FAILED: patch "[PATCH] s390/chsc: Add exception handler for CHSC instruction" failed to apply to 4.4-stable tree

FAILED: patch "[PATCH] s390/chsc: Add exception handler for CHSC instruction" failed to apply to 4.4-stable tree

[gregkh]

The patch below does not apply to the 4.4-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

>From 77759137248f34864a8f7a58bbcebfcf1047504a Mon Sep 17 00:00:00 2001
From: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Date: Mon, 20 Feb 2017 14:52:58 +0100
Subject: [PATCH] s390/chsc: Add exception handler for CHSC instruction

Prevent kernel crashes due to unhandled exceptions raised by the CHSC
instruction which may for example be triggered by invalid ioctl data.

Fixes: 64150adf89df ("s390/cio: Introduce generic synchronous CHSC IOCTL")
Cc: <stable@vger.kernel.org> # v3.11+
Signed-off-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Reviewed-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

diff --git a/drivers/s390/cio/ioasm.c b/drivers/s390/cio/ioasm.c
index 8225da619014..4182f60124da 100644
--- a/drivers/s390/cio/ioasm.c
+++ b/drivers/s390/cio/ioasm.c
@@ -165,13 +165,15 @@ int tpi(struct tpi_info *addr)
 int chsc(void *chsc_area)
 {
 	typedef struct { char _[4096]; } addr_type;
-	int cc;
+	int cc = -EIO;
 
 	asm volatile(
 		"	.insn	rre,0xb25f0000,%2,0\n"
-		"	ipm	%0\n"
+		"0:	ipm	%0\n"
 		"	srl	%0,28\n"
-		: "=d" (cc), "=m" (*(addr_type *) chsc_area)
+		"1:\n"
+		EX_TABLE(0b, 1b)
+		: "+d" (cc), "=m" (*(addr_type *) chsc_area)
 		: "d" (chsc_area), "m" (*(addr_type *) chsc_area)
 		: "cc");
 	trace_s390_cio_chsc(chsc_area, cc);