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/mutex.h>
  20 #include <linux/spinlock.h>
  21 #include <asm/efi.h>
  22
  23 /*
  24  * According to section 7.1 of the UEFI spec, Runtime Services are not fully
  25  * reentrant, and there are particular combinations of calls that need to be
  26  * serialized. (source: UEFI Specification v2.4A)
  27  *
  28  * Table 31. Rules for Reentry Into Runtime Services
  29  * +------------------------------------+-------------------------------+
  30  * | If previous call is busy in        | Forbidden to call             |
  31  * +------------------------------------+-------------------------------+
  32  * | Any                                | SetVirtualAddressMap()        |
  33  * +------------------------------------+-------------------------------+
  34  * | ConvertPointer()                   | ConvertPointer()              |
  35  * +------------------------------------+-------------------------------+
  36  * | SetVariable()                      | ResetSystem()                 |
  37  * | UpdateCapsule()                    |                               |
  38  * | SetTime()                          |                               |
  39  * | SetWakeupTime()                    |                               |
  40  * | GetNextHighMonotonicCount()        |                               |
  41  * +------------------------------------+-------------------------------+
  42  * | GetVariable()                      | GetVariable()                 |
  43  * | GetNextVariableName()              | GetNextVariableName()         |
  44  * | SetVariable()                      | SetVariable()                 |
  45  * | QueryVariableInfo()                | QueryVariableInfo()           |
  46  * | UpdateCapsule()                    | UpdateCapsule()               |
  47  * | QueryCapsuleCapabilities()         | QueryCapsuleCapabilities()    |
  48  * | GetNextHighMonotonicCount()        | GetNextHighMonotonicCount()   |
  49  * +------------------------------------+-------------------------------+
  50  * | GetTime()                          | GetTime()                     |
  51  * | SetTime()                          | SetTime()                     |
  52  * | GetWakeupTime()                    | GetWakeupTime()               |
  53  * | SetWakeupTime()                    | SetWakeupTime()               |
  54  * +------------------------------------+-------------------------------+
  55  *
  56  * Due to the fact that the EFI pstore may write to the variable store in
  57  * interrupt context, we need to use a spinlock for at least the groups that
  58  * contain SetVariable() and QueryVariableInfo(). That leaves little else, as
  59  * none of the remaining functions are actually ever called at runtime.
  60  * So let's just use a single spinlock to serialize all Runtime Services calls.
  61  */
  62 static DEFINE_SPINLOCK(efi_runtime_lock);
  63
  64 static efi_status_t virt_efi_get_time(efi_time_t *tm, efi_time_cap_t *tc)
  65 {
  66         efi_status_t status;
  67
  68         spin_lock(&efi_runtime_lock);
  69         status = efi_call_virt(get_time, tm, tc);
  70         spin_unlock(&efi_runtime_lock);
  71         return status;
  72 }
  73
  74 static efi_status_t virt_efi_set_time(efi_time_t *tm)
  75 {
  76         efi_status_t status;
  77
  78         spin_lock(&efi_runtime_lock);
  79         status = efi_call_virt(set_time, tm);
  80         spin_unlock(&efi_runtime_lock);
  81         return status;
  82 }
  83
  84 static efi_status_t virt_efi_get_wakeup_time(efi_bool_t *enabled,
  85                                              efi_bool_t *pending,
  86                                              efi_time_t *tm)
  87 {
  88         efi_status_t status;
  89
  90         spin_lock(&efi_runtime_lock);
  91         status = efi_call_virt(get_wakeup_time, enabled, pending, tm);
  92         spin_unlock(&efi_runtime_lock);
  93         return status;
  94 }
  95
  96 static efi_status_t virt_efi_set_wakeup_time(efi_bool_t enabled, efi_time_t *tm)
  97 {
  98         efi_status_t status;
  99
 100         spin_lock(&efi_runtime_lock);
 101         status = efi_call_virt(set_wakeup_time, enabled, tm);
 102         spin_unlock(&efi_runtime_lock);
 103         return status;
 104 }
 105
 106 static efi_status_t virt_efi_get_variable(efi_char16_t *name,
 107                                           efi_guid_t *vendor,
 108                                           u32 *attr,
 109                                           unsigned long *data_size,
 110                                           void *data)
 111 {
 112         efi_status_t status;
 113
 114         spin_lock(&efi_runtime_lock);
 115         status = efi_call_virt(get_variable, name, vendor, attr, data_size,
 116                                data);
 117         spin_unlock(&efi_runtime_lock);
 118         return status;
 119 }
 120
 121 static efi_status_t virt_efi_get_next_variable(unsigned long *name_size,
 122                                                efi_char16_t *name,
 123                                                efi_guid_t *vendor)
 124 {
 125         efi_status_t status;
 126
 127         spin_lock(&efi_runtime_lock);
 128         status = efi_call_virt(get_next_variable, name_size, name, vendor);
 129         spin_unlock(&efi_runtime_lock);
 130         return status;
 131 }
 132
 133 static efi_status_t virt_efi_set_variable(efi_char16_t *name,
 134                                           efi_guid_t *vendor,
 135                                           u32 attr,
 136                                           unsigned long data_size,
 137                                           void *data)
 138 {
 139         efi_status_t status;
 140
 141         spin_lock(&efi_runtime_lock);
 142         status = efi_call_virt(set_variable, name, vendor, attr, data_size,
 143                                data);
 144         spin_unlock(&efi_runtime_lock);
 145         return status;
 146 }
 147
 148 static efi_status_t
 149 virt_efi_set_variable_nonblocking(efi_char16_t *name, efi_guid_t *vendor,
 150                                   u32 attr, unsigned long data_size,
 151                                   void *data)
 152 {
 153         efi_status_t status;
 154
 155         if (!spin_trylock(&efi_runtime_lock))
 156                 return EFI_NOT_READY;
 157
 158         status = efi_call_virt(set_variable, name, vendor, attr, data_size,
 159                                data);
 160         spin_unlock(&efi_runtime_lock);
 161         return status;
 162 }
 163
 164
 165 static efi_status_t virt_efi_query_variable_info(u32 attr,
 166                                                  u64 *storage_space,
 167                                                  u64 *remaining_space,
 168                                                  u64 *max_variable_size)
 169 {
 170         efi_status_t status;
 171
 172         if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION)
 173                 return EFI_UNSUPPORTED;
 174
 175         spin_lock(&efi_runtime_lock);
 176         status = efi_call_virt(query_variable_info, attr, storage_space,
 177                                remaining_space, max_variable_size);
 178         spin_unlock(&efi_runtime_lock);
 179         return status;
 180 }
 181
 182 static efi_status_t
 183 virt_efi_query_variable_info_nonblocking(u32 attr,
 184                                          u64 *storage_space,
 185                                          u64 *remaining_space,
 186                                          u64 *max_variable_size)
 187 {
 188         efi_status_t status;
 189
 190         if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION)
 191                 return EFI_UNSUPPORTED;
 192
 193         if (!spin_trylock(&efi_runtime_lock))
 194                 return EFI_NOT_READY;
 195
 196         status = efi_call_virt(query_variable_info, attr, storage_space,
 197                                remaining_space, max_variable_size);
 198         spin_unlock(&efi_runtime_lock);
 199         return status;
 200 }
 201
 202 static efi_status_t virt_efi_get_next_high_mono_count(u32 *count)
 203 {
 204         efi_status_t status;
 205
 206         spin_lock(&efi_runtime_lock);
 207         status = efi_call_virt(get_next_high_mono_count, count);
 208         spin_unlock(&efi_runtime_lock);
 209         return status;
 210 }
 211
 212 static void virt_efi_reset_system(int reset_type,
 213                                   efi_status_t status,
 214                                   unsigned long data_size,
 215                                   efi_char16_t *data)
 216 {
 217         spin_lock(&efi_runtime_lock);
 218         __efi_call_virt(reset_system, reset_type, status, data_size, data);
 219         spin_unlock(&efi_runtime_lock);
 220 }
 221
 222 static efi_status_t virt_efi_update_capsule(efi_capsule_header_t **capsules,
 223                                             unsigned long count,
 224                                             unsigned long sg_list)
 225 {
 226         efi_status_t status;
 227
 228         if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION)
 229                 return EFI_UNSUPPORTED;
 230
 231         spin_lock(&efi_runtime_lock);
 232         status = efi_call_virt(update_capsule, capsules, count, sg_list);
 233         spin_unlock(&efi_runtime_lock);
 234         return status;
 235 }
 236
 237 static efi_status_t virt_efi_query_capsule_caps(efi_capsule_header_t **capsules,
 238                                                 unsigned long count,
 239                                                 u64 *max_size,
 240                                                 int *reset_type)
 241 {
 242         efi_status_t status;
 243
 244         if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION)
 245                 return EFI_UNSUPPORTED;
 246
 247         spin_lock(&efi_runtime_lock);
 248         status = efi_call_virt(query_capsule_caps, capsules, count, max_size,
 249                                reset_type);
 250         spin_unlock(&efi_runtime_lock);
 251         return status;
 252 }
 253
 254 void efi_native_runtime_setup(void)
 255 {
 256         efi.get_time = virt_efi_get_time;
 257         efi.set_time = virt_efi_set_time;
 258         efi.get_wakeup_time = virt_efi_get_wakeup_time;
 259         efi.set_wakeup_time = virt_efi_set_wakeup_time;
 260         efi.get_variable = virt_efi_get_variable;
 261         efi.get_next_variable = virt_efi_get_next_variable;
 262         efi.set_variable = virt_efi_set_variable;
 263         efi.set_variable_nonblocking = virt_efi_set_variable_nonblocking;
 264         efi.get_next_high_mono_count = virt_efi_get_next_high_mono_count;
 265         efi.reset_system = virt_efi_reset_system;
 266         efi.query_variable_info = virt_efi_query_variable_info;
 267         efi.query_variable_info_nonblocking = virt_efi_query_variable_info_nonblocking;
 268         efi.update_capsule = virt_efi_update_capsule;
 269         efi.query_capsule_caps = virt_efi_query_capsule_caps;
 270 }