releases/4.14.44/s390-lib-use-expoline-for-indirect-branches.patch

   1 From foo@baz Wed May 23 19:38:57 CEST 2018
   2 From: Martin Schwidefsky <schwidefsky@de.ibm.com>
   3 Date: Wed, 23 May 2018 18:22:04 +0200
   4 Subject: s390/lib: use expoline for indirect branches
   5 To: stable@vger.kernel.org
   6 Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
   7 Message-ID: <1527092529-24383-5-git-send-email-schwidefsky@de.ibm.com>
   8
   9 From: Martin Schwidefsky <schwidefsky@de.ibm.com>
  10
  11 [ Upstream commit 97489e0663fa700d6e7febddc43b58df98d7bcda ]
  12
  13 The return from the memmove, memset, memcpy, __memset16, __memset32 and
  14 __memset64 functions are done with "br %r14". These are indirect branches
  15 as well and need to use execute trampolines for CONFIG_EXPOLINE=y.
  16
  17 Cc: stable@vger.kernel.org # 4.16
  18 Fixes: f19fbd5ed6 ("s390: introduce execute-trampolines for branches")
  19 Reviewed-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
  20 Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
  21 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  22 ---
  23  arch/s390/lib/mem.S |   13 ++++++++-----
  24  1 file changed, 8 insertions(+), 5 deletions(-)
  25
  26 --- a/arch/s390/lib/mem.S
  27 +++ b/arch/s390/lib/mem.S
  28 @@ -7,6 +7,9 @@
  29
  30  #include <linux/linkage.h>
  31  #include <asm/export.h>
  32 +#include <asm/nospec-insn.h>
  33 +
  34 +       GEN_BR_THUNK %r14
  35
  36  /*
  37   * void *memmove(void *dest, const void *src, size_t n)
  38 @@ -33,14 +36,14 @@ ENTRY(memmove)
  39  .Lmemmove_forward_remainder:
  40         larl    %r5,.Lmemmove_mvc
  41         ex      %r4,0(%r5)
  42 -       br      %r14
  43 +       BR_EX   %r14
  44  .Lmemmove_reverse:
  45         ic      %r0,0(%r4,%r3)
  46         stc     %r0,0(%r4,%r1)
  47         brctg   %r4,.Lmemmove_reverse
  48         ic      %r0,0(%r4,%r3)
  49         stc     %r0,0(%r4,%r1)
  50 -       br      %r14
  51 +       BR_EX   %r14
  52  .Lmemmove_mvc:
  53         mvc     0(1,%r1),0(%r3)
  54  EXPORT_SYMBOL(memmove)
  55 @@ -77,7 +80,7 @@ ENTRY(memset)
  56  .Lmemset_clear_remainder:
  57         larl    %r3,.Lmemset_xc
  58         ex      %r4,0(%r3)
  59 -       br      %r14
  60 +       BR_EX   %r14
  61  .Lmemset_fill:
  62         stc     %r3,0(%r2)
  63         cghi    %r4,1
  64 @@ -94,7 +97,7 @@ ENTRY(memset)
  65  .Lmemset_fill_remainder:
  66         larl    %r3,.Lmemset_mvc
  67         ex      %r4,0(%r3)
  68 -       br      %r14
  69 +       BR_EX   %r14
  70  .Lmemset_xc:
  71         xc      0(1,%r1),0(%r1)
  72  .Lmemset_mvc:
  73 @@ -117,7 +120,7 @@ ENTRY(memcpy)
  74  .Lmemcpy_remainder:
  75         larl    %r5,.Lmemcpy_mvc
  76         ex      %r4,0(%r5)
  77 -       br      %r14
  78 +       BR_EX   %r14
  79  .Lmemcpy_loop:
  80         mvc     0(256,%r1),0(%r3)
  81         la      %r1,256(%r1)