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[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>
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2 changed files with 47 additions and 0 deletions
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@ -1124,6 +1124,8 @@ unsigned long vmalloc_to_pfn(void *addr);
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int remap_pfn_range(struct vm_area_struct *, unsigned long addr,
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unsigned long pfn, unsigned long size, pgprot_t);
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int vm_insert_page(struct vm_area_struct *, unsigned long addr, struct page *);
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int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
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unsigned long pfn);
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struct page *follow_page(struct vm_area_struct *, unsigned long address,
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unsigned int foll_flags);
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45
mm/memory.c
45
mm/memory.c
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@ -1277,6 +1277,51 @@ int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, struct page *
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}
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EXPORT_SYMBOL(vm_insert_page);
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/**
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* vm_insert_pfn - insert single pfn into user vma
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* @vma: user vma to map to
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* @addr: target user address of this page
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* @pfn: source kernel pfn
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*
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* Similar to vm_inert_page, this allows drivers to insert individual pages
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* they've allocated into a user vma. Same comments apply.
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*
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* This function should only be called from a vm_ops->fault handler, and
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* in that case the handler should return NULL.
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*/
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int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
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unsigned long pfn)
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{
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struct mm_struct *mm = vma->vm_mm;
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int retval;
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pte_t *pte, entry;
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spinlock_t *ptl;
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BUG_ON(!(vma->vm_flags & VM_PFNMAP));
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BUG_ON(is_cow_mapping(vma->vm_flags));
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retval = -ENOMEM;
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pte = get_locked_pte(mm, addr, &ptl);
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if (!pte)
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goto out;
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retval = -EBUSY;
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if (!pte_none(*pte))
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goto out_unlock;
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/* Ok, finally just insert the thing.. */
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entry = pfn_pte(pfn, vma->vm_page_prot);
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set_pte_at(mm, addr, pte, entry);
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update_mmu_cache(vma, addr, entry);
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retval = 0;
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out_unlock:
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pte_unmap_unlock(pte, ptl);
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out:
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return retval;
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}
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EXPORT_SYMBOL(vm_insert_pfn);
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/*
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* maps a range of physical memory into the requested pages. the old
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* mappings are removed. any references to nonexistent pages results
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