efi: Export EFI runtime memory mapping to sysfs

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 directory /sys/firmware/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

Signed-off-by: Dave Young <dyoung@redhat.com>
Tested-by: Toshi Kani <toshi.kani@hp.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>

4 files changed, 197 insertions, 0 deletions

diff --git a/drivers/firmware/efi/Kconfig b/drivers/firmware/efi/Kconfig
index 3150aa4874e8..730f5f2e8b7f 100644
--- a/drivers/firmware/efi/Kconfig
+++ b/drivers/firmware/efi/Kconfig
@@ -39,4 +39,15 @@ config EFI_VARS_PSTORE_DEFAULT_DISABLE
 config UEFI_CPER
         def_bool n
 
+config EFI_RUNTIME_MAP
+        bool "Export efi runtime maps to sysfs"
+        depends on X86 && EFI && KEXEC
+        default y
+        help
+          Export efi runtime memory maps 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-firmware-efi-runtime-map.
+
 endmenu
diff --git a/drivers/firmware/efi/Makefile b/drivers/firmware/efi/Makefile
index 9ba156d3c775..a58e0f183a08 100644
--- a/drivers/firmware/efi/Makefile
+++ b/drivers/firmware/efi/Makefile
@@ -5,3 +5,4 @@ obj-y					+= efi.o vars.o
 obj-$(CONFIG_EFI_VARS)                  += efivars.o
 obj-$(CONFIG_EFI_VARS_PSTORE)           += efi-pstore.o
 obj-$(CONFIG_UEFI_CPER)                 += cper.o
+obj-$(CONFIG_EFI_RUNTIME_MAP)           += runtime-map.o
diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index 72533af72b98..4753bac65279 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -167,6 +167,10 @@ static int __init efisubsys_init(void)
                 goto err_unregister;
         }
 
+        error = efi_runtime_map_init(efi_kobj);
+        if (error)
+                goto err_remove_group;
+
         /* and the standard mountpoint for efivarfs */
         efivars_kobj = kobject_create_and_add("efivars", efi_kobj);
         if (!efivars_kobj) {
diff --git a/drivers/firmware/efi/runtime-map.c b/drivers/firmware/efi/runtime-map.c
new file mode 100644
index 000000000000..97cdd16a2169
--- /dev/null
+++ b/drivers/firmware/efi/runtime-map.c
@@ -0,0 +1,181 @@
+/*
+ * linux/drivers/efi/runtime-map.c
+ * Copyright (C) 2013 Red Hat, Inc., Dave Young <dyoung@redhat.com>
+ *
+ * This file is released under the GPLv2.
+ */
+
+#include <linux/string.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/efi.h>
+#include <linux/slab.h>
+
+#include <asm/setup.h>
+
+static void *efi_runtime_map;
+static int nr_efi_runtime_map;
+static u32 efi_memdesc_size;
+
+struct efi_runtime_map_entry {
+        efi_memory_desc_t md;
+        struct kobject kobj;   /* kobject for each entry */
+};
+
+static struct efi_runtime_map_entry **map_entries;
+
+struct map_attribute {
+        struct attribute attr;
+        ssize_t (*show)(struct efi_runtime_map_entry *entry, char *buf);
+};
+
+static inline struct map_attribute *to_map_attr(struct attribute *attr)
+{
+        return container_of(attr, struct map_attribute, attr);
+}
+
+static ssize_t type_show(struct efi_runtime_map_entry *entry, char *buf)
+{
+        return snprintf(buf, PAGE_SIZE, "0x%x\n", entry->md.type);
+}
+
+#define EFI_RUNTIME_FIELD(var) entry->md.var
+
+#define EFI_RUNTIME_U64_ATTR_SHOW(name) \
+static ssize_t name##_show(struct efi_runtime_map_entry *entry, char *buf) \
+{ \
+        return snprintf(buf, PAGE_SIZE, "0x%llx\n", EFI_RUNTIME_FIELD(name)); \
+}
+
+EFI_RUNTIME_U64_ATTR_SHOW(phys_addr);
+EFI_RUNTIME_U64_ATTR_SHOW(virt_addr);
+EFI_RUNTIME_U64_ATTR_SHOW(num_pages);
+EFI_RUNTIME_U64_ATTR_SHOW(attribute);
+
+static inline struct efi_runtime_map_entry *to_map_entry(struct kobject *kobj)
+{
+        return container_of(kobj, struct efi_runtime_map_entry, kobj);
+}
+
+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 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 void map_release(struct kobject *kobj)
+{
+        struct efi_runtime_map_entry *entry;
+
+        entry = to_map_entry(kobj);
+        kfree(entry);
+}
+
+static struct kobj_type __refdata map_ktype = {
+        .sysfs_ops      = &map_attr_ops,
+        .default_attrs  = def_attrs,
+        .release        = map_release,
+};
+
+static struct kset *map_kset;
+
+static struct efi_runtime_map_entry *
+add_sysfs_runtime_map_entry(struct kobject *kobj, int nr)
+{
+        int ret;
+        struct efi_runtime_map_entry *entry;
+
+        if (!map_kset) {
+                map_kset = kset_create_and_add("runtime-map", NULL, kobj);
+                if (!map_kset)
+                        return ERR_PTR(-ENOMEM);
+        }
+
+        entry = kzalloc(sizeof(*entry), GFP_KERNEL);
+        if (!entry) {
+                kset_unregister(map_kset);
+                return entry;
+        }
+
+        memcpy(&entry->md, efi_runtime_map + nr * efi_memdesc_size,
+               sizeof(efi_memory_desc_t));
+
+        kobject_init(&entry->kobj, &map_ktype);
+        entry->kobj.kset = map_kset;
+        ret = kobject_add(&entry->kobj, NULL, "%d", nr);
+        if (ret) {
+                kobject_put(&entry->kobj);
+                kset_unregister(map_kset);
+                return ERR_PTR(ret);
+        }
+
+        return entry;
+}
+
+void efi_runtime_map_setup(void *map, int nr_entries, u32 desc_size)
+{
+        efi_runtime_map = map;
+        nr_efi_runtime_map = nr_entries;
+        efi_memdesc_size = desc_size;
+}
+
+int __init efi_runtime_map_init(struct kobject *efi_kobj)
+{
+        int i, j, ret = 0;
+        struct efi_runtime_map_entry *entry;
+
+        if (!efi_runtime_map)
+                return 0;
+
+        map_entries = kzalloc(nr_efi_runtime_map * sizeof(entry), GFP_KERNEL);
+        if (!map_entries) {
+                ret = -ENOMEM;
+                goto out;
+        }
+
+        for (i = 0; i < nr_efi_runtime_map; i++) {
+                entry = add_sysfs_runtime_map_entry(efi_kobj, i);
+                if (IS_ERR(entry)) {
+                        ret = PTR_ERR(entry);
+                        goto out_add_entry;
+                }
+                *(map_entries + i) = entry;
+        }
+
+        return 0;
+out_add_entry:
+        for (j = i - 1; j > 0; j--) {
+                entry = *(map_entries + j);
+                kobject_put(&entry->kobj);
+        }
+        if (map_kset)
+                kset_unregister(map_kset);
+out:
+        return ret;
+}