x86: separate extable.h, switch sections.h to it

drivers/platform/x86/dell-smo8800.c is touched due to the following obscenity:
drivers/platform/x86/dell-smo8800.c ->
	linux/interrupt.h ->
		linux/hardirq.h ->
			asm/hardirq.h ->
				linux/irq.h ->
					asm/hw_irq.h ->
						asm/sections.h ->
							asm/uaccess.h
is the only chain of includes pulling asm/uaccess.h there.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

arch/x86/include/asm/extable.h

+#ifndef _ASM_X86_EXTABLE_H
+#define _ASM_X86_EXTABLE_H
+/*
+ * The exception table consists of triples of addresses relative to the
+ * exception table entry itself. The first address is of an instruction
+ * that is allowed to fault, the second is the target at which the program
+ * should continue. The third is a handler function to deal with the fault
+ * caused by the instruction in the first field.
+ *
+ * All the routines below use bits of fixup code that are out of line
+ * with the main instruction path.  This means when everything is well,
+ * we don't even have to jump over them.  Further, they do not intrude
+ * on our cache or tlb entries.
+ */
+
+struct exception_table_entry {
+	int insn, fixup, handler;
+};
+struct pt_regs;
+
+#define ARCH_HAS_RELATIVE_EXTABLE
+
+#define swap_ex_entry_fixup(a, b, tmp, delta)			\
+	do {							\
+		(a)->fixup = (b)->fixup + (delta);		\
+		(b)->fixup = (tmp).fixup - (delta);		\
+		(a)->handler = (b)->handler + (delta);		\
+		(b)->handler = (tmp).handler - (delta);		\
+	} while (0)
+
+extern int fixup_exception(struct pt_regs *regs, int trapnr);
+extern bool ex_has_fault_handler(unsigned long ip);
+extern void early_fixup_exception(struct pt_regs *regs, int trapnr);
+
+#endif

arch/x86/include/asm/sections.h

@@ -2,7 +2,7 @@
 #define _ASM_X86_SECTIONS_H
 
 #include <asm-generic/sections.h>
-#include <asm/uaccess.h>
+#include <asm/extable.h>
 
 extern char __brk_base[], __brk_limit[];
 extern struct exception_table_entry __stop___ex_table[];

arch/x86/include/asm/uaccess.h

@@ -11,6 +11,7 @@
 #include <asm/asm.h>
 #include <asm/page.h>
 #include <asm/smap.h>
+#include <asm/extable.h>
 
 #define VERIFY_READ 0
 #define VERIFY_WRITE 1
@@ -90,37 +91,6 @@ static inline bool __chk_range_not_ok(unsigned long addr, unsigned long size, un
 #define access_ok(type, addr, size) \
 	likely(!__range_not_ok(addr, size, user_addr_max()))
 
-/*
- * The exception table consists of triples of addresses relative to the
- * exception table entry itself. The first address is of an instruction
- * that is allowed to fault, the second is the target at which the program
- * should continue. The third is a handler function to deal with the fault
- * caused by the instruction in the first field.
- *
- * All the routines below use bits of fixup code that are out of line
- * with the main instruction path.  This means when everything is well,
- * we don't even have to jump over them.  Further, they do not intrude
- * on our cache or tlb entries.
- */
-
-struct exception_table_entry {
-	int insn, fixup, handler;
-};
-
-#define ARCH_HAS_RELATIVE_EXTABLE
-
-#define swap_ex_entry_fixup(a, b, tmp, delta)			\
-	do {							\
-		(a)->fixup = (b)->fixup + (delta);		\
-		(b)->fixup = (tmp).fixup - (delta);		\
-		(a)->handler = (b)->handler + (delta);		\
-		(b)->handler = (tmp).handler - (delta);		\
-	} while (0)
-
-extern int fixup_exception(struct pt_regs *regs, int trapnr);
-extern bool ex_has_fault_handler(unsigned long ip);
-extern void early_fixup_exception(struct pt_regs *regs, int trapnr);
-
 /*
  * These are the main single-value transfer routines.  They automatically
  * use the right size if we just have the right pointer type.

drivers/platform/x86/dell-smo8800.c

@@ -24,6 +24,7 @@
 #include <linux/acpi.h>
 #include <linux/interrupt.h>
 #include <linux/miscdevice.h>
+#include <linux/uaccess.h>
 
 struct smo8800_device {
 	u32 irq;                     /* acpi device irq */