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 /* 65 * Some runtime services calls can be reentrant under NMI, even if the table 66 * above says they are not. (source: UEFI Specification v2.4A) 67 * 68 * Table 32. Functions that may be called after Machine Check, INIT and NMI 69 * +----------------------------+------------------------------------------+ 70 * | Function | Called after Machine Check, INIT and NMI | 71 * +----------------------------+------------------------------------------+ 72 * | GetTime() | Yes, even if previously busy. | 73 * | GetVariable() | Yes, even if previously busy | 74 * | GetNextVariableName() | Yes, even if previously busy | 75 * | QueryVariableInfo() | Yes, even if previously busy | 76 * | SetVariable() | Yes, even if previously busy | 77 * | UpdateCapsule() | Yes, even if previously busy | 78 * | QueryCapsuleCapabilities() | Yes, even if previously busy | 79 * | ResetSystem() | Yes, even if previously busy | 80 * +----------------------------+------------------------------------------+ 81 * 82 * In order to prevent deadlocks under NMI, the wrappers for these functions 83 * may only grab the efi_runtime_lock or rtc_lock spinlocks if !efi_in_nmi(). 84 * However, not all of the services listed are reachable through NMI code paths, 85 * so the the special handling as suggested by the UEFI spec is only implemented 86 * for QueryVariableInfo() and SetVariable(), as these can be reached in NMI 87 * context through efi_pstore_write(). 88 */ 89 90 /* 91 * As per commit ef68c8f87ed1 ("x86: Serialize EFI time accesses on rtc_lock"), 92 * the EFI specification requires that callers of the time related runtime 93 * functions serialize with other CMOS accesses in the kernel, as the EFI time 94 * functions may choose to also use the legacy CMOS RTC. 95 */ 96 __weak DEFINE_SPINLOCK(rtc_lock); 97 98 static efi_status_t virt_efi_get_time(efi_time_t *tm, efi_time_cap_t *tc) 99 { 100 unsigned long flags; 101 efi_status_t status; 102 103 spin_lock_irqsave(&rtc_lock, flags); 104 spin_lock(&efi_runtime_lock); 105 status = efi_call_virt(get_time, tm, tc); 106 spin_unlock(&efi_runtime_lock); 107 spin_unlock_irqrestore(&rtc_lock, flags); 108 return status; 109 } 110 111 static efi_status_t virt_efi_set_time(efi_time_t *tm) 112 { 113 unsigned long flags; 114 efi_status_t status; 115 116 spin_lock_irqsave(&rtc_lock, flags); 117 spin_lock(&efi_runtime_lock); 118 status = efi_call_virt(set_time, tm); 119 spin_unlock(&efi_runtime_lock); 120 spin_unlock_irqrestore(&rtc_lock, flags); 121 return status; 122 } 123 124 static efi_status_t virt_efi_get_wakeup_time(efi_bool_t *enabled, 125 efi_bool_t *pending, 126 efi_time_t *tm) 127 { 128 unsigned long flags; 129 efi_status_t status; 130 131 spin_lock_irqsave(&rtc_lock, flags); 132 spin_lock(&efi_runtime_lock); 133 status = efi_call_virt(get_wakeup_time, enabled, pending, tm); 134 spin_unlock(&efi_runtime_lock); 135 spin_unlock_irqrestore(&rtc_lock, flags); 136 return status; 137 } 138 139 static efi_status_t virt_efi_set_wakeup_time(efi_bool_t enabled, efi_time_t *tm) 140 { 141 unsigned long flags; 142 efi_status_t status; 143 144 spin_lock_irqsave(&rtc_lock, flags); 145 spin_lock(&efi_runtime_lock); 146 status = efi_call_virt(set_wakeup_time, enabled, tm); 147 spin_unlock(&efi_runtime_lock); 148 spin_unlock_irqrestore(&rtc_lock, flags); 149 return status; 150 } 151 152 static efi_status_t virt_efi_get_variable(efi_char16_t *name, 153 efi_guid_t *vendor, 154 u32 *attr, 155 unsigned long *data_size, 156 void *data) 157 { 158 unsigned long flags; 159 efi_status_t status; 160 161 spin_lock_irqsave(&efi_runtime_lock, flags); 162 status = efi_call_virt(get_variable, name, vendor, attr, data_size, 163 data); 164 spin_unlock_irqrestore(&efi_runtime_lock, flags); 165 return status; 166 } 167 168 static efi_status_t virt_efi_get_next_variable(unsigned long *name_size, 169 efi_char16_t *name, 170 efi_guid_t *vendor) 171 { 172 unsigned long flags; 173 efi_status_t status; 174 175 spin_lock_irqsave(&efi_runtime_lock, flags); 176 status = efi_call_virt(get_next_variable, name_size, name, vendor); 177 spin_unlock_irqrestore(&efi_runtime_lock, flags); 178 return status; 179 } 180 181 static efi_status_t virt_efi_set_variable(efi_char16_t *name, 182 efi_guid_t *vendor, 183 u32 attr, 184 unsigned long data_size, 185 void *data) 186 { 187 unsigned long flags; 188 efi_status_t status; 189 190 spin_lock_irqsave(&efi_runtime_lock, flags); 191 status = efi_call_virt(set_variable, name, vendor, attr, data_size, 192 data); 193 spin_unlock_irqrestore(&efi_runtime_lock, flags); 194 return status; 195 } 196 197 static efi_status_t 198 virt_efi_set_variable_nonblocking(efi_char16_t *name, efi_guid_t *vendor, 199 u32 attr, unsigned long data_size, 200 void *data) 201 { 202 unsigned long flags; 203 efi_status_t status; 204 205 if (!spin_trylock_irqsave(&efi_runtime_lock, flags)) 206 return EFI_NOT_READY; 207 208 status = efi_call_virt(set_variable, name, vendor, attr, data_size, 209 data); 210 spin_unlock_irqrestore(&efi_runtime_lock, flags); 211 return status; 212 } 213 214 215 static efi_status_t virt_efi_query_variable_info(u32 attr, 216 u64 *storage_space, 217 u64 *remaining_space, 218 u64 *max_variable_size) 219 { 220 unsigned long flags; 221 efi_status_t status; 222 223 if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION) 224 return EFI_UNSUPPORTED; 225 226 spin_lock_irqsave(&efi_runtime_lock, flags); 227 status = efi_call_virt(query_variable_info, attr, storage_space, 228 remaining_space, max_variable_size); 229 spin_unlock_irqrestore(&efi_runtime_lock, flags); 230 return status; 231 } 232 233 static efi_status_t virt_efi_get_next_high_mono_count(u32 *count) 234 { 235 unsigned long flags; 236 efi_status_t status; 237 238 spin_lock_irqsave(&efi_runtime_lock, flags); 239 status = efi_call_virt(get_next_high_mono_count, count); 240 spin_unlock_irqrestore(&efi_runtime_lock, flags); 241 return status; 242 } 243 244 static void virt_efi_reset_system(int reset_type, 245 efi_status_t status, 246 unsigned long data_size, 247 efi_char16_t *data) 248 { 249 unsigned long flags; 250 251 spin_lock_irqsave(&efi_runtime_lock, flags); 252 __efi_call_virt(reset_system, reset_type, status, data_size, data); 253 spin_unlock_irqrestore(&efi_runtime_lock, flags); 254 } 255 256 static efi_status_t virt_efi_update_capsule(efi_capsule_header_t **capsules, 257 unsigned long count, 258 unsigned long sg_list) 259 { 260 unsigned long flags; 261 efi_status_t status; 262 263 if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION) 264 return EFI_UNSUPPORTED; 265 266 spin_lock_irqsave(&efi_runtime_lock, flags); 267 status = efi_call_virt(update_capsule, capsules, count, sg_list); 268 spin_unlock_irqrestore(&efi_runtime_lock, flags); 269 return status; 270 } 271 272 static efi_status_t virt_efi_query_capsule_caps(efi_capsule_header_t **capsules, 273 unsigned long count, 274 u64 *max_size, 275 int *reset_type) 276 { 277 unsigned long flags; 278 efi_status_t status; 279 280 if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION) 281 return EFI_UNSUPPORTED; 282 283 spin_lock_irqsave(&efi_runtime_lock, flags); 284 status = efi_call_virt(query_capsule_caps, capsules, count, max_size, 285 reset_type); 286 spin_unlock_irqrestore(&efi_runtime_lock, flags); 287 return status; 288 } 289 290 void efi_native_runtime_setup(void) 291 { 292 efi.get_time = virt_efi_get_time; 293 efi.set_time = virt_efi_set_time; 294 efi.get_wakeup_time = virt_efi_get_wakeup_time; 295 efi.set_wakeup_time = virt_efi_set_wakeup_time; 296 efi.get_variable = virt_efi_get_variable; 297 efi.get_next_variable = virt_efi_get_next_variable; 298 efi.set_variable = virt_efi_set_variable; 299 efi.set_variable_nonblocking = virt_efi_set_variable_nonblocking; 300 efi.get_next_high_mono_count = virt_efi_get_next_high_mono_count; 301 efi.reset_system = virt_efi_reset_system; 302 efi.query_variable_info = virt_efi_query_variable_info; 303 efi.update_capsule = virt_efi_update_capsule; 304 efi.query_capsule_caps = virt_efi_query_capsule_caps; 305 } 306