releases/4.4.133/s390-remove-indirect-branch-from-do_softirq_own_stack.patch

   1 From 9f18fff63cfd6f559daa1eaae60640372c65f84b Mon Sep 17 00:00:00 2001
   2 From: Martin Schwidefsky <schwidefsky@de.ibm.com>
   3 Date: Tue, 24 Apr 2018 11:18:49 +0200
   4 Subject: s390: remove indirect branch from do_softirq_own_stack
   5
   6 From: Martin Schwidefsky <schwidefsky@de.ibm.com>
   7
   8 commit 9f18fff63cfd6f559daa1eaae60640372c65f84b upstream.
   9
  10 The inline assembly to call __do_softirq on the irq stack uses
  11 an indirect branch. This can be replaced with a normal relative
  12 branch.
  13
  14 Cc: stable@vger.kernel.org # 4.16
  15 Fixes: f19fbd5ed6 ("s390: introduce execute-trampolines for branches")
  16 Reviewed-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
  17 Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
  18 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  19
  20 ---
  21  arch/s390/kernel/irq.c |    5 ++---
  22  1 file changed, 2 insertions(+), 3 deletions(-)
  23
  24 --- a/arch/s390/kernel/irq.c
  25 +++ b/arch/s390/kernel/irq.c
  26 @@ -173,10 +173,9 @@ void do_softirq_own_stack(void)
  27                 new -= STACK_FRAME_OVERHEAD;
  28                 ((struct stack_frame *) new)->back_chain = old;
  29                 asm volatile("   la    15,0(%0)\n"
  30 -                            "   basr  14,%2\n"
  31 +                            "   brasl 14,__do_softirq\n"
  32                              "   la    15,0(%1)\n"
  33 -                            : : "a" (new), "a" (old),
  34 -                                "a" (__do_softirq)
  35 +                            : : "a" (new), "a" (old)
  36                              : "0", "1", "2", "3", "4", "5", "14",
  37                                "cc", "memory" );
  38         } else {