[PATCH] vmlinux.lds: add missing VMLINUX_SYMBOL macros

[Jessica]

From: Jessica Yu <jeyu@xxxxxxxxxx>

When __{start,end}_ro_after_init is referenced from C code, we run into the
following build errors on blackfin:

  kernel/extable.c:169: undefined reference to `__start_ro_after_init'
  kernel/extable.c:169: undefined reference to `__end_ro_after_init'

The build error is due to the fact that blackfin is one of the few arches
that prepends an underscore '_' to all symbols defined in C. Fix this by
wrapping __{start,end}_ro_after_init in vmlinux.lds.h with VMLINUX_SYMBOL(),
which adds the necessary prefix for arches that have HAVE_UNDERSCORE_SYMBOL_PREFIX.

Signed-off-by: Jessica Yu <jeyu@xxxxxxxxxx>
---
This patch is based on next-20170403.

 include/asm-generic/vmlinux.lds.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index 979b573..54918ae 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -261,9 +261,9 @@
  */
 #ifndef RO_AFTER_INIT_DATA
 #define RO_AFTER_INIT_DATA						\
-	__start_ro_after_init = .;					\
+	VMLINUX_SYMBOL(__start_ro_after_init) = .;			\
 	*(.data..ro_after_init)						\
-	__end_ro_after_init = .;
+	VMLINUX_SYMBOL(__end_ro_after_init) = .;
 #endif
 
 /*
-- 
2.5.5