13 files changed, 325 insertions, 83 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 4609e81dbc37..d1cc3a9fa14f 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -788,6 +788,12 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
         edd=            [EDD]
                         Format: {"off" | "on" | "skip[mbr]"}
 
+        efi_no_storage_paranoia [EFI; X86]
+                        Using this parameter you can use more than 50% of
+                        your efi variable storage. Use this parameter only if
+                        you are really sure that your UEFI does sane gc and
+                        fulfills the spec otherwise your board may brick.
+
         eisa_irq_edge=  [PARISC,HW]
                         See header of drivers/parisc/eisa.c.
 
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 70c0f3da0476..15b5cef4aa38 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -1549,6 +1549,7 @@ config X86_SMAP
 config EFI
         bool "EFI runtime service support"
         depends on ACPI
+        select UCS2_STRING
         ---help---
           This enables the kernel to use EFI runtime services that are
           available (such as the EFI variable services).
diff --git a/arch/x86/boot/compressed/eboot.c b/arch/x86/boot/compressed/eboot.c
index c205035a6b96..8615f7581820 100644
--- a/arch/x86/boot/compressed/eboot.c
+++ b/arch/x86/boot/compressed/eboot.c
@@ -251,6 +251,51 @@ static void find_bits(unsigned long mask, u8 *pos, u8 *size)
         *size = len;
 }
 
+static efi_status_t setup_efi_vars(struct boot_params *params)
+{
+        struct setup_data *data;
+        struct efi_var_bootdata *efidata;
+        u64 store_size, remaining_size, var_size;
+        efi_status_t status;
+
+        if (!sys_table->runtime->query_variable_info)
+                return EFI_UNSUPPORTED;
+
+        data = (struct setup_data *)(unsigned long)params->hdr.setup_data;
+
+        while (data && data->next)
+                data = (struct setup_data *)(unsigned long)data->next;
+
+        status = efi_call_phys4(sys_table->runtime->query_variable_info,
+                                EFI_VARIABLE_NON_VOLATILE |
+                                EFI_VARIABLE_BOOTSERVICE_ACCESS |
+                                EFI_VARIABLE_RUNTIME_ACCESS, &store_size,
+                                &remaining_size, &var_size);
+
+        if (status != EFI_SUCCESS)
+                return status;
+
+        status = efi_call_phys3(sys_table->boottime->allocate_pool,
+                                EFI_LOADER_DATA, sizeof(*efidata), &efidata);
+
+        if (status != EFI_SUCCESS)
+                return status;
+
+        efidata->data.type = SETUP_EFI_VARS;
+        efidata->data.len = sizeof(struct efi_var_bootdata) -
+                sizeof(struct setup_data);
+        efidata->data.next = 0;
+        efidata->store_size = store_size;
+        efidata->remaining_size = remaining_size;
+        efidata->max_var_size = var_size;
+
+        if (data)
+                data->next = (unsigned long)efidata;
+        else
+                params->hdr.setup_data = (unsigned long)efidata;
+
+}
+
 static efi_status_t setup_efi_pci(struct boot_params *params)
 {
         efi_pci_io_protocol *pci;
@@ -1157,6 +1202,8 @@ struct boot_params *efi_main(void *handle, efi_system_table_t *_table,
 
         setup_graphics(boot_params);
 
+        setup_efi_vars(boot_params);
+
         setup_efi_pci(boot_params);
 
         status = efi_call_phys3(sys_table->boottime->allocate_pool,
diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h
index 60c89f30c727..2fb5d5884e23 100644
--- a/arch/x86/include/asm/efi.h
+++ b/arch/x86/include/asm/efi.h
@@ -102,6 +102,13 @@ extern void efi_call_phys_epilog(void);
 extern void efi_unmap_memmap(void);
 extern void efi_memory_uc(u64 addr, unsigned long size);
 
+struct efi_var_bootdata {
+        struct setup_data data;
+        u64 store_size;
+        u64 remaining_size;
+        u64 max_var_size;
+};
+
 #ifdef CONFIG_EFI
 
 static inline bool efi_is_native(void)
diff --git a/arch/x86/include/uapi/asm/bootparam.h b/arch/x86/include/uapi/asm/bootparam.h
index c15ddaf90710..08744242b8d2 100644
--- a/arch/x86/include/uapi/asm/bootparam.h
+++ b/arch/x86/include/uapi/asm/bootparam.h
@@ -6,6 +6,7 @@
 #define SETUP_E820_EXT                  1
 #define SETUP_DTB                       2
 #define SETUP_PCI                       3
+#define SETUP_EFI_VARS                  4
 
 /* ram_size flags */
 #define RAMDISK_IMAGE_START_MASK        0x07FF
diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index 5f2ecaf3f9d8..e4a86a677ce1 100644
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -41,6 +41,7 @@
 #include <linux/io.h>
 #include <linux/reboot.h>
 #include <linux/bcd.h>
+#include <linux/ucs2_string.h>
 
 #include <asm/setup.h>
 #include <asm/efi.h>
@@ -51,6 +52,13 @@
 
 #define EFI_DEBUG       1
 
+/*
+ * There's some additional metadata associated with each
+ * variable. Intel's reference implementation is 60 bytes - bump that
+ * to account for potential alignment constraints
+ */
+#define VAR_METADATA_SIZE 64
+
 struct efi __read_mostly efi = {
         .mps        = EFI_INVALID_TABLE_ADDR,
         .acpi       = EFI_INVALID_TABLE_ADDR,
@@ -69,6 +77,13 @@ struct efi_memory_map memmap;
 static struct efi efi_phys __initdata;
 static efi_system_table_t efi_systab __initdata;
 
+static u64 efi_var_store_size;
+static u64 efi_var_remaining_size;
+static u64 efi_var_max_var_size;
+static u64 boot_used_size;
+static u64 boot_var_size;
+static u64 active_size;
+
 unsigned long x86_efi_facility;
 
 /*
@@ -98,6 +113,15 @@ static int __init setup_add_efi_memmap(char *arg)
 }
 early_param("add_efi_memmap", setup_add_efi_memmap);
 
+static bool efi_no_storage_paranoia;
+
+static int __init setup_storage_paranoia(char *arg)
+{
+        efi_no_storage_paranoia = true;
+        return 0;
+}
+early_param("efi_no_storage_paranoia", setup_storage_paranoia);
+
 
 static efi_status_t virt_efi_get_time(efi_time_t *tm, efi_time_cap_t *tc)
 {
@@ -162,8 +186,53 @@ static efi_status_t virt_efi_get_next_variable(unsigned long *name_size,
                                                efi_char16_t *name,
                                                efi_guid_t *vendor)
 {
-        return efi_call_virt3(get_next_variable,
-                              name_size, name, vendor);
+        efi_status_t status;
+        static bool finished = false;
+        static u64 var_size;
+
+        status = efi_call_virt3(get_next_variable,
+                                name_size, name, vendor);
+
+        if (status == EFI_NOT_FOUND) {
+                finished = true;
+                if (var_size < boot_used_size) {
+                        boot_var_size = boot_used_size - var_size;
+                        active_size += boot_var_size;
+                } else {
+                        printk(KERN_WARNING FW_BUG  "efi: Inconsistent initial sizes\n");
+                }
+        }
+
+        if (boot_used_size && !finished) {
+                unsigned long size;
+                u32 attr;
+                efi_status_t s;
+                void *tmp;
+
+                s = virt_efi_get_variable(name, vendor, &attr, &size, NULL);
+
+                if (s != EFI_BUFFER_TOO_SMALL || !size)
+                        return status;
+
+                tmp = kmalloc(size, GFP_ATOMIC);
+
+                if (!tmp)
+                        return status;
+
+                s = virt_efi_get_variable(name, vendor, &attr, &size, tmp);
+
+                if (s == EFI_SUCCESS && (attr & EFI_VARIABLE_NON_VOLATILE)) {
+                        var_size += size;
+                        var_size += ucs2_strsize(name, 1024);
+                        active_size += size;
+                        active_size += VAR_METADATA_SIZE;
+                        active_size += ucs2_strsize(name, 1024);
+                }
+
+                kfree(tmp);
+        }
+
+        return status;
 }
 
 static efi_status_t virt_efi_set_variable(efi_char16_t *name,
@@ -172,9 +241,34 @@ static efi_status_t virt_efi_set_variable(efi_char16_t *name,
                                           unsigned long data_size,
                                           void *data)
 {
-        return efi_call_virt5(set_variable,
-                              name, vendor, attr,
-                              data_size, data);
+        efi_status_t status;
+        u32 orig_attr = 0;
+        unsigned long orig_size = 0;
+
+        status = virt_efi_get_variable(name, vendor, &orig_attr, &orig_size,
+                                       NULL);
+
+        if (status != EFI_BUFFER_TOO_SMALL)
+                orig_size = 0;
+
+        status = efi_call_virt5(set_variable,
+                                name, vendor, attr,
+                                data_size, data);
+
+        if (status == EFI_SUCCESS) {
+                if (orig_size) {
+                        active_size -= orig_size;
+                        active_size -= ucs2_strsize(name, 1024);
+                        active_size -= VAR_METADATA_SIZE;
+                }
+                if (data_size) {
+                        active_size += data_size;
+                        active_size += ucs2_strsize(name, 1024);
+                        active_size += VAR_METADATA_SIZE;
+                }
+        }
+
+        return status;
 }
 
 static efi_status_t virt_efi_query_variable_info(u32 attr,
@@ -682,6 +776,9 @@ void __init efi_init(void)
         char vendor[100] = "unknown";
         int i = 0;
         void *tmp;
+        struct setup_data *data;
+        struct efi_var_bootdata *efi_var_data;
+        u64 pa_data;
 
 #ifdef CONFIG_X86_32
         if (boot_params.efi_info.efi_systab_hi ||
@@ -699,6 +796,22 @@ void __init efi_init(void)
         if (efi_systab_init(efi_phys.systab))
                 return;
 
+        pa_data = boot_params.hdr.setup_data;
+        while (pa_data) {
+                data = early_ioremap(pa_data, sizeof(*efi_var_data));
+                if (data->type == SETUP_EFI_VARS) {
+                        efi_var_data = (struct efi_var_bootdata *)data;
+
+                        efi_var_store_size = efi_var_data->store_size;
+                        efi_var_remaining_size = efi_var_data->remaining_size;
+                        efi_var_max_var_size = efi_var_data->max_var_size;
+                }
+                pa_data = data->next;
+                early_iounmap(data, sizeof(*efi_var_data));
+        }
+
+        boot_used_size = efi_var_store_size - efi_var_remaining_size;
+
         set_bit(EFI_SYSTEM_TABLES, &x86_efi_facility);
 
         /*
@@ -999,3 +1112,48 @@ u64 efi_mem_attributes(unsigned long phys_addr)
         }
         return 0;
 }
+
+/*
+ * Some firmware has serious problems when using more than 50% of the EFI
+ * variable store, i.e. it triggers bugs that can brick machines. Ensure that
+ * we never use more than this safe limit.
+ *
+ * Return EFI_SUCCESS if it is safe to write 'size' bytes to the variable
+ * store.
+ */
+efi_status_t efi_query_variable_store(u32 attributes, unsigned long size)
+{
+        efi_status_t status;
+        u64 storage_size, remaining_size, max_size;
+
+        status = efi.query_variable_info(attributes, &storage_size,
+                                         &remaining_size, &max_size);
+        if (status != EFI_SUCCESS)
+                return status;
+
+        if (!max_size && remaining_size > size)
+                printk_once(KERN_ERR FW_BUG "Broken EFI implementation"
+                            " is returning MaxVariableSize=0\n");
+        /*
+         * Some firmware implementations refuse to boot if there's insufficient
+         * space in the variable store. We account for that by refusing the
+         * write if permitting it would reduce the available space to under
+         * 50%. However, some firmware won't reclaim variable space until
+         * after the used (not merely the actively used) space drops below
+         * a threshold. We can approximate that case with the value calculated
+         * above. If both the firmware and our calculations indicate that the
+         * available space would drop below 50%, refuse the write.
+         */
+
+        if (!storage_size || size > remaining_size ||
+            (max_size && size > max_size))
+                return EFI_OUT_OF_RESOURCES;
+
+        if (!efi_no_storage_paranoia &&
+            ((active_size + size + VAR_METADATA_SIZE > storage_size / 2) &&
+             (remaining_size - size < storage_size / 2)))
+                return EFI_OUT_OF_RESOURCES;
+
+        return EFI_SUCCESS;
+}
+EXPORT_SYMBOL_GPL(efi_query_variable_store);
diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig
index 42c759a4d047..3e532002e4d1 100644
--- a/drivers/firmware/Kconfig
+++ b/drivers/firmware/Kconfig
@@ -39,6 +39,7 @@ config FIRMWARE_MEMMAP
 config EFI_VARS
         tristate "EFI Variable Support via sysfs"
         depends on EFI
+        select UCS2_STRING
         default n
         help
           If you say Y here, you are able to get EFI (Extensible Firmware
diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c
index 7acafb80fd4c..182ce9471175 100644
--- a/drivers/firmware/efivars.c
+++ b/drivers/firmware/efivars.c
@@ -80,6 +80,7 @@
 #include <linux/slab.h>
 #include <linux/pstore.h>
 #include <linux/ctype.h>
+#include <linux/ucs2_string.h>
 
 #include <linux/fs.h>
 #include <linux/ramfs.h>
@@ -172,51 +173,6 @@ static void efivar_update_sysfs_entries(struct work_struct *);
 static DECLARE_WORK(efivar_work, efivar_update_sysfs_entries);
 static bool efivar_wq_enabled = true;
 
-/* Return the number of unicode characters in data */
-static unsigned long
-utf16_strnlen(efi_char16_t *s, size_t maxlength)
-{
-        unsigned long length = 0;
-
-        while (*s++ != 0 && length < maxlength)
-                length++;
-        return length;
-}
-
-static inline unsigned long
-utf16_strlen(efi_char16_t *s)
-{
-        return utf16_strnlen(s, ~0UL);
-}
-
-/*
- * Return the number of bytes is the length of this string
- * Note: this is NOT the same as the number of unicode characters
- */
-static inline unsigned long
-utf16_strsize(efi_char16_t *data, unsigned long maxlength)
-{
-        return utf16_strnlen(data, maxlength/sizeof(efi_char16_t)) * sizeof(efi_char16_t);
-}
-
-static inline int
-utf16_strncmp(const efi_char16_t *a, const efi_char16_t *b, size_t len)
-{
-        while (1) {
-                if (len == 0)
-                        return 0;
-                if (*a < *b)
-                        return -1;
-                if (*a > *b)
-                        return 1;
-                if (*a == 0) /* implies *b == 0 */
-                        return 0;
-                a++;
-                b++;
-                len--;
-        }
-}
-
 static bool
 validate_device_path(struct efi_variable *var, int match, u8 *buffer,
                      unsigned long len)
@@ -268,7 +224,7 @@ validate_load_option(struct efi_variable *var, int match, u8 *buffer,
         u16 filepathlength;
         int i, desclength = 0, namelen;
 
-        namelen = utf16_strnlen(var->VariableName, sizeof(var->VariableName));
+        namelen = ucs2_strnlen(var->VariableName, sizeof(var->VariableName));
 
         /* Either "Boot" or "Driver" followed by four digits of hex */
         for (i = match; i < match+4; i++) {
@@ -291,7 +247,7 @@ validate_load_option(struct efi_variable *var, int match, u8 *buffer,
          * There's no stored length for the description, so it has to be
          * found by hand
          */
-        desclength = utf16_strsize((efi_char16_t *)(buffer + 6), len - 6) + 2;
+        desclength = ucs2_strsize((efi_char16_t *)(buffer + 6), len - 6) + 2;
 
         /* Each boot entry must have a descriptor */
         if (!desclength)
@@ -436,24 +392,12 @@ static efi_status_t
 check_var_size_locked(struct efivars *efivars, u32 attributes,
                         unsigned long size)
 {
-        u64 storage_size, remaining_size, max_size;
-        efi_status_t status;
         const struct efivar_operations *fops = efivars->ops;
 
-        if (!efivars->ops->query_variable_info)
+        if (!efivars->ops->query_variable_store)
                 return EFI_UNSUPPORTED;
 
-        status = fops->query_variable_info(attributes, &storage_size,
-                                           &remaining_size, &max_size);
-
-        if (status != EFI_SUCCESS)
-                return status;
-
-        if (!storage_size || size > remaining_size || size > max_size ||
-            (remaining_size - size) < (storage_size / 2))
-                return EFI_OUT_OF_RESOURCES;
-
-        return status;
+        return fops->query_variable_store(attributes, size);
 }
 
 
@@ -593,7 +537,7 @@ efivar_store_raw(struct efivar_entry *entry, const char *buf, size_t count)
         spin_lock_irq(&efivars->lock);
 
         status = check_var_size_locked(efivars, new_var->Attributes,
-               new_var->DataSize + utf16_strsize(new_var->VariableName, 1024));
+               new_var->DataSize + ucs2_strsize(new_var->VariableName, 1024));
 
         if (status == EFI_SUCCESS || status == EFI_UNSUPPORTED)
                 status = efivars->ops->set_variable(new_var->VariableName,
@@ -771,7 +715,7 @@ static ssize_t efivarfs_file_write(struct file *file,
          * QueryVariableInfo() isn't supported by the firmware.
          */
 
-        varsize = datasize + utf16_strsize(var->var.VariableName, 1024);
+        varsize = datasize + ucs2_strsize(var->var.VariableName, 1024);
         status = check_var_size(efivars, attributes, varsize);
 
         if (status != EFI_SUCCESS) {
@@ -1223,7 +1167,7 @@ static int efivarfs_fill_super(struct super_block *sb, void *data, int silent)
 
                 inode = NULL;
 
-                len = utf16_strlen(entry->var.VariableName);
+                len = ucs2_strlen(entry->var.VariableName);
 
                 /* name, plus '-', plus GUID, plus NUL*/
                 name = kmalloc(len + 1 + GUID_LEN + 1, GFP_ATOMIC);
@@ -1481,8 +1425,8 @@ static int efi_pstore_erase(enum pstore_type_id type, u64 id, int count,
 
                 if (efi_guidcmp(entry->var.VendorGuid, vendor))
                         continue;
-                if (utf16_strncmp(entry->var.VariableName, efi_name,
-                                  utf16_strlen(efi_name))) {
+                if (ucs2_strncmp(entry->var.VariableName, efi_name,
+                                  ucs2_strlen(efi_name))) {
                         /*
                          * Check if an old format,
                          * which doesn't support holding
@@ -1494,8 +1438,8 @@ static int efi_pstore_erase(enum pstore_type_id type, u64 id, int count,
                         for (i = 0; i < DUMP_NAME_LEN; i++)
                                 efi_name_old[i] = name_old[i];
 
-                        if (utf16_strncmp(entry->var.VariableName, efi_name_old,
-                                          utf16_strlen(efi_name_old)))
+                        if (ucs2_strncmp(entry->var.VariableName, efi_name_old,
+                                          ucs2_strlen(efi_name_old)))
                                 continue;
                 }
 
@@ -1573,8 +1517,8 @@ static ssize_t efivar_create(struct file *filp, struct kobject *kobj,
          * Does this variable already exist?
          */
         list_for_each_entry_safe(search_efivar, n, &efivars->list, list) {
-                strsize1 = utf16_strsize(search_efivar->var.VariableName, 1024);
-                strsize2 = utf16_strsize(new_var->VariableName, 1024);
+                strsize1 = ucs2_strsize(search_efivar->var.VariableName, 1024);
+                strsize2 = ucs2_strsize(new_var->VariableName, 1024);
                 if (strsize1 == strsize2 &&
                         !memcmp(&(search_efivar->var.VariableName),
                                 new_var->VariableName, strsize1) &&
@@ -1590,7 +1534,7 @@ static ssize_t efivar_create(struct file *filp, struct kobject *kobj,
         }
 
         status = check_var_size_locked(efivars, new_var->Attributes,
-               new_var->DataSize + utf16_strsize(new_var->VariableName, 1024));
+               new_var->DataSize + ucs2_strsize(new_var->VariableName, 1024));
 
         if (status && status != EFI_UNSUPPORTED) {
                 spin_unlock_irq(&efivars->lock);
@@ -1614,7 +1558,7 @@ static ssize_t efivar_create(struct file *filp, struct kobject *kobj,
 
         /* Create the entry in sysfs.  Locking is not required here */
         status = efivar_create_sysfs_entry(efivars,
-                                           utf16_strsize(new_var->VariableName,
+                                           ucs2_strsize(new_var->VariableName,
                                                          1024),
                                            new_var->VariableName,
                                            &new_var->VendorGuid);
@@ -1644,8 +1588,8 @@ static ssize_t efivar_delete(struct file *filp, struct kobject *kobj,
          * Does this variable already exist?
          */
         list_for_each_entry_safe(search_efivar, n, &efivars->list, list) {
-                strsize1 = utf16_strsize(search_efivar->var.VariableName, 1024);
-                strsize2 = utf16_strsize(del_var->VariableName, 1024);
+                strsize1 = ucs2_strsize(search_efivar->var.VariableName, 1024);
+                strsize2 = ucs2_strsize(del_var->VariableName, 1024);
                 if (strsize1 == strsize2 &&
                         !memcmp(&(search_efivar->var.VariableName),
                                 del_var->VariableName, strsize1) &&
@@ -1691,9 +1635,9 @@ static bool variable_is_present(efi_char16_t *variable_name, efi_guid_t *vendor)
         unsigned long strsize1, strsize2;
         bool found = false;
 
-        strsize1 = utf16_strsize(variable_name, 1024);
+        strsize1 = ucs2_strsize(variable_name, 1024);
         list_for_each_entry_safe(entry, n, &efivars->list, list) {
-                strsize2 = utf16_strsize(entry->var.VariableName, 1024);
+                strsize2 = ucs2_strsize(entry->var.VariableName, 1024);
                 if (strsize1 == strsize2 &&
                         !memcmp(variable_name, &(entry->var.VariableName),
                                 strsize2) &&
@@ -2131,7 +2075,7 @@ efivars_init(void)
         ops.get_variable = efi.get_variable;
         ops.set_variable = efi.set_variable;
         ops.get_next_variable = efi.get_next_variable;
-        ops.query_variable_info = efi.query_variable_info;
+        ops.query_variable_store = efi_query_variable_store;
 
         error = register_efivars(&__efivars, &ops, efi_kobj);
         if (error)
diff --git a/include/linux/efi.h b/include/linux/efi.h
index 9bf2f1fcae27..3d7df3d32c66 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -333,6 +333,7 @@ typedef efi_status_t efi_query_capsule_caps_t(efi_capsule_header_t **capsules,
                                               unsigned long count,
                                               u64 *max_size,
                                               int *reset_type);
+typedef efi_status_t efi_query_variable_store_t(u32 attributes, unsigned long size);
 
 /*
  *  EFI Configuration Table and GUID definitions
@@ -575,9 +576,15 @@ extern void efi_enter_virtual_mode (void);	/* switch EFI to virtual mode, if pos
 #ifdef CONFIG_X86
 extern void efi_late_init(void);
 extern void efi_free_boot_services(void);
+extern efi_status_t efi_query_variable_store(u32 attributes, unsigned long size);
 #else
 static inline void efi_late_init(void) {}
 static inline void efi_free_boot_services(void) {}
+
+static inline efi_status_t efi_query_variable_store(u32 attributes, unsigned long size)
+{
+        return EFI_SUCCESS;
+}
 #endif
 extern void __iomem *efi_lookup_mapped_addr(u64 phys_addr);
 extern u64 efi_get_iobase (void);
@@ -731,7 +738,7 @@ struct efivar_operations {
         efi_get_variable_t *get_variable;
         efi_get_next_variable_t *get_next_variable;
         efi_set_variable_t *set_variable;
-        efi_query_variable_info_t *query_variable_info;
+        efi_query_variable_store_t *query_variable_store;
 };
 
 struct efivars {
diff --git a/include/linux/ucs2_string.h b/include/linux/ucs2_string.h
new file mode 100644
index 000000000000..cbb20afdbc01
--- /dev/null
+++ b/include/linux/ucs2_string.h
@@ -0,0 +1,14 @@
+#ifndef _LINUX_UCS2_STRING_H_
+#define _LINUX_UCS2_STRING_H_
+
+#include <linux/types.h>        /* for size_t */
+#include <linux/stddef.h>       /* for NULL */
+
+typedef u16 ucs2_char_t;
+
+unsigned long ucs2_strnlen(const ucs2_char_t *s, size_t maxlength);
+unsigned long ucs2_strlen(const ucs2_char_t *s);
+unsigned long ucs2_strsize(const ucs2_char_t *data, unsigned long maxlength);
+int ucs2_strncmp(const ucs2_char_t *a, const ucs2_char_t *b, size_t len);
+
+#endif /* _LINUX_UCS2_STRING_H_ */
diff --git a/lib/Kconfig b/lib/Kconfig
index 3958dc4389f9..fe01d418b09a 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -404,4 +404,7 @@ config OID_REGISTRY
         help
           Enable fast lookup object identifier registry.
 
+config UCS2_STRING
+        tristate
+
 endmenu
diff --git a/lib/Makefile b/lib/Makefile
index d7946ff75b2e..6e2cc561f761 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -174,3 +174,5 @@ quiet_cmd_build_OID_registry = GEN     $@
       cmd_build_OID_registry = perl $(srctree)/$(src)/build_OID_registry $< $@
 
 clean-files     += oid_registry_data.c
+
+obj-$(CONFIG_UCS2_STRING) += ucs2_string.o
diff --git a/lib/ucs2_string.c b/lib/ucs2_string.c
new file mode 100644
index 000000000000..6f500ef2301d
--- /dev/null
+++ b/lib/ucs2_string.c
@@ -0,0 +1,51 @@
+#include <linux/ucs2_string.h>
+#include <linux/module.h>
+
+/* Return the number of unicode characters in data */
+unsigned long
+ucs2_strnlen(const ucs2_char_t *s, size_t maxlength)
+{
+        unsigned long length = 0;
+
+        while (*s++ != 0 && length < maxlength)
+                length++;
+        return length;
+}
+EXPORT_SYMBOL(ucs2_strnlen);
+
+unsigned long
+ucs2_strlen(const ucs2_char_t *s)
+{
+        return ucs2_strnlen(s, ~0UL);
+}
+EXPORT_SYMBOL(ucs2_strlen);
+
+/*
+ * Return the number of bytes is the length of this string
+ * Note: this is NOT the same as the number of unicode characters
+ */
+unsigned long
+ucs2_strsize(const ucs2_char_t *data, unsigned long maxlength)
+{
+        return ucs2_strnlen(data, maxlength/sizeof(ucs2_char_t)) * sizeof(ucs2_char_t);
+}
+EXPORT_SYMBOL(ucs2_strsize);
+
+int
+ucs2_strncmp(const ucs2_char_t *a, const ucs2_char_t *b, size_t len)
+{
+        while (1) {
+                if (len == 0)
+                        return 0;
+                if (*a < *b)
+                        return -1;
+                if (*a > *b)
+                        return 1;
+                if (*a == 0) /* implies *b == 0 */
+                        return 0;
+                a++;
+                b++;
+                len--;
+        }
+}
+EXPORT_SYMBOL(ucs2_strncmp);