[S390] Remove initial kernel stack backchain initialization.

Early init code clears the backchain of the initial kernel stack frame.
This is not necessary since it is pre initialized with zeros. Plus it
was broken on 64 bit since it cleared only four of eight bytes.

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/head31.S b/arch/s390/kernel/head31.S
index 7add845..db476d1 100644 (file)
--- a/arch/s390/kernel/head31.S
+++ b/arch/s390/kernel/head31.S
@@ -29,7 +29,6 @@ startup_continue:
        ahi     %r15,1<<(PAGE_SHIFT+THREAD_ORDER) # init_task_union+THREAD_SIZE
        st      %r15,__LC_KERNEL_STACK  # set end of kernel stack
        ahi     %r15,-96
-       xc      __SF_BACKCHAIN(4,%r15),__SF_BACKCHAIN(%r15) # clear backchain
 #
 # Save ipl parameters, clear bss memory, initialize storage key for kernel pages,
 # and create a kernel NSS if the SAVESYS= parm is defined

diff --git a/arch/s390/kernel/head64.S b/arch/s390/kernel/head64.S
index b1a8ceb..3ccd36b 100644 (file)
--- a/arch/s390/kernel/head64.S
+++ b/arch/s390/kernel/head64.S
@@ -96,7 +96,6 @@ startup_continue:
        aghi    %r15,1<<(PAGE_SHIFT+THREAD_ORDER) # init_task_union + THREAD_SIZE
        stg     %r15,__LC_KERNEL_STACK  # set end of kernel stack
        aghi    %r15,-160
-       xc      __SF_BACKCHAIN(4,%r15),__SF_BACKCHAIN(%r15) # clear backchain
 #
 # Save ipl parameters, clear bss memory, initialize storage key for kernel pages,
 # and create a kernel NSS if the SAVESYS= parm is defined