1 files changed, 27 insertions, 9 deletions

diff --git a/arch/arm/lib/uaccess_with_memcpy.c b/arch/arm/lib/uaccess_with_memcpy.c
index bf987b4a2571..92838e79654d 100644
--- a/arch/arm/lib/uaccess_with_memcpy.c
+++ b/arch/arm/lib/uaccess_with_memcpy.c
@@ -49,14 +49,11 @@ pin_page_for_write(const void __user *_addr, pte_t **ptep, spinlock_t **ptlp)
         return 1;
 }
 
-unsigned long
-__copy_to_user(void __user *to, const void *from, unsigned long n)
+static unsigned long noinline
+__copy_to_user_memcpy(void __user *to, const void *from, unsigned long n)
 {
         int atomic;
 
-        if (n < 1024)
-                return __copy_to_user_std(to, from, n);
-
         if (unlikely(segment_eq(get_fs(), KERNEL_DS))) {
                 memcpy((void *)to, from, n);
                 return 0;
@@ -99,11 +96,24 @@ out:
         return n;
 }
 
-unsigned long __clear_user(void __user *addr, unsigned long n)
+unsigned long
+__copy_to_user(void __user *to, const void *from, unsigned long n)
+{
+        /*
+         * This test is stubbed out of the main function above to keep
+         * the overhead for small copies low by avoiding a large
+         * register dump on the stack just to reload them right away.
+         * With frame pointer disabled, tail call optimization kicks in
+         * as well making this test almost invisible.
+         */
+        if (n < 1024)
+                return __copy_to_user_std(to, from, n);
+        return __copy_to_user_memcpy(to, from, n);
+}
+        
+static unsigned long noinline
+__clear_user_memset(void __user *addr, unsigned long n)
 {
-        if (n < 256)
-                return __clear_user_std(addr, n);
-
         if (unlikely(segment_eq(get_fs(), KERNEL_DS))) {
                 memset((void *)addr, 0, n);
                 return 0;
@@ -137,3 +147,11 @@ unsigned long __clear_user(void __user *addr, unsigned long n)
 out:
         return n;
 }
+
+unsigned long __clear_user(void __user *addr, unsigned long n)
+{
+        /* See rational for this in __copy_to_user() above. */
+        if (n < 256)
+                return __clear_user_std(addr, n);
+        return __clear_user_memset(addr, n);
+}