From 035c2777d82d1edbdf5cf22244ac47245c06a064 Mon Sep 17 00:00:00 2001
From: Vitaly Mayatskikh <v.mayatskih@gmail.com>
Date: Wed, 2 Jul 2008 15:48:21 +0200
Subject: [PATCH] --- yaml --- r: 100084 b: refs/heads/master c:
 1129585a08baf58582c0da91e572cb29e3179acf h: refs/heads/master v: v3

---
 [refs]                             |  2 +-
 trunk/arch/x86/lib/usercopy_64.c   | 23 +++++++++++++++++++++++
 trunk/include/asm-x86/uaccess_64.h |  3 +++
 3 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index f9c18ab46763..7e143e92105f 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: de989ef093623ab5259f885f30be699c431d4006
+refs/heads/master: 1129585a08baf58582c0da91e572cb29e3179acf
diff --git a/trunk/arch/x86/lib/usercopy_64.c b/trunk/arch/x86/lib/usercopy_64.c
index 0c89d1bb0287..f4df6e7c718b 100644
--- a/trunk/arch/x86/lib/usercopy_64.c
+++ b/trunk/arch/x86/lib/usercopy_64.c
@@ -158,3 +158,26 @@ unsigned long copy_in_user(void __user *to, const void __user *from, unsigned le
 }
 EXPORT_SYMBOL(copy_in_user);
 
+/*
+ * Try to copy last bytes and clear the rest if needed.
+ * Since protection fault in copy_from/to_user is not a normal situation,
+ * it is not necessary to optimize tail handling.
+ */
+unsigned long
+copy_user_handle_tail(char *to, char *from, unsigned len, unsigned zerorest)
+{
+	char c;
+	unsigned zero_len;
+
+	for (; len; --len) {
+		if (__get_user_nocheck(c, from++, sizeof(char)))
+			break;
+		if (__put_user_nocheck(c, to++, sizeof(char)))
+			break;
+	}
+
+	for (c = 0, zero_len = len; zerorest && zero_len; --zero_len)
+		if (__put_user_nocheck(c, to++, sizeof(char)))
+			break;
+	return len;
+}
diff --git a/trunk/include/asm-x86/uaccess_64.h b/trunk/include/asm-x86/uaccess_64.h
index 4e3ec004e14a..515d4dce96b5 100644
--- a/trunk/include/asm-x86/uaccess_64.h
+++ b/trunk/include/asm-x86/uaccess_64.h
@@ -195,4 +195,7 @@ static inline int __copy_from_user_inatomic_nocache(void *dst,
 	return __copy_user_nocache(dst, src, size, 0);
 }
 
+unsigned long
+copy_user_handle_tail(char *to, char *from, unsigned len, unsigned zerorest);
+
 #endif /* __X86_64_UACCESS_H */