/* * runtime-wrappers.c - Runtime Services function call wrappers * * Copyright (C) 2014 Linaro Ltd. * * Split off from arch/x86/platform/efi/efi.c * * Copyright (C) 1999 VA Linux Systems * Copyright (C) 1999 Walt Drummond * Copyright (C) 1999-2002 Hewlett-Packard Co. * Copyright (C) 2005-2008 Intel Co. * Copyright (C) 2013 SuSE Labs * * This file is released under the GPLv2. */ #include #include #include #include #include /* * According to section 7.1 of the UEFI spec, Runtime Services are not fully * reentrant, and there are particular combinations of calls that need to be * serialized. (source: UEFI Specification v2.4A) * * Table 31. Rules for Reentry Into Runtime Services * +------------------------------------+-------------------------------+ * | If previous call is busy in | Forbidden to call | * +------------------------------------+-------------------------------+ * | Any | SetVirtualAddressMap() | * +------------------------------------+-------------------------------+ * | ConvertPointer() | ConvertPointer() | * +------------------------------------+-------------------------------+ * | SetVariable() | ResetSystem() | * | UpdateCapsule() | | * | SetTime() | | * | SetWakeupTime() | | * | GetNextHighMonotonicCount() | | * +------------------------------------+-------------------------------+ * | GetVariable() | GetVariable() | * | GetNextVariableName() | GetNextVariableName() | * | SetVariable() | SetVariable() | * | QueryVariableInfo() | QueryVariableInfo() | * | UpdateCapsule() | UpdateCapsule() | * | QueryCapsuleCapabilities() | QueryCapsuleCapabilities() | * | GetNextHighMonotonicCount() | GetNextHighMonotonicCount() | * +------------------------------------+-------------------------------+ * | GetTime() | GetTime() | * | SetTime() | SetTime() | * | GetWakeupTime() | GetWakeupTime() | * | SetWakeupTime() | SetWakeupTime() | * +------------------------------------+-------------------------------+ * * Due to the fact that the EFI pstore may write to the variable store in * interrupt context, we need to use a spinlock for at least the groups that * contain SetVariable() and QueryVariableInfo(). That leaves little else, as * none of the remaining functions are actually ever called at runtime. * So let's just use a single spinlock to serialize all Runtime Services calls. */ static DEFINE_SPINLOCK(efi_runtime_lock); /* * Some runtime services calls can be reentrant under NMI, even if the table * above says they are not. (source: UEFI Specification v2.4A) * * Table 32. Functions that may be called after Machine Check, INIT and NMI * +----------------------------+------------------------------------------+ * | Function | Called after Machine Check, INIT and NMI | * +----------------------------+------------------------------------------+ * | GetTime() | Yes, even if previously busy. | * | GetVariable() | Yes, even if previously busy | * | GetNextVariableName() | Yes, even if previously busy | * | QueryVariableInfo() | Yes, even if previously busy | * | SetVariable() | Yes, even if previously busy | * | UpdateCapsule() | Yes, even if previously busy | * | QueryCapsuleCapabilities() | Yes, even if previously busy | * | ResetSystem() | Yes, even if previously busy | * +----------------------------+------------------------------------------+ * * In order to prevent deadlocks under NMI, the wrappers for these functions * may only grab the efi_runtime_lock or rtc_lock spinlocks if !efi_in_nmi(). * However, not all of the services listed are reachable through NMI code paths, * so the the special handling as suggested by the UEFI spec is only implemented * for QueryVariableInfo() and SetVariable(), as these can be reached in NMI * context through efi_pstore_write(). */ /* * As per commit ef68c8f87ed1 ("x86: Serialize EFI time accesses on rtc_lock"), * the EFI specification requires that callers of the time related runtime * functions serialize with other CMOS accesses in the kernel, as the EFI time * functions may choose to also use the legacy CMOS RTC. */ __weak DEFINE_SPINLOCK(rtc_lock); static efi_status_t virt_efi_get_time(efi_time_t *tm, efi_time_cap_t *tc) { unsigned long flags; efi_status_t status; spin_lock_irqsave(&rtc_lock, flags); spin_lock(&efi_runtime_lock); status = efi_call_virt(get_time, tm, tc); spin_unlock(&efi_runtime_lock); spin_unlock_irqrestore(&rtc_lock, flags); return status; } static efi_status_t virt_efi_set_time(efi_time_t *tm) { unsigned long flags; efi_status_t status; spin_lock_irqsave(&rtc_lock, flags); spin_lock(&efi_runtime_lock); status = efi_call_virt(set_time, tm); spin_unlock(&efi_runtime_lock); spin_unlock_irqrestore(&rtc_lock, flags); return status; } static efi_status_t virt_efi_get_wakeup_time(efi_bool_t *enabled, efi_bool_t *pending, efi_time_t *tm) { unsigned long flags; efi_status_t status; spin_lock_irqsave(&rtc_lock, flags); spin_lock(&efi_runtime_lock); status = efi_call_virt(get_wakeup_time, enabled, pending, tm); spin_unlock(&efi_runtime_lock); spin_unlock_irqrestore(&rtc_lock, flags); return status; } static efi_status_t virt_efi_set_wakeup_time(efi_bool_t enabled, efi_time_t *tm) { unsigned long flags; efi_status_t status; spin_lock_irqsave(&rtc_lock, flags); spin_lock(&efi_runtime_lock); status = efi_call_virt(set_wakeup_time, enabled, tm); spin_unlock(&efi_runtime_lock); spin_unlock_irqrestore(&rtc_lock, flags); return status; } static efi_status_t virt_efi_get_variable(efi_char16_t *name, efi_guid_t *vendor, u32 *attr, unsigned long *data_size, void *data) { unsigned long flags; efi_status_t status; spin_lock_irqsave(&efi_runtime_lock, flags); status = efi_call_virt(get_variable, name, vendor, attr, data_size, data); spin_unlock_irqrestore(&efi_runtime_lock, flags); return status; } static efi_status_t virt_efi_get_next_variable(unsigned long *name_size, efi_char16_t *name, efi_guid_t *vendor) { unsigned long flags; efi_status_t status; spin_lock_irqsave(&efi_runtime_lock, flags); status = efi_call_virt(get_next_variable, name_size, name, vendor); spin_unlock_irqrestore(&efi_runtime_lock, flags); return status; } static efi_status_t virt_efi_set_variable(efi_char16_t *name, efi_guid_t *vendor, u32 attr, unsigned long data_size, void *data) { unsigned long flags; efi_status_t status; spin_lock_irqsave(&efi_runtime_lock, flags); status = efi_call_virt(set_variable, name, vendor, attr, data_size, data); spin_unlock_irqrestore(&efi_runtime_lock, flags); return status; } static efi_status_t virt_efi_set_variable_nonblocking(efi_char16_t *name, efi_guid_t *vendor, u32 attr, unsigned long data_size, void *data) { unsigned long flags; efi_status_t status; if (!spin_trylock_irqsave(&efi_runtime_lock, flags)) return EFI_NOT_READY; status = efi_call_virt(set_variable, name, vendor, attr, data_size, data); spin_unlock_irqrestore(&efi_runtime_lock, flags); return status; } static efi_status_t virt_efi_query_variable_info(u32 attr, u64 *storage_space, u64 *remaining_space, u64 *max_variable_size) { unsigned long flags; efi_status_t status; if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION) return EFI_UNSUPPORTED; spin_lock_irqsave(&efi_runtime_lock, flags); status = efi_call_virt(query_variable_info, attr, storage_space, remaining_space, max_variable_size); spin_unlock_irqrestore(&efi_runtime_lock, flags); return status; } static efi_status_t virt_efi_get_next_high_mono_count(u32 *count) { unsigned long flags; efi_status_t status; spin_lock_irqsave(&efi_runtime_lock, flags); status = efi_call_virt(get_next_high_mono_count, count); spin_unlock_irqrestore(&efi_runtime_lock, flags); return status; } static void virt_efi_reset_system(int reset_type, efi_status_t status, unsigned long data_size, efi_char16_t *data) { unsigned long flags; spin_lock_irqsave(&efi_runtime_lock, flags); __efi_call_virt(reset_system, reset_type, status, data_size, data); spin_unlock_irqrestore(&efi_runtime_lock, flags); } static efi_status_t virt_efi_update_capsule(efi_capsule_header_t **capsules, unsigned long count, unsigned long sg_list) { unsigned long flags; efi_status_t status; if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION) return EFI_UNSUPPORTED; spin_lock_irqsave(&efi_runtime_lock, flags); status = efi_call_virt(update_capsule, capsules, count, sg_list); spin_unlock_irqrestore(&efi_runtime_lock, flags); return status; } static efi_status_t virt_efi_query_capsule_caps(efi_capsule_header_t **capsules, unsigned long count, u64 *max_size, int *reset_type) { unsigned long flags; efi_status_t status; if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION) return EFI_UNSUPPORTED; spin_lock_irqsave(&efi_runtime_lock, flags); status = efi_call_virt(query_capsule_caps, capsules, count, max_size, reset_type); spin_unlock_irqrestore(&efi_runtime_lock, flags); return status; } void efi_native_runtime_setup(void) { efi.get_time = virt_efi_get_time; efi.set_time = virt_efi_set_time; efi.get_wakeup_time = virt_efi_get_wakeup_time; efi.set_wakeup_time = virt_efi_set_wakeup_time; efi.get_variable = virt_efi_get_variable; efi.get_next_variable = virt_efi_get_next_variable; efi.set_variable = virt_efi_set_variable; efi.set_variable_nonblocking = virt_efi_set_variable_nonblocking; efi.get_next_high_mono_count = virt_efi_get_next_high_mono_count; efi.reset_system = virt_efi_reset_system; efi.query_variable_info = virt_efi_query_variable_info; efi.update_capsule = virt_efi_update_capsule; efi.query_capsule_caps = virt_efi_query_capsule_caps; }