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[PATCH] add vm_insert_pfn()

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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 <npiggin@suse.de>
Signed-off-by: Benjamin 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Nick Piggin 2007-02-12 00:51:36 -08:00 committed by Linus Torvalds
parent 2ca48ed5cc
commit e0dc0d8f4a
2 changed files with 47 additions and 0 deletions
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2
include/linux/mm.h
View file

@ -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);

45
mm/memory.c
View file

@ -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