mm: use generic follow_pte() in follow_phys()

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Christoph Hellwig <hch@infradead.org>
Acked-by: Magnus Damm <magnus.damm@gmail.com>
Cc: Hans Verkuil <hverkuil@xs4all.nl>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/memory.c b/mm/memory.c
index 7135d6b..24ff204 100644 (file)
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3145,50 +3145,24 @@ int follow_phys(struct vm_area_struct *vma,
                unsigned long address, unsigned int flags,
                unsigned long *prot, resource_size_t *phys)
 {
-       pgd_t *pgd;
-       pud_t *pud;
-       pmd_t *pmd;
+       int ret = -EINVAL;
        pte_t *ptep, pte;
        spinlock_t *ptl;
-       resource_size_t phys_addr = 0;
-       struct mm_struct *mm = vma->vm_mm;
-       int ret = -EINVAL;
 
        if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
                goto out;
 
-       pgd = pgd_offset(mm, address);
-       if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
-               goto out;
-
-       pud = pud_offset(pgd, address);
-       if (pud_none(*pud) || unlikely(pud_bad(*pud)))
-               goto out;
-
-       pmd = pmd_offset(pud, address);
-       if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
-               goto out;
-
-       /* We cannot handle huge page PFN maps. Luckily they don't exist. */
-       if (pmd_huge(*pmd))
+       if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
                goto out;
-
-       ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
-       if (!ptep)
-               goto out;
-
        pte = *ptep;
-       if (!pte_present(pte))
-               goto unlock;
+
        if ((flags & FOLL_WRITE) && !pte_write(pte))
                goto unlock;
-       phys_addr = pte_pfn(pte);
-       phys_addr <<= PAGE_SHIFT; /* Shift here to avoid overflow on PAE */
 
        *prot = pgprot_val(pte_pgprot(pte));
-       *phys = phys_addr;
-       ret = 0;
+       *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
 
+       ret = 0;
 unlock:
        pte_unmap_unlock(ptep, ptl);
 out: