From: Martin Schwidefsky <schwidefsky@de.ibm.com>
Date: Wed, 23 May 2018 16:21:30 +0000 (+0200)
Subject: s390/lib: use expoline for indirect branches
X-Git-Tag: v4.4.133~14
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5ce9dc0f76519ac7ef2d861172ae280fc9d6c3e2;p=thirdparty%2Fkernel%2Fstable.git

s390/lib: use expoline for indirect branches

[ Upstream commit 97489e0663fa700d6e7febddc43b58df98d7bcda ]

The return from the memmove, memset, memcpy, __memset16, __memset32 and
__memset64 functions are done with "br %r14". These are indirect branches
as well and need to use execute trampolines for CONFIG_EXPOLINE=y.

Cc: stable@vger.kernel.org # 4.16
Fixes: f19fbd5ed6 ("s390: introduce execute-trampolines for branches")
Reviewed-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/arch/s390/lib/mem.S b/arch/s390/lib/mem.S
index c6d553e85ab11..16c5998b97922 100644
--- a/arch/s390/lib/mem.S
+++ b/arch/s390/lib/mem.S
@@ -5,6 +5,9 @@
  */
 
 #include <linux/linkage.h>
+#include <asm/nospec-insn.h>
+
+	GEN_BR_THUNK %r14
 
 /*
  * memset implementation
@@ -38,7 +41,7 @@ ENTRY(memset)
 .Lmemset_clear_rest:
 	larl	%r3,.Lmemset_xc
 	ex	%r4,0(%r3)
-	br	%r14
+	BR_EX	%r14
 .Lmemset_fill:
 	stc	%r3,0(%r2)
 	cghi	%r4,1
@@ -55,7 +58,7 @@ ENTRY(memset)
 .Lmemset_fill_rest:
 	larl	%r3,.Lmemset_mvc
 	ex	%r4,0(%r3)
-	br	%r14
+	BR_EX	%r14
 .Lmemset_xc:
 	xc	0(1,%r1),0(%r1)
 .Lmemset_mvc:
@@ -77,7 +80,7 @@ ENTRY(memcpy)
 .Lmemcpy_rest:
 	larl	%r5,.Lmemcpy_mvc
 	ex	%r4,0(%r5)
-	br	%r14
+	BR_EX	%r14
 .Lmemcpy_loop:
 	mvc	0(256,%r1),0(%r3)
 	la	%r1,256(%r1)