[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>

diff --git a/arch/s390/kernel/mcount.S b/arch/s390/kernel/mcount.S
index 397d131..8064122 100644 (file)
--- 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