linux-kernel - [PATCH 4.9 74/78] s390/lib: use expoline for all bcr instructions

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Date:   Thu, 13 Sep 2018 15:32:01 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Heiko Carstens <heiko.carstens@...ibm.com>,
        Martin Schwidefsky <schwidefsky@...ibm.com>
Subject: [PATCH 4.9 74/78] s390/lib: use expoline for all bcr instructions

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Martin Schwidefsky <schwidefsky@...ibm.com>

commit 5eda25b10297684c1f46a14199ec00210f3c346e upstream.

The memove, memset, memcpy, __memset16, __memset32 and __memset64
function have an additional indirect return branch in form of a
"bzr" instruction. These need to use expolines as well.

Cc: <stable@...r.kernel.org> # v4.17+
Fixes: 97489e0663 ("s390/lib: use expoline for indirect branches")
Reviewed-by: Heiko Carstens <heiko.carstens@...ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@...ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>


---
 arch/s390/lib/mem.S |    9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

--- a/arch/s390/lib/mem.S
+++ b/arch/s390/lib/mem.S
@@ -27,7 +27,7 @@
  */
 ENTRY(memset)
 	ltgr	%r4,%r4
-	bzr	%r14
+	jz	.Lmemset_exit
 	ltgr	%r3,%r3
 	jnz	.Lmemset_fill
 	aghi	%r4,-1
@@ -42,12 +42,13 @@ ENTRY(memset)
 .Lmemset_clear_rest:
 	larl	%r3,.Lmemset_xc
 	ex	%r4,0(%r3)
+.Lmemset_exit:
 	BR_EX	%r14
 .Lmemset_fill:
 	stc	%r3,0(%r2)
 	cghi	%r4,1
 	lgr	%r1,%r2
-	ber	%r14
+	je	.Lmemset_fill_exit
 	aghi	%r4,-2
 	srlg	%r3,%r4,8
 	ltgr	%r3,%r3
@@ -59,6 +60,7 @@ ENTRY(memset)
 .Lmemset_fill_rest:
 	larl	%r3,.Lmemset_mvc
 	ex	%r4,0(%r3)
+.Lmemset_fill_exit:
 	BR_EX	%r14
 .Lmemset_xc:
 	xc	0(1,%r1),0(%r1)
@@ -73,7 +75,7 @@ EXPORT_SYMBOL(memset)
  */
 ENTRY(memcpy)
 	ltgr	%r4,%r4
-	bzr	%r14
+	jz	.Lmemcpy_exit
 	aghi	%r4,-1
 	srlg	%r5,%r4,8
 	ltgr	%r5,%r5
@@ -82,6 +84,7 @@ ENTRY(memcpy)
 .Lmemcpy_rest:
 	larl	%r5,.Lmemcpy_mvc
 	ex	%r4,0(%r5)
+.Lmemcpy_exit:
 	BR_EX	%r14
 .Lmemcpy_loop:
 	mvc	0(256,%r1),0(%r3)