kcore: register module area in generic way

Some archs define MODULED_VADDR/MODULES_END which is not in VMALLOC area.
This is handled only in x86-64.  This patch make it more generic.  And we
can use vread/vwrite to access the area.  Fix it.
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Jiri Slaby <jirislaby@gmail.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/x86/mm/init_64.c

@@ -647,7 +647,7 @@ EXPORT_SYMBOL_GPL(memory_add_physaddr_to_nid);
 
 #endif /* CONFIG_MEMORY_HOTPLUG */
 
-static struct kcore_list kcore_modules, kcore_vsyscall;
+static struct kcore_list kcore_vsyscall;
 
 void __init mem_init(void)
 {
@@ -676,8 +676,6 @@ void __init mem_init(void)
 	initsize =  (unsigned long) &__init_end - (unsigned long) &__init_begin;
 
 	/* Register memory areas for /proc/kcore */
-	kclist_add(&kcore_modules, (void *)MODULES_VADDR, MODULES_LEN,
-			KCORE_OTHER);
 	kclist_add(&kcore_vsyscall, (void *)VSYSCALL_START,
 			 VSYSCALL_END - VSYSCALL_START, KCORE_OTHER);
 

fs/proc/kcore.c

@@ -490,7 +490,7 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos)
 		if (m == NULL) {
 			if (clear_user(buffer, tsz))
 				return -EFAULT;
-		} else if (is_vmalloc_addr((void *)start)) {
+		} else if (is_vmalloc_or_module_addr((void *)start)) {
 			char * elf_buf;
 
 			elf_buf = kzalloc(tsz, GFP_KERNEL);
@@ -586,6 +586,22 @@ static void __init proc_kcore_text_init(void)
 }
 #endif
 
+#if defined(CONFIG_MODULES) && defined(MODULES_VADDR)
+/*
+ * MODULES_VADDR has no intersection with VMALLOC_ADDR.
+ */
+struct kcore_list kcore_modules;
+static void __init add_modules_range(void)
+{
+	kclist_add(&kcore_modules, (void *)MODULES_VADDR,
+			MODULES_END - MODULES_VADDR, KCORE_VMALLOC);
+}
+#else
+static void __init add_modules_range(void)
+{
+}
+#endif
+
 static int __init proc_kcore_init(void)
 {
 	proc_root_kcore = proc_create("kcore", S_IRUSR, NULL,
@@ -595,6 +611,7 @@ static int __init proc_kcore_init(void)
 	/* Store vmalloc area */
 	kclist_add(&kcore_vmalloc, (void *)VMALLOC_START,
 		VMALLOC_END - VMALLOC_START, KCORE_VMALLOC);
+	add_modules_range();
 	/* Store direct-map area from physical memory map */
 	kcore_update_ram();
 	hotplug_memory_notifier(kcore_callback, 0);

include/linux/mm.h

@@ -285,6 +285,14 @@ static inline int is_vmalloc_addr(const void *x)
 	return 0;
 #endif
 }
+#ifdef CONFIG_MMU
+extern int is_vmalloc_or_module_addr(const void *x);
+#else
+static int is_vmalloc_or_module_addr(const void *x)
+{
+	return 0;
+}
+#endif
 
 static inline struct page *compound_head(struct page *page)
 {

mm/vmalloc.c

@@ -184,7 +184,7 @@ static int vmap_page_range(unsigned long start, unsigned long end,
 	return ret;
 }
 
-static inline int is_vmalloc_or_module_addr(const void *x)
+int is_vmalloc_or_module_addr(const void *x)
 {
 	/*
 	 * ARM, x86-64 and sparc64 put modules in a special place,