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author | Nick Piggin <npiggin@suse.de> | 2007-02-12 09:51:36 +0100 |
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committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-02-12 18:48:27 +0100 |
commit | e0dc0d8f4a327d033bfb63d43f113d5f31d11b3c (patch) | |
tree | 7af435f3caacd18eef6e30577e61d62e0afbe4d2 /mm | |
parent | [PATCH] null pointer dereference in appledisplay driver (diff) | |
download | linux-e0dc0d8f4a327d033bfb63d43f113d5f31d11b3c.tar.xz linux-e0dc0d8f4a327d033bfb63d43f113d5f31d11b3c.zip |
[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: 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>
Diffstat (limited to 'mm')
-rw-r--r-- | mm/memory.c | 45 |
1 files changed, 45 insertions, 0 deletions
diff --git a/mm/memory.c b/mm/memory.c index 072c1135ad37..8b8f0d2b453d 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -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 |