Date:	Wed, 22 Jul 2009 14:10:24 +0900
From:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>
Subject: [PATCH 3/4] kcore: build physical memory direct map information in
 proper way

From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>

For /proc/kcore, each arch registers its memory range by kclist_add().
In usual,
	- range of physical memory
	- range of vmalloc area
	- text, etc...
are registered but "range of physical memory" has some troubles.
It doesn't updated at memory hotplug and it tend to include
unnecessary memory holes. Now, /proc/iomem (kernel/resource.c)
includes required physical memory range information and it's
properly updated at memory hotplug. Then, it's good to avoid
using its own code(duplicating information) and to rebuild
kclist for physical memory based on /proc/iomem.

Note: walk_memory_resource() works based on lmb inforamtion in PPC
but no problem. It's updated at memory hotplug.

Changelog: v1 -> v2
 - removed -EBUSY at memory hotplug in read_kcore()
   (continue reading is no problem in general.)
 - fixed initial value of kcore_need_update to be 1.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
---
 arch/ia64/mm/init.c            |    1 
 arch/mips/mm/init.c            |    1 
 arch/powerpc/mm/init_32.c      |   24 ------
 arch/powerpc/mm/init_64.c      |   17 ----
 arch/sh/mm/init.c              |    1 
 arch/x86/mm/init_32.c          |    1 
 arch/x86/mm/init_64.c          |    1 
 fs/proc/kcore.c                |  151 ++++++++++++++++++++++++++++++++++++++---
 include/linux/ioport.h         |    8 ++
 include/linux/memory_hotplug.h |    7 -
 kernel/resource.c              |    2 
 11 files changed, 149 insertions(+), 65 deletions(-)

Index: mmotm-2.6.31-Jul16/fs/proc/kcore.c
===================================================================
--- mmotm-2.6.31-Jul16.orig/fs/proc/kcore.c
+++ mmotm-2.6.31-Jul16/fs/proc/kcore.c
@@ -21,6 +21,9 @@
 #include <asm/uaccess.h>
 #include <asm/io.h>
 #include <linux/list.h>
+#include <linux/ioport.h>
+#include <linux/memory_hotplug.h>
+#include <linux/memory.h>
 
 #define CORE_STR "CORE"
 
@@ -30,17 +33,6 @@
 
 static struct proc_dir_entry *proc_root_kcore;
 
-static int open_kcore(struct inode * inode, struct file * filp)
-{
-	return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
-}
-
-static ssize_t read_kcore(struct file *, char __user *, size_t, loff_t *);
-
-static const struct file_operations proc_kcore_operations = {
-	.read		= read_kcore,
-	.open		= open_kcore,
-};
 
 #ifndef kc_vaddr_to_offset
 #define	kc_vaddr_to_offset(v) ((v) - PAGE_OFFSET)
@@ -60,6 +52,7 @@ struct memelfnote
 
 static LIST_HEAD(kclist_head);
 static DEFINE_RWLOCK(kclist_lock);
+static int kcore_need_update = 1;
 
 void
 kclist_add(struct kcore_list *new, void *addr, size_t size, int type)
@@ -98,6 +91,104 @@ static size_t get_kcore_size(int *nphdr,
 	return size + *elf_buflen;
 }
 
+static void free_kclist_ents(struct list_head *head)
+{
+	struct kcore_list *tmp, *pos;
+
+	list_for_each_entry_safe(pos, tmp, head, list) {
+		list_del(&pos->list);
+		kfree(pos);
+	}
+}
+/*
+ * Replace all KCORE_RAM information with passed list.
+ */
+static void __kcore_update_ram(struct list_head *list)
+{
+	struct kcore_list *tmp, *pos;
+	LIST_HEAD(garbage);
+
+	write_lock(&kclist_lock);
+	if (kcore_need_update) {
+		list_for_each_entry_safe(pos, tmp, &kclist_head, list) {
+			if (pos->type == KCORE_RAM)
+				list_move(&pos->list, &garbage);
+		}
+		list_splice(list, &kclist_head);
+	} else
+		list_splice(list, &garbage);
+	kcore_need_update = 0;
+	write_unlock(&kclist_lock);
+
+	free_kclist_ents(&garbage);
+}
+
+
+#ifdef CONFIG_HIGHMEM
+/*
+ * If no highmem, we can assume [0...max_low_pfn) continuous range of memory
+ * because memory hole is not as big as !HIGHMEM case.
+ * (HIGHMEM is special because part of memory is _invisible_ from the kernel.)
+ */
+static int kcore_update_ram(void)
+{
+	LIST_HEAD(head);
+	struct kcore_list *ent;
+	int ret = 0;
+
+	ent = kmalloc(sizeof(*head), GFP_KERNEL);
+	if (!ent) {
+		ret = -ENOMEM;
+		goto unlock_out;
+	}
+	ent->addr = __va(0);
+	ent->size = max_low_pfn << PAGE_SHIFT;
+	ent->type = SYSTEM_RAM;
+	list_add(&ent->list, &head);
+	__kcore_update_ram(&head);
+	return ret;
+}
+
+#else /* !CONFIG_HIGHMEM */
+
+static int
+kclist_add_private(unsigned long pfn, unsigned long nr_pages, void *arg)
+{
+	struct list_head *head = (struct list_head *)arg;
+	struct kcore_list *ent;
+
+	ent = kmalloc(sizeof(*ent), GFP_KERNEL);
+	if (!ent)
+		return -ENOMEM;
+	ent->addr = (unsigned long)__va((pfn << PAGE_SHIFT));
+	ent->size = nr_pages << PAGE_SHIFT;
+	ent->type = KCORE_RAM;
+	list_add(&ent->list, head);
+	return 0;
+}
+
+static int kcore_update_ram(void)
+{
+	int nid, ret;
+	unsigned long end_pfn;
+	LIST_HEAD(head);
+
+	/* Not inialized....update now */
+	/* find out "max pfn" */
+	end_pfn = 0;
+	for_each_node_state(nid, N_HIGH_MEMORY)
+		if (end_pfn < node_end_pfn(nid))
+			end_pfn = node_end_pfn(nid);
+	/* scan 0 to max_pfn */
+	ret = walk_memory_resource(0, end_pfn, &head, kclist_add_private);
+	if (ret) {
+		free_kclist_ents(&head);
+		return -ENOMEM;
+	}
+	__kcore_update_ram(&head);
+	return ret;
+}
+#endif /* CONFIG_HIGH_MEM */
 
 /*****************************************************************************/
 /*
@@ -271,6 +362,11 @@ read_kcore(struct file *file, char __use
 		read_unlock(&kclist_lock);
 		return 0;
 	}
+	/* memory hotplug ?? */
+	if (kcore_need_update) {
+		read_unlock(&kclist_lock);
+		return -EBUSY;
+	}
 
 	/* trim buflen to not go beyond EOF */
 	if (buflen > size - *fpos)
@@ -406,9 +502,42 @@ read_kcore(struct file *file, char __use
 	return acc;
 }
 
+static int open_kcore(struct inode * inode, struct file *filp)
+{
+	if (!capable(CAP_SYS_RAWIO))
+		return -EPERM;
+	if (kcore_need_update)
+		kcore_update_ram();
+	return 0;
+}
+
+
+static const struct file_operations proc_kcore_operations = {
+	.read		= read_kcore,
+	.open		= open_kcore,
+};
+
+/* just remember that we have to update kcore */
+static int __meminit kcore_callback(struct notifier_block *self,
+				    unsigned long action, void *arg)
+{
+	switch (action) {
+	case MEM_ONLINE:
+	case MEM_OFFLINE:
+		write_lock(&kclist_lock);
+		kcore_need_update = 1;
+		write_unlock(&kclist_lock);
+	}
+	return NOTIFY_OK;
+}
+
+
 static int __init proc_kcore_init(void)
 {
 	proc_root_kcore = proc_create("kcore", S_IRUSR, NULL, &proc_kcore_operations);
+	kcore_update_ram();
+	hotplug_memory_notifier(kcore_callback, 0);
 	return 0;
 }
 module_init(proc_kcore_init);
+
Index: mmotm-2.6.31-Jul16/include/linux/ioport.h
===================================================================
--- mmotm-2.6.31-Jul16.orig/include/linux/ioport.h
+++ mmotm-2.6.31-Jul16/include/linux/ioport.h
@@ -186,5 +186,13 @@ extern void __devm_release_region(struct
 extern int iomem_map_sanity_check(resource_size_t addr, unsigned long size);
 extern int iomem_is_exclusive(u64 addr);
 
+/*
+ * Walk through all SYSTEM_RAM which is registered as resource.
+ * arg is (start_pfn, nr_pages, private_arg_pointer)
+ */
+extern int walk_memory_resource(unsigned long start_pfn,
+			unsigned long nr_pages, void *arg,
+			int (*func)(unsigned long, unsigned long, void *));
+
 #endif /* __ASSEMBLY__ */
 #endif	/* _LINUX_IOPORT_H */
Index: mmotm-2.6.31-Jul16/include/linux/memory_hotplug.h
===================================================================
--- mmotm-2.6.31-Jul16.orig/include/linux/memory_hotplug.h
+++ mmotm-2.6.31-Jul16/include/linux/memory_hotplug.h
@@ -191,13 +191,6 @@ static inline void register_page_bootmem
 
 #endif /* ! CONFIG_MEMORY_HOTPLUG */
 
-/*
- * Walk through all memory which is registered as resource.
- * arg is (start_pfn, nr_pages, private_arg_pointer)
- */
-extern int walk_memory_resource(unsigned long start_pfn,
-			unsigned long nr_pages, void *arg,
-			int (*func)(unsigned long, unsigned long, void *));
 
 #ifdef CONFIG_MEMORY_HOTREMOVE
 
Index: mmotm-2.6.31-Jul16/kernel/resource.c
===================================================================
--- mmotm-2.6.31-Jul16.orig/kernel/resource.c
+++ mmotm-2.6.31-Jul16/kernel/resource.c
@@ -234,7 +234,7 @@ int release_resource(struct resource *ol
 
 EXPORT_SYMBOL(release_resource);
 
-#if defined(CONFIG_MEMORY_HOTPLUG) && !defined(CONFIG_ARCH_HAS_WALK_MEMORY)
+#if !defined(CONFIG_ARCH_HAS_WALK_MEMORY)
 /*
  * Finds the lowest memory reosurce exists within [res->start.res->end)
  * the caller must specify res->start, res->end, res->flags.
Index: mmotm-2.6.31-Jul16/arch/ia64/mm/init.c
===================================================================
--- mmotm-2.6.31-Jul16.orig/arch/ia64/mm/init.c
+++ mmotm-2.6.31-Jul16/arch/ia64/mm/init.c
@@ -639,7 +639,6 @@ 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_vmem, (void *)VMALLOC_START,
 			VMALLOC_END-VMALLOC_START, KCORE_VMALLOC);
 	kclist_add(&kcore_kernel, _stext, _end - _stext, KCORE_TEXT);
Index: mmotm-2.6.31-Jul16/arch/mips/mm/init.c
===================================================================
--- mmotm-2.6.31-Jul16.orig/arch/mips/mm/init.c
+++ mmotm-2.6.31-Jul16/arch/mips/mm/init.c
@@ -412,7 +412,6 @@ void __init mem_init(void)
 		kclist_add(&kcore_kseg0, (void *) CKSEG0,
 				0x80000000 - 4, KCORE_TEXT);
 #endif
-	kclist_add(&kcore_mem, __va(0), max_low_pfn << PAGE_SHIFT, KCORE_RAM);
 	kclist_add(&kcore_vmalloc, (void *)VMALLOC_START,
 		   VMALLOC_END-VMALLOC_START, KCORE_VMALLOC);
 
Index: mmotm-2.6.31-Jul16/arch/powerpc/mm/init_32.c
===================================================================
--- mmotm-2.6.31-Jul16.orig/arch/powerpc/mm/init_32.c
+++ mmotm-2.6.31-Jul16/arch/powerpc/mm/init_32.c
@@ -249,30 +249,6 @@ static struct kcore_list kcore_vmem;
 
 static int __init setup_kcore(void)
 {
-	int i;
-
-	for (i = 0; i < lmb.memory.cnt; i++) {
-		unsigned long base;
-		unsigned long size;
-		struct kcore_list *kcore_mem;
-
-		base = lmb.memory.region[i].base;
-		size = lmb.memory.region[i].size;
-
-		kcore_mem = kmalloc(sizeof(struct kcore_list), GFP_ATOMIC);
-		if (!kcore_mem)
-			panic("%s: kmalloc failed\n", __func__);
-
-		/* must stay under 32 bits */
-		if ( 0xfffffffful - (unsigned long)__va(base) < size) {
-			size = 0xfffffffful - (unsigned long)(__va(base));
-			printk(KERN_DEBUG "setup_kcore: restrict size=%lx\n",
-						size);
-		}
-
-		kclist_add(kcore_mem, __va(base), size, KCORE_RAM);
-	}
-
 	kclist_add(&kcore_vmem, (void *)VMALLOC_START,
 		VMALLOC_END-VMALLOC_START, KCORE_VMALLOC);
 
Index: mmotm-2.6.31-Jul16/arch/powerpc/mm/init_64.c
===================================================================
--- mmotm-2.6.31-Jul16.orig/arch/powerpc/mm/init_64.c
+++ mmotm-2.6.31-Jul16/arch/powerpc/mm/init_64.c
@@ -114,23 +114,6 @@ static struct kcore_list kcore_vmem;
 
 static int __init setup_kcore(void)
 {
-	int i;
-
-	for (i=0; i < lmb.memory.cnt; i++) {
-		unsigned long base, size;
-		struct kcore_list *kcore_mem;
-
-		base = lmb.memory.region[i].base;
-		size = lmb.memory.region[i].size;
-
-		/* GFP_ATOMIC to avoid might_sleep warnings during boot */
-		kcore_mem = kmalloc(sizeof(struct kcore_list), GFP_ATOMIC);
-		if (!kcore_mem)
-			panic("%s: kmalloc failed\n", __func__);
-
-		kclist_add(kcore_mem, __va(base), size, KCORE_RAM);
-	}
-
 	kclist_add(&kcore_vmem, (void *)VMALLOC_START,
 		VMALLOC_END-VMALLOC_START, KCORE_VMALLOC);
 
Index: mmotm-2.6.31-Jul16/arch/sh/mm/init.c
===================================================================
--- mmotm-2.6.31-Jul16.orig/arch/sh/mm/init.c
+++ mmotm-2.6.31-Jul16/arch/sh/mm/init.c
@@ -218,7 +218,6 @@ void __init mem_init(void)
 	datasize =  (unsigned long) &_edata - (unsigned long) &_etext;
 	initsize =  (unsigned long) &__init_end - (unsigned long) &__init_begin;
 
-	kclist_add(&kcore_mem, __va(0), max_low_pfn << PAGE_SHIFT, KCORE_RAM);
 	kclist_add(&kcore_vmalloc, (void *)VMALLOC_START,
 		   VMALLOC_END - VMALLOC_START, KCORE_VMALLOC);
 
Index: mmotm-2.6.31-Jul16/arch/x86/mm/init_32.c
===================================================================
--- mmotm-2.6.31-Jul16.orig/arch/x86/mm/init_32.c
+++ mmotm-2.6.31-Jul16/arch/x86/mm/init_32.c
@@ -886,7 +886,6 @@ void __init mem_init(void)
 	datasize =  (unsigned long) &_edata - (unsigned long) &_etext;
 	initsize =  (unsigned long) &__init_end - (unsigned long) &__init_begin;
 
-	kclist_add(&kcore_mem, __va(0), max_low_pfn << PAGE_SHIFT, KCORE_RAM);
 	kclist_add(&kcore_vmalloc, (void *)VMALLOC_START,
 		   VMALLOC_END-VMALLOC_START, KCORE_VMALLOC);
 
Index: mmotm-2.6.31-Jul16/arch/x86/mm/init_64.c
===================================================================
--- mmotm-2.6.31-Jul16.orig/arch/x86/mm/init_64.c
+++ mmotm-2.6.31-Jul16/arch/x86/mm/init_64.c
@@ -677,7 +677,6 @@ void __init mem_init(void)
 	initsize =  (unsigned long) &__init_end - (unsigned long) &__init_begin;
 
 	/* Register memory areas for /proc/kcore */
-	kclist_add(&kcore_mem, __va(0), max_low_pfn << PAGE_SHIFT, KCORE_RAM);
 	kclist_add(&kcore_vmalloc, (void *)VMALLOC_START,
 		   VMALLOC_END-VMALLOC_START, KCORE_VMALLOC);
 	kclist_add(&kcore_kernel, &_stext, _end - _stext, KCORE_TEXT);

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