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.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
---
drivers/firmware/efi/runtime-wrappers.c | 109 +++++++++++++++++++++++++++++---
1 file changed, 99 insertions(+), 10 deletions(-)
diff --git a/drivers/firmware/efi/runtime-wrappers.c b/drivers/firmware/efi/runtime-wrappers.c
index 10daa4bbb258..6588d054af99 100644
--- a/drivers/firmware/efi/runtime-wrappers.c
+++ b/drivers/firmware/efi/runtime-wrappers.c
@@ -15,10 +15,50 @@
*/
#include <linux/efi.h>
-#include <linux/spinlock.h> /* spinlock_t */
+#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.
+ *
+ * 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() |
+ * +------------------------------------+-------------------------------+
+ *
+ * The first two are disregarded here, as SetVirtualAddressMap() is called
+ * only once, and very early, and ConvertPointer() is not exposed at all.
+ */
+static DEFINE_MUTEX(var_ro_mutex);
+static DEFINE_MUTEX(var_rw_mutex);
+
+/*
* 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
@@ -78,14 +118,25 @@ static efi_status_t virt_efi_get_variable(efi_char16_t *name,
unsigned long *data_size,
void *data)
{
- return efi_call_virt(get_variable, name, vendor, attr, data_size, data);
+ efi_status_t status;
+
+ mutex_lock(&var_ro_mutex);
+ status = efi_call_virt(get_variable, name, vendor, attr, data_size,
+ data);
+ mutex_unlock(&var_ro_mutex);
+ return status;
}
static efi_status_t virt_efi_get_next_variable(unsigned long *name_size,
efi_char16_t *name,
efi_guid_t *vendor)
{
- return efi_call_virt(get_next_variable, name_size, name, vendor);
+ efi_status_t status;
+
+ mutex_lock(&var_ro_mutex);
+ status = efi_call_virt(get_next_variable, name_size, name, vendor);
+ mutex_unlock(&var_ro_mutex);
+ return status;
}
static efi_status_t virt_efi_set_variable(efi_char16_t *name,
@@ -94,7 +145,15 @@ static efi_status_t virt_efi_set_variable(efi_char16_t *name,
unsigned long data_size,
void *data)
{
- return efi_call_virt(set_variable, name, vendor, attr, data_size, data);
+ efi_status_t status;
+
+ mutex_lock(&var_ro_mutex);
+ mutex_lock(&var_rw_mutex);
+ status = efi_call_virt(set_variable, name, vendor, attr, data_size,
+ data);
+ mutex_unlock(&var_rw_mutex);
+ mutex_unlock(&var_ro_mutex);
+ return status;
}
static efi_status_t virt_efi_query_variable_info(u32 attr,
@@ -102,16 +161,28 @@ static efi_status_t virt_efi_query_variable_info(u32 attr,
u64 *remaining_space,
u64 *max_variable_size)
{
+ efi_status_t status;
+
if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION)
return EFI_UNSUPPORTED;
- return efi_call_virt(query_variable_info, attr, storage_space,
- remaining_space, max_variable_size);
+ mutex_lock(&var_ro_mutex);
+ status = efi_call_virt(query_variable_info, attr, storage_space,
+ remaining_space, max_variable_size);
+ mutex_unlock(&var_ro_mutex);
+ return status;
}
static efi_status_t virt_efi_get_next_high_mono_count(u32 *count)
{
- return efi_call_virt(get_next_high_mono_count, count);
+ efi_status_t status;
+
+ mutex_lock(&var_ro_mutex);
+ mutex_lock(&var_rw_mutex);
+ status = efi_call_virt(get_next_high_mono_count, count);
+ mutex_unlock(&var_rw_mutex);
+ mutex_unlock(&var_ro_mutex);
+ return status;
}
static void virt_efi_reset_system(int reset_type,
@@ -119,17 +190,30 @@ static void virt_efi_reset_system(int reset_type,
unsigned long data_size,
efi_char16_t *data)
{
+ unsigned long flags;
+
+ mutex_lock(&var_rw_mutex);
+ spin_lock_irqsave(&rtc_lock, flags);
__efi_call_virt(reset_system, reset_type, status, data_size, data);
+ spin_unlock_irqrestore(&rtc_lock, flags);
+ mutex_unlock(&var_rw_mutex);
}
static efi_status_t virt_efi_update_capsule(efi_capsule_header_t **capsules,
unsigned long count,
unsigned long sg_list)
{
+ efi_status_t status;
+
if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION)
return EFI_UNSUPPORTED;
- return efi_call_virt(update_capsule, capsules, count, sg_list);
+ mutex_lock(&var_ro_mutex);
+ mutex_lock(&var_rw_mutex);
+ status = efi_call_virt(update_capsule, capsules, count, sg_list);
+ mutex_unlock(&var_rw_mutex);
+ mutex_unlock(&var_ro_mutex);
+ return status;
}
static efi_status_t virt_efi_query_capsule_caps(efi_capsule_header_t **capsules,
@@ -137,11 +221,16 @@ static efi_status_t virt_efi_query_capsule_caps(efi_capsule_header_t **capsules,
u64 *max_size,
int *reset_type)
{
+ efi_status_t status;
+
if (efi.runtime_version < EFI_2_00_SYSTEM_TABLE_REVISION)
return EFI_UNSUPPORTED;
- return efi_call_virt(query_capsule_caps, capsules, count, max_size,
- reset_type);
+ mutex_lock(&var_ro_mutex);
+ status = efi_call_virt(query_capsule_caps, capsules, count, max_size,
+ reset_type);
+ mutex_unlock(&var_ro_mutex);
+ return status;
}
void efi_native_runtime_setup(void)
--
1.8.3.2
--
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