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-rw-r--r--include/linux/mm.h2
-rw-r--r--mm/memory.c29
2 files changed, 31 insertions, 0 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 7b548e7cfbd9..c80dbd4a62c6 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -792,6 +792,8 @@ int copy_page_range(struct mm_struct *dst, struct mm_struct *src,
792 struct vm_area_struct *vma); 792 struct vm_area_struct *vma);
793void unmap_mapping_range(struct address_space *mapping, 793void unmap_mapping_range(struct address_space *mapping,
794 loff_t const holebegin, loff_t const holelen, int even_cows); 794 loff_t const holebegin, loff_t const holelen, int even_cows);
795int follow_pfn(struct vm_area_struct *vma, unsigned long address,
796 unsigned long *pfn);
795int follow_phys(struct vm_area_struct *vma, unsigned long address, 797int follow_phys(struct vm_area_struct *vma, unsigned long address,
796 unsigned int flags, unsigned long *prot, resource_size_t *phys); 798 unsigned int flags, unsigned long *prot, resource_size_t *phys);
797int generic_access_phys(struct vm_area_struct *vma, unsigned long addr, 799int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
diff --git a/mm/memory.c b/mm/memory.c
index 24ff20480bb7..d5d1653d60a6 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3140,6 +3140,35 @@ out:
3140 return -EINVAL; 3140 return -EINVAL;
3141} 3141}
3142 3142
3143/**
3144 * follow_pfn - look up PFN at a user virtual address
3145 * @vma: memory mapping
3146 * @address: user virtual address
3147 * @pfn: location to store found PFN
3148 *
3149 * Only IO mappings and raw PFN mappings are allowed.
3150 *
3151 * Returns zero and the pfn at @pfn on success, -ve otherwise.
3152 */
3153int follow_pfn(struct vm_area_struct *vma, unsigned long address,
3154 unsigned long *pfn)
3155{
3156 int ret = -EINVAL;
3157 spinlock_t *ptl;
3158 pte_t *ptep;
3159
3160 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
3161 return ret;
3162
3163 ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
3164 if (ret)
3165 return ret;
3166 *pfn = pte_pfn(*ptep);
3167 pte_unmap_unlock(ptep, ptl);
3168 return 0;
3169}
3170EXPORT_SYMBOL(follow_pfn);
3171
3143#ifdef CONFIG_HAVE_IOREMAP_PROT 3172#ifdef CONFIG_HAVE_IOREMAP_PROT
3144int follow_phys(struct vm_area_struct *vma, 3173int follow_phys(struct vm_area_struct *vma,
3145 unsigned long address, unsigned int flags, 3174 unsigned long address, unsigned int flags,