[patch 6/9 v3] efi: export efi runtime memory mapping to sysfs

dyoung
2013-11-21T06:20:51Z

[-- Attachment #1: 06-export-efi-runtime-mapping.patch --]
[-- Type: text/plain, Size: 11534 bytes --]

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/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.

Matt: s/efi-runtime-map.c/runtime-map.c
change dir name to runtime-map
update to use desc_size in efi_runtime_map
cleaup the code, add function efi_save_runtime_map
improve err handling

Signed-off-by: Dave Young <dyoung@redhat.com>
---
Documentation/ABI/testing/sysfs-firmware-efi-runtime-map | 45 +++
arch/x86/platform/efi/efi.c | 26 +
drivers/firmware/efi/Kconfig | 10
drivers/firmware/efi/Makefile | 1
drivers/firmware/efi/efi.c | 3
drivers/firmware/efi/runtime-map.c | 200 +++++++++++++++
include/linux/efi.h | 6
7 files changed, 290 insertions(+), 1 deletion(-)

--- efi.orig/arch/x86/platform/efi/efi.c
+++ efi/arch/x86/platform/efi/efi.c
@@ -76,6 +76,9 @@ static __initdata efi_config_table_type_
{NULL_GUID, NULL, NULL},
};

+void *efi_runtime_map;
+int nr_efi_runtime_map;
+
/*
* Returns 1 if 'facility' is enabled, 0 otherwise.
*/
@@ -811,6 +814,21 @@ static void __init efi_merge_regions(voi
}
}

+static int __init efi_save_runtime_map(efi_memory_desc_t *md)
+{
+ efi_runtime_map = krealloc(efi_runtime_map,
+ (nr_efi_runtime_map + 1) *
+ memmap.desc_size, GFP_KERNEL);
+ if (!efi_runtime_map)
+ return -ENOMEM;
+
+ memcpy(efi_runtime_map + nr_efi_runtime_map * memmap.desc_size,
+ md, memmap.desc_size);
+ nr_efi_runtime_map++;
+
+ return 0;
+}
+
/*
* Map efi memory ranges for runtime serivce and
* update new_memmap with virtual addresses.
@@ -821,6 +839,7 @@ static void * __init efi_map_regions(int
void *p, *new_memmap = NULL;
unsigned long size;
u64 end, systab;
+ int error = 0;

for (p = memmap.map; p < memmap.map_end; p += memmap.desc_size) {
md = p;
@@ -852,9 +871,16 @@ static void * __init efi_map_regions(int

memcpy(new_memmap + (*count * memmap.desc_size), md,
memmap.desc_size);
+ if (!error && md->type != EFI_BOOT_SERVICES_CODE &&
+ md->type != EFI_BOOT_SERVICES_DATA)
+ error = efi_save_runtime_map(md);
(*count)++;
}

+ if (error) {
+ nr_efi_runtime_map = 0;
+ kfree(efi_runtime_map);
+ }
ret:
return new_memmap;
}
--- efi.orig/drivers/firmware/efi/Kconfig
+++ efi/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 "Export efi runtime maps to sysfs" if EXPERT
+ default X86 && EFI
+ 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
--- efi.orig/drivers/firmware/efi/Makefile
+++ efi/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) += runtime-map.o
--- /dev/null
+++ efi/drivers/firmware/efi/runtime-map.c
@@ -0,0 +1,200 @@
+/*
+ * linux/drivers/efi/runtime-map.c
+ * Copyright (C) 2013 Red Hat, Inc., Dave Young <dyoung@redhat.com>
+ *
+ * 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>
+
+#include <asm/setup.h>
+
+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;
+
+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 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 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 struct kset *map_kset;
+
+/*
+ * Add map entry on sysfs
+ */
+static struct efi_runtime_map_entry *add_sysfs_runtime_map_entry(int nr)
+{
+ int ret;
+ unsigned long desc_size;
+ struct efi_runtime_map_entry *entry;
+ struct efi_info *e = &boot_params.efi_info;
+
+ if (!map_kset) {
+ map_kset = kset_create_and_add("runtime-map", NULL,
+ efi_kobj);
+ if (!map_kset)
+ return ERR_PTR(-ENOMEM);
+ }
+
+ entry = kzalloc(sizeof(*entry), GFP_KERNEL);
+ if (!entry) {
+ kset_unregister(map_kset);
+ return entry;
+ }
+
+ desc_size = e->efi_memdesc_size;
+ memcpy(&entry->md, efi_runtime_map + nr * desc_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;
+}
+
+static int __init efi_runtime_map_init(void)
+{
+ int i, j, ret = 0;
+ struct efi_runtime_map_entry *entry;
+
+ if (!efi_runtime_map) {
+ pr_warn("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;
+
+ for (i = 0; i < nr_efi_runtime_map; i++) {
+ entry = add_sysfs_runtime_map_entry(i);
+ if (IS_ERR(entry)) {
+ for (j = i - 1; j > 0; j--) {
+ entry = *(map_entries + j);
+ kobject_put(&entry->kobj);
+ }
+ if (map_kset)
+ kset_unregister(map_kset);
+ ret = PTR_ERR(entry);
+ goto out;
+ }
+ *(map_entries + i) = entry;
+ }
+
+out:
+ return ret;
+}
+late_initcall(efi_runtime_map_init);
--- efi.orig/drivers/firmware/efi/efi.c
+++ efi/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;

/*
--- /dev/null
+++ efi/Documentation/ABI/testing/sysfs-firmware-efi-runtime-map
@@ -0,0 +1,45 @@
+What: /sys/firmware/efi/runtime-map/
+Date: Oct 2013
+Contact: Dave Young <dyoung@redhat.com>
+Description:
+ Switching efi runtime services to virtual mode requires
+ that all efi memory ranges which has the runtime attribute
+ bit set to be mapped to virtual addresses.
+
+ In kexec kernel kernel can not entering virtual mode again
+ because there's a limitation that SetVirtualAddressMap can
+ only be called once for entering virtual mode. But kexec
+ kernel still need maintain same physical address to virtual
+ address mapping as the 1st kernel. The mappings are exported
+ to sysfs so userspace tools can reassemble them and pass them
+ into kexec kernel.
+
+ /sys/firmware/efi/runtim-map/ is what kernel export for
+ this purpose. The structure is as follows:
+
+ subdirectories are named with the number of the memory range:
+
+ /sys/firmware/efi/runtime-map/0
+ /sys/firmware/efi/runtime-map/1
+ /sys/firmware/efi/runtime-map/2
+ /sys/firmware/efi/runtime-map/3
+ ...
+
+ Each subdirectory contains five files:
+
+ attribute : The attribute of the memory range.
+ num_pages : The size of the memory range in page number.
+ phys_addr : The start physical address of the memory range.
+ type : The type of the memory range.
+ virt_addr : The start virtual address of the memory range.
+
+ Above values are all hexadecimal number with the '0x' prefix.
+
+ So, for example:
+
+ /sys/firmware/efi/runtime-map/0/attribute
+ /sys/firmware/efi/runtime-map/0/num_pages
+ /sys/firmware/efi/runtime-map/0/phys_addr
+ /sys/firmware/efi/runtime-map/0/type
+ /sys/firmware/efi/runtime-map/0/virt_addr
+ ...
--- efi.orig/include/linux/efi.h
+++ efi/include/linux/efi.h
@@ -872,4 +872,10 @@ int efivars_sysfs_init(void);

#endif /* CONFIG_EFI_VARS */

+#ifdef CONFIG_EFI_RUNTIME_MAP
+extern void *efi_runtime_map;
+extern int nr_efi_runtime_map;
+extern struct kobject *efi_kobj;
+#endif
+
#endif /* _LINUX_EFI_H */