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-rw-r--r--arch/arm/lib/uaccess_with_memcpy.c36
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 bf987b4a257..92838e79654 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);
+}