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Commit e0dc0d8f authored by Nick Piggin's avatar Nick Piggin Committed by Linus Torvalds
Browse files

[PATCH] add vm_insert_pfn() 



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: default avatarNick Piggin <npiggin@suse.de>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 2ca48ed5

include/linux/mm.h

+2 −0
Original line number Diff line number Diff line
@@ -1124,6 +1124,8 @@ 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 *vma, unsigned long addr,

			unsigned long pfn);



struct page *follow_page(struct vm_area_struct *, unsigned long address,

			unsigned int foll_flags);

mm/memory.c

+45 −0
Original line number Diff line number Diff line
@@ -1277,6 +1277,51 @@ int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, struct page * 
}

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