From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1752972AbbCYNZc (ORCPT <rfc822;w@1wt.eu>);
	Wed, 25 Mar 2015 09:25:32 -0400
Received: from e06smtp12.uk.ibm.com ([195.75.94.108]:40049 "EHLO
	e06smtp12.uk.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1752742AbbCYNZ3 (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Wed, 25 Mar 2015 09:25:29 -0400
Message-ID: <5512B73C.5050509@linux.vnet.ibm.com>
Date: Wed, 25 Mar 2015 14:25:16 +0100
From: Laurent Dufour <ldufour@linux.vnet.ibm.com>
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.5.0
MIME-Version: 1.0
To: Ingo Molnar <mingo@kernel.org>
CC: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Michael Ellerman <mpe@ellerman.id.au>, Jeff Dike <jdike@addtoit.com>,
        Richard Weinberger <richard@nod.at>, Guan Xuetao <gxt@mprc.pku.edu.cn>,
        Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>,
        "H. Peter Anvin" <hpa@zytor.com>, x86@kernel.org,
        Arnd Bergmann <arnd@arndb.de>, linuxppc-dev@lists.ozlabs.org,
        linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org,
        user-mode-linux-devel@lists.sourceforge.net,
        user-mode-linux-user@lists.sourceforge.net, linux-arch@vger.kernel.org,
        linux-mm@kvack.org, cov@codeaurora.org, criu@openvz.org
Subject: Re: [PATCH v2 2/2] powerpc/mm: Tracking vDSO remap
References: <20150323085209.GA28965@gmail.com> <cover.1427280806.git.ldufour@linux.vnet.ibm.com> <25152b76585716dc635945c3455ab9b49e645f6d.1427280806.git.ldufour@linux.vnet.ibm.com> <20150325121118.GA2542@gmail.com>
In-Reply-To: <20150325121118.GA2542@gmail.com>
Content-Type: text/plain; charset=windows-1252
Content-Transfer-Encoding: 7bit
X-TM-AS-MML: disable
X-Content-Scanned: Fidelis XPS MAILER
x-cbid: 15032513-0009-0000-0000-0000039B4FCB
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On 25/03/2015 13:11, Ingo Molnar wrote:
> 
> * Laurent Dufour <ldufour@linux.vnet.ibm.com> wrote:
> 
>> Some processes (CRIU) are moving the vDSO area using the mremap system
>> call. As a consequence the kernel reference to the vDSO base address is
>> no more valid and the signal return frame built once the vDSO has been
>> moved is not pointing to the new sigreturn address.
>>
>> This patch handles vDSO remapping and unmapping.
>>
>> Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com>
>> ---
>>  arch/powerpc/include/asm/mmu_context.h | 36 +++++++++++++++++++++++++++++++++-
>>  1 file changed, 35 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/powerpc/include/asm/mmu_context.h b/arch/powerpc/include/asm/mmu_context.h
>> index 73382eba02dc..be5dca3f7826 100644
>> --- a/arch/powerpc/include/asm/mmu_context.h
>> +++ b/arch/powerpc/include/asm/mmu_context.h
>> @@ -8,7 +8,6 @@
>>  #include <linux/spinlock.h>
>>  #include <asm/mmu.h>	
>>  #include <asm/cputable.h>
>> -#include <asm-generic/mm_hooks.h>
>>  #include <asm/cputhreads.h>
>>  
>>  /*
>> @@ -109,5 +108,40 @@ static inline void enter_lazy_tlb(struct mm_struct *mm,
>>  #endif
>>  }
>>  
>> +static inline void arch_dup_mmap(struct mm_struct *oldmm,
>> +				 struct mm_struct *mm)
>> +{
>> +}
>> +
>> +static inline void arch_exit_mmap(struct mm_struct *mm)
>> +{
>> +}
>> +
>> +static inline void arch_unmap(struct mm_struct *mm,
>> +			struct vm_area_struct *vma,
>> +			unsigned long start, unsigned long end)
>> +{
>> +	if (start <= mm->context.vdso_base && mm->context.vdso_base < end)
>> +		mm->context.vdso_base = 0;
>> +}
>> +
>> +static inline void arch_bprm_mm_init(struct mm_struct *mm,
>> +				     struct vm_area_struct *vma)
>> +{
>> +}
>> +
>> +#define __HAVE_ARCH_REMAP
>> +static inline void arch_remap(struct mm_struct *mm,
>> +			      unsigned long old_start, unsigned long old_end,
>> +			      unsigned long new_start, unsigned long new_end)
>> +{
>> +	/*
>> +	 * mremap don't allow moving multiple vma so we can limit the check
>> +	 * to old_start == vdso_base.
> 
> s/mremap don't allow moving multiple vma
>   mremap() doesn't allow moving multiple vmas
> 
> right?

Sure you're right.

I'll provide a v3 fixing that comment.

Thanks,
Laurent.