drivers/firmware/efivars.c

   1 /*
   2  * EFI Variables - efivars.c
   3  *
   4  * Copyright (C) 2001,2003,2004 Dell <Matt_Domsch@dell.com>
   5  * Copyright (C) 2004 Intel Corporation <matthew.e.tolentino@intel.com>
   6  *
   7  * This code takes all variables accessible from EFI runtime and
   8  *  exports them via sysfs
   9  *
  10  *  This program is free software; you can redistribute it and/or modify
  11  *  it under the terms of the GNU General Public License as published by
  12  *  the Free Software Foundation; either version 2 of the License, or
  13  *  (at your option) any later version.
  14  *
  15  *  This program is distributed in the hope that it will be useful,
  16  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  *  GNU General Public License for more details.
  19  *
  20  *  You should have received a copy of the GNU General Public License
  21  *  along with this program; if not, write to the Free Software
  22  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  23  *
  24  * Changelog:
  25  *
  26  *  17 May 2004 - Matt Domsch <Matt_Domsch@dell.com>
  27  *   remove check for efi_enabled in exit
  28  *   add MODULE_VERSION
  29  *
  30  *  26 Apr 2004 - Matt Domsch <Matt_Domsch@dell.com>
  31  *   minor bug fixes
  32  *
  33  *  21 Apr 2004 - Matt Tolentino <matthew.e.tolentino@intel.com)
  34  *   converted driver to export variable information via sysfs
  35  *   and moved to drivers/firmware directory
  36  *   bumped revision number to v0.07 to reflect conversion & move
  37  *
  38  *  10 Dec 2002 - Matt Domsch <Matt_Domsch@dell.com>
  39  *   fix locking per Peter Chubb's findings
  40  *
  41  *  25 Mar 2002 - Matt Domsch <Matt_Domsch@dell.com>
  42  *   move uuid_unparse() to include/asm-ia64/efi.h:efi_guid_unparse()
  43  *
  44  *  12 Feb 2002 - Matt Domsch <Matt_Domsch@dell.com>
  45  *   use list_for_each_safe when deleting vars.
  46  *   remove ifdef CONFIG_SMP around include <linux/smp.h>
  47  *   v0.04 release to linux-ia64@linuxia64.org
  48  *
  49  *  20 April 2001 - Matt Domsch <Matt_Domsch@dell.com>
  50  *   Moved vars from /proc/efi to /proc/efi/vars, and made
  51  *   efi.c own the /proc/efi directory.
  52  *   v0.03 release to linux-ia64@linuxia64.org
  53  *
  54  *  26 March 2001 - Matt Domsch <Matt_Domsch@dell.com>
  55  *   At the request of Stephane, moved ownership of /proc/efi
  56  *   to efi.c, and now efivars lives under /proc/efi/vars.
  57  *
  58  *  12 March 2001 - Matt Domsch <Matt_Domsch@dell.com>
  59  *   Feedback received from Stephane Eranian incorporated.
  60  *   efivar_write() checks copy_from_user() return value.
  61  *   efivar_read/write() returns proper errno.
  62  *   v0.02 release to linux-ia64@linuxia64.org
  63  *
  64  *  26 February 2001 - Matt Domsch <Matt_Domsch@dell.com>
  65  *   v0.01 release to linux-ia64@linuxia64.org
  66  */
  67
  68 #include <linux/capability.h>
  69 #include <linux/types.h>
  70 #include <linux/errno.h>
  71 #include <linux/init.h>
  72 #include <linux/mm.h>
  73 #include <linux/module.h>
  74 #include <linux/string.h>
  75 #include <linux/smp.h>
  76 #include <linux/efi.h>
  77 #include <linux/sysfs.h>
  78 #include <linux/kobject.h>
  79 #include <linux/device.h>
  80 #include <linux/slab.h>
  81 #include <linux/pstore.h>
  82
  83 #include <asm/uaccess.h>
  84
  85 #define EFIVARS_VERSION "0.08"
  86 #define EFIVARS_DATE "2004-May-17"
  87
  88 MODULE_AUTHOR("Matt Domsch <Matt_Domsch@Dell.com>");
  89 MODULE_DESCRIPTION("sysfs interface to EFI Variables");
  90 MODULE_LICENSE("GPL");
  91 MODULE_VERSION(EFIVARS_VERSION);
  92
  93 #define DUMP_NAME_LEN 52
  94
  95 /*
  96  * The maximum size of VariableName + Data = 1024
  97  * Therefore, it's reasonable to save that much
  98  * space in each part of the structure,
  99  * and we use a page for reading/writing.
 100  */
 101
 102 struct efi_variable {
 103         efi_char16_t  VariableName[1024/sizeof(efi_char16_t)];
 104         efi_guid_t    VendorGuid;
 105         unsigned long DataSize;
 106         __u8          Data[1024];
 107         efi_status_t  Status;
 108         __u32         Attributes;
 109 } __attribute__((packed));
 110
 111
 112 struct efivar_entry {
 113         struct efivars *efivars;
 114         struct efi_variable var;
 115         struct list_head list;
 116         struct kobject kobj;
 117 };
 118
 119 struct efivar_attribute {
 120         struct attribute attr;
 121         ssize_t (*show) (struct efivar_entry *entry, char *buf);
 122         ssize_t (*store)(struct efivar_entry *entry, const char *buf, size_t count);
 123 };
 124
 125 #define PSTORE_EFI_ATTRIBUTES \
 126         (EFI_VARIABLE_NON_VOLATILE | \
 127          EFI_VARIABLE_BOOTSERVICE_ACCESS | \
 128          EFI_VARIABLE_RUNTIME_ACCESS)
 129
 130 #define EFIVAR_ATTR(_name, _mode, _show, _store) \
 131 struct efivar_attribute efivar_attr_##_name = { \
 132         .attr = {.name = __stringify(_name), .mode = _mode}, \
 133         .show = _show, \
 134         .store = _store, \
 135 };
 136
 137 #define to_efivar_attr(_attr) container_of(_attr, struct efivar_attribute, attr)
 138 #define to_efivar_entry(obj)  container_of(obj, struct efivar_entry, kobj)
 139
 140 /*
 141  * Prototype for sysfs creation function
 142  */
 143 static int
 144 efivar_create_sysfs_entry(struct efivars *efivars,
 145                           unsigned long variable_name_size,
 146                           efi_char16_t *variable_name,
 147                           efi_guid_t *vendor_guid);
 148
 149 /* Return the number of unicode characters in data */
 150 static unsigned long
 151 utf16_strnlen(efi_char16_t *s, size_t maxlength)
 152 {
 153         unsigned long length = 0;
 154
 155         while (*s++ != 0 && length < maxlength)
 156                 length++;
 157         return length;
 158 }
 159
 160 static inline unsigned long
 161 utf16_strlen(efi_char16_t *s)
 162 {
 163         return utf16_strnlen(s, ~0UL);
 164 }
 165
 166 /*
 167  * Return the number of bytes is the length of this string
 168  * Note: this is NOT the same as the number of unicode characters
 169  */
 170 static inline unsigned long
 171 utf16_strsize(efi_char16_t *data, unsigned long maxlength)
 172 {
 173         return utf16_strnlen(data, maxlength/sizeof(efi_char16_t)) * sizeof(efi_char16_t);
 174 }
 175
 176 static inline int
 177 utf16_strncmp(const efi_char16_t *a, const efi_char16_t *b, size_t len)
 178 {
 179         while (1) {
 180                 if (len == 0)
 181                         return 0;
 182                 if (*a < *b)
 183                         return -1;
 184                 if (*a > *b)
 185                         return 1;
 186                 if (*a == 0) /* implies *b == 0 */
 187                         return 0;
 188                 a++;
 189                 b++;
 190                 len--;
 191         }
 192 }
 193
 194 static efi_status_t
 195 get_var_data_locked(struct efivars *efivars, struct efi_variable *var)
 196 {
 197         efi_status_t status;
 198
 199         var->DataSize = 1024;
 200         status = efivars->ops->get_variable(var->VariableName,
 201                                             &var->VendorGuid,
 202                                             &var->Attributes,
 203                                             &var->DataSize,
 204                                             var->Data);
 205         return status;
 206 }
 207
 208 static efi_status_t
 209 get_var_data(struct efivars *efivars, struct efi_variable *var)
 210 {
 211         efi_status_t status;
 212
 213         spin_lock(&efivars->lock);
 214         status = get_var_data_locked(efivars, var);
 215         spin_unlock(&efivars->lock);
 216
 217         if (status != EFI_SUCCESS) {
 218                 printk(KERN_WARNING "efivars: get_variable() failed 0x%lx!\n",
 219                         status);
 220         }
 221         return status;
 222 }
 223
 224 static ssize_t
 225 efivar_guid_read(struct efivar_entry *entry, char *buf)
 226 {
 227         struct efi_variable *var = &entry->var;
 228         char *str = buf;
 229
 230         if (!entry || !buf)
 231                 return 0;
 232
 233         efi_guid_unparse(&var->VendorGuid, str);
 234         str += strlen(str);
 235         str += sprintf(str, "\n");
 236
 237         return str - buf;
 238 }
 239
 240 static ssize_t
 241 efivar_attr_read(struct efivar_entry *entry, char *buf)
 242 {
 243         struct efi_variable *var = &entry->var;
 244         char *str = buf;
 245         efi_status_t status;
 246
 247         if (!entry || !buf)
 248                 return -EINVAL;
 249
 250         status = get_var_data(entry->efivars, var);
 251         if (status != EFI_SUCCESS)
 252                 return -EIO;
 253
 254         if (var->Attributes & 0x1)
 255                 str += sprintf(str, "EFI_VARIABLE_NON_VOLATILE\n");
 256         if (var->Attributes & 0x2)
 257                 str += sprintf(str, "EFI_VARIABLE_BOOTSERVICE_ACCESS\n");
 258         if (var->Attributes & 0x4)
 259                 str += sprintf(str, "EFI_VARIABLE_RUNTIME_ACCESS\n");
 260         return str - buf;
 261 }
 262
 263 static ssize_t
 264 efivar_size_read(struct efivar_entry *entry, char *buf)
 265 {
 266         struct efi_variable *var = &entry->var;
 267         char *str = buf;
 268         efi_status_t status;
 269
 270         if (!entry || !buf)
 271                 return -EINVAL;
 272
 273         status = get_var_data(entry->efivars, var);
 274         if (status != EFI_SUCCESS)
 275                 return -EIO;
 276
 277         str += sprintf(str, "0x%lx\n", var->DataSize);
 278         return str - buf;
 279 }
 280
 281 static ssize_t
 282 efivar_data_read(struct efivar_entry *entry, char *buf)
 283 {
 284         struct efi_variable *var = &entry->var;
 285         efi_status_t status;
 286
 287         if (!entry || !buf)
 288                 return -EINVAL;
 289
 290         status = get_var_data(entry->efivars, var);
 291         if (status != EFI_SUCCESS)
 292                 return -EIO;
 293
 294         memcpy(buf, var->Data, var->DataSize);
 295         return var->DataSize;
 296 }
 297 /*
 298  * We allow each variable to be edited via rewriting the
 299  * entire efi variable structure.
 300  */
 301 static ssize_t
 302 efivar_store_raw(struct efivar_entry *entry, const char *buf, size_t count)
 303 {
 304         struct efi_variable *new_var, *var = &entry->var;
 305         struct efivars *efivars = entry->efivars;
 306         efi_status_t status = EFI_NOT_FOUND;
 307
 308         if (count != sizeof(struct efi_variable))
 309                 return -EINVAL;
 310
 311         new_var = (struct efi_variable *)buf;
 312         /*
 313          * If only updating the variable data, then the name
 314          * and guid should remain the same
 315          */
 316         if (memcmp(new_var->VariableName, var->VariableName, sizeof(var->VariableName)) ||
 317                 efi_guidcmp(new_var->VendorGuid, var->VendorGuid)) {
 318                 printk(KERN_ERR "efivars: Cannot edit the wrong variable!\n");
 319                 return -EINVAL;
 320         }
 321
 322         if ((new_var->DataSize <= 0) || (new_var->Attributes == 0)){
 323                 printk(KERN_ERR "efivars: DataSize & Attributes must be valid!\n");
 324                 return -EINVAL;
 325         }
 326
 327         spin_lock(&efivars->lock);
 328         status = efivars->ops->set_variable(new_var->VariableName,
 329                                             &new_var->VendorGuid,
 330                                             new_var->Attributes,
 331                                             new_var->DataSize,
 332                                             new_var->Data);
 333
 334         spin_unlock(&efivars->lock);
 335
 336         if (status != EFI_SUCCESS) {
 337                 printk(KERN_WARNING "efivars: set_variable() failed: status=%lx\n",
 338                         status);
 339                 return -EIO;
 340         }
 341
 342         memcpy(&entry->var, new_var, count);
 343         return count;
 344 }
 345
 346 static ssize_t
 347 efivar_show_raw(struct efivar_entry *entry, char *buf)
 348 {
 349         struct efi_variable *var = &entry->var;
 350         efi_status_t status;
 351
 352         if (!entry || !buf)
 353                 return 0;
 354
 355         status = get_var_data(entry->efivars, var);
 356         if (status != EFI_SUCCESS)
 357                 return -EIO;
 358
 359         memcpy(buf, var, sizeof(*var));
 360         return sizeof(*var);
 361 }
 362
 363 /*
 364  * Generic read/write functions that call the specific functions of
 365  * the attributes...
 366  */
 367 static ssize_t efivar_attr_show(struct kobject *kobj, struct attribute *attr,
 368                                 char *buf)
 369 {
 370         struct efivar_entry *var = to_efivar_entry(kobj);
 371         struct efivar_attribute *efivar_attr = to_efivar_attr(attr);
 372         ssize_t ret = -EIO;
 373
 374         if (!capable(CAP_SYS_ADMIN))
 375                 return -EACCES;
 376
 377         if (efivar_attr->show) {
 378                 ret = efivar_attr->show(var, buf);
 379         }
 380         return ret;
 381 }
 382
 383 static ssize_t efivar_attr_store(struct kobject *kobj, struct attribute *attr,
 384                                 const char *buf, size_t count)
 385 {
 386         struct efivar_entry *var = to_efivar_entry(kobj);
 387         struct efivar_attribute *efivar_attr = to_efivar_attr(attr);
 388         ssize_t ret = -EIO;
 389
 390         if (!capable(CAP_SYS_ADMIN))
 391                 return -EACCES;
 392
 393         if (efivar_attr->store)
 394                 ret = efivar_attr->store(var, buf, count);
 395
 396         return ret;
 397 }
 398
 399 static const struct sysfs_ops efivar_attr_ops = {
 400         .show = efivar_attr_show,
 401         .store = efivar_attr_store,
 402 };
 403
 404 static void efivar_release(struct kobject *kobj)
 405 {
 406         struct efivar_entry *var = container_of(kobj, struct efivar_entry, kobj);
 407         kfree(var);
 408 }
 409
 410 static EFIVAR_ATTR(guid, 0400, efivar_guid_read, NULL);
 411 static EFIVAR_ATTR(attributes, 0400, efivar_attr_read, NULL);
 412 static EFIVAR_ATTR(size, 0400, efivar_size_read, NULL);
 413 static EFIVAR_ATTR(data, 0400, efivar_data_read, NULL);
 414 static EFIVAR_ATTR(raw_var, 0600, efivar_show_raw, efivar_store_raw);
 415
 416 static struct attribute *def_attrs[] = {
 417         &efivar_attr_guid.attr,
 418         &efivar_attr_size.attr,
 419         &efivar_attr_attributes.attr,
 420         &efivar_attr_data.attr,
 421         &efivar_attr_raw_var.attr,
 422         NULL,
 423 };
 424
 425 static struct kobj_type efivar_ktype = {
 426         .release = efivar_release,
 427         .sysfs_ops = &efivar_attr_ops,
 428         .default_attrs = def_attrs,
 429 };
 430
 431 static struct pstore_info efi_pstore_info;
 432
 433 static inline void
 434 efivar_unregister(struct efivar_entry *var)
 435 {
 436         kobject_put(&var->kobj);
 437 }
 438
 439 #ifdef CONFIG_PSTORE
 440
 441 static int efi_pstore_open(struct pstore_info *psi)
 442 {
 443         struct efivars *efivars = psi->data;
 444
 445         spin_lock(&efivars->lock);
 446         efivars->walk_entry = list_first_entry(&efivars->list,
 447                                                struct efivar_entry, list);
 448         return 0;
 449 }
 450
 451 static int efi_pstore_close(struct pstore_info *psi)
 452 {
 453         struct efivars *efivars = psi->data;
 454
 455         spin_unlock(&efivars->lock);
 456         return 0;
 457 }
 458
 459 static ssize_t efi_pstore_read(u64 *id, enum pstore_type_id *type,
 460                                struct timespec *timespec, struct pstore_info *psi)
 461 {
 462         efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
 463         struct efivars *efivars = psi->data;
 464         char name[DUMP_NAME_LEN];
 465         int i;
 466         unsigned int part, size;
 467         unsigned long time;
 468
 469         while (&efivars->walk_entry->list != &efivars->list) {
 470                 if (!efi_guidcmp(efivars->walk_entry->var.VendorGuid,
 471                                  vendor)) {
 472                         for (i = 0; i < DUMP_NAME_LEN; i++) {
 473                                 name[i] = efivars->walk_entry->var.VariableName[i];
 474                         }
 475                         if (sscanf(name, "dump-type%u-%u-%lu", type, &part, &time) == 3) {
 476                                 *id = part;
 477                                 timespec->tv_sec = time;
 478                                 timespec->tv_nsec = 0;
 479                                 get_var_data_locked(efivars, &efivars->walk_entry->var);
 480                                 size = efivars->walk_entry->var.DataSize;
 481                                 memcpy(psi->buf, efivars->walk_entry->var.Data, size);
 482                                 efivars->walk_entry = list_entry(efivars->walk_entry->list.next,
 483                                                    struct efivar_entry, list);
 484                                 return size;
 485                         }
 486                 }
 487                 efivars->walk_entry = list_entry(efivars->walk_entry->list.next,
 488                                                  struct efivar_entry, list);
 489         }
 490         return 0;
 491 }
 492
 493 static int efi_pstore_write(enum pstore_type_id type, u64 *id,
 494                 unsigned int part, size_t size, struct pstore_info *psi)
 495 {
 496         char name[DUMP_NAME_LEN];
 497         char stub_name[DUMP_NAME_LEN];
 498         efi_char16_t efi_name[DUMP_NAME_LEN];
 499         efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
 500         struct efivars *efivars = psi->data;
 501         struct efivar_entry *entry, *found = NULL;
 502         int i, ret = 0;
 503
 504         sprintf(stub_name, "dump-type%u-%u-", type, part);
 505         sprintf(name, "%s%lu", stub_name, get_seconds());
 506
 507         spin_lock(&efivars->lock);
 508
 509         for (i = 0; i < DUMP_NAME_LEN; i++)
 510                 efi_name[i] = stub_name[i];
 511
 512         /*
 513          * Clean up any entries with the same name
 514          */
 515
 516         list_for_each_entry(entry, &efivars->list, list) {
 517                 get_var_data_locked(efivars, &entry->var);
 518
 519                 if (efi_guidcmp(entry->var.VendorGuid, vendor))
 520                         continue;
 521                 if (utf16_strncmp(entry->var.VariableName, efi_name,
 522                                   utf16_strlen(efi_name)))
 523                         continue;
 524                 /* Needs to be a prefix */
 525                 if (entry->var.VariableName[utf16_strlen(efi_name)] == 0)
 526                         continue;
 527
 528                 /* found */
 529                 found = entry;
 530                 efivars->ops->set_variable(entry->var.VariableName,
 531                                            &entry->var.VendorGuid,
 532                                            PSTORE_EFI_ATTRIBUTES,
 533                                            0, NULL);
 534         }
 535
 536         if (found)
 537                 list_del(&found->list);
 538
 539         for (i = 0; i < DUMP_NAME_LEN; i++)
 540                 efi_name[i] = name[i];
 541
 542         efivars->ops->set_variable(efi_name, &vendor, PSTORE_EFI_ATTRIBUTES,
 543                                    size, psi->buf);
 544
 545         spin_unlock(&efivars->lock);
 546
 547         if (found)
 548                 efivar_unregister(found);
 549
 550         if (size)
 551                 ret = efivar_create_sysfs_entry(efivars,
 552                                           utf16_strsize(efi_name,
 553                                                         DUMP_NAME_LEN * 2),
 554                                           efi_name, &vendor);
 555
 556         *id = part;
 557         return ret;
 558 };
 559
 560 static int efi_pstore_erase(enum pstore_type_id type, u64 id,
 561                             struct pstore_info *psi)
 562 {
 563         efi_pstore_write(type, &id, (unsigned int)id, 0, psi);
 564
 565         return 0;
 566 }
 567 #else
 568 static int efi_pstore_open(struct pstore_info *psi)
 569 {
 570         return 0;
 571 }
 572
 573 static int efi_pstore_close(struct pstore_info *psi)
 574 {
 575         return 0;
 576 }
 577
 578 static ssize_t efi_pstore_read(u64 *id, enum pstore_type_id *type,
 579                                struct timespec *time, struct pstore_info *psi)
 580 {
 581         return -1;
 582 }
 583
 584 static int efi_pstore_write(enum pstore_type_id type, u64 *id,
 585                 unsigned int part, size_t size, struct pstore_info *psi)
 586 {
 587         return 0;
 588 }
 589
 590 static int efi_pstore_erase(enum pstore_type_id type, u64 id,
 591                             struct pstore_info *psi)
 592 {
 593         return 0;
 594 }
 595 #endif
 596
 597 static struct pstore_info efi_pstore_info = {
 598         .owner          = THIS_MODULE,
 599         .name           = "efi",
 600         .open           = efi_pstore_open,
 601         .close          = efi_pstore_close,
 602         .read           = efi_pstore_read,
 603         .write          = efi_pstore_write,
 604         .erase          = efi_pstore_erase,
 605 };
 606
 607 static ssize_t efivar_create(struct file *filp, struct kobject *kobj,
 608                              struct bin_attribute *bin_attr,
 609                              char *buf, loff_t pos, size_t count)
 610 {
 611         struct efi_variable *new_var = (struct efi_variable *)buf;
 612         struct efivars *efivars = bin_attr->private;
 613         struct efivar_entry *search_efivar, *n;
 614         unsigned long strsize1, strsize2;
 615         efi_status_t status = EFI_NOT_FOUND;
 616         int found = 0;
 617
 618         if (!capable(CAP_SYS_ADMIN))
 619                 return -EACCES;
 620
 621         spin_lock(&efivars->lock);
 622
 623         /*
 624          * Does this variable already exist?
 625          */
 626         list_for_each_entry_safe(search_efivar, n, &efivars->list, list) {
 627                 strsize1 = utf16_strsize(search_efivar->var.VariableName, 1024);
 628                 strsize2 = utf16_strsize(new_var->VariableName, 1024);
 629                 if (strsize1 == strsize2 &&
 630                         !memcmp(&(search_efivar->var.VariableName),
 631                                 new_var->VariableName, strsize1) &&
 632                         !efi_guidcmp(search_efivar->var.VendorGuid,
 633                                 new_var->VendorGuid)) {
 634                         found = 1;
 635                         break;
 636                 }
 637         }
 638         if (found) {
 639                 spin_unlock(&efivars->lock);
 640                 return -EINVAL;
 641         }
 642
 643         /* now *really* create the variable via EFI */
 644         status = efivars->ops->set_variable(new_var->VariableName,
 645                                             &new_var->VendorGuid,
 646                                             new_var->Attributes,
 647                                             new_var->DataSize,
 648                                             new_var->Data);
 649
 650         if (status != EFI_SUCCESS) {
 651                 printk(KERN_WARNING "efivars: set_variable() failed: status=%lx\n",
 652                         status);
 653                 spin_unlock(&efivars->lock);
 654                 return -EIO;
 655         }
 656         spin_unlock(&efivars->lock);
 657
 658         /* Create the entry in sysfs.  Locking is not required here */
 659         status = efivar_create_sysfs_entry(efivars,
 660                                            utf16_strsize(new_var->VariableName,
 661                                                          1024),
 662                                            new_var->VariableName,
 663                                            &new_var->VendorGuid);
 664         if (status) {
 665                 printk(KERN_WARNING "efivars: variable created, but sysfs entry wasn't.\n");
 666         }
 667         return count;
 668 }
 669
 670 static ssize_t efivar_delete(struct file *filp, struct kobject *kobj,
 671                              struct bin_attribute *bin_attr,
 672                              char *buf, loff_t pos, size_t count)
 673 {
 674         struct efi_variable *del_var = (struct efi_variable *)buf;
 675         struct efivars *efivars = bin_attr->private;
 676         struct efivar_entry *search_efivar, *n;
 677         unsigned long strsize1, strsize2;
 678         efi_status_t status = EFI_NOT_FOUND;
 679         int found = 0;
 680
 681         if (!capable(CAP_SYS_ADMIN))
 682                 return -EACCES;
 683
 684         spin_lock(&efivars->lock);
 685
 686         /*
 687          * Does this variable already exist?
 688          */
 689         list_for_each_entry_safe(search_efivar, n, &efivars->list, list) {
 690                 strsize1 = utf16_strsize(search_efivar->var.VariableName, 1024);
 691                 strsize2 = utf16_strsize(del_var->VariableName, 1024);
 692                 if (strsize1 == strsize2 &&
 693                         !memcmp(&(search_efivar->var.VariableName),
 694                                 del_var->VariableName, strsize1) &&
 695                         !efi_guidcmp(search_efivar->var.VendorGuid,
 696                                 del_var->VendorGuid)) {
 697                         found = 1;
 698                         break;
 699                 }
 700         }
 701         if (!found) {
 702                 spin_unlock(&efivars->lock);
 703                 return -EINVAL;
 704         }
 705         /* force the Attributes/DataSize to 0 to ensure deletion */
 706         del_var->Attributes = 0;
 707         del_var->DataSize = 0;
 708
 709         status = efivars->ops->set_variable(del_var->VariableName,
 710                                             &del_var->VendorGuid,
 711                                             del_var->Attributes,
 712                                             del_var->DataSize,
 713                                             del_var->Data);
 714
 715         if (status != EFI_SUCCESS) {
 716                 printk(KERN_WARNING "efivars: set_variable() failed: status=%lx\n",
 717                         status);
 718                 spin_unlock(&efivars->lock);
 719                 return -EIO;
 720         }
 721         list_del(&search_efivar->list);
 722         /* We need to release this lock before unregistering. */
 723         spin_unlock(&efivars->lock);
 724         efivar_unregister(search_efivar);
 725
 726         /* It's dead Jim.... */
 727         return count;
 728 }
 729
 730 /*
 731  * Let's not leave out systab information that snuck into
 732  * the efivars driver
 733  */
 734 static ssize_t systab_show(struct kobject *kobj,
 735                            struct kobj_attribute *attr, char *buf)
 736 {
 737         char *str = buf;
 738
 739         if (!kobj || !buf)
 740                 return -EINVAL;
 741
 742         if (efi.mps != EFI_INVALID_TABLE_ADDR)
 743                 str += sprintf(str, "MPS=0x%lx\n", efi.mps);
 744         if (efi.acpi20 != EFI_INVALID_TABLE_ADDR)
 745                 str += sprintf(str, "ACPI20=0x%lx\n", efi.acpi20);
 746         if (efi.acpi != EFI_INVALID_TABLE_ADDR)
 747                 str += sprintf(str, "ACPI=0x%lx\n", efi.acpi);
 748         if (efi.smbios != EFI_INVALID_TABLE_ADDR)
 749                 str += sprintf(str, "SMBIOS=0x%lx\n", efi.smbios);
 750         if (efi.hcdp != EFI_INVALID_TABLE_ADDR)
 751                 str += sprintf(str, "HCDP=0x%lx\n", efi.hcdp);
 752         if (efi.boot_info != EFI_INVALID_TABLE_ADDR)
 753                 str += sprintf(str, "BOOTINFO=0x%lx\n", efi.boot_info);
 754         if (efi.uga != EFI_INVALID_TABLE_ADDR)
 755                 str += sprintf(str, "UGA=0x%lx\n", efi.uga);
 756
 757         return str - buf;
 758 }
 759
 760 static struct kobj_attribute efi_attr_systab =
 761                         __ATTR(systab, 0400, systab_show, NULL);
 762
 763 static struct attribute *efi_subsys_attrs[] = {
 764         &efi_attr_systab.attr,
 765         NULL,   /* maybe more in the future? */
 766 };
 767
 768 static struct attribute_group efi_subsys_attr_group = {
 769         .attrs = efi_subsys_attrs,
 770 };
 771
 772 static struct kobject *efi_kobj;
 773
 774 /*
 775  * efivar_create_sysfs_entry()
 776  * Requires:
 777  *    variable_name_size = number of bytes required to hold
 778  *                         variable_name (not counting the NULL
 779  *                         character at the end.
 780  *    efivars->lock is not held on entry or exit.
 781  * Returns 1 on failure, 0 on success
 782  */
 783 static int
 784 efivar_create_sysfs_entry(struct efivars *efivars,
 785                           unsigned long variable_name_size,
 786                           efi_char16_t *variable_name,
 787                           efi_guid_t *vendor_guid)
 788 {
 789         int i, short_name_size = variable_name_size / sizeof(efi_char16_t) + 38;
 790         char *short_name;
 791         struct efivar_entry *new_efivar;
 792
 793         short_name = kzalloc(short_name_size + 1, GFP_KERNEL);
 794         new_efivar = kzalloc(sizeof(struct efivar_entry), GFP_KERNEL);
 795
 796         if (!short_name || !new_efivar)  {
 797                 kfree(short_name);
 798                 kfree(new_efivar);
 799                 return 1;
 800         }
 801
 802         new_efivar->efivars = efivars;
 803         memcpy(new_efivar->var.VariableName, variable_name,
 804                 variable_name_size);
 805         memcpy(&(new_efivar->var.VendorGuid), vendor_guid, sizeof(efi_guid_t));
 806
 807         /* Convert Unicode to normal chars (assume top bits are 0),
 808            ala UTF-8 */
 809         for (i=0; i < (int)(variable_name_size / sizeof(efi_char16_t)); i++) {
 810                 short_name[i] = variable_name[i] & 0xFF;
 811         }
 812         /* This is ugly, but necessary to separate one vendor's
 813            private variables from another's.         */
 814
 815         *(short_name + strlen(short_name)) = '-';
 816         efi_guid_unparse(vendor_guid, short_name + strlen(short_name));
 817
 818         new_efivar->kobj.kset = efivars->kset;
 819         i = kobject_init_and_add(&new_efivar->kobj, &efivar_ktype, NULL,
 820                                  "%s", short_name);
 821         if (i) {
 822                 kfree(short_name);
 823                 kfree(new_efivar);
 824                 return 1;
 825         }
 826
 827         kobject_uevent(&new_efivar->kobj, KOBJ_ADD);
 828         kfree(short_name);
 829         short_name = NULL;
 830
 831         spin_lock(&efivars->lock);
 832         list_add(&new_efivar->list, &efivars->list);
 833         spin_unlock(&efivars->lock);
 834
 835         return 0;
 836 }
 837
 838 static int
 839 create_efivars_bin_attributes(struct efivars *efivars)
 840 {
 841         struct bin_attribute *attr;
 842         int error;
 843
 844         /* new_var */
 845         attr = kzalloc(sizeof(*attr), GFP_KERNEL);
 846         if (!attr)
 847                 return -ENOMEM;
 848
 849         attr->attr.name = "new_var";
 850         attr->attr.mode = 0200;
 851         attr->write = efivar_create;
 852         attr->private = efivars;
 853         efivars->new_var = attr;
 854
 855         /* del_var */
 856         attr = kzalloc(sizeof(*attr), GFP_KERNEL);
 857         if (!attr) {
 858                 error = -ENOMEM;
 859                 goto out_free;
 860         }
 861         attr->attr.name = "del_var";
 862         attr->attr.mode = 0200;
 863         attr->write = efivar_delete;
 864         attr->private = efivars;
 865         efivars->del_var = attr;
 866
 867         sysfs_bin_attr_init(efivars->new_var);
 868         sysfs_bin_attr_init(efivars->del_var);
 869
 870         /* Register */
 871         error = sysfs_create_bin_file(&efivars->kset->kobj,
 872                                       efivars->new_var);
 873         if (error) {
 874                 printk(KERN_ERR "efivars: unable to create new_var sysfs file"
 875                         " due to error %d\n", error);
 876                 goto out_free;
 877         }
 878         error = sysfs_create_bin_file(&efivars->kset->kobj,
 879                                       efivars->del_var);
 880         if (error) {
 881                 printk(KERN_ERR "efivars: unable to create del_var sysfs file"
 882                         " due to error %d\n", error);
 883                 sysfs_remove_bin_file(&efivars->kset->kobj,
 884                                       efivars->new_var);
 885                 goto out_free;
 886         }
 887
 888         return 0;
 889 out_free:
 890         kfree(efivars->del_var);
 891         efivars->del_var = NULL;
 892         kfree(efivars->new_var);
 893         efivars->new_var = NULL;
 894         return error;
 895 }
 896
 897 void unregister_efivars(struct efivars *efivars)
 898 {
 899         struct efivar_entry *entry, *n;
 900
 901         list_for_each_entry_safe(entry, n, &efivars->list, list) {
 902                 spin_lock(&efivars->lock);
 903                 list_del(&entry->list);
 904                 spin_unlock(&efivars->lock);
 905                 efivar_unregister(entry);
 906         }
 907         if (efivars->new_var)
 908                 sysfs_remove_bin_file(&efivars->kset->kobj, efivars->new_var);
 909         if (efivars->del_var)
 910                 sysfs_remove_bin_file(&efivars->kset->kobj, efivars->del_var);
 911         kfree(efivars->new_var);
 912         kfree(efivars->del_var);
 913         kset_unregister(efivars->kset);
 914 }
 915 EXPORT_SYMBOL_GPL(unregister_efivars);
 916
 917 int register_efivars(struct efivars *efivars,
 918                      const struct efivar_operations *ops,
 919                      struct kobject *parent_kobj)
 920 {
 921         efi_status_t status = EFI_NOT_FOUND;
 922         efi_guid_t vendor_guid;
 923         efi_char16_t *variable_name;
 924         unsigned long variable_name_size = 1024;
 925         int error = 0;
 926
 927         variable_name = kzalloc(variable_name_size, GFP_KERNEL);
 928         if (!variable_name) {
 929                 printk(KERN_ERR "efivars: Memory allocation failed.\n");
 930                 return -ENOMEM;
 931         }
 932
 933         spin_lock_init(&efivars->lock);
 934         INIT_LIST_HEAD(&efivars->list);
 935         efivars->ops = ops;
 936
 937         efivars->kset = kset_create_and_add("vars", NULL, parent_kobj);
 938         if (!efivars->kset) {
 939                 printk(KERN_ERR "efivars: Subsystem registration failed.\n");
 940                 error = -ENOMEM;
 941                 goto out;
 942         }
 943
 944         /*
 945          * Per EFI spec, the maximum storage allocated for both
 946          * the variable name and variable data is 1024 bytes.
 947          */
 948
 949         do {
 950                 variable_name_size = 1024;
 951
 952                 status = ops->get_next_variable(&variable_name_size,
 953                                                 variable_name,
 954                                                 &vendor_guid);
 955                 switch (status) {
 956                 case EFI_SUCCESS:
 957                         efivar_create_sysfs_entry(efivars,
 958                                                   variable_name_size,
 959                                                   variable_name,
 960                                                   &vendor_guid);
 961                         break;
 962                 case EFI_NOT_FOUND:
 963                         break;
 964                 default:
 965                         printk(KERN_WARNING "efivars: get_next_variable: status=%lx\n",
 966                                 status);
 967                         status = EFI_NOT_FOUND;
 968                         break;
 969                 }
 970         } while (status != EFI_NOT_FOUND);
 971
 972         error = create_efivars_bin_attributes(efivars);
 973         if (error)
 974                 unregister_efivars(efivars);
 975
 976         efivars->efi_pstore_info = efi_pstore_info;
 977
 978         efivars->efi_pstore_info.buf = kmalloc(4096, GFP_KERNEL);
 979         if (efivars->efi_pstore_info.buf) {
 980                 efivars->efi_pstore_info.bufsize = 1024;
 981                 efivars->efi_pstore_info.data = efivars;
 982                 spin_lock_init(&efivars->efi_pstore_info.buf_lock);
 983                 pstore_register(&efivars->efi_pstore_info);
 984         }
 985
 986 out:
 987         kfree(variable_name);
 988
 989         return error;
 990 }
 991 EXPORT_SYMBOL_GPL(register_efivars);
 992
 993 static struct efivars __efivars;
 994 static struct efivar_operations ops;
 995
 996 /*
 997  * For now we register the efi subsystem with the firmware subsystem
 998  * and the vars subsystem with the efi subsystem.  In the future, it
 999  * might make sense to split off the efi subsystem into its own
1000  * driver, but for now only efivars will register with it, so just
1001  * include it here.
1002  */
1003
1004 static int __init
1005 efivars_init(void)
1006 {
1007         int error = 0;
1008
1009         printk(KERN_INFO "EFI Variables Facility v%s %s\n", EFIVARS_VERSION,
1010                EFIVARS_DATE);
1011
1012         if (!efi_enabled)
1013                 return 0;
1014
1015         /* For now we'll register the efi directory at /sys/firmware/efi */
1016         efi_kobj = kobject_create_and_add("efi", firmware_kobj);
1017         if (!efi_kobj) {
1018                 printk(KERN_ERR "efivars: Firmware registration failed.\n");
1019                 return -ENOMEM;
1020         }
1021
1022         ops.get_variable = efi.get_variable;
1023         ops.set_variable = efi.set_variable;
1024         ops.get_next_variable = efi.get_next_variable;
1025         error = register_efivars(&__efivars, &ops, efi_kobj);
1026         if (error)
1027                 goto err_put;
1028
1029         /* Don't forget the systab entry */
1030         error = sysfs_create_group(efi_kobj, &efi_subsys_attr_group);
1031         if (error) {
1032                 printk(KERN_ERR
1033                        "efivars: Sysfs attribute export failed with error %d.\n",
1034                        error);
1035                 goto err_unregister;
1036         }
1037
1038         return 0;
1039
1040 err_unregister:
1041         unregister_efivars(&__efivars);
1042 err_put:
1043         kobject_put(efi_kobj);
1044         return error;
1045 }
1046
1047 static void __exit
1048 efivars_exit(void)
1049 {
1050         if (efi_enabled) {
1051                 unregister_efivars(&__efivars);
1052                 kobject_put(efi_kobj);
1053         }
1054 }
1055
1056 module_init(efivars_init);
1057 module_exit(efivars_exit);
1058