s390/stack: use STACK_INIT_OFFSET where possible

Make STACK_INIT_OFFSET also available for assembler code, and
use it everywhere instead of open-coding it at several places.
Reviewed-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

arch/s390/include/asm/thread_info.h

@@ -9,6 +9,9 @@
 #define _ASM_THREAD_INFO_H
 
 #include <linux/bits.h>
+#ifndef ASM_OFFSETS_C
+#include <asm/asm-offsets.h>
+#endif
 
 /*
  * General size of kernel stacks
@@ -21,13 +24,12 @@
 #define BOOT_STACK_SIZE (PAGE_SIZE << 2)
 #define THREAD_SIZE (PAGE_SIZE << THREAD_SIZE_ORDER)
 
+#define STACK_INIT_OFFSET (THREAD_SIZE - STACK_FRAME_OVERHEAD - __PT_SIZE)
+
 #ifndef __ASSEMBLY__
 #include <asm/lowcore.h>
 #include <asm/page.h>
 
-#define STACK_INIT_OFFSET \
-	(THREAD_SIZE - STACK_FRAME_OVERHEAD - sizeof(struct pt_regs))
-
 /*
  * low level task data that entry.S needs immediate access to
  * - this struct should fit entirely inside of one cache line

arch/s390/kernel/entry.S

@@ -29,10 +29,6 @@
 #include <asm/export.h>
 #include <asm/nospec-insn.h>
 
-STACK_SHIFT = PAGE_SHIFT + THREAD_SIZE_ORDER
-STACK_SIZE  = 1 << STACK_SHIFT
-STACK_INIT = STACK_SIZE - STACK_FRAME_OVERHEAD - __PT_SIZE
-
 _LPP_OFFSET	= __LC_LPP
 
 	.macro STBEAR address
@@ -53,7 +49,7 @@ _LPP_OFFSET	= __LC_LPP
 
 	.macro	CHECK_STACK savearea
 #ifdef CONFIG_CHECK_STACK
-	tml	%r15,STACK_SIZE - CONFIG_STACK_GUARD
+	tml	%r15,THREAD_SIZE - CONFIG_STACK_GUARD
 	lghi	%r14,\savearea
 	jz	stack_overflow
 #endif
@@ -62,8 +58,8 @@ _LPP_OFFSET	= __LC_LPP
 	.macro	CHECK_VMAP_STACK savearea,oklabel
 #ifdef CONFIG_VMAP_STACK
 	lgr	%r14,%r15
-	nill	%r14,0x10000 - STACK_SIZE
-	oill	%r14,STACK_INIT
+	nill	%r14,0x10000 - THREAD_SIZE
+	oill	%r14,STACK_INIT_OFFSET
 	clg	%r14,__LC_KERNEL_STACK
 	je	\oklabel
 	clg	%r14,__LC_ASYNC_STACK
@@ -179,7 +175,7 @@ ENTRY(__switch_to)
 	stmg	%r6,%r15,__SF_GPRS(%r15)	# store gprs of prev task
 	lghi	%r4,__TASK_stack
 	lghi	%r1,__TASK_thread
-	llill	%r5,STACK_INIT
+	llill	%r5,STACK_INIT_OFFSET
 	stg	%r15,__THREAD_ksp(%r1,%r2)	# store kernel stack of prev
 	lg	%r15,0(%r4,%r3)			# start of kernel stack of next
 	agr	%r15,%r5			# end of kernel stack of next

arch/s390/kernel/head64.S

@@ -24,7 +24,7 @@ ENTRY(startup_continue)
 #
 	larl	%r14,init_task
 	stg	%r14,__LC_CURRENT
-	larl	%r15,init_thread_union+THREAD_SIZE-STACK_FRAME_OVERHEAD-__PT_SIZE
+	larl	%r15,init_thread_union+STACK_INIT_OFFSET
 	brasl	%r14,sclp_early_adjust_va	# allow sclp_early_printk
 	brasl	%r14,startup_init		# s390 specific early init
 	brasl	%r14,start_kernel		# common init code

arch/s390/kernel/setup.c

@@ -436,8 +436,7 @@ static void __init setup_lowcore(void)
 	lc->io_new_psw.mask = PSW_KERNEL_BITS | PSW_MASK_MCHECK;
 	lc->io_new_psw.addr = (unsigned long) io_int_handler;
 	lc->clock_comparator = clock_comparator_max;
-	lc->nodat_stack = ((unsigned long) &init_thread_union)
-		+ THREAD_SIZE - STACK_FRAME_OVERHEAD - sizeof(struct pt_regs);
+	lc->nodat_stack = ((unsigned long)&init_thread_union) + STACK_INIT_OFFSET;
 	lc->current_task = (unsigned long)&init_task;
 	lc->lpp = LPP_MAGIC;
 	lc->machine_flags = S390_lowcore.machine_flags;

arch/s390/kernel/smp.c

@@ -280,9 +280,8 @@ static void pcpu_attach_task(struct pcpu *pcpu, struct task_struct *tsk)
 
 	cpu = pcpu - pcpu_devices;
 	lc = lowcore_ptr[cpu];
-	lc->kernel_stack = (unsigned long) task_stack_page(tsk)
-		+ THREAD_SIZE - STACK_FRAME_OVERHEAD - sizeof(struct pt_regs);
-	lc->current_task = (unsigned long) tsk;
+	lc->kernel_stack = (unsigned long)task_stack_page(tsk) + STACK_INIT_OFFSET;
+	lc->current_task = (unsigned long)tsk;
 	lc->lpp = LPP_MAGIC;
 	lc->current_pid = tsk->pid;
 	lc->user_timer = tsk->thread.user_timer;