drivers/firmware/efi/runtime-wrappers.c

   1 /*
   2  * runtime-wrappers.c - Runtime Services function call wrappers
   3  *
   4  * Implementation summary:
   5  * -----------------------
   6  * 1. When user/kernel thread requests to execute efi_runtime_service(),
   7  * enqueue work to efi_rts_wq.
   8  * 2. Caller thread waits for completion until the work is finished
   9  * because it's dependent on the return status and execution of
  10  * efi_runtime_service().
  11  * For instance, get_variable() and get_next_variable().
  12  *
  13  * Copyright (C) 2014 Linaro Ltd. <ard.biesheuvel@linaro.org>
  14  *
  15  * Split off from arch/x86/platform/efi/efi.c
  16  *
  17  * Copyright (C) 1999 VA Linux Systems
  18  * Copyright (C) 1999 Walt Drummond <drummond@valinux.com>
  19  * Copyright (C) 1999-2002 Hewlett-Packard Co.
  20  * Copyright (C) 2005-2008 Intel Co.
  21  * Copyright (C) 2013 SuSE Labs
  22  *
  23  * This file is released under the GPLv2.
  24  */
  25
  26 #define pr_fmt(fmt)     "efi: " fmt
  27
  28 #include <linux/bug.h>
  29 #include <linux/efi.h>
  30 #include <linux/irqflags.h>
  31 #include <linux/mutex.h>
  32 #include <linux/semaphore.h>
  33 #include <linux/stringify.h>
  34 #include <linux/workqueue.h>
  35 #include <linux/completion.h>
  36
  37 #include <asm/efi.h>
  38
  39 /*
  40  * Wrap around the new efi_call_virt_generic() macros so that the
  41  * code doesn't get too cluttered:
  42  */
  43 #define efi_call_virt(f, args...)   \
  44         efi_call_virt_pointer(efi.systab->runtime, f, args)
  45 #define __efi_call_virt(f, args...) \
  46         __efi_call_virt_pointer(efi.systab->runtime, f, args)
  47
  48 struct efi_runtime_work efi_rts_work;
  49
  50 /*
  51  * efi_queue_work:      Queue efi_runtime_service() and wait until it's done
  52  * @rts:                efi_runtime_service() function identifier
  53  * @rts_arg<1-5>:       efi_runtime_service() function arguments
  54  *
  55  * Accesses to efi_runtime_services() are serialized by a binary
  56  * semaphore (efi_runtime_lock) and caller waits until the work is
  57  * finished, hence _only_ one work is queued at a time and the caller
  58  * thread waits for completion.
  59  */
  60 #define efi_queue_work(_rts, _arg1, _arg2, _arg3, _arg4, _arg5)         \
  61 ({                                                                      \
  62         efi_rts_work.status = EFI_ABORTED;                              \
  63                                                                         \
  64         if (!efi_enabled(EFI_RUNTIME_SERVICES)) {                       \
  65                 pr_warn_once("EFI Runtime Services are disabled!\n");   \
  66                 goto exit;                                              \
  67         }                                                               \
  68                                                                         \
  69         init_completion(&efi_rts_work.efi_rts_comp);                    \
  70         INIT_WORK(&efi_rts_work.work, efi_call_rts);                    \
  71         efi_rts_work.arg1 = _arg1;                                      \
  72         efi_rts_work.arg2 = _arg2;                                      \
  73         efi_rts_work.arg3 = _arg3;                                      \
  74         efi_rts_work.arg4 = _arg4;                                      \
  75         efi_rts_work.arg5 = _arg5;                                      \
  76         efi_rts_work.efi_rts_id = _rts;                                 \
  77                                                                         \
  78         /*                                                              \
  79          * queue_work() returns 0 if work was already on queue,         \
  80          * _ideally_ this should never happen.                          \
  81          */                                                             \
  82         if (queue_work(efi_rts_wq, &efi_rts_work.work))                 \
  83                 wait_for_completion(&efi_rts_work.efi_rts_comp);        \
  84         else                                                            \
  85                 pr_err("Failed to queue work to efi_rts_wq.\n");        \
  86                                                                         \
  87 exit:                                                                   \
  88         efi_rts_work.efi_rts_id = NONE;                                 \
  89         efi_rts_work.status;                                            \
  90 })
  91
  92 void efi_call_virt_check_flags(unsigned long flags, const char *call)
  93 {
  94         unsigned long cur_flags, mismatch;
  95
  96         local_save_flags(cur_flags);
  97
  98         mismatch = flags ^ cur_flags;
  99         if (!WARN_ON_ONCE(mismatch & ARCH_EFI_IRQ_FLAGS_MASK))
 100                 return;
 101
 102         add_taint(TAINT_FIRMWARE_WORKAROUND, LOCKDEP_NOW_UNRELIABLE);
 103         pr_err_ratelimited(FW_BUG "IRQ flags corrupted (0x%08lx=>0x%08lx) by EFI %s\n",
 104                            flags, cur_flags, call);
 105         local_irq_restore(flags);
 106 }
 107
 108 /*
 109  * According to section 7.1 of the UEFI spec, Runtime Services are not fully
 110  * reentrant, and there are particular combinations of calls that need to be
 111  * serialized. (source: UEFI Specification v2.4A)
 112  *
 113  * Table 31. Rules for Reentry Into Runtime Services
 114  * +------------------------------------+-------------------------------+
 115  * | If previous call is busy in        | Forbidden to call             |
 116  * +------------------------------------+-------------------------------+
 117  * | Any                                | SetVirtualAddressMap()        |
 118  * +------------------------------------+-------------------------------+
 119  * | ConvertPointer()                   | ConvertPointer()              |
 120  * +------------------------------------+-------------------------------+
 121  * | SetVariable()                      | ResetSystem()                 |
 122  * | UpdateCapsule()                    |                               |
 123  * | SetTime()                          |                               |
 124  * | SetWakeupTime()                    |                               |
 125  * | GetNextHighMonotonicCount()        |                               |
 126  * +------------------------------------+-------------------------------+
 127  * | GetVariable()                      | GetVariable()                 |
 128  * | GetNextVariableName()              | GetNextVariableName()         |
 129  * | SetVariable()                      | SetVariable()                 |
 130  * | QueryVariableInfo()                | QueryVariableInfo()           |
 131  * | UpdateCapsule()                    | UpdateCapsule()               |
 132  * | QueryCapsuleCapabilities()         | QueryCapsuleCapabilities()    |
 133  * | GetNextHighMonotonicCount()        | GetNextHighMonotonicCount()   |
 134  * +------------------------------------+-------------------------------+
 135  * | GetTime()                          | GetTime()                     |
 136  * | SetTime()                          | SetTime()                     |
 137  * | GetWakeupTime()                    | GetWakeupTime()               |
 138  * | SetWakeupTime()                    | SetWakeupTime()               |
 139  * +------------------------------------+-------------------------------+
 140  *
 141  * Due to the fact that the EFI pstore may write to the variable store in
 142  * interrupt context, we need to use a lock for at least the groups that
 143  * contain SetVariable() and QueryVariableInfo(). That leaves little else, as
 144  * none of the remaining functions are actually ever called at runtime.
 145  * So let's just use a single lock to serialize all Runtime Services calls.
 146  */
 147 static DEFINE_SEMAPHORE(efi_runtime_lock);
 148
 149 /*
 150  * Calls the appropriate efi_runtime_service() with the appropriate
 151  * arguments.
 152  *
 153  * Semantics followed by efi_call_rts() to understand efi_runtime_work:
 154  * 1. If argument was a pointer, recast it from void pointer to original
 155  * pointer type.
 156  * 2. If argument was a value, recast it from void pointer to original
 157  * pointer type and dereference it.
 158  */
 159 static void efi_call_rts(struct work_struct *work)
 160 {
 161         void *arg1, *arg2, *arg3, *arg4, *arg5;
 162         efi_status_t status = EFI_NOT_FOUND;
 163
 164         arg1 = efi_rts_work.arg1;
 165         arg2 = efi_rts_work.arg2;
 166         arg3 = efi_rts_work.arg3;
 167         arg4 = efi_rts_work.arg4;
 168         arg5 = efi_rts_work.arg5;
 169
 170         switch (efi_rts_work.efi_rts_id) {
 171         case GET_TIME:
 172                 status = efi_call_virt(get_time, (efi_time_t *)arg1,
 173                                        (efi_time_cap_t *)arg2);
 174                 break;
 175         case SET_TIME:
 176                 status = efi_call_virt(set_time, (efi_time_t *)arg1);
 177                 break;
 178         case GET_WAKEUP_TIME:
 179                 status = efi_call_virt(get_wakeup_time, (efi_bool_t *)arg1,
 180                                        (efi_bool_t *)arg2, (efi_time_t *)arg3);
 181                 break;
 182         case SET_WAKEUP_TIME:
 183                 status = efi_call_virt(set_wakeup_time, *(efi_bool_t *)arg1,
 184                                        (efi_time_t *)arg2);
 185                 break;
 186         case GET_VARIABLE:
 187                 status = efi_call_virt(get_variable, (efi_char16_t *)arg1,
 188                                        (efi_guid_t *)arg2, (u32 *)arg3,
 189                                        (unsigned long *)arg4, (void *)arg5);
 190                 break;
 191         case GET_NEXT_VARIABLE:
 192                 status = efi_call_virt(get_next_variable, (unsigned long *)arg1,
 193                                        (efi_char16_t *)arg2,
 194                                        (efi_guid_t *)arg3);
 195                 break;
 196         case SET_VARIABLE:
 197                 status = efi_call_virt(set_variable, (efi_char16_t *)arg1,
 198                                        (efi_guid_t *)arg2, *(u32 *)arg3,
 199                                        *(unsigned long *)arg4, (void *)arg5);
 200                 break;
 201         case QUERY_VARIABLE_INFO:
 202                 status = efi_call_virt(query_variable_info, *(u32 *)arg1,
 203                                        (u64 *)arg2, (u64 *)arg3, (u64 *)arg4);
 204                 break;
 205         case GET_NEXT_HIGH_MONO_COUNT:
 206                 status = efi_call_virt(get_next_high_mono_count, (u32 *)arg1);
 207                 break;
 208         case UPDATE_CAPSULE:
 209                 status = efi_call_virt(update_capsule,
 210                                        (efi_capsule_header_t **)arg1,
 211                                        *(unsigned long *)arg2,
 212                                        *(unsigned long *)arg3);
 213                 break;
 214         case QUERY_CAPSULE_CAPS:
 215                 status = efi_call_virt(query_capsule_caps,
 216                                        (efi_capsule_header_t **)arg1,
 217                                        *(unsigned long *)arg2, (u64 *)arg3,
 218                                        (int *)arg4);
 219                 break;
 220         default:
 221                 /*
 222                  * Ideally, we should never reach here because a caller of this
 223                  * function should have put the right efi_runtime_service()
 224                  * function identifier into efi_rts_work->efi_rts_id
 225                  */
 226                 pr_err("Requested executing invalid EFI Runtime Service.\n");
 227         }
 228         efi_rts_work.status = status;
 229         complete(&efi_rts_work.efi_rts_comp);
 230 }
 231
 232 static efi_status_t virt_efi_get_time(efi_time_t *tm, efi_time_cap_t *tc)
 233 {
 234         efi_status_t status;
 235
 236         if (down_interruptible(&efi_runtime_lock))
 237                 return EFI_ABORTED;
 238         status = efi_queue_work(GET_TIME, tm, tc, NULL, NULL, NULL);
 239         up(&efi_runtime_lock);
 240         return status;
 241 }
 242
 243 static efi_status_t virt_efi_set_time(efi_time_t *tm)
 244 {
 245         efi_status_t status;
 246
 247         if (down_interruptible(&efi_runtime_lock))
 248                 return EFI_ABORTED;
 249         status = efi_queue_work(SET_TIME, tm, NULL, NULL, NULL, NULL);
 250         up(&efi_runtime_lock);
 251         return status;
 252 }
 253
 254 static efi_status_t virt_efi_get_wakeup_time(efi_bool_t *enabled,
 255                                              efi_bool_t *pending,
 256                                              efi_time_t *tm)
 257 {
 258         efi_status_t status;
 259
 260         if (down_interruptible(&efi_runtime_lock))
 261                 return EFI_ABORTED;
 262         status = efi_queue_work(GET_WAKEUP_TIME, enabled, pending, tm, NULL,
 263                                 NULL);
 264         up(&efi_runtime_lock);
 265         return status;
 266 }
 267
 268 static efi_status_t virt_efi_set_wakeup_time(efi_bool_t enabled, efi_time_t *tm)
 269 {
 270         efi_status_t status;
 271
 272         if (down_interruptible(&efi_runtime_lock))
 273                 return EFI_ABORTED;
 274         status = efi_queue_work(SET_WAKEUP_TIME, &enabled, tm, NULL, NULL,
 275                                 NULL);
 276         up(&efi_runtime_lock);
 277         return status;
 278 }
 279
 280 static efi_status_t virt_efi_get_variable(efi_char16_t *name,
 281                                           efi_guid_t *vendor,
 282                                           u32 *attr,
 283                                           unsigned long *data_size,
 284                                           void *data)
 285 {
 286         efi_status_t status;
 287
 288         if (down_interruptible(&efi_runtime_lock))
 289                 return EFI_ABORTED;
 290         status = efi_queue_work(GET_VARIABLE, name, vendor, attr, data_size,
 291                                 data);
 292         up(&efi_runtime_lock);
 293         return status;
 294 }
 295
 296 static efi_status_t virt_efi_get_next_variable(unsigned long *name_size,
 297                                                efi_char16_t *name,
 298                                                efi_guid_t *vendor)
 299 {
 300         efi_status_t status;
 301
 302         if (down_interruptible(&efi_runtime_lock))
 303                 return EFI_ABORTED;
 304         status = efi_queue_work(GET_NEXT_VARIABLE, name_size, name, vendor,
 305                                 NULL, NULL);
 306         up(&efi_runtime_lock);
 307         return status;
 308 }
 309
 310 static efi_status_t virt_efi_set_variable(efi_char16_t *name,
 311                                           efi_guid_t *vendor,
 312                                           u32 attr,
 313                                           unsigned long data_size,
 314                                           void *data)
 315 {
 316         efi_status_t status;
 317
 318         if (down_interruptible(&efi_runtime_lock))
 319                 return EFI_ABORTED;
 320         status = efi_queue_work(SET_VARIABLE, name, vendor, &attr, &data_size,
 321                                 data);
 322         up(&efi_runtime_lock);
 323         return status;
 324 }
 325
 326 static efi_status_t
 327 virt_efi_set_variable_nonblocking(efi_char16_t *name, efi_guid_t *vendor,
 328                                   u32 attr, unsigned long data_size,
 329                                   void *data)
 330 {
 331         efi_status_t status;
 332
 333         if (down_trylock(&efi_runtime_lock))
 334                 return EFI_NOT_READY;
 335
 336         status = efi_call_virt(set_variable, name, vendor, attr, data_size,
 337                                data);
 338         up(&efi_runtime_lock);
 339         return status;
 340 }
 341
 342
 343 static efi_status_t virt_efi_query_variable_info(u32 attr,
 344                                                  u64 *storage_space,
 345                                                  u64 *remaining_space,
 346                                                  u64 *max_variable_size)
 347 {
 348         efi_status_t status;
 349
 350         if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION)
 351                 return EFI_UNSUPPORTED;
 352
 353         if (down_interruptible(&efi_runtime_lock))
 354                 return EFI_ABORTED;
 355         status = efi_queue_work(QUERY_VARIABLE_INFO, &attr, storage_space,
 356                                 remaining_space, max_variable_size, NULL);
 357         up(&efi_runtime_lock);
 358         return status;
 359 }
 360
 361 static efi_status_t
 362 virt_efi_query_variable_info_nonblocking(u32 attr,
 363                                          u64 *storage_space,
 364                                          u64 *remaining_space,
 365                                          u64 *max_variable_size)
 366 {
 367         efi_status_t status;
 368
 369         if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION)
 370                 return EFI_UNSUPPORTED;
 371
 372         if (down_trylock(&efi_runtime_lock))
 373                 return EFI_NOT_READY;
 374
 375         status = efi_call_virt(query_variable_info, attr, storage_space,
 376                                remaining_space, max_variable_size);
 377         up(&efi_runtime_lock);
 378         return status;
 379 }
 380
 381 static efi_status_t virt_efi_get_next_high_mono_count(u32 *count)
 382 {
 383         efi_status_t status;
 384
 385         if (down_interruptible(&efi_runtime_lock))
 386                 return EFI_ABORTED;
 387         status = efi_queue_work(GET_NEXT_HIGH_MONO_COUNT, count, NULL, NULL,
 388                                 NULL, NULL);
 389         up(&efi_runtime_lock);
 390         return status;
 391 }
 392
 393 static void virt_efi_reset_system(int reset_type,
 394                                   efi_status_t status,
 395                                   unsigned long data_size,
 396                                   efi_char16_t *data)
 397 {
 398         if (down_interruptible(&efi_runtime_lock)) {
 399                 pr_warn("failed to invoke the reset_system() runtime service:\n"
 400                         "could not get exclusive access to the firmware\n");
 401                 return;
 402         }
 403         efi_rts_work.efi_rts_id = RESET_SYSTEM;
 404         __efi_call_virt(reset_system, reset_type, status, data_size, data);
 405         up(&efi_runtime_lock);
 406 }
 407
 408 static efi_status_t virt_efi_update_capsule(efi_capsule_header_t **capsules,
 409                                             unsigned long count,
 410                                             unsigned long sg_list)
 411 {
 412         efi_status_t status;
 413
 414         if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION)
 415                 return EFI_UNSUPPORTED;
 416
 417         if (down_interruptible(&efi_runtime_lock))
 418                 return EFI_ABORTED;
 419         status = efi_queue_work(UPDATE_CAPSULE, capsules, &count, &sg_list,
 420                                 NULL, NULL);
 421         up(&efi_runtime_lock);
 422         return status;
 423 }
 424
 425 static efi_status_t virt_efi_query_capsule_caps(efi_capsule_header_t **capsules,
 426                                                 unsigned long count,
 427                                                 u64 *max_size,
 428                                                 int *reset_type)
 429 {
 430         efi_status_t status;
 431
 432         if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION)
 433                 return EFI_UNSUPPORTED;
 434
 435         if (down_interruptible(&efi_runtime_lock))
 436                 return EFI_ABORTED;
 437         status = efi_queue_work(QUERY_CAPSULE_CAPS, capsules, &count,
 438                                 max_size, reset_type, NULL);
 439         up(&efi_runtime_lock);
 440         return status;
 441 }
 442
 443 void efi_native_runtime_setup(void)
 444 {
 445         efi.get_time = virt_efi_get_time;
 446         efi.set_time = virt_efi_set_time;
 447         efi.get_wakeup_time = virt_efi_get_wakeup_time;
 448         efi.set_wakeup_time = virt_efi_set_wakeup_time;
 449         efi.get_variable = virt_efi_get_variable;
 450         efi.get_next_variable = virt_efi_get_next_variable;
 451         efi.set_variable = virt_efi_set_variable;
 452         efi.set_variable_nonblocking = virt_efi_set_variable_nonblocking;
 453         efi.get_next_high_mono_count = virt_efi_get_next_high_mono_count;
 454         efi.reset_system = virt_efi_reset_system;
 455         efi.query_variable_info = virt_efi_query_variable_info;
 456         efi.query_variable_info_nonblocking = virt_efi_query_variable_info_nonblocking;
 457         efi.update_capsule = virt_efi_update_capsule;
 458         efi.query_capsule_caps = virt_efi_query_capsule_caps;
 459 }