diff options
Diffstat (limited to 'drivers/firmware/efi/runtime-wrappers.c')
| -rw-r--r-- | drivers/firmware/efi/runtime-wrappers.c | 305 |
1 files changed, 305 insertions, 0 deletions
diff --git a/drivers/firmware/efi/runtime-wrappers.c b/drivers/firmware/efi/runtime-wrappers.c new file mode 100644 index 000000000..228bbf910 --- /dev/null +++ b/drivers/firmware/efi/runtime-wrappers.c @@ -0,0 +1,305 @@ +/* + * runtime-wrappers.c - Runtime Services function call wrappers + * + * Copyright (C) 2014 Linaro Ltd. <ard.biesheuvel@linaro.org> + * + * Split off from arch/x86/platform/efi/efi.c + * + * Copyright (C) 1999 VA Linux Systems + * Copyright (C) 1999 Walt Drummond <drummond@valinux.com> + * 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 <linux/bug.h> +#include <linux/efi.h> +#include <linux/mutex.h> +#include <linux/spinlock.h> +#include <asm/efi.h> + +/* + * 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; +} |