[S390] nss: Free unused memory in kernel image.

With CONFIG_SHARED_KERNEL the kernel text segment that might be in a
read only memory sections starts at 1MB. Memory between 0x12000 and
0x100000 is unused then. Free this, so we have appr. an extra MB
of memory available.

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

arch/s390/kernel/head31.S

@@ -148,20 +148,9 @@ startup_continue:
 .Lstartup_init:
 	    .long startup_init
 
-	.globl ipl_schib
-ipl_schib:
-	.rept 13
-	.long 0
-	.endr
-
-	.globl ipl_flags
-ipl_flags:
-	.long 0
-	.globl ipl_devno
-ipl_devno:
-	.word 0
-
 	.org	0x12000
+	.globl	_ehead
+_ehead:
 #ifdef CONFIG_SHARED_KERNEL
 	.org	0x100000
 #endif

arch/s390/kernel/head64.S

@@ -154,21 +154,9 @@ startup_continue:
 .Lparmaddr:
 	.quad	PARMAREA
 
-	.globl	ipl_schib
-ipl_schib:
-	.rept 13
-	.long 0
-	.endr
-
-	.globl	ipl_flags
-ipl_flags:
-	.long	0
-	.globl	ipl_devno
-ipl_devno:
-	.word 0
-
 	.org	0x12000
-
+	.globl	_ehead
+_ehead:
 #ifdef CONFIG_SHARED_KERNEL
 	.org	0x100000
 #endif

arch/s390/kernel/ipl.c

@@ -43,6 +43,13 @@ enum ipl_type {
 #define IPL_FCP_STR	 "fcp"
 #define IPL_NSS_STR	 "nss"
 
+/*
+ * Must be in data section since the bss section
+ * is not cleared when these are accessed.
+ */
+u16 ipl_devno __attribute__((__section__(".data"))) = 0;
+u32 ipl_flags __attribute__((__section__(".data"))) = 0;
+
 static char *ipl_type_str(enum ipl_type type)
 {
 	switch (type) {

arch/s390/kernel/setup.c

@@ -690,8 +690,13 @@ setup_memory(void)
 	psw_set_key(PAGE_DEFAULT_KEY);
 
 	free_bootmem_with_active_regions(0, max_pfn);
-	reserve_bootmem(0, PFN_PHYS(start_pfn));
 
+	/*
+	 * Reserve memory used for lowcore/command line/kernel image.
+	 */
+	reserve_bootmem(0, (unsigned long)_ehead);
+	reserve_bootmem((unsigned long)_stext,
+			PFN_PHYS(start_pfn) - (unsigned long)_stext);
 	/*
 	 * Reserve the bootmem bitmap itself as well. We do this in two
 	 * steps (first step was init_bootmem()) because this catches

drivers/s390/cio/cio.c

@@ -1048,7 +1048,7 @@ void reipl_ccw_dev(struct ccw_dev_id *devid)
 	do_reipl_asm(*((__u32*)&schid));
 }
 
-extern struct schib ipl_schib;
+static struct schib __initdata ipl_schib;
 
 /*
  * ipl_save_parameters gets called very early. It is not allowed to access

include/asm-s390/sections.h

@@ -3,6 +3,6 @@
 
 #include <asm-generic/sections.h>
 
-extern char _eshared[];
+extern char _eshared[], _ehead[];
 
 #endif