From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756716AbcBHW0x (ORCPT ); Mon, 8 Feb 2016 17:26:53 -0500 Received: from mailapp01.imgtec.com ([195.59.15.196]:55902 "EHLO mailapp01.imgtec.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756530AbcBHW0w (ORCPT ); Mon, 8 Feb 2016 17:26:52 -0500 Subject: Re: [PATCH] MIPS: Always page align TASK_SIZE To: David Daney References: <1454954723-24887-1-git-send-email-harvey.hunt@imgtec.com> <56B8DA56.9020108@caviumnetworks.com> <56B8DB2D.3070604@imgtec.com> <56B90A3E.7000507@gentoo.org> <56B90D30.5020904@imgtec.com> <56B911D1.2090402@caviumnetworks.com> CC: Joshua Kinard , , , David Daney , Paul Burton , James Hogan , From: Harvey Hunt Message-ID: <56B91623.4020408@imgtec.com> Date: Mon, 8 Feb 2016 14:26:43 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.5.1 MIME-Version: 1.0 In-Reply-To: <56B911D1.2090402@caviumnetworks.com> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.20.79.140] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/08/2016 02:08 PM, David Daney wrote: > On 02/08/2016 01:48 PM, Harvey Hunt wrote: >> Hi Joshua, >> >> On 02/08/2016 01:35 PM, Joshua Kinard wrote: >>> On 02/08/2016 13:15, Harvey Hunt wrote: >>>> Hi David, >>>> >>>> On 02/08/2016 10:11 AM, David Daney wrote: >>>>> On 02/08/2016 10:05 AM, Harvey Hunt wrote: >>>>>> STACK_TOP_MAX is aligned on a 32k boundary. When __bprm_mm_init() >>>>>> creates an >>>>>> initial stack for a process, it does so using STACK_TOP_MAX as the >>>>>> end >>>>>> of the >>>>>> vma. A process's arguments and environment information are placed on >>>>>> the stack >>>>>> and then the stack is relocated and aligned on a page boundary. When >>>>>> using a 32 >>>>>> bit kernel with 64k pages, the relocated stack has the process's args >>>>>> erroneously stored in the middle of the stack. This means that >>>>>> processes >>>>>> receive no arguments or environment variables, preventing them from >>>>>> running >>>>>> correctly. >>>>>> >>>>>> Fix this by aligning TASK_SIZE on a page boundary. >>>>>> >>>>>> Signed-off-by: Harvey Hunt >>>>>> Cc: David Daney >>>>>> Cc: Paul Burton >>>>>> Cc: James Hogan >>>>>> Cc: linux-kernel@vger.kernel.org >>>>>> --- >>>>>> arch/mips/include/asm/processor.h | 6 +++--- >>>>>> 1 file changed, 3 insertions(+), 3 deletions(-) >>>>>> >>>>>> diff --git a/arch/mips/include/asm/processor.h >>>>>> b/arch/mips/include/asm/processor.h >>>>>> index 3f832c3..b618b40 100644 >>>>>> --- a/arch/mips/include/asm/processor.h >>>>>> +++ b/arch/mips/include/asm/processor.h >>>>>> @@ -39,13 +39,13 @@ extern unsigned int vced_count, vcei_count; >>>>>> #ifdef CONFIG_32BIT >>>>>> #ifdef CONFIG_KVM_GUEST >>>>>> /* User space process size is limited to 1GB in KVM Guest Mode */ >>>>>> -#define TASK_SIZE 0x3fff8000UL >>>>>> +#define TASK_SIZE (0x40000000UL - PAGE_SIZE) >>>>>> #else >>>>>> /* >>>>>> * User space process size: 2GB. This is hardcoded into a few >>>>>> places, >>>>>> * so don't change it unless you know what you are doing. >>>>>> */ >>>>>> -#define TASK_SIZE 0x7fff8000UL >>>>>> +#define TASK_SIZE (0x7fff8000UL & PAGE_SIZE) >>>>> >>>>> Can you check your math here. This doesn't seem correct. >>>> >>>> Thanks for spotting that - it should have been: >>>> >>>> (0x7fff8000UL & PAGE_MASK) >>>> >>>> I'll do a v2 now. >>>> >>> >>> FYI, TASK_SIZE was recently changed to 0x80000000UL in commit >>> 7f8ca9cb1ed3 on >>> the linux-mips.org tree. >> >> Thanks, I'll rebase. > > You may find that in rebasing, suddenly you have a completely empty patch! > Yeah, I noticed that. I'll just drop this patch... Thanks, Harvey > >> >>> >>> >>>>> >>>>>> #endif >>>>>> >>>>>> #define STACK_TOP_MAX TASK_SIZE >>>>>> @@ -62,7 +62,7 @@ extern unsigned int vced_count, vcei_count; >>>>>> * support 16TB; the architectural reserve for future expansion is >>>>>> * 8192EB ... >>>>>> */ >>>>>> -#define TASK_SIZE32 0x7fff8000UL >>>>>> +#define TASK_SIZE32 (0x7fff8000UL & PAGE_SIZE) >>>>> >>>>> Same here. >>>> >>>> As above. >>>> >>>>> >>>>>> #define TASK_SIZE64 0x10000000000UL >>>>>> #define TASK_SIZE (test_thread_flag(TIF_32BIT_ADDR) ? >>>>>> TASK_SIZE32 : >>>>>> TASK_SIZE64) >>>>>> #define STACK_TOP_MAX TASK_SIZE64 >>>>>> >>>>> >>>> >>>> Thanks, >>>> >>>> Harvey >>>> >>>> >>> >>> >