Merge remote-tracking branch 'drm/drm-next'

[karo-tx-linux.git] / arch / arm / lib / uaccess_with_memcpy.c

diff --git a/arch/arm/lib/uaccess_with_memcpy.c b/arch/arm/lib/uaccess_with_memcpy.c
index 025f742dd4df6bf79b279babd264980d851f01d5..3e58d710013c3ad9b377fc76e6dad58f377e88a7 100644 (file)
--- a/arch/arm/lib/uaccess_with_memcpy.c
+++ b/arch/arm/lib/uaccess_with_memcpy.c
@@ -18,6 +18,7 @@
 #include <linux/hardirq.h> /* for in_atomic() */
 #include <linux/gfp.h>
 #include <linux/highmem.h>
+#include <linux/hugetlb.h>
 #include <asm/current.h>
 #include <asm/page.h>
 
@@ -40,7 +41,35 @@ pin_page_for_write(const void __user *_addr, pte_t **ptep, spinlock_t **ptlp)
                return 0;
 
        pmd = pmd_offset(pud, addr);
-       if (unlikely(pmd_none(*pmd) || pmd_bad(*pmd)))
+       if (unlikely(pmd_none(*pmd)))
+               return 0;
+
+       /*
+        * A pmd can be bad if it refers to a HugeTLB or THP page.
+        *
+        * Both THP and HugeTLB pages have the same pmd layout
+        * and should not be manipulated by the pte functions.
+        *
+        * Lock the page table for the destination and check
+        * to see that it's still huge and whether or not we will
+        * need to fault on write, or if we have a splitting THP.
+        */
+       if (unlikely(pmd_thp_or_huge(*pmd))) {
+               ptl = &current->mm->page_table_lock;
+               spin_lock(ptl);
+               if (unlikely(!pmd_thp_or_huge(*pmd)
+                       || pmd_hugewillfault(*pmd)
+                       || pmd_trans_splitting(*pmd))) {
+                       spin_unlock(ptl);
+                       return 0;
+               }
+
+               *ptep = NULL;
+               *ptlp = ptl;
+               return 1;
+       }
+
+       if (unlikely(pmd_bad(*pmd)))
                return 0;
 
        pte = pte_offset_map_lock(current->mm, pmd, addr, &ptl);
@@ -94,7 +123,10 @@ __copy_to_user_memcpy(void __user *to, const void *from, unsigned long n)
                from += tocopy;
                n -= tocopy;
 
-               pte_unmap_unlock(pte, ptl);
+               if (pte)
+                       pte_unmap_unlock(pte, ptl);
+               else
+                       spin_unlock(ptl);
        }
        if (!atomic)
                up_read(&current->mm->mmap_sem);
@@ -147,7 +179,10 @@ __clear_user_memset(void __user *addr, unsigned long n)
                addr += tocopy;
                n -= tocopy;
 
-               pte_unmap_unlock(pte, ptl);
+               if (pte)
+                       pte_unmap_unlock(pte, ptl);
+               else
+                       spin_unlock(ptl);
        }
        up_read(&current->mm->mmap_sem);