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" <[email protected]> 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 <[email protected]> > > Cc: Ingo Molnar <[email protected]> > > Cc: H. Peter Anvin <[email protected]> > > Cc: Thomas Gleixner <[email protected]> > > --- > > 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 <[email protected]> > 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 <[email protected]> > --- > 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
