diff options
| -rw-r--r-- | mm/memory.c | 36 |
1 files changed, 5 insertions, 31 deletions
diff --git a/mm/memory.c b/mm/memory.c index 7135d6b2599..24ff20480bb 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: |