kcore: register text area in generic way

Some 64bit arch has special segment for mapping kernel text.  It should be
entried to /proc/kcore in addtion to direct-linear-map, vmalloc area.
This patch unifies KCORE_TEXT entry scattered under x86 and ia64.

I'm not familiar with other archs (mips has its own even after this patch)
but range of [_stext ..._end) is a valid area of text and it's not in
direct-map area, defining CONFIG_ARCH_PROC_KCORE_TEXT is only a necessary
thing to do.

Note: I left mips as it is now.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: WANG Cong <xiyou.wangcong@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/ia64/mm/init.c

@@ -617,7 +617,7 @@ mem_init (void)
 	long reserved_pages, codesize, datasize, initsize;
 	pg_data_t *pgdat;
 	int i;
-	static struct kcore_list kcore_mem, kcore_kernel;
+	static struct kcore_list kcore_mem;
 
 	BUG_ON(PTRS_PER_PGD * sizeof(pgd_t) != PAGE_SIZE);
 	BUG_ON(PTRS_PER_PMD * sizeof(pmd_t) != PAGE_SIZE);
@@ -640,7 +640,6 @@ mem_init (void)
 	high_memory = __va(max_low_pfn * PAGE_SIZE);
 
 	kclist_add(&kcore_mem, __va(0), max_low_pfn * PAGE_SIZE, KCORE_RAM);
-	kclist_add(&kcore_kernel, _stext, _end - _stext, KCORE_TEXT);
 
 	for_each_online_pgdat(pgdat)
 		if (pgdat->bdata->node_bootmem_map)