[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 7add8454773b3218ecb049a6253497261c0b23ee..db476d114caabd5c79b016110f503d507de2f312 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 b1a8ceb522b18ea9284844c14f951c9c8e939428..3ccd36b24b8f82b10efe7ccb37d92bf31bf9fb10 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