Initial import

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;
+}