Upgrade to 4.4.50-rt62

The current kernel is based on rt kernel v4.4.6-rt14. We will upgrade it
to 4.4.50-rt62.
The command to achieve it is:
a) Clone a git repo from
git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-stable-rt.git

b) Get the diff between this two changesets:
git diff 640eca2901f3435e616157b11379d3223a44b391
705619beeea1b0b48219a683fd1a901a86fdaf5e

where the two commits are:
[yjiang5@jnakajim-build linux-stable-rt]$ git show --oneline --name-only
640eca2901f3435e616157b11379d3223a44b391
640eca2901f3 v4.4.6-rt14
localversion-rt
[yjiang5@jnakajim-build linux-stable-rt]$ git show --oneline --name-only
705619beeea1b0b48219a683fd1a901a86fdaf5e
705619beeea1 Linux 4.4.50-rt62
localversion-rt

c) One patch has been backported thus revert the patch before applying.

 filterdiff -p1 -x scripts/package/Makefile
~/tmp/v4.4.6-rt14-4.4.50-rt62.diff  |patch -p1 --dry-run

Upstream status: backport

Change-Id: I244d57a32f6066e5a5b9915f9fbf99e7bbca6e01
Signed-off-by: Yunhong Jiang <yunhong.jiang@linux.intel.com>

1 files changed, 13 insertions, 7 deletions

diff --git a/kernel/include/asm-generic/uaccess.h b/kernel/include/asm-generic/uaccess.h
index 1bfa60295..32901d11f 100644
--- a/kernel/include/asm-generic/uaccess.h
+++ b/kernel/include/asm-generic/uaccess.h
@@ -230,14 +230,18 @@ extern int __put_user_bad(void) __attribute__((noreturn));
 	might_fault();						\
 	access_ok(VERIFY_READ, __p, sizeof(*ptr)) ?		\
 		__get_user((x), (__typeof__(*(ptr)) *)__p) :	\
-		-EFAULT;					\
+		((x) = (__typeof__(*(ptr)))0,-EFAULT);		\
 })
 
 #ifndef __get_user_fn
 static inline int __get_user_fn(size_t size, const void __user *ptr, void *x)
 {
-	size = __copy_from_user(x, ptr, size);
-	return size ? -EFAULT : size;
+	size_t n = __copy_from_user(x, ptr, size);
+	if (unlikely(n)) {
+		memset(x + (size - n), 0, n);
+		return -EFAULT;
+	}
+	return 0;
 }
 
 #define __get_user_fn(sz, u, k)	__get_user_fn(sz, u, k)
@@ -257,11 +261,13 @@ extern int __get_user_bad(void) __attribute__((noreturn));
 static inline long copy_from_user(void *to,
 		const void __user * from, unsigned long n)
 {
+	unsigned long res = n;
 	might_fault();
-	if (access_ok(VERIFY_READ, from, n))
-		return __copy_from_user(to, from, n);
-	else
-		return n;
+	if (likely(access_ok(VERIFY_READ, from, n)))
+		res = __copy_from_user(to, from, n);
+	if (unlikely(res))
+		memset(to + (n - res), 0, res);
+	return res;
 }
 
 static inline long copy_to_user(void __user *to,