From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:52964 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934242AbeFRIQI (ORCPT ); Mon, 18 Jun 2018 04:16:08 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Madhavan Srinivasan , Michael Ellerman , Sasha Levin Subject: [PATCH 4.16 031/279] powerpc/64s: Default l1d_size to 64K in RFI fallback flush Date: Mon, 18 Jun 2018 10:10:16 +0200 Message-Id: <20180618080610.113679785@linuxfoundation.org> In-Reply-To: <20180618080608.851973560@linuxfoundation.org> References: <20180618080608.851973560@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.16-stable review patch. If anyone has any objections, please let me know. ------------------ From: Madhavan Srinivasan [ Upstream commit 9dfbf78e4114fcaf4ef61c49885c3ab5bad40d0b ] If there is no d-cache-size property in the device tree, l1d_size could be zero. We don't actually expect that to happen, it's only been seen on mambo (simulator) in some configurations. A zero-size l1d_size leads to the loop in the asm wrapping around to 2^64-1, and then walking off the end of the fallback area and eventually causing a page fault which is fatal. Just default to 64K which is correct on some CPUs, and sane enough to not cause a crash on others. Fixes: aa8a5e0062ac9 ('powerpc/64s: Add support for RFI flush of L1-D cache') Signed-off-by: Madhavan Srinivasan [mpe: Rewrite comment and change log] Signed-off-by: Michael Ellerman Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- arch/powerpc/kernel/setup_64.c | 11 +++++++++++ 1 file changed, 11 insertions(+) --- a/arch/powerpc/kernel/setup_64.c +++ b/arch/powerpc/kernel/setup_64.c @@ -864,6 +864,17 @@ static void init_fallback_flush(void) int cpu; l1d_size = ppc64_caches.l1d.size; + + /* + * If there is no d-cache-size property in the device tree, l1d_size + * could be zero. That leads to the loop in the asm wrapping around to + * 2^64-1, and then walking off the end of the fallback area and + * eventually causing a page fault which is fatal. Just default to + * something vaguely sane. + */ + if (!l1d_size) + l1d_size = (64 * 1024); + limit = min(ppc64_bolted_size(), ppc64_rma_size); /*