---

yaml
---
r: 149321
b: refs/heads/master
c: cb9dc92
h: refs/heads/master
i:
  149319: dfcfc43
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 39ec58f3fea47c242724109cc1da999f74810bbc
+refs/heads/master: cb9dc92c0a1b76165c8c334402e27191084b2047

trunk/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 @@ __copy_to_user(void __user *to, const void *from, unsigned long n)
 	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);
+}