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 = EFI_NONE;                             \
  89         efi_rts_work.status;                                            \
  90 })
  91
  92 #ifndef arch_efi_save_flags
  93 #define arch_efi_save_flags(state_flags)        local_save_flags(state_flags)
  94 #define arch_efi_restore_flags(state_flags)     local_irq_restore(state_flags)
  95 #endif
  96
  97 unsigned long efi_call_virt_save_flags(void)
  98 {
  99         unsigned long flags;
 100
 101         arch_efi_save_flags(flags);
 102         return flags;
 103 }
 104
 105 void efi_call_virt_check_flags(unsigned long flags, const char *call)
 106 {
 107         unsigned long cur_flags, mismatch;
 108
 109         cur_flags = efi_call_virt_save_flags();
 110
 111         mismatch = flags ^ cur_flags;
 112         if (!WARN_ON_ONCE(mismatch & ARCH_EFI_IRQ_FLAGS_MASK))
 113                 return;
 114
 115         add_taint(TAINT_FIRMWARE_WORKAROUND, LOCKDEP_NOW_UNRELIABLE);
 116         pr_err_ratelimited(FW_BUG "IRQ flags corrupted (0x%08lx=>0x%08lx) by EFI %s\n",
 117                            flags, cur_flags, call);
 118         arch_efi_restore_flags(flags);
 119 }
 120
 121 /*
 122  * According to section 7.1 of the UEFI spec, Runtime Services are not fully
 123  * reentrant, and there are particular combinations of calls that need to be
 124  * serialized. (source: UEFI Specification v2.4A)
 125  *
 126  * Table 31. Rules for Reentry Into Runtime Services
 127  * +------------------------------------+-------------------------------+
 128  * | If previous call is busy in        | Forbidden to call             |
 129  * +------------------------------------+-------------------------------+
 130  * | Any                                | SetVirtualAddressMap()        |
 131  * +------------------------------------+-------------------------------+
 132  * | ConvertPointer()                   | ConvertPointer()              |
 133  * +------------------------------------+-------------------------------+
 134  * | SetVariable()                      | ResetSystem()                 |
 135  * | UpdateCapsule()                    |                               |
 136  * | SetTime()                          |                               |
 137  * | SetWakeupTime()                    |                               |
 138  * | GetNextHighMonotonicCount()        |                               |
 139  * +------------------------------------+-------------------------------+
 140  * | GetVariable()                      | GetVariable()                 |
 141  * | GetNextVariableName()              | GetNextVariableName()         |
 142  * | SetVariable()                      | SetVariable()                 |
 143  * | QueryVariableInfo()                | QueryVariableInfo()           |
 144  * | UpdateCapsule()                    | UpdateCapsule()               |
 145  * | QueryCapsuleCapabilities()         | QueryCapsuleCapabilities()    |
 146  * | GetNextHighMonotonicCount()        | GetNextHighMonotonicCount()   |
 147  * +------------------------------------+-------------------------------+
 148  * | GetTime()                          | GetTime()                     |
 149  * | SetTime()                          | SetTime()                     |
 150  * | GetWakeupTime()                    | GetWakeupTime()               |
 151  * | SetWakeupTime()                    | SetWakeupTime()               |
 152  * +------------------------------------+-------------------------------+
 153  *
 154  * Due to the fact that the EFI pstore may write to the variable store in
 155  * interrupt context, we need to use a lock for at least the groups that
 156  * contain SetVariable() and QueryVariableInfo(). That leaves little else, as
 157  * none of the remaining functions are actually ever called at runtime.
 158  * So let's just use a single lock to serialize all Runtime Services calls.
 159  */
 160 static DEFINE_SEMAPHORE(efi_runtime_lock);
 161
 162 /*
 163  * Expose the EFI runtime lock to the UV platform
 164  */
 165 #ifdef CONFIG_X86_UV
 166 extern struct semaphore __efi_uv_runtime_lock __alias(efi_runtime_lock);
 167 #endif
 168
 169 /*
 170  * Calls the appropriate efi_runtime_service() with the appropriate
 171  * arguments.
 172  *
 173  * Semantics followed by efi_call_rts() to understand efi_runtime_work:
 174  * 1. If argument was a pointer, recast it from void pointer to original
 175  * pointer type.
 176  * 2. If argument was a value, recast it from void pointer to original
 177  * pointer type and dereference it.
 178  */
 179 static void efi_call_rts(struct work_struct *work)
 180 {
 181         void *arg1, *arg2, *arg3, *arg4, *arg5;
 182         efi_status_t status = EFI_NOT_FOUND;
 183
 184         arg1 = efi_rts_work.arg1;
 185         arg2 = efi_rts_work.arg2;
 186         arg3 = efi_rts_work.arg3;
 187         arg4 = efi_rts_work.arg4;
 188         arg5 = efi_rts_work.arg5;
 189
 190         switch (efi_rts_work.efi_rts_id) {
 191         case EFI_GET_TIME:
 192                 status = efi_call_virt(get_time, (efi_time_t *)arg1,
 193                                        (efi_time_cap_t *)arg2);
 194                 break;
 195         case EFI_SET_TIME:
 196                 status = efi_call_virt(set_time, (efi_time_t *)arg1);
 197                 break;
 198         case EFI_GET_WAKEUP_TIME:
 199                 status = efi_call_virt(get_wakeup_time, (efi_bool_t *)arg1,
 200                                        (efi_bool_t *)arg2, (efi_time_t *)arg3);
 201                 break;
 202         case EFI_SET_WAKEUP_TIME:
 203                 status = efi_call_virt(set_wakeup_time, *(efi_bool_t *)arg1,
 204                                        (efi_time_t *)arg2);
 205                 break;
 206         case EFI_GET_VARIABLE:
 207                 status = efi_call_virt(get_variable, (efi_char16_t *)arg1,
 208                                        (efi_guid_t *)arg2, (u32 *)arg3,
 209                                        (unsigned long *)arg4, (void *)arg5);
 210                 break;
 211         case EFI_GET_NEXT_VARIABLE:
 212                 status = efi_call_virt(get_next_variable, (unsigned long *)arg1,
 213                                        (efi_char16_t *)arg2,
 214                                        (efi_guid_t *)arg3);
 215                 break;
 216         case EFI_SET_VARIABLE:
 217                 status = efi_call_virt(set_variable, (efi_char16_t *)arg1,
 218                                        (efi_guid_t *)arg2, *(u32 *)arg3,
 219                                        *(unsigned long *)arg4, (void *)arg5);
 220                 break;
 221         case EFI_QUERY_VARIABLE_INFO:
 222                 status = efi_call_virt(query_variable_info, *(u32 *)arg1,
 223                                        (u64 *)arg2, (u64 *)arg3, (u64 *)arg4);
 224                 break;
 225         case EFI_GET_NEXT_HIGH_MONO_COUNT:
 226                 status = efi_call_virt(get_next_high_mono_count, (u32 *)arg1);
 227                 break;
 228         case EFI_UPDATE_CAPSULE:
 229                 status = efi_call_virt(update_capsule,
 230                                        (efi_capsule_header_t **)arg1,
 231                                        *(unsigned long *)arg2,
 232                                        *(unsigned long *)arg3);
 233                 break;
 234         case EFI_QUERY_CAPSULE_CAPS:
 235                 status = efi_call_virt(query_capsule_caps,
 236                                        (efi_capsule_header_t **)arg1,
 237                                        *(unsigned long *)arg2, (u64 *)arg3,
 238                                        (int *)arg4);
 239                 break;
 240         default:
 241                 /*
 242                  * Ideally, we should never reach here because a caller of this
 243                  * function should have put the right efi_runtime_service()
 244                  * function identifier into efi_rts_work->efi_rts_id
 245                  */
 246                 pr_err("Requested executing invalid EFI Runtime Service.\n");
 247         }
 248         efi_rts_work.status = status;
 249         complete(&efi_rts_work.efi_rts_comp);
 250 }
 251
 252 static efi_status_t virt_efi_get_time(efi_time_t *tm, efi_time_cap_t *tc)
 253 {
 254         efi_status_t status;
 255
 256         if (down_interruptible(&efi_runtime_lock))
 257                 return EFI_ABORTED;
 258         status = efi_queue_work(EFI_GET_TIME, tm, tc, NULL, NULL, NULL);
 259         up(&efi_runtime_lock);
 260         return status;
 261 }
 262
 263 static efi_status_t virt_efi_set_time(efi_time_t *tm)
 264 {
 265         efi_status_t status;
 266
 267         if (down_interruptible(&efi_runtime_lock))
 268                 return EFI_ABORTED;
 269         status = efi_queue_work(EFI_SET_TIME, tm, NULL, NULL, NULL, NULL);
 270         up(&efi_runtime_lock);
 271         return status;
 272 }
 273
 274 static efi_status_t virt_efi_get_wakeup_time(efi_bool_t *enabled,
 275                                              efi_bool_t *pending,
 276                                              efi_time_t *tm)
 277 {
 278         efi_status_t status;
 279
 280         if (down_interruptible(&efi_runtime_lock))
 281                 return EFI_ABORTED;
 282         status = efi_queue_work(EFI_GET_WAKEUP_TIME, enabled, pending, tm, NULL,
 283                                 NULL);
 284         up(&efi_runtime_lock);
 285         return status;
 286 }
 287
 288 static efi_status_t virt_efi_set_wakeup_time(efi_bool_t enabled, efi_time_t *tm)
 289 {
 290         efi_status_t status;
 291
 292         if (down_interruptible(&efi_runtime_lock))
 293                 return EFI_ABORTED;
 294         status = efi_queue_work(EFI_SET_WAKEUP_TIME, &enabled, tm, NULL, NULL,
 295                                 NULL);
 296         up(&efi_runtime_lock);
 297         return status;
 298 }
 299
 300 static efi_status_t virt_efi_get_variable(efi_char16_t *name,
 301                                           efi_guid_t *vendor,
 302                                           u32 *attr,
 303                                           unsigned long *data_size,
 304                                           void *data)
 305 {
 306         efi_status_t status;
 307
 308         if (down_interruptible(&efi_runtime_lock))
 309                 return EFI_ABORTED;
 310         status = efi_queue_work(EFI_GET_VARIABLE, name, vendor, attr, data_size,
 311                                 data);
 312         up(&efi_runtime_lock);
 313         return status;
 314 }
 315
 316 static efi_status_t virt_efi_get_next_variable(unsigned long *name_size,
 317                                                efi_char16_t *name,
 318                                                efi_guid_t *vendor)
 319 {
 320         efi_status_t status;
 321
 322         if (down_interruptible(&efi_runtime_lock))
 323                 return EFI_ABORTED;
 324         status = efi_queue_work(EFI_GET_NEXT_VARIABLE, name_size, name, vendor,
 325                                 NULL, NULL);
 326         up(&efi_runtime_lock);
 327         return status;
 328 }
 329
 330 static efi_status_t virt_efi_set_variable(efi_char16_t *name,
 331                                           efi_guid_t *vendor,
 332                                           u32 attr,
 333                                           unsigned long data_size,
 334                                           void *data)
 335 {
 336         efi_status_t status;
 337
 338         if (down_interruptible(&efi_runtime_lock))
 339                 return EFI_ABORTED;
 340         status = efi_queue_work(EFI_SET_VARIABLE, name, vendor, &attr, &data_size,
 341                                 data);
 342         up(&efi_runtime_lock);
 343         return status;
 344 }
 345
 346 static efi_status_t
 347 virt_efi_set_variable_nonblocking(efi_char16_t *name, efi_guid_t *vendor,
 348                                   u32 attr, unsigned long data_size,
 349                                   void *data)
 350 {
 351         efi_status_t status;
 352
 353         if (down_trylock(&efi_runtime_lock))
 354                 return EFI_NOT_READY;
 355
 356         status = efi_call_virt(set_variable, name, vendor, attr, data_size,
 357                                data);
 358         up(&efi_runtime_lock);
 359         return status;
 360 }
 361
 362
 363 static efi_status_t virt_efi_query_variable_info(u32 attr,
 364                                                  u64 *storage_space,
 365                                                  u64 *remaining_space,
 366                                                  u64 *max_variable_size)
 367 {
 368         efi_status_t status;
 369
 370         if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION)
 371                 return EFI_UNSUPPORTED;
 372
 373         if (down_interruptible(&efi_runtime_lock))
 374                 return EFI_ABORTED;
 375         status = efi_queue_work(EFI_QUERY_VARIABLE_INFO, &attr, storage_space,
 376                                 remaining_space, max_variable_size, NULL);
 377         up(&efi_runtime_lock);
 378         return status;
 379 }
 380
 381 static efi_status_t
 382 virt_efi_query_variable_info_nonblocking(u32 attr,
 383                                          u64 *storage_space,
 384                                          u64 *remaining_space,
 385                                          u64 *max_variable_size)
 386 {
 387         efi_status_t status;
 388
 389         if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION)
 390                 return EFI_UNSUPPORTED;
 391
 392         if (down_trylock(&efi_runtime_lock))
 393                 return EFI_NOT_READY;
 394
 395         status = efi_call_virt(query_variable_info, attr, storage_space,
 396                                remaining_space, max_variable_size);
 397         up(&efi_runtime_lock);
 398         return status;
 399 }
 400
 401 static efi_status_t virt_efi_get_next_high_mono_count(u32 *count)
 402 {
 403         efi_status_t status;
 404
 405         if (down_interruptible(&efi_runtime_lock))
 406                 return EFI_ABORTED;
 407         status = efi_queue_work(EFI_GET_NEXT_HIGH_MONO_COUNT, count, NULL, NULL,
 408                                 NULL, NULL);
 409         up(&efi_runtime_lock);
 410         return status;
 411 }
 412
 413 static void virt_efi_reset_system(int reset_type,
 414                                   efi_status_t status,
 415                                   unsigned long data_size,
 416                                   efi_char16_t *data)
 417 {
 418         if (down_interruptible(&efi_runtime_lock)) {
 419                 pr_warn("failed to invoke the reset_system() runtime service:\n"
 420                         "could not get exclusive access to the firmware\n");
 421                 return;
 422         }
 423         efi_rts_work.efi_rts_id = EFI_RESET_SYSTEM;
 424         __efi_call_virt(reset_system, reset_type, status, data_size, data);
 425         up(&efi_runtime_lock);
 426 }
 427
 428 static efi_status_t virt_efi_update_capsule(efi_capsule_header_t **capsules,
 429                                             unsigned long count,
 430                                             unsigned long sg_list)
 431 {
 432         efi_status_t status;
 433
 434         if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION)
 435                 return EFI_UNSUPPORTED;
 436
 437         if (down_interruptible(&efi_runtime_lock))
 438                 return EFI_ABORTED;
 439         status = efi_queue_work(EFI_UPDATE_CAPSULE, capsules, &count, &sg_list,
 440                                 NULL, NULL);
 441         up(&efi_runtime_lock);
 442         return status;
 443 }
 444
 445 static efi_status_t virt_efi_query_capsule_caps(efi_capsule_header_t **capsules,
 446                                                 unsigned long count,
 447                                                 u64 *max_size,
 448                                                 int *reset_type)
 449 {
 450         efi_status_t status;
 451
 452         if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION)
 453                 return EFI_UNSUPPORTED;
 454
 455         if (down_interruptible(&efi_runtime_lock))
 456                 return EFI_ABORTED;
 457         status = efi_queue_work(EFI_QUERY_CAPSULE_CAPS, capsules, &count,
 458                                 max_size, reset_type, NULL);
 459         up(&efi_runtime_lock);
 460         return status;
 461 }
 462
 463 void efi_native_runtime_setup(void)
 464 {
 465         efi.get_time = virt_efi_get_time;
 466         efi.set_time = virt_efi_set_time;
 467         efi.get_wakeup_time = virt_efi_get_wakeup_time;
 468         efi.set_wakeup_time = virt_efi_set_wakeup_time;
 469         efi.get_variable = virt_efi_get_variable;
 470         efi.get_next_variable = virt_efi_get_next_variable;
 471         efi.set_variable = virt_efi_set_variable;
 472         efi.set_variable_nonblocking = virt_efi_set_variable_nonblocking;
 473         efi.get_next_high_mono_count = virt_efi_get_next_high_mono_count;
 474         efi.reset_system = virt_efi_reset_system;
 475         efi.query_variable_info = virt_efi_query_variable_info;
 476         efi.query_variable_info_nonblocking = virt_efi_query_variable_info_nonblocking;
 477         efi.update_capsule = virt_efi_update_capsule;
 478         efi.query_capsule_caps = virt_efi_query_capsule_caps;
 479 }