[S390] Cleanup struct _lowcore usage and defines.

Use asm offsets to make sure the offset defines to struct _lowcore and
its layout don't get out of sync.
Also add a BUILD_BUG_ON() which checks that the size of the structure
is sane.
And while being at it change those sites which use odd casts to access
the current lowcore. These should use S390_lowcore instead.

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

1 files changed, 2 insertions, 4 deletions

diff --git a/arch/s390/kernel/ipl.c b/arch/s390/kernel/ipl.c
index 998bde3ec5ea..7eedbbcb54aa 100644
--- a/arch/s390/kernel/ipl.c
+++ b/arch/s390/kernel/ipl.c
@@ -1917,7 +1917,6 @@ void __init ipl_update_parameters(void)
 void __init ipl_save_parameters(void)
 {
         struct cio_iplinfo iplinfo;
-        unsigned int *ipl_ptr;
         void *src, *dst;
 
         if (cio_get_iplinfo(&iplinfo))
@@ -1928,11 +1927,10 @@ void __init ipl_save_parameters(void)
         if (!iplinfo.is_qdio)
                 return;
         ipl_flags |= IPL_PARMBLOCK_VALID;
-        ipl_ptr = (unsigned int *)__LC_IPL_PARMBLOCK_PTR;
-        src = (void *)(unsigned long)*ipl_ptr;
+        src = (void *)(unsigned long)S390_lowcore.ipl_parmblock_ptr;
         dst = (void *)IPL_PARMBLOCK_ORIGIN;
         memmove(dst, src, PAGE_SIZE);
-        *ipl_ptr = IPL_PARMBLOCK_ORIGIN;
+        S390_lowcore.ipl_parmblock_ptr = IPL_PARMBLOCK_ORIGIN;
 }
 
 static LIST_HEAD(rcall);