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Violators will be prosecuted for from ; Mon, 19 Jun 2017 14:04:30 +0100 Date: Mon, 19 Jun 2017 15:04:22 +0200 From: Martin Schwidefsky Subject: Re: [PATCHv2 1/3] x86/mm: Provide pmdp_establish() helper In-Reply-To: <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> <20170619124819.tlbprgi7tima6rzl@node.shutemov.name> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Message-Id: <20170619150422.0d45cff2@mschwideX1> Sender: owner-linux-mm@kvack.org List-ID: To: "Kirill A. Shutemov" 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 On Mon, 19 Jun 2017 15:48:19 +0300 "Kirill A. Shutemov" wrote: > 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. Ahh, yes. vma + addr please ;-) -- blue skies, Martin. "Reality continues to ruin my life." - Calvin. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org