um: Create asm/sections.h

arch/um/kernel/dyn.lds.S and arch/um/kernel/uml.lds.S define some
UML-specific symbols. These symbols are used in the kernel part of UML
with extern declarations.

Move these declarations to a new header, asm/sections.h, like other
architectures do.

Signed-off-by: Nicolas Iooss <[e-mail]>
Signed-off-by: Richard Weinberger <[e-mail]>

arch/um/include/asm/Kbuild

···
 generic-y += percpu.h
 generic-y += preempt.h
 generic-y += scatterlist.h
-generic-y += sections.h
 generic-y += switch_to.h
 generic-y += topology.h
 generic-y += trace_clock.h

arch/um/include/asm/sections.h

···
+#ifndef __UM_SECTIONS_H
+#define __UM_SECTIONS_H
+
+#include <asm-generic/sections.h>
+
+extern char __binary_start;
+extern int __syscall_stub_start, __syscall_stub_end;
+
+#endif

arch/um/kernel/physmem.c

···
 #include <linux/mm.h>
 #include <linux/pfn.h>
 #include <asm/page.h>
+#include <asm/sections.h>
 #include <as-layout.h>
 #include <init.h>
 #include <kern.h>
···
 		      "err = %d\n", virt, fd, offset, len, r, w, x, err);
 	}
 }
-
-extern int __syscall_stub_start;
 
 /**
  * setup_physmem() - Setup physical memory for UML

arch/um/kernel/skas/mmu.c

···
 #include <linux/slab.h>
 #include <asm/pgalloc.h>
 #include <asm/pgtable.h>
+#include <asm/sections.h>
 #include <as-layout.h>
 #include <os.h>
 #include <skas.h>
-
-extern int __syscall_stub_start;
 
 static int init_stub_pte(struct mm_struct *mm, unsigned long proc,
 			 unsigned long kernel)

arch/um/kernel/um_arch.c

···
 
 #define MIN_VMALLOC (32 * 1024 * 1024)
 
-extern char __binary_start;
-
 int __init linux_main(int argc, char **argv)
 {
 	unsigned long avail, diff;