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 d66751397e721e7eee8a2ea117ab8d4c8549f248..e1fa974ac5005e7909996d9075fd30c13964cd8a 100644 (file)
--- 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:
        stc     %r3,0(%r2)
        cghi    %r4,1
@@ -94,7 +97,7 @@ ENTRY(memset)
 .Lmemset_fill_remainder:
        larl    %r3,.Lmemset_mvc
        ex      %r4,0(%r3)
-       br      %r14
+       BR_EX   %r14
 .Lmemset_xc:
        xc      0(1,%r1),0(%r1)
 .Lmemset_mvc:
@@ -117,7 +120,7 @@ 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)