s390: remove indirect branch from do_softirq_own_stack

BugLink: http://bugs.launchpad.net/bugs/1782846
commit 9f18fff63cfd6f559daa1eaae60640372c65f84b upstream.

The inline assembly to call __do_softirq on the irq stack uses
an indirect branch. This can be replaced with a normal relative
branch.

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>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/arch/s390/kernel/irq.c b/arch/s390/kernel/irq.c
index 94f2099bceb04cbfdc73d8f498a42e777a4b4e07..3d17c41074ca55d59fbe156c5967605912af9734 100644 (file)
--- a/arch/s390/kernel/irq.c
+++ b/arch/s390/kernel/irq.c
@@ -176,10 +176,9 @@ void do_softirq_own_stack(void)
                new -= STACK_FRAME_OVERHEAD;
                ((struct stack_frame *) new)->back_chain = old;
                asm volatile("   la    15,0(%0)\n"
-                            "   basr  14,%2\n"
+                            "   brasl 14,__do_softirq\n"
                             "   la    15,0(%1)\n"
-                            : : "a" (new), "a" (old),
-                                "a" (__do_softirq)
+                            : : "a" (new), "a" (old)
                             : "0", "1", "2", "3", "4", "5", "14",
                               "cc", "memory" );
        } else {