The patch below does not apply to the 4.16-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@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From 97489e0663fa700d6e7febddc43b58df98d7bcda Mon Sep 17 00:00:00 2001
From: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Date: Mon, 23 Apr 2018 14:31:36 +0200
Subject: [PATCH] s390/lib: use expoline for indirect branches
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@xxxxxxxxxxxxxxx # 4.16
Fixes: f19fbd5ed6 ("s390: introduce execute-trampolines for branches")
Reviewed-by: Hendrik Brueckner <brueckner@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
diff --git a/arch/s390/lib/mem.S b/arch/s390/lib/mem.S
index 495c9c4bacc7..2311f15be9cf 100644
--- a/arch/s390/lib/mem.S
+++ b/arch/s390/lib/mem.S
@@ -7,6 +7,9 @@
#include <linux/linkage.h>
#include <asm/export.h>
+#include <asm/nospec-insn.h>
+
+ GEN_BR_THUNK %r14
/*
* void *memmove(void *dest, const void *src, size_t n)
@@ -33,14 +36,14 @@ ENTRY(memmove)
.Lmemmove_forward_remainder:
larl %r5,.Lmemmove_mvc
ex %r4,0(%r5)
- br %r14
+ BR_EX %r14
.Lmemmove_reverse:
ic %r0,0(%r4,%r3)
stc %r0,0(%r4,%r1)
brctg %r4,.Lmemmove_reverse
ic %r0,0(%r4,%r3)
stc %r0,0(%r4,%r1)
- br %r14
+ BR_EX %r14
.Lmemmove_mvc:
mvc 0(1,%r1),0(%r3)
EXPORT_SYMBOL(memmove)
@@ -77,7 +80,7 @@ ENTRY(memset)
.Lmemset_clear_remainder:
larl %r3,.Lmemset_xc
ex %r4,0(%r3)
- br %r14
+ BR_EX %r14
.Lmemset_fill:
cghi %r4,1
lgr %r1,%r2
@@ -95,10 +98,10 @@ ENTRY(memset)
stc %r3,0(%r1)
larl %r5,.Lmemset_mvc
ex %r4,0(%r5)
- br %r14
+ BR_EX %r14
.Lmemset_fill_exit:
stc %r3,0(%r1)
- br %r14
+ BR_EX %r14
.Lmemset_xc:
xc 0(1,%r1),0(%r1)
.Lmemset_mvc:
@@ -121,7 +124,7 @@ ENTRY(memcpy)
.Lmemcpy_remainder:
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)
@@ -159,10 +162,10 @@ ENTRY(__memset\bits)
\insn %r3,0(%r1)
larl %r5,.L__memset_mvc\bits
ex %r4,0(%r5)
- br %r14
+ BR_EX %r14
.L__memset_exit\bits:
\insn %r3,0(%r2)
- br %r14
+ BR_EX %r14
.L__memset_mvc\bits:
mvc \bytes(1,%r1),0(%r1)
.endm
