspace to have its registers clobbered after a segfault. Fixes: f0f558b131db ("powerpc/mm: Preserve CFAR value on SLB miss caused by access to bogus address") Cc: stable@vger.kernel.org # v4.9+ Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman Signed-off-by: Greg Kroah-Hartman --- arch/powerpc/kernel/exceptions-64s.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/arch/powerpc/kernel/exceptions-64s.S +++ b/arch/powerpc/kernel/exceptions-64s.S @@ -706,7 +706,7 @@ EXC_COMMON_BEGIN(bad_addr_slb) ld r3, PACA_EXSLB+EX_DAR(r13) std r3, _DAR(r1) beq cr6, 2f - li r10, 0x480 /* fix trap number for I-SLB miss */ + li r10, 0x481 /* fix trap number for I-SLB miss */ std r10, _TRAP(r1) 2: bl save_nvgprs addi r3, r1, STACK_FRAME_OVERHEAD