ARM: uaccess: consolidate uaccess asm to asm/uaccess-asm.h

Consolidate the user access assembly code to asm/uaccess-asm.h.  This
moves the csdb, check_uaccess, uaccess_mask_range_ptr, uaccess_enable,
uaccess_disable, uaccess_save, uaccess_restore macros, and creates two
new ones for exception entry and exit - uaccess_entry and uaccess_exit.

This makes the uaccess_save and uaccess_restore macros private to
asm/uaccess-asm.h.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

arch/arm/kernel/entry-armv.S

@@ -27,6 +27,7 @@
 #include <asm/unistd.h>
 #include <asm/tls.h>
 #include <asm/system_info.h>
+#include <asm/uaccess-asm.h>
 
 #include "entry-header.S"
 #include <asm/entry-macro-multi.S>
@@ -179,15 +180,7 @@ ENDPROC(__und_invalid)
 	stmia	r7, {r2 - r6}
 
 	get_thread_info tsk
-	ldr	r0, [tsk, #TI_ADDR_LIMIT]
-	mov	r1, #TASK_SIZE
-	str	r1, [tsk, #TI_ADDR_LIMIT]
-	str	r0, [sp, #SVC_ADDR_LIMIT]
-
-	uaccess_save r0
-	.if \uaccess
-	uaccess_disable r0
-	.endif
+	uaccess_entry tsk, r0, r1, r2, \uaccess
 
 	.if \trace
 #ifdef CONFIG_TRACE_IRQFLAGS

arch/arm/kernel/entry-header.S

@@ -6,6 +6,7 @@
 #include <asm/asm-offsets.h>
 #include <asm/errno.h>
 #include <asm/thread_info.h>
+#include <asm/uaccess-asm.h>
 #include <asm/v7m.h>
 
 @ Bad Abort numbers
@@ -217,9 +218,7 @@
 	blne	trace_hardirqs_off
 #endif
 	.endif
-	ldr	r1, [sp, #SVC_ADDR_LIMIT]
-	uaccess_restore
-	str	r1, [tsk, #TI_ADDR_LIMIT]
+	uaccess_exit tsk, r0, r1
 
 #ifndef CONFIG_THUMB2_KERNEL
 	@ ARM mode SVC restore
@@ -263,9 +262,7 @@
 	@ on the stack remains correct).
 	@
 	.macro  svc_exit_via_fiq
-	ldr	r1, [sp, #SVC_ADDR_LIMIT]
-	uaccess_restore
-	str	r1, [tsk, #TI_ADDR_LIMIT]
+	uaccess_exit tsk, r0, r1
 #ifndef CONFIG_THUMB2_KERNEL
 	@ ARM mode restore
 	mov	r0, sp