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 be9fa65bfac4e16d1d71f5dc6ee3dcb7c9d69299..e7672edc284a7c49007503bd89006a6535c23500 100644 (file)
--- a/arch/s390/lib/mem.S
+++ b/arch/s390/lib/mem.S
@@ -6,6 +6,9 @@
 
 #include <linux/linkage.h>
 #include <asm/export.h>
+#include <asm/nospec-insn.h>
+
+       GEN_BR_THUNK %r14
 
 /*
  * memset implementation
@@ -39,7 +42,7 @@ 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
@@ -56,7 +59,7 @@ 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:
@@ -79,7 +82,7 @@ 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)