root/drivers/firmware/efi/runtime-wrappers.c

DEFINITIONS

1. efi_call_virt_save_flags
2. efi_call_virt_check_flags
3. efi_call_rts
4. virt_efi_get_time
5. virt_efi_set_time
6. virt_efi_get_wakeup_time
7. virt_efi_set_wakeup_time
8. virt_efi_get_variable
9. virt_efi_get_next_variable
10. virt_efi_set_variable
11. virt_efi_set_variable_nonblocking
12. virt_efi_query_variable_info
13. virt_efi_query_variable_info_nonblocking
14. virt_efi_get_next_high_mono_count
15. virt_efi_reset_system
16. virt_efi_update_capsule
17. virt_efi_query_capsule_caps
18. efi_native_runtime_setup

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * runtime-wrappers.c - Runtime Services function call wrappers
   4  *
   5  * Implementation summary:
   6  * -----------------------
   7  * 1. When user/kernel thread requests to execute efi_runtime_service(),
   8  * enqueue work to efi_rts_wq.
   9  * 2. Caller thread waits for completion until the work is finished
  10  * because it's dependent on the return status and execution of
  11  * efi_runtime_service().
  12  * For instance, get_variable() and get_next_variable().
  13  *
  14  * Copyright (C) 2014 Linaro Ltd. <ard.biesheuvel@linaro.org>
  15  *
  16  * Split off from arch/x86/platform/efi/efi.c
  17  *
  18  * Copyright (C) 1999 VA Linux Systems
  19  * Copyright (C) 1999 Walt Drummond <drummond@valinux.com>
  20  * Copyright (C) 1999-2002 Hewlett-Packard Co.
  21  * Copyright (C) 2005-2008 Intel Co.
  22  * Copyright (C) 2013 SuSE Labs
  23  */
  24 
  25 #define pr_fmt(fmt)     "efi: " fmt
  26 
  27 #include <linux/bug.h>
  28 #include <linux/efi.h>
  29 #include <linux/irqflags.h>
  30 #include <linux/mutex.h>
  31 #include <linux/semaphore.h>
  32 #include <linux/stringify.h>
  33 #include <linux/workqueue.h>
  34 #include <linux/completion.h>
  35 
  36 #include <asm/efi.h>
  37 
  38 /*
  39  * Wrap around the new efi_call_virt_generic() macros so that the
  40  * code doesn't get too cluttered:
  41  */
  42 #define efi_call_virt(f, args...)   \
  43         efi_call_virt_pointer(efi.systab->runtime, f, args)
  44 #define __efi_call_virt(f, args...) \
  45         __efi_call_virt_pointer(efi.systab->runtime, f, args)
  46 
  47 struct efi_runtime_work efi_rts_work;
  48 
  49 /*
  50  * efi_queue_work:      Queue efi_runtime_service() and wait until it's done
  51  * @rts:                efi_runtime_service() function identifier
  52  * @rts_arg<1-5>:       efi_runtime_service() function arguments
  53  *
  54  * Accesses to efi_runtime_services() are serialized by a binary
  55  * semaphore (efi_runtime_lock) and caller waits until the work is
  56  * finished, hence _only_ one work is queued at a time and the caller
  57  * thread waits for completion.
  58  */
  59 #define efi_queue_work(_rts, _arg1, _arg2, _arg3, _arg4, _arg5)         \
  60 ({                                                                      \
  61         efi_rts_work.status = EFI_ABORTED;                              \
  62                                                                         \
  63         if (!efi_enabled(EFI_RUNTIME_SERVICES)) {                       \
  64                 pr_warn_once("EFI Runtime Services are disabled!\n");   \
  65                 goto exit;                                              \
  66         }                                                               \
  67                                                                         \
  68         init_completion(&efi_rts_work.efi_rts_comp);                    \
  69         INIT_WORK(&efi_rts_work.work, efi_call_rts);                    \
  70         efi_rts_work.arg1 = _arg1;                                      \
  71         efi_rts_work.arg2 = _arg2;                                      \
  72         efi_rts_work.arg3 = _arg3;                                      \
  73         efi_rts_work.arg4 = _arg4;                                      \
  74         efi_rts_work.arg5 = _arg5;                                      \
  75         efi_rts_work.efi_rts_id = _rts;                                 \
  76                                                                         \
  77         /*                                                              \
  78          * queue_work() returns 0 if work was already on queue,         \
  79          * _ideally_ this should never happen.                          \
  80          */                                                             \
  81         if (queue_work(efi_rts_wq, &efi_rts_work.work))                 \
  82                 wait_for_completion(&efi_rts_work.efi_rts_comp);        \
  83         else                                                            \
  84                 pr_err("Failed to queue work to efi_rts_wq.\n");        \
  85                                                                         \
  86 exit:                                                                   \
  87         efi_rts_work.efi_rts_id = EFI_NONE;                             \
  88         efi_rts_work.status;                                            \
  89 })
  90 
  91 #ifndef arch_efi_save_flags
  92 #define arch_efi_save_flags(state_flags)        local_save_flags(state_flags)
  93 #define arch_efi_restore_flags(state_flags)     local_irq_restore(state_flags)
  94 #endif
  95 
  96 unsigned long efi_call_virt_save_flags(void)
  97 {
  98         unsigned long flags;
  99 
 100         arch_efi_save_flags(flags);
 101         return flags;
 102 }
 103 
 104 void efi_call_virt_check_flags(unsigned long flags, const char *call)
 105 {
 106         unsigned long cur_flags, mismatch;
 107 
 108         cur_flags = efi_call_virt_save_flags();
 109 
 110         mismatch = flags ^ cur_flags;
 111         if (!WARN_ON_ONCE(mismatch & ARCH_EFI_IRQ_FLAGS_MASK))
 112                 return;
 113 
 114         add_taint(TAINT_FIRMWARE_WORKAROUND, LOCKDEP_NOW_UNRELIABLE);
 115         pr_err_ratelimited(FW_BUG "IRQ flags corrupted (0x%08lx=>0x%08lx) by EFI %s\n",
 116                            flags, cur_flags, call);
 117         arch_efi_restore_flags(flags);
 118 }
 119 
 120 /*
 121  * According to section 7.1 of the UEFI spec, Runtime Services are not fully
 122  * reentrant, and there are particular combinations of calls that need to be
 123  * serialized. (source: UEFI Specification v2.4A)
 124  *
 125  * Table 31. Rules for Reentry Into Runtime Services
 126  * +------------------------------------+-------------------------------+
 127  * | If previous call is busy in        | Forbidden to call             |
 128  * +------------------------------------+-------------------------------+
 129  * | Any                                | SetVirtualAddressMap()        |
 130  * +------------------------------------+-------------------------------+
 131  * | ConvertPointer()                   | ConvertPointer()              |
 132  * +------------------------------------+-------------------------------+
 133  * | SetVariable()                      | ResetSystem()                 |
 134  * | UpdateCapsule()                    |                               |
 135  * | SetTime()                          |                               |
 136  * | SetWakeupTime()                    |                               |
 137  * | GetNextHighMonotonicCount()        |                               |
 138  * +------------------------------------+-------------------------------+
 139  * | GetVariable()                      | GetVariable()                 |
 140  * | GetNextVariableName()              | GetNextVariableName()         |
 141  * | SetVariable()                      | SetVariable()                 |
 142  * | QueryVariableInfo()                | QueryVariableInfo()           |
 143  * | UpdateCapsule()                    | UpdateCapsule()               |
 144  * | QueryCapsuleCapabilities()         | QueryCapsuleCapabilities()    |
 145  * | GetNextHighMonotonicCount()        | GetNextHighMonotonicCount()   |
 146  * +------------------------------------+-------------------------------+
 147  * | GetTime()                          | GetTime()                     |
 148  * | SetTime()                          | SetTime()                     |
 149  * | GetWakeupTime()                    | GetWakeupTime()               |
 150  * | SetWakeupTime()                    | SetWakeupTime()               |
 151  * +------------------------------------+-------------------------------+
 152  *
 153  * Due to the fact that the EFI pstore may write to the variable store in
 154  * interrupt context, we need to use a lock for at least the groups that
 155  * contain SetVariable() and QueryVariableInfo(). That leaves little else, as
 156  * none of the remaining functions are actually ever called at runtime.
 157  * So let's just use a single lock to serialize all Runtime Services calls.
 158  */
 159 static DEFINE_SEMAPHORE(efi_runtime_lock);
 160 
 161 /*
 162  * Expose the EFI runtime lock to the UV platform
 163  */
 164 #ifdef CONFIG_X86_UV
 165 extern struct semaphore __efi_uv_runtime_lock __alias(efi_runtime_lock);
 166 #endif
 167 
 168 /*
 169  * Calls the appropriate efi_runtime_service() with the appropriate
 170  * arguments.
 171  *
 172  * Semantics followed by efi_call_rts() to understand efi_runtime_work:
 173  * 1. If argument was a pointer, recast it from void pointer to original
 174  * pointer type.
 175  * 2. If argument was a value, recast it from void pointer to original
 176  * pointer type and dereference it.
 177  */
 178 static void efi_call_rts(struct work_struct *work)
 179 {
 180         void *arg1, *arg2, *arg3, *arg4, *arg5;
 181         efi_status_t status = EFI_NOT_FOUND;
 182 
 183         arg1 = efi_rts_work.arg1;
 184         arg2 = efi_rts_work.arg2;
 185         arg3 = efi_rts_work.arg3;
 186         arg4 = efi_rts_work.arg4;
 187         arg5 = efi_rts_work.arg5;
 188 
 189         switch (efi_rts_work.efi_rts_id) {
 190         case EFI_GET_TIME:
 191                 status = efi_call_virt(get_time, (efi_time_t *)arg1,
 192                                        (efi_time_cap_t *)arg2);
 193                 break;
 194         case EFI_SET_TIME:
 195                 status = efi_call_virt(set_time, (efi_time_t *)arg1);
 196                 break;
 197         case EFI_GET_WAKEUP_TIME:
 198                 status = efi_call_virt(get_wakeup_time, (efi_bool_t *)arg1,
 199                                        (efi_bool_t *)arg2, (efi_time_t *)arg3);
 200                 break;
 201         case EFI_SET_WAKEUP_TIME:
 202                 status = efi_call_virt(set_wakeup_time, *(efi_bool_t *)arg1,
 203                                        (efi_time_t *)arg2);
 204                 break;
 205         case EFI_GET_VARIABLE:
 206                 status = efi_call_virt(get_variable, (efi_char16_t *)arg1,
 207                                        (efi_guid_t *)arg2, (u32 *)arg3,
 208                                        (unsigned long *)arg4, (void *)arg5);
 209                 break;
 210         case EFI_GET_NEXT_VARIABLE:
 211                 status = efi_call_virt(get_next_variable, (unsigned long *)arg1,
 212                                        (efi_char16_t *)arg2,
 213                                        (efi_guid_t *)arg3);
 214                 break;
 215         case EFI_SET_VARIABLE:
 216                 status = efi_call_virt(set_variable, (efi_char16_t *)arg1,
 217                                        (efi_guid_t *)arg2, *(u32 *)arg3,
 218                                        *(unsigned long *)arg4, (void *)arg5);
 219                 break;
 220         case EFI_QUERY_VARIABLE_INFO:
 221                 status = efi_call_virt(query_variable_info, *(u32 *)arg1,
 222                                        (u64 *)arg2, (u64 *)arg3, (u64 *)arg4);
 223                 break;
 224         case EFI_GET_NEXT_HIGH_MONO_COUNT:
 225                 status = efi_call_virt(get_next_high_mono_count, (u32 *)arg1);
 226                 break;
 227         case EFI_UPDATE_CAPSULE:
 228                 status = efi_call_virt(update_capsule,
 229                                        (efi_capsule_header_t **)arg1,
 230                                        *(unsigned long *)arg2,
 231                                        *(unsigned long *)arg3);
 232                 break;
 233         case EFI_QUERY_CAPSULE_CAPS:
 234                 status = efi_call_virt(query_capsule_caps,
 235                                        (efi_capsule_header_t **)arg1,
 236                                        *(unsigned long *)arg2, (u64 *)arg3,
 237                                        (int *)arg4);
 238                 break;
 239         default:
 240                 /*
 241                  * Ideally, we should never reach here because a caller of this
 242                  * function should have put the right efi_runtime_service()
 243                  * function identifier into efi_rts_work->efi_rts_id
 244                  */
 245                 pr_err("Requested executing invalid EFI Runtime Service.\n");
 246         }
 247         efi_rts_work.status = status;
 248         complete(&efi_rts_work.efi_rts_comp);
 249 }
 250 
 251 static efi_status_t virt_efi_get_time(efi_time_t *tm, efi_time_cap_t *tc)
 252 {
 253         efi_status_t status;
 254 
 255         if (down_interruptible(&efi_runtime_lock))
 256                 return EFI_ABORTED;
 257         status = efi_queue_work(EFI_GET_TIME, tm, tc, NULL, NULL, NULL);
 258         up(&efi_runtime_lock);
 259         return status;
 260 }
 261 
 262 static efi_status_t virt_efi_set_time(efi_time_t *tm)
 263 {
 264         efi_status_t status;
 265 
 266         if (down_interruptible(&efi_runtime_lock))
 267                 return EFI_ABORTED;
 268         status = efi_queue_work(EFI_SET_TIME, tm, NULL, NULL, NULL, NULL);
 269         up(&efi_runtime_lock);
 270         return status;
 271 }
 272 
 273 static efi_status_t virt_efi_get_wakeup_time(efi_bool_t *enabled,
 274                                              efi_bool_t *pending,
 275                                              efi_time_t *tm)
 276 {
 277         efi_status_t status;
 278 
 279         if (down_interruptible(&efi_runtime_lock))
 280                 return EFI_ABORTED;
 281         status = efi_queue_work(EFI_GET_WAKEUP_TIME, enabled, pending, tm, NULL,
 282                                 NULL);
 283         up(&efi_runtime_lock);
 284         return status;
 285 }
 286 
 287 static efi_status_t virt_efi_set_wakeup_time(efi_bool_t enabled, efi_time_t *tm)
 288 {
 289         efi_status_t status;
 290 
 291         if (down_interruptible(&efi_runtime_lock))
 292                 return EFI_ABORTED;
 293         status = efi_queue_work(EFI_SET_WAKEUP_TIME, &enabled, tm, NULL, NULL,
 294                                 NULL);
 295         up(&efi_runtime_lock);
 296         return status;
 297 }
 298 
 299 static efi_status_t virt_efi_get_variable(efi_char16_t *name,
 300                                           efi_guid_t *vendor,
 301                                           u32 *attr,
 302                                           unsigned long *data_size,
 303                                           void *data)
 304 {
 305         efi_status_t status;
 306 
 307         if (down_interruptible(&efi_runtime_lock))
 308                 return EFI_ABORTED;
 309         status = efi_queue_work(EFI_GET_VARIABLE, name, vendor, attr, data_size,
 310                                 data);
 311         up(&efi_runtime_lock);
 312         return status;
 313 }
 314 
 315 static efi_status_t virt_efi_get_next_variable(unsigned long *name_size,
 316                                                efi_char16_t *name,
 317                                                efi_guid_t *vendor)
 318 {
 319         efi_status_t status;
 320 
 321         if (down_interruptible(&efi_runtime_lock))
 322                 return EFI_ABORTED;
 323         status = efi_queue_work(EFI_GET_NEXT_VARIABLE, name_size, name, vendor,
 324                                 NULL, NULL);
 325         up(&efi_runtime_lock);
 326         return status;
 327 }
 328 
 329 static efi_status_t virt_efi_set_variable(efi_char16_t *name,
 330                                           efi_guid_t *vendor,
 331                                           u32 attr,
 332                                           unsigned long data_size,
 333                                           void *data)
 334 {
 335         efi_status_t status;
 336 
 337         if (down_interruptible(&efi_runtime_lock))
 338                 return EFI_ABORTED;
 339         status = efi_queue_work(EFI_SET_VARIABLE, name, vendor, &attr, &data_size,
 340                                 data);
 341         up(&efi_runtime_lock);
 342         return status;
 343 }
 344 
 345 static efi_status_t
 346 virt_efi_set_variable_nonblocking(efi_char16_t *name, efi_guid_t *vendor,
 347                                   u32 attr, unsigned long data_size,
 348                                   void *data)
 349 {
 350         efi_status_t status;
 351 
 352         if (down_trylock(&efi_runtime_lock))
 353                 return EFI_NOT_READY;
 354 
 355         status = efi_call_virt(set_variable, name, vendor, attr, data_size,
 356                                data);
 357         up(&efi_runtime_lock);
 358         return status;
 359 }
 360 
 361 
 362 static efi_status_t virt_efi_query_variable_info(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_interruptible(&efi_runtime_lock))
 373                 return EFI_ABORTED;
 374         status = efi_queue_work(EFI_QUERY_VARIABLE_INFO, &attr, storage_space,
 375                                 remaining_space, max_variable_size, NULL);
 376         up(&efi_runtime_lock);
 377         return status;
 378 }
 379 
 380 static efi_status_t
 381 virt_efi_query_variable_info_nonblocking(u32 attr,
 382                                          u64 *storage_space,
 383                                          u64 *remaining_space,
 384                                          u64 *max_variable_size)
 385 {
 386         efi_status_t status;
 387 
 388         if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION)
 389                 return EFI_UNSUPPORTED;
 390 
 391         if (down_trylock(&efi_runtime_lock))
 392                 return EFI_NOT_READY;
 393 
 394         status = efi_call_virt(query_variable_info, attr, storage_space,
 395                                remaining_space, max_variable_size);
 396         up(&efi_runtime_lock);
 397         return status;
 398 }
 399 
 400 static efi_status_t virt_efi_get_next_high_mono_count(u32 *count)
 401 {
 402         efi_status_t status;
 403 
 404         if (down_interruptible(&efi_runtime_lock))
 405                 return EFI_ABORTED;
 406         status = efi_queue_work(EFI_GET_NEXT_HIGH_MONO_COUNT, count, NULL, NULL,
 407                                 NULL, NULL);
 408         up(&efi_runtime_lock);
 409         return status;
 410 }
 411 
 412 static void virt_efi_reset_system(int reset_type,
 413                                   efi_status_t status,
 414                                   unsigned long data_size,
 415                                   efi_char16_t *data)
 416 {
 417         if (down_interruptible(&efi_runtime_lock)) {
 418                 pr_warn("failed to invoke the reset_system() runtime service:\n"
 419                         "could not get exclusive access to the firmware\n");
 420                 return;
 421         }
 422         efi_rts_work.efi_rts_id = EFI_RESET_SYSTEM;
 423         __efi_call_virt(reset_system, reset_type, status, data_size, data);
 424         up(&efi_runtime_lock);
 425 }
 426 
 427 static efi_status_t virt_efi_update_capsule(efi_capsule_header_t **capsules,
 428                                             unsigned long count,
 429                                             unsigned long sg_list)
 430 {
 431         efi_status_t status;
 432 
 433         if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION)
 434                 return EFI_UNSUPPORTED;
 435 
 436         if (down_interruptible(&efi_runtime_lock))
 437                 return EFI_ABORTED;
 438         status = efi_queue_work(EFI_UPDATE_CAPSULE, capsules, &count, &sg_list,
 439                                 NULL, NULL);
 440         up(&efi_runtime_lock);
 441         return status;
 442 }
 443 
 444 static efi_status_t virt_efi_query_capsule_caps(efi_capsule_header_t **capsules,
 445                                                 unsigned long count,
 446                                                 u64 *max_size,
 447                                                 int *reset_type)
 448 {
 449         efi_status_t status;
 450 
 451         if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION)
 452                 return EFI_UNSUPPORTED;
 453 
 454         if (down_interruptible(&efi_runtime_lock))
 455                 return EFI_ABORTED;
 456         status = efi_queue_work(EFI_QUERY_CAPSULE_CAPS, capsules, &count,
 457                                 max_size, reset_type, NULL);
 458         up(&efi_runtime_lock);
 459         return status;
 460 }
 461 
 462 void efi_native_runtime_setup(void)
 463 {
 464         efi.get_time = virt_efi_get_time;
 465         efi.set_time = virt_efi_set_time;
 466         efi.get_wakeup_time = virt_efi_get_wakeup_time;
 467         efi.set_wakeup_time = virt_efi_set_wakeup_time;
 468         efi.get_variable = virt_efi_get_variable;
 469         efi.get_next_variable = virt_efi_get_next_variable;
 470         efi.set_variable = virt_efi_set_variable;
 471         efi.set_variable_nonblocking = virt_efi_set_variable_nonblocking;
 472         efi.get_next_high_mono_count = virt_efi_get_next_high_mono_count;
 473         efi.reset_system = virt_efi_reset_system;
 474         efi.query_variable_info = virt_efi_query_variable_info;
 475         efi.query_variable_info_nonblocking = virt_efi_query_variable_info_nonblocking;
 476         efi.update_capsule = virt_efi_update_capsule;
 477         efi.query_capsule_caps = virt_efi_query_capsule_caps;
 478 }