[patch 5/6] export efi runtime memory mapping to sysfs

[dyoung]

kexec kernel will need exactly same mapping for
efi runtime memory ranges. Thus here export the
runtime ranges mapping to sysfs, kexec-tools
will assemble them and pass to 2nd kernel via
setup_data.

Introducing a new directly /sys/firmware/efi/efi-runtime-map
Just like /sys/firmware/memmap. Containing below attribute
in each file of that directory:
attribute  num_pages  phys_addr  type  virt_addr

It will not work for efi 32bit. Only x86_64 currently.

Signed-off-by: Dave Young <dyoung@xxxxxxxxxx>
---
 arch/x86/include/asm/efi.h             |    3 
 arch/x86/platform/efi/efi.c            |   11 ++
 drivers/firmware/efi/Kconfig           |   10 +
 drivers/firmware/efi/Makefile          |    1 
 drivers/firmware/efi/efi-runtime-map.c |  166 +++++++++++++++++++++++++++++++++
 drivers/firmware/efi/efi.c             |    3 
 6 files changed, 193 insertions(+), 1 deletion(-)

--- linux-2.6.orig/arch/x86/platform/efi/efi.c
+++ linux-2.6/arch/x86/platform/efi/efi.c
@@ -57,6 +57,9 @@
 
 #define EFI_MIN_RESERVE 5120
 
+efi_memory_desc_t *efi_runtime_map;
+int nr_efi_runtime_map;
+
 /*
  * We allocate runtime services regions bottom-up, starting from -4G, i.e.
  * 0xffff_ffff_0000_0000 and limit EFI VA mapping space to 64G.
@@ -865,6 +868,14 @@ void efi_map_regions(void **new_memmap,
 				      GFP_KERNEL);
 		memcpy(*new_memmap + (*count * memmap.desc_size), md,
 		       memmap.desc_size);
+		if (md->type != EFI_BOOT_SERVICES_CODE &&
+			md->type != EFI_BOOT_SERVICES_DATA) {
+			efi_runtime_map = krealloc(efi_runtime_map,
+					(nr_efi_runtime_map + 1) *
+					sizeof(efi_memory_desc_t), GFP_KERNEL);
+			*(efi_runtime_map + nr_efi_runtime_map) = *md;
+			nr_efi_runtime_map++;
+		}
 		(*count)++;
 	}
 }
--- linux-2.6.orig/drivers/firmware/efi/Kconfig
+++ linux-2.6/drivers/firmware/efi/Kconfig
@@ -36,4 +36,14 @@ config EFI_VARS_PSTORE_DEFAULT_DISABLE
 	  backend for pstore by default. This setting can be overridden
 	  using the efivars module's pstore_disable parameter.
 
+config EFI_RUNTIME_MAP
+	bool "Add efi runtime map to sysfs" if EXPERT
+	default X86 && EFI
+	help
+	  Add the efi runtime memory map to /sys/firmware/efi/runtime-map.
+	  That memory map is used for example by kexec to set up efi virtual
+	  mapping the 2nd kernel, but can also be used for debugging purposes.
+
+	  See also Documentation/ABI/testing/sysfs-efi-runtime-map.
+
 endmenu
--- linux-2.6.orig/drivers/firmware/efi/Makefile
+++ linux-2.6/drivers/firmware/efi/Makefile
@@ -4,3 +4,4 @@
 obj-y					+= efi.o vars.o
 obj-$(CONFIG_EFI_VARS)			+= efivars.o
 obj-$(CONFIG_EFI_VARS_PSTORE)		+= efi-pstore.o
+obj-$(CONFIG_EFI_RUNTIME_MAP)		+= efi-runtime-map.o
--- /dev/null
+++ linux-2.6/drivers/firmware/efi/efi-runtime-map.c
@@ -0,0 +1,166 @@
+/*
+ * linux/drivers/efi/efi-runtime-map.c
+ * Copyright (C) 2013 Red Hat, Inc., Dave Young <dyoung@xxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License v2.0 as published by
+ * the Free Software Foundation
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <linux/string.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/efi.h>
+#include <linux/slab.h>
+
+struct efi_runtime_map_entry {
+	efi_memory_desc_t md;
+	struct kobject kobj;   /* kobject for each entry */
+};
+
+extern efi_memory_desc_t *efi_runtime_map;
+extern int nr_efi_runtime_map;
+struct efi_runtime_map_entry *map_entries;
+extern struct kobject *efi_kobj;
+
+static ssize_t map_attr_show(struct kobject *kobj,
+				struct attribute *attr, char *buf);
+static ssize_t type_show(struct efi_runtime_map_entry *entry, char *buf);
+static ssize_t phys_addr_show(struct efi_runtime_map_entry *entry, char *buf);
+static ssize_t virt_addr_show(struct efi_runtime_map_entry *entry, char *buf);
+static ssize_t num_pages_show(struct efi_runtime_map_entry *entry, char *buf);
+static ssize_t attribute_show(struct efi_runtime_map_entry *entry, char *buf);
+
+struct map_attribute {
+	struct attribute attr;
+	ssize_t (*show)(struct efi_runtime_map_entry *entry, char *buf);
+};
+
+static struct map_attribute map_type_attr = __ATTR_RO(type);
+static struct map_attribute map_phys_addr_attr   = __ATTR_RO(phys_addr);
+static struct map_attribute map_virt_addr_attr  = __ATTR_RO(virt_addr);
+static struct map_attribute map_num_pages_attr  = __ATTR_RO(num_pages);
+static struct map_attribute map_attribute_attr  = __ATTR_RO(attribute);
+
+/*
+ * These are default attributes that are added for every memmap entry.
+ */
+static struct attribute *def_attrs[] = {
+	&map_type_attr.attr,
+	&map_phys_addr_attr.attr,
+	&map_virt_addr_attr.attr,
+	&map_num_pages_attr.attr,
+	&map_attribute_attr.attr,
+	NULL
+};
+
+static const struct sysfs_ops map_attr_ops = {
+	.show = map_attr_show,
+};
+
+static inline struct efi_runtime_map_entry *
+to_map_entry(struct kobject *kobj)
+{
+	return container_of(kobj, struct efi_runtime_map_entry, kobj);
+}
+
+static struct kobj_type __refdata map_ktype = {
+	.sysfs_ops	= &map_attr_ops,
+	.default_attrs	= def_attrs,
+};
+
+/*
+ * Add map entry on sysfs
+ */
+static int add_sysfs_fw_map_entry(struct efi_runtime_map_entry *entry)
+{
+	static int map_entries_nr;
+	static struct kset *map_kset;
+
+	if (!map_kset) {
+		map_kset = kset_create_and_add("efi-runtime-map", NULL,
+				efi_kobj);
+		if (!map_kset)
+			return -ENOMEM;
+	}
+
+	kobject_init(&entry->kobj, &map_ktype);
+	entry->kobj.kset = map_kset;
+	if (kobject_add(&entry->kobj, NULL, "%d", map_entries_nr++))
+		kobject_put(&entry->kobj);
+
+	return 0;
+}
+
+static ssize_t type_show(struct efi_runtime_map_entry *entry, char *buf)
+{
+	return snprintf(buf, PAGE_SIZE, "0x%x\n", entry->md.type);
+}
+
+static ssize_t phys_addr_show(struct efi_runtime_map_entry *entry, char *buf)
+{
+	return snprintf(buf, PAGE_SIZE, "0x%llx\n", entry->md.phys_addr);
+}
+
+static ssize_t virt_addr_show(struct efi_runtime_map_entry *entry, char *buf)
+{
+	return snprintf(buf, PAGE_SIZE, "0x%llx\n", entry->md.virt_addr);
+}
+
+static ssize_t num_pages_show(struct efi_runtime_map_entry *entry, char *buf)
+{
+	return snprintf(buf, PAGE_SIZE, "0x%llx\n", entry->md.num_pages);
+}
+
+static ssize_t attribute_show(struct efi_runtime_map_entry *entry, char *buf)
+{
+	return snprintf(buf, PAGE_SIZE, "0x%llx\n", entry->md.attribute);
+}
+
+static inline struct map_attribute *to_map_attr(struct attribute *attr)
+{
+	return container_of(attr, struct map_attribute, attr);
+}
+
+static ssize_t map_attr_show(struct kobject *kobj,
+				struct attribute *attr, char *buf)
+{
+	struct efi_runtime_map_entry *entry = to_map_entry(kobj);
+	struct map_attribute *map_attr = to_map_attr(attr);
+
+	return map_attr->show(entry, buf);
+}
+
+static int __init efi_runtime_map_init(void)
+{
+	int i;
+	struct efi_runtime_map_entry *entry;
+	efi_memory_desc_t *md = efi_runtime_map;
+
+	if (!efi_runtime_map) {
+		pr_warning("no efi_runtime_map found\n");
+		return -EINVAL;
+	}
+
+	map_entries = kzalloc(nr_efi_runtime_map * sizeof(struct efi_runtime_map_entry), GFP_KERNEL);
+	if (!map_entries)
+		return -ENOMEM;
+	entry = map_entries;
+
+	for (i = 0; i < nr_efi_runtime_map; i++){
+		entry->md = *md;
+		add_sysfs_fw_map_entry(entry);
+		entry++;
+		md++;
+	}
+
+	return 0;
+}
+late_initcall(efi_runtime_map_init);
--- linux-2.6.orig/drivers/firmware/efi/efi.c
+++ linux-2.6/drivers/firmware/efi/efi.c
@@ -38,7 +38,8 @@ struct efi __read_mostly efi = {
 };
 EXPORT_SYMBOL(efi);
 
-static struct kobject *efi_kobj;
+struct kobject *efi_kobj;
+EXPORT_SYMBOL_GPL(efi_kobj);
 static struct kobject *efivars_kobj;
 
 /*
--- linux-2.6.orig/arch/x86/include/asm/efi.h
+++ linux-2.6/arch/x86/include/asm/efi.h
@@ -116,6 +116,9 @@ extern void __init efi_remap_region(efi_
 extern void efi_sync_low_kernel_mappings(void);
 extern void __init old_map_region(efi_memory_desc_t *md);
 
+extern efi_memory_desc_t *efi_runtime_map;
+extern int nr_efi_runtime_map;
+
 #ifdef CONFIG_EFI
 
 static inline bool efi_is_native(void)

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