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>

arch/ia64/Kconfig

@@ -500,6 +500,10 @@ config HAVE_ARCH_NODEDATA_EXTENSION
 	def_bool y
 	depends on NUMA
 
+config ARCH_PROC_KCORE_TEXT
+	def_bool y
+	depends on PROC_KCORE
+
 config IA32_SUPPORT
 	bool "Support for Linux/x86 binaries"
 	help

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)

arch/x86/Kconfig

@@ -1223,6 +1223,10 @@ config ARCH_MEMORY_PROBE
 	def_bool X86_64
 	depends on MEMORY_HOTPLUG
 
+config ARCH_PROC_KCORE_TEXT
+	def_bool y
+	depends on X86_64 && PROC_KCORE
+
 config ILLEGAL_POINTER_VALUE
        hex
        default 0 if X86_32

arch/x86/mm/init_64.c

@@ -647,8 +647,7 @@ EXPORT_SYMBOL_GPL(memory_add_physaddr_to_nid);
 
 #endif /* CONFIG_MEMORY_HOTPLUG */
 
-static struct kcore_list kcore_mem, kcore_kernel,
-			 kcore_modules, kcore_vsyscall;
+static struct kcore_list kcore_mem, kcore_modules, kcore_vsyscall;
 
 void __init mem_init(void)
 {
@@ -678,7 +677,6 @@ void __init mem_init(void)
 
 	/* Register memory areas for /proc/kcore */
 	kclist_add(&kcore_mem, __va(0), max_low_pfn << PAGE_SHIFT, KCORE_RAM);
-	kclist_add(&kcore_kernel, &_stext, _end - _stext, KCORE_TEXT);
 	kclist_add(&kcore_modules, (void *)MODULES_VADDR, MODULES_LEN,
 			KCORE_OTHER);
 	kclist_add(&kcore_vsyscall, (void *)VSYSCALL_START,

fs/proc/kcore.c

@@ -21,6 +21,7 @@
 #include <asm/uaccess.h>
 #include <asm/io.h>
 #include <linux/list.h>
+#include <asm/sections.h>
 
 #define CORE_STR "CORE"
 
@@ -374,10 +375,26 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos)
 
 static struct kcore_list kcore_vmalloc;
 
+#ifdef CONFIG_ARCH_PROC_KCORE_TEXT
+static struct kcore_list kcore_text;
+/*
+ * If defined, special segment is used for mapping kernel text instead of
+ * direct-map area. We need to create special TEXT section.
+ */
+static void __init proc_kcore_text_init(void)
+{
+	kclist_add(&kcore_text, _stext, _end - _stext, KCORE_TEXT);
+}
+#else
+static void __init proc_kcore_text_init(void)
+{
+}
+#endif
+
 static int __init proc_kcore_init(void)
 {
 	proc_root_kcore = proc_create("kcore", S_IRUSR, NULL, &proc_kcore_operations);
-
+	proc_kcore_text_init();
 	kclist_add(&kcore_vmalloc, (void *)VMALLOC_START,
 		VMALLOC_END - VMALLOC_START, KCORE_VMALLOC);
 	return 0;