[S390] ftrace/mcount: fix kernel stack backchain

With packed stack the backchain is at a different location.
Just use __SF_BACKCHAIN as an offset to store the backchain.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/arch/s390/kernel/mcount.S b/arch/s390/kernel/mcount.S
index 397d131a345f..80641224a095 100644
--- a/arch/s390/kernel/mcount.S
+++ b/arch/s390/kernel/mcount.S
@@ -5,6 +5,8 @@
  *
  */
 
+#include <asm/asm-offsets.h>
+
 #ifndef CONFIG_64BIT
 .globl _mcount
 _mcount:
@@ -14,7 +16,7 @@ _mcount:
         ahi     %r15,-96
         l       %r3,100(%r15)
         la      %r2,0(%r14)
-        st      %r1,0(%r15)
+        st      %r1,__SF_BACKCHAIN(%r15)
         la      %r3,0(%r3)
         bras    %r14,0f
         .long   ftrace_trace_function
@@ -38,7 +40,7 @@ _mcount:
         stg     %r14,112(%r15)
         lgr     %r1,%r15
         aghi    %r15,-160
-        stg     %r1,0(%r15)
+        stg     %r1,__SF_BACKCHAIN(%r15)
         lgr     %r2,%r14
         lg      %r3,168(%r15)
         larl    %r14,ftrace_trace_function