nds32: linker script: GCOV kernel may refers data in __exit

This patch is used to fix nds32 allmodconfig/allyesconfig build error
because GCOV kernel embeds counters in the kernel for each line
and a part of that embed in __exit text. So we need to keep the
EXIT_TEXT and EXIT_DATA  if CONFIG_GCOV_KERNEL=y.

Link: https://lkml.org/lkml/2018/9/1/125
Signed-off-by: Greentime Hu <greentime@andestech.com>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>

arch/nds32/kernel/vmlinux.lds.S

@@ -13,14 +13,26 @@ OUTPUT_ARCH(nds32)
 ENTRY(_stext_lma)
 jiffies = jiffies_64;
 
+#if defined(CONFIG_GCOV_KERNEL)
+#define NDS32_EXIT_KEEP(x)	x
+#else
+#define NDS32_EXIT_KEEP(x)
+#endif
+
 SECTIONS
 {
 	_stext_lma = TEXTADDR - LOAD_OFFSET;
 	. = TEXTADDR;
 	__init_begin = .;
 	HEAD_TEXT_SECTION
+	.exit.text : {
+		NDS32_EXIT_KEEP(EXIT_TEXT)
+	}
 	INIT_TEXT_SECTION(PAGE_SIZE)
 	INIT_DATA_SECTION(16)
+	.exit.data : {
+		NDS32_EXIT_KEEP(EXIT_DATA)
+	}
 	PERCPU_SECTION(L1_CACHE_BYTES)
 	__init_end = .;