Subject: add vm_insert_pfn() From: Benjamin Herrenschmidt From: Nick Piggin Add a vm_insert_pfn helper, so that ->fault handlers can have nopfn functionality by installing their own pte and returning NULL. Signed-off-by: Nick Piggin Signed-off-by: Benjamin Herrenschmidt Signed-off-by: Arnd Bergmann --- include/linux/mm.h | 1 + mm/memory.c | 44 ++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 45 insertions(+) Index: linux-2.6/include/linux/mm.h =================================================================== --- linux-2.6.orig/include/linux/mm.h +++ linux-2.6/include/linux/mm.h @@ -1121,6 +1121,7 @@ unsigned long vmalloc_to_pfn(void *addr) int remap_pfn_range(struct vm_area_struct *, unsigned long addr, unsigned long pfn, unsigned long size, pgprot_t); int vm_insert_page(struct vm_area_struct *, unsigned long addr, struct page *); +int vm_insert_pfn(struct vm_area_struct *, unsigned long addr, unsigned long pfn); struct page *follow_page(struct vm_area_struct *, unsigned long address, unsigned int foll_flags); Index: linux-2.6/mm/memory.c =================================================================== --- linux-2.6.orig/mm/memory.c +++ linux-2.6/mm/memory.c @@ -1277,6 +1277,50 @@ int vm_insert_page(struct vm_area_struct } EXPORT_SYMBOL(vm_insert_page); +/** + * vm_insert_pfn - insert single pfn into user vma + * @vma: user vma to map to + * @addr: target user address of this page + * @pfn: source kernel pfn + * + * Similar to vm_inert_page, this allows drivers to insert individual pages + * they've allocated into a user vma. Same comments apply. + * + * This function should only be called from a vm_ops->fault handler, and + * in that case the handler should return NULL. + */ +int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr, unsigned long pfn) +{ + struct mm_struct *mm = vma->vm_mm; + int retval; + pte_t *pte, entry; + spinlock_t *ptl; + + BUG_ON(!(vma->vm_flags & VM_PFNMAP)); + BUG_ON(is_cow_mapping(vma->vm_flags)); + + retval = -ENOMEM; + pte = get_locked_pte(mm, addr, &ptl); + if (!pte) + goto out; + retval = -EBUSY; + if (!pte_none(*pte)) + goto out_unlock; + + /* Ok, finally just insert the thing.. */ + entry = pfn_pte(pfn, vma->vm_page_prot); + set_pte_at(mm, addr, pte, entry); + update_mmu_cache(vma, addr, entry); + + retval = 0; +out_unlock: + pte_unmap_unlock(pte, ptl); + +out: + return retval; +} +EXPORT_SYMBOL(vm_insert_pfn); + /* * maps a range of physical memory into the requested pages. the old * mappings are removed. any references to nonexistent pages results