Messages in this thread | | | From | Nick Piggin <> | Subject | Re: [PATCH 1/2] mm: implement remap_pfn_range with apply_to_page_range | Date | Fri, 14 Nov 2008 13:19:56 +1100 |
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On Friday 14 November 2008 04:19, Jeremy Fitzhardinge wrote: > remap_pte_range() just wants to apply a function over a range of ptes > corresponding to a virtual address range. That's exactly what > apply_to_page_range() does, so use it.
This isn't performance critical to anyone?
I see DRM, IB, GRU, other media and video drivers use it.
It IS exactly what apply_to_page_range does, I grant you. But so does our traditional set of nested loops. So is there any particular reason to change it? You're not planning to change fork/exit next, are you? :)
> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> > --- > mm/memory.c | 92 > ++++++++++++----------------------------------------------- 1 file changed, > 20 insertions(+), 72 deletions(-) > > =================================================================== > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -1472,69 +1472,20 @@ > } > EXPORT_SYMBOL(vm_insert_mixed); > > -/* > - * maps a range of physical memory into the requested pages. the old > - * mappings are removed. any references to nonexistent pages results > - * in null mappings (currently treated as "copy-on-access") > - */ > -static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd, > - unsigned long addr, unsigned long end, > - unsigned long pfn, pgprot_t prot) > +struct remap_data { > + struct mm_struct *mm; > + unsigned long pfn; > + pgprot_t prot; > +}; > + > +static int remap_area_pte_fn(pte_t *ptep, pgtable_t token, > + unsigned long addr, void *data) > { > - pte_t *pte; > - spinlock_t *ptl; > + struct remap_data *rmd = data; > + pte_t pte = pte_mkspecial(pfn_pte(rmd->pfn++, rmd->prot)); > > - pte = pte_alloc_map_lock(mm, pmd, addr, &ptl); > - if (!pte) > - return -ENOMEM; > - arch_enter_lazy_mmu_mode(); > - do { > - BUG_ON(!pte_none(*pte)); > - set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot))); > - pfn++; > - } while (pte++, addr += PAGE_SIZE, addr != end); > - arch_leave_lazy_mmu_mode(); > - pte_unmap_unlock(pte - 1, ptl); > - return 0; > -} > + set_pte_at(rmd->mm, addr, ptep, pte); > > -static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud, > - unsigned long addr, unsigned long end, > - unsigned long pfn, pgprot_t prot) > -{ > - pmd_t *pmd; > - unsigned long next; > - > - pfn -= addr >> PAGE_SHIFT; > - pmd = pmd_alloc(mm, pud, addr); > - if (!pmd) > - return -ENOMEM; > - do { > - next = pmd_addr_end(addr, end); > - if (remap_pte_range(mm, pmd, addr, next, > - pfn + (addr >> PAGE_SHIFT), prot)) > - return -ENOMEM; > - } while (pmd++, addr = next, addr != end); > - return 0; > -} > - > -static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd, > - unsigned long addr, unsigned long end, > - unsigned long pfn, pgprot_t prot) > -{ > - pud_t *pud; > - unsigned long next; > - > - pfn -= addr >> PAGE_SHIFT; > - pud = pud_alloc(mm, pgd, addr); > - if (!pud) > - return -ENOMEM; > - do { > - next = pud_addr_end(addr, end); > - if (remap_pmd_range(mm, pud, addr, next, > - pfn + (addr >> PAGE_SHIFT), prot)) > - return -ENOMEM; > - } while (pud++, addr = next, addr != end); > return 0; > } > > @@ -1551,10 +1502,9 @@ > int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr, > unsigned long pfn, unsigned long size, pgprot_t prot) > { > - pgd_t *pgd; > - unsigned long next; > unsigned long end = addr + PAGE_ALIGN(size); > struct mm_struct *mm = vma->vm_mm; > + struct remap_data rmd; > int err; > > /* > @@ -1584,16 +1534,14 @@ > vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP; > > BUG_ON(addr >= end); > - pfn -= addr >> PAGE_SHIFT; > - pgd = pgd_offset(mm, addr); > - flush_cache_range(vma, addr, end); > - do { > - next = pgd_addr_end(addr, end); > - err = remap_pud_range(mm, pgd, addr, next, > - pfn + (addr >> PAGE_SHIFT), prot); > - if (err) > - break; > - } while (pgd++, addr = next, addr != end); > + > + rmd.mm = mm; > + rmd.pfn = pfn; > + rmd.prot = prot; > + > + err = apply_to_page_range(mm, addr, end - addr, > + remap_area_pte_fn, &rmd); > + > return err; > } > EXPORT_SYMBOL(remap_pfn_range);
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