xtensa: consolidate kernel stack size related definitions

Define kernel stack size in kmem_layout and use it in
current_thread_info, GET_THREAD_INFO, THREAD_SIZE and THERAD_SIZE_ORDER
definitions.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

arch/xtensa/include/asm/current.h

@@ -11,6 +11,8 @@
 #ifndef _XTENSA_CURRENT_H
 #define _XTENSA_CURRENT_H
 
+#include <asm/thread_info.h>
+
 #ifndef __ASSEMBLY__
 
 #include <linux/thread_info.h>
@@ -26,8 +28,6 @@ static inline struct task_struct *get_current(void)
 
 #else
 
-#define CURRENT_SHIFT 13
-
 #define GET_CURRENT(reg,sp)		\
 	GET_THREAD_INFO(reg,sp);	\
 	l32i reg, reg, TI_TASK		\

arch/xtensa/include/asm/kmem_layout.h

@@ -71,4 +71,7 @@
 
 #endif
 
+#define KERNEL_STACK_SHIFT	13
+#define KERNEL_STACK_SIZE	(1 << KERNEL_STACK_SHIFT)
+
 #endif

arch/xtensa/include/asm/ptrace.h

@@ -10,6 +10,7 @@
 #ifndef _XTENSA_PTRACE_H
 #define _XTENSA_PTRACE_H
 
+#include <asm/kmem_layout.h>
 #include <uapi/asm/ptrace.h>
 
 /*
@@ -38,8 +39,6 @@
  *		+-----------------------+ --------
  */
 
-#define KERNEL_STACK_SIZE (2 * PAGE_SIZE)
-
 /*  Offsets for exception_handlers[] (3 x 64-entries x 4-byte tables). */
 
 #define EXC_TABLE_KSTK		0x004	/* Kernel Stack */

arch/xtensa/include/asm/thread_info.h

@@ -11,7 +11,9 @@
 #ifndef _XTENSA_THREAD_INFO_H
 #define _XTENSA_THREAD_INFO_H
 
-#ifdef __KERNEL__
+#include <asm/kmem_layout.h>
+
+#define CURRENT_SHIFT KERNEL_STACK_SHIFT
 
 #ifndef __ASSEMBLY__
 # include <asm/processor.h>
@@ -84,7 +86,7 @@ struct thread_info {
 static inline struct thread_info *current_thread_info(void)
 {
 	struct thread_info *ti;
-	 __asm__("extui %0,a1,0,13\n\t"
+	 __asm__("extui %0, a1, 0, "__stringify(CURRENT_SHIFT)"\n\t"
 	         "xor %0, a1, %0" : "=&r" (ti) : );
 	return ti;
 }
@@ -93,7 +95,7 @@ static inline struct thread_info *current_thread_info(void)
 
 /* how to get the thread information struct from ASM */
 #define GET_THREAD_INFO(reg,sp) \
-	extui reg, sp, 0, 13; \
+	extui reg, sp, 0, CURRENT_SHIFT; \
 	xor   reg, sp, reg
 #endif
 
@@ -130,8 +132,7 @@ static inline struct thread_info *current_thread_info(void)
  */
 #define TS_USEDFPU		0x0001	/* FPU was used by this task this quantum (SMP) */
 
-#define THREAD_SIZE 8192	//(2*PAGE_SIZE)
-#define THREAD_SIZE_ORDER 1
+#define THREAD_SIZE KERNEL_STACK_SIZE
+#define THREAD_SIZE_ORDER (KERNEL_STACK_SHIFT - PAGE_SHIFT)
 
-#endif	/* __KERNEL__ */
 #endif	/* _XTENSA_THREAD_INFO */