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>

1 files changed, 5 insertions, 31 deletions

diff --git a/mm/memory.c b/mm/memory.c
index 7135d6b25995..24ff20480bb7 100644
--- 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: