Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754088AbdFSMs0 (ORCPT ); Mon, 19 Jun 2017 08:48:26 -0400 Received: from mail-lf0-f68.google.com ([209.85.215.68]:34183 "EHLO mail-lf0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753696AbdFSMsY (ORCPT ); Mon, 19 Jun 2017 08:48:24 -0400 Date: Mon, 19 Jun 2017 15:48:19 +0300 From: "Kirill A. Shutemov" To: Martin Schwidefsky Cc: "Kirill A. Shutemov" , Andrew Morton , Vlastimil Babka , Vineet Gupta , Russell King , Will Deacon , Catalin Marinas , Ralf Baechle , "David S. Miller" , "Aneesh Kumar K . V" , Heiko Carstens , Andrea Arcangeli , linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Ingo Molnar , "H . Peter Anvin" , Thomas Gleixner Subject: Re: [PATCHv2 1/3] x86/mm: Provide pmdp_establish() helper Message-ID: <20170619124819.tlbprgi7tima6rzl@node.shutemov.name> References: <20170615145224.66200-1-kirill.shutemov@linux.intel.com> <20170615145224.66200-2-kirill.shutemov@linux.intel.com> <20170619074801.18fa2a16@mschwideX1> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170619074801.18fa2a16@mschwideX1> User-Agent: NeoMutt/20170609 (1.8.3) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3082 Lines: 84 On Mon, Jun 19, 2017 at 07:48:01AM +0200, Martin Schwidefsky wrote: > On Thu, 15 Jun 2017 17:52:22 +0300 > "Kirill A. Shutemov" wrote: > > > We need an atomic way to setup pmd page table entry, avoiding races with > > CPU setting dirty/accessed bits. This is required to implement > > pmdp_invalidate() that doesn't loose these bits. > > > > On PAE we have to use cmpxchg8b as we cannot assume what is value of new pmd and > > setting it up half-by-half can expose broken corrupted entry to CPU. > > > > Signed-off-by: Kirill A. Shutemov > > Cc: Ingo Molnar > > Cc: H. Peter Anvin > > Cc: Thomas Gleixner > > --- > > arch/x86/include/asm/pgtable-3level.h | 18 ++++++++++++++++++ > > arch/x86/include/asm/pgtable.h | 14 ++++++++++++++ > > 2 files changed, 32 insertions(+) > > > > diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h > > index f5af95a0c6b8..a924fc6a96b9 100644 > > --- a/arch/x86/include/asm/pgtable.h > > +++ b/arch/x86/include/asm/pgtable.h > > @@ -1092,6 +1092,20 @@ static inline void pmdp_set_wrprotect(struct mm_struct *mm, > > clear_bit(_PAGE_BIT_RW, (unsigned long *)pmdp); > > } > > > > +#ifndef pmdp_establish > > +#define pmdp_establish pmdp_establish > > +static inline pmd_t pmdp_establish(pmd_t *pmdp, pmd_t pmd) > > +{ > > + if (IS_ENABLED(CONFIG_SMP)) { > > + return xchg(pmdp, pmd); > > + } else { > > + pmd_t old = *pmdp; > > + *pmdp = pmd; > > + return old; > > + } > > +} > > +#endif > > + > > /* > > * clone_pgd_range(pgd_t *dst, pgd_t *src, int count); > > * > > For the s390 version of the pmdp_establish function we need the mm to be able > to do the TLB flush correctly. Can we please add a "struct vm_area_struct *vma" > argument to pmdp_establish analog to pmdp_invalidate? > > The s390 patch would then look like this: > -- > From 4d4641249d5e826c21c522d149553e89d73fcd4f Mon Sep 17 00:00:00 2001 > From: Martin Schwidefsky > Date: Mon, 19 Jun 2017 07:40:11 +0200 > Subject: [PATCH] s390/mm: add pmdp_establish > > Define the pmdp_establish function to replace a pmd entry with a new > one and return the old value. > > Signed-off-by: Martin Schwidefsky > --- > arch/s390/include/asm/pgtable.h | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h > index bb59a0aa3249..dedeecd5455c 100644 > --- a/arch/s390/include/asm/pgtable.h > +++ b/arch/s390/include/asm/pgtable.h > @@ -1511,6 +1511,13 @@ static inline void pmdp_invalidate(struct vm_area_struct *vma, > pmdp_xchg_direct(vma->vm_mm, addr, pmdp, __pmd(_SEGMENT_ENTRY_EMPTY)); > } > > +static inline pmd_t pmdp_establish(struct vm_area_struct *vma, > + pmd_t *pmdp, pmd_t pmd) > +{ > + return pmdp_xchg_direct(vma->vm_mm, addr, pmdp, pmd); I guess, you need address too :-P. I'll change prototype of pmdp_establish() and apply your patch. -- Kirill A. Shutemov