From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:58768 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730741AbeIXSku (ORCPT ); Mon, 24 Sep 2018 14:40:50 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Finn Thain , Stan Johnson , Frank Rowand , Benjamin Herrenschmidt , Rob Herring Subject: [PATCH 4.18 140/235] of: fix phandle cache creation for DTs with no phandles Date: Mon, 24 Sep 2018 13:52:06 +0200 Message-Id: <20180924113119.652905591@linuxfoundation.org> In-Reply-To: <20180924113103.999624566@linuxfoundation.org> References: <20180924113103.999624566@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: 4.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Rob Herring commit e54192b48da75f025ae4b277925eaf6aca1d13bd upstream. With commit 0b3ce78e90fc ("of: cache phandle nodes to reduce cost of of_find_node_by_phandle()"), a G3 PowerMac fails to boot. The root cause is the DT for this system has no phandle properties when booted with BootX. of_populate_phandle_cache() does not handle the case of no phandles correctly. The problem is roundup_pow_of_two() for 0 is undefined. The implementation subtracts 1 underflowing and then things are in the weeds. Fixes: 0b3ce78e90fc ("of: cache phandle nodes to reduce cost of of_find_node_by_phandle()") Cc: stable@vger.kernel.org # 4.17+ Reported-by: Finn Thain Tested-by: Stan Johnson Reviewed-by: Frank Rowand Cc: Benjamin Herrenschmidt Signed-off-by: Rob Herring Signed-off-by: Greg Kroah-Hartman --- drivers/of/base.c | 3 +++ 1 file changed, 3 insertions(+) --- a/drivers/of/base.c +++ b/drivers/of/base.c @@ -118,6 +118,9 @@ void of_populate_phandle_cache(void) if (np->phandle && np->phandle != OF_PHANDLE_ILLEGAL) phandles++; + if (!phandles) + goto out; + cache_entries = roundup_pow_of_two(phandles); phandle_cache_mask = cache_entries - 1;