drivers/firmware/efi/runtime-wrappers.c

   1 /*
   2  * runtime-wrappers.c - Runtime Services function call wrappers
   3  *
   4  * Copyright (C) 2014 Linaro Ltd. <ard.biesheuvel@linaro.org>
   5  *
   6  * Split off from arch/x86/platform/efi/efi.c
   7  *
   8  * Copyright (C) 1999 VA Linux Systems
   9  * Copyright (C) 1999 Walt Drummond <drummond@valinux.com>
  10  * Copyright (C) 1999-2002 Hewlett-Packard Co.
  11  * Copyright (C) 2005-2008 Intel Co.
  12  * Copyright (C) 2013 SuSE Labs
  13  *
  14  * This file is released under the GPLv2.
  15  */
  16
  17 #include <linux/bug.h>
  18 #include <linux/efi.h>
  19 #include <linux/irqflags.h>
  20 #include <linux/mutex.h>
  21 #include <linux/spinlock.h>
  22 #include <linux/stringify.h>
  23 #include <asm/efi.h>
  24
  25 static void efi_call_virt_check_flags(unsigned long flags, const char *call)
  26 {
  27         unsigned long cur_flags, mismatch;
  28
  29         local_save_flags(cur_flags);
  30
  31         mismatch = flags ^ cur_flags;
  32         if (!WARN_ON_ONCE(mismatch & ARCH_EFI_IRQ_FLAGS_MASK))
  33                 return;
  34
  35         add_taint(TAINT_FIRMWARE_WORKAROUND, LOCKDEP_NOW_UNRELIABLE);
  36         pr_err_ratelimited(FW_BUG "IRQ flags corrupted (0x%08lx=>0x%08lx) by EFI %s\n",
  37                            flags, cur_flags, call);
  38         local_irq_restore(flags);
  39 }
  40
  41 /*
  42  * Arch code can implement the following three template macros, avoiding
  43  * reptition for the void/non-void return cases of {__,}efi_call_virt:
  44  *
  45  *  * arch_efi_call_virt_setup
  46  *
  47  *    Sets up the environment for the call (e.g. switching page tables,
  48  *    allowing kernel-mode use of floating point, if required).
  49  *
  50  *  * arch_efi_call_virt
  51  *
  52  *    Performs the call. The last expression in the macro must be the call
  53  *    itself, allowing the logic to be shared by the void and non-void
  54  *    cases.
  55  *
  56  *  * arch_efi_call_virt_teardown
  57  *
  58  *    Restores the usual kernel environment once the call has returned.
  59  */
  60
  61 #define efi_call_virt(f, args...)                                       \
  62 ({                                                                      \
  63         efi_status_t __s;                                               \
  64         unsigned long flags;                                            \
  65         arch_efi_call_virt_setup();                                     \
  66         local_save_flags(flags);                                        \
  67         __s = arch_efi_call_virt(f, args);                              \
  68         efi_call_virt_check_flags(flags, __stringify(f));               \
  69         arch_efi_call_virt_teardown();                                  \
  70         __s;                                                            \
  71 })
  72
  73 #define __efi_call_virt(f, args...)                                     \
  74 ({                                                                      \
  75         unsigned long flags;                                            \
  76         arch_efi_call_virt_setup();                                     \
  77         local_save_flags(flags);                                        \
  78         arch_efi_call_virt(f, args);                                    \
  79         efi_call_virt_check_flags(flags, __stringify(f));               \
  80         arch_efi_call_virt_teardown();                                  \
  81 })
  82
  83 /*
  84  * According to section 7.1 of the UEFI spec, Runtime Services are not fully
  85  * reentrant, and there are particular combinations of calls that need to be
  86  * serialized. (source: UEFI Specification v2.4A)
  87  *
  88  * Table 31. Rules for Reentry Into Runtime Services
  89  * +------------------------------------+-------------------------------+
  90  * | If previous call is busy in        | Forbidden to call             |
  91  * +------------------------------------+-------------------------------+
  92  * | Any                                | SetVirtualAddressMap()        |
  93  * +------------------------------------+-------------------------------+
  94  * | ConvertPointer()                   | ConvertPointer()              |
  95  * +------------------------------------+-------------------------------+
  96  * | SetVariable()                      | ResetSystem()                 |
  97  * | UpdateCapsule()                    |                               |
  98  * | SetTime()                          |                               |
  99  * | SetWakeupTime()                    |                               |
 100  * | GetNextHighMonotonicCount()        |                               |
 101  * +------------------------------------+-------------------------------+
 102  * | GetVariable()                      | GetVariable()                 |
 103  * | GetNextVariableName()              | GetNextVariableName()         |
 104  * | SetVariable()                      | SetVariable()                 |
 105  * | QueryVariableInfo()                | QueryVariableInfo()           |
 106  * | UpdateCapsule()                    | UpdateCapsule()               |
 107  * | QueryCapsuleCapabilities()         | QueryCapsuleCapabilities()    |
 108  * | GetNextHighMonotonicCount()        | GetNextHighMonotonicCount()   |
 109  * +------------------------------------+-------------------------------+
 110  * | GetTime()                          | GetTime()                     |
 111  * | SetTime()                          | SetTime()                     |
 112  * | GetWakeupTime()                    | GetWakeupTime()               |
 113  * | SetWakeupTime()                    | SetWakeupTime()               |
 114  * +------------------------------------+-------------------------------+
 115  *
 116  * Due to the fact that the EFI pstore may write to the variable store in
 117  * interrupt context, we need to use a spinlock for at least the groups that
 118  * contain SetVariable() and QueryVariableInfo(). That leaves little else, as
 119  * none of the remaining functions are actually ever called at runtime.
 120  * So let's just use a single spinlock to serialize all Runtime Services calls.
 121  */
 122 static DEFINE_SPINLOCK(efi_runtime_lock);
 123
 124 static efi_status_t virt_efi_get_time(efi_time_t *tm, efi_time_cap_t *tc)
 125 {
 126         efi_status_t status;
 127
 128         spin_lock(&efi_runtime_lock);
 129         status = efi_call_virt(get_time, tm, tc);
 130         spin_unlock(&efi_runtime_lock);
 131         return status;
 132 }
 133
 134 static efi_status_t virt_efi_set_time(efi_time_t *tm)
 135 {
 136         efi_status_t status;
 137
 138         spin_lock(&efi_runtime_lock);
 139         status = efi_call_virt(set_time, tm);
 140         spin_unlock(&efi_runtime_lock);
 141         return status;
 142 }
 143
 144 static efi_status_t virt_efi_get_wakeup_time(efi_bool_t *enabled,
 145                                              efi_bool_t *pending,
 146                                              efi_time_t *tm)
 147 {
 148         efi_status_t status;
 149
 150         spin_lock(&efi_runtime_lock);
 151         status = efi_call_virt(get_wakeup_time, enabled, pending, tm);
 152         spin_unlock(&efi_runtime_lock);
 153         return status;
 154 }
 155
 156 static efi_status_t virt_efi_set_wakeup_time(efi_bool_t enabled, efi_time_t *tm)
 157 {
 158         efi_status_t status;
 159
 160         spin_lock(&efi_runtime_lock);
 161         status = efi_call_virt(set_wakeup_time, enabled, tm);
 162         spin_unlock(&efi_runtime_lock);
 163         return status;
 164 }
 165
 166 static efi_status_t virt_efi_get_variable(efi_char16_t *name,
 167                                           efi_guid_t *vendor,
 168                                           u32 *attr,
 169                                           unsigned long *data_size,
 170                                           void *data)
 171 {
 172         efi_status_t status;
 173
 174         spin_lock(&efi_runtime_lock);
 175         status = efi_call_virt(get_variable, name, vendor, attr, data_size,
 176                                data);
 177         spin_unlock(&efi_runtime_lock);
 178         return status;
 179 }
 180
 181 static efi_status_t virt_efi_get_next_variable(unsigned long *name_size,
 182                                                efi_char16_t *name,
 183                                                efi_guid_t *vendor)
 184 {
 185         efi_status_t status;
 186
 187         spin_lock(&efi_runtime_lock);
 188         status = efi_call_virt(get_next_variable, name_size, name, vendor);
 189         spin_unlock(&efi_runtime_lock);
 190         return status;
 191 }
 192
 193 static efi_status_t virt_efi_set_variable(efi_char16_t *name,
 194                                           efi_guid_t *vendor,
 195                                           u32 attr,
 196                                           unsigned long data_size,
 197                                           void *data)
 198 {
 199         efi_status_t status;
 200
 201         spin_lock(&efi_runtime_lock);
 202         status = efi_call_virt(set_variable, name, vendor, attr, data_size,
 203                                data);
 204         spin_unlock(&efi_runtime_lock);
 205         return status;
 206 }
 207
 208 static efi_status_t
 209 virt_efi_set_variable_nonblocking(efi_char16_t *name, efi_guid_t *vendor,
 210                                   u32 attr, unsigned long data_size,
 211                                   void *data)
 212 {
 213         efi_status_t status;
 214
 215         if (!spin_trylock(&efi_runtime_lock))
 216                 return EFI_NOT_READY;
 217
 218         status = efi_call_virt(set_variable, name, vendor, attr, data_size,
 219                                data);
 220         spin_unlock(&efi_runtime_lock);
 221         return status;
 222 }
 223
 224
 225 static efi_status_t virt_efi_query_variable_info(u32 attr,
 226                                                  u64 *storage_space,
 227                                                  u64 *remaining_space,
 228                                                  u64 *max_variable_size)
 229 {
 230         efi_status_t status;
 231
 232         if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION)
 233                 return EFI_UNSUPPORTED;
 234
 235         spin_lock(&efi_runtime_lock);
 236         status = efi_call_virt(query_variable_info, attr, storage_space,
 237                                remaining_space, max_variable_size);
 238         spin_unlock(&efi_runtime_lock);
 239         return status;
 240 }
 241
 242 static efi_status_t
 243 virt_efi_query_variable_info_nonblocking(u32 attr,
 244                                          u64 *storage_space,
 245                                          u64 *remaining_space,
 246                                          u64 *max_variable_size)
 247 {
 248         efi_status_t status;
 249
 250         if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION)
 251                 return EFI_UNSUPPORTED;
 252
 253         if (!spin_trylock(&efi_runtime_lock))
 254                 return EFI_NOT_READY;
 255
 256         status = efi_call_virt(query_variable_info, attr, storage_space,
 257                                remaining_space, max_variable_size);
 258         spin_unlock(&efi_runtime_lock);
 259         return status;
 260 }
 261
 262 static efi_status_t virt_efi_get_next_high_mono_count(u32 *count)
 263 {
 264         efi_status_t status;
 265
 266         spin_lock(&efi_runtime_lock);
 267         status = efi_call_virt(get_next_high_mono_count, count);
 268         spin_unlock(&efi_runtime_lock);
 269         return status;
 270 }
 271
 272 static void virt_efi_reset_system(int reset_type,
 273                                   efi_status_t status,
 274                                   unsigned long data_size,
 275                                   efi_char16_t *data)
 276 {
 277         spin_lock(&efi_runtime_lock);
 278         __efi_call_virt(reset_system, reset_type, status, data_size, data);
 279         spin_unlock(&efi_runtime_lock);
 280 }
 281
 282 static efi_status_t virt_efi_update_capsule(efi_capsule_header_t **capsules,
 283                                             unsigned long count,
 284                                             unsigned long sg_list)
 285 {
 286         efi_status_t status;
 287
 288         if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION)
 289                 return EFI_UNSUPPORTED;
 290
 291         spin_lock(&efi_runtime_lock);
 292         status = efi_call_virt(update_capsule, capsules, count, sg_list);
 293         spin_unlock(&efi_runtime_lock);
 294         return status;
 295 }
 296
 297 static efi_status_t virt_efi_query_capsule_caps(efi_capsule_header_t **capsules,
 298                                                 unsigned long count,
 299                                                 u64 *max_size,
 300                                                 int *reset_type)
 301 {
 302         efi_status_t status;
 303
 304         if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION)
 305                 return EFI_UNSUPPORTED;
 306
 307         spin_lock(&efi_runtime_lock);
 308         status = efi_call_virt(query_capsule_caps, capsules, count, max_size,
 309                                reset_type);
 310         spin_unlock(&efi_runtime_lock);
 311         return status;
 312 }
 313
 314 void efi_native_runtime_setup(void)
 315 {
 316         efi.get_time = virt_efi_get_time;
 317         efi.set_time = virt_efi_set_time;
 318         efi.get_wakeup_time = virt_efi_get_wakeup_time;
 319         efi.set_wakeup_time = virt_efi_set_wakeup_time;
 320         efi.get_variable = virt_efi_get_variable;
 321         efi.get_next_variable = virt_efi_get_next_variable;
 322         efi.set_variable = virt_efi_set_variable;
 323         efi.set_variable_nonblocking = virt_efi_set_variable_nonblocking;
 324         efi.get_next_high_mono_count = virt_efi_get_next_high_mono_count;
 325         efi.reset_system = virt_efi_reset_system;
 326         efi.query_variable_info = virt_efi_query_variable_info;
 327         efi.query_variable_info_nonblocking = virt_efi_query_variable_info_nonblocking;
 328         efi.update_capsule = virt_efi_update_capsule;
 329         efi.query_capsule_caps = virt_efi_query_capsule_caps;
 330 }