LXR linux/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
  48struct 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                                                                        \
  87exit:                                                                   \
  88        efi_rts_work.efi_rts_id = NONE;                                 \
  89        efi_rts_work.status;                                            \
  90})
  91
  92void 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 */
 147static 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 */
 159static 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
 232static 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
 243static 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
 254static 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
 268static 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
 280static 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
 296static 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
 310static 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
 326static efi_status_t
 327virt_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
 343static 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
 361static efi_status_t
 362virt_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
 381static 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
 393static 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
 408static 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
 425static 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
 443void 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}
 460