diff options
| -rw-r--r-- | drivers/firmware/efi/runtime-wrappers.c | 19 | ||||
| -rw-r--r-- | drivers/firmware/efi/vars.c | 47 | ||||
| -rw-r--r-- | include/linux/efi.h | 6 |
3 files changed, 72 insertions, 0 deletions
diff --git a/drivers/firmware/efi/runtime-wrappers.c b/drivers/firmware/efi/runtime-wrappers.c index 9694cba665c4..4349206198b2 100644 --- a/drivers/firmware/efi/runtime-wrappers.c +++ b/drivers/firmware/efi/runtime-wrappers.c @@ -200,6 +200,24 @@ static efi_status_t virt_efi_set_variable(efi_char16_t *name, 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, @@ -287,6 +305,7 @@ void efi_native_runtime_setup(void) 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; diff --git a/drivers/firmware/efi/vars.c b/drivers/firmware/efi/vars.c index 1fa724f31b0e..fa3c66bdc1e5 100644 --- a/drivers/firmware/efi/vars.c +++ b/drivers/firmware/efi/vars.c @@ -595,6 +595,39 @@ int efivar_entry_set(struct efivar_entry *entry, u32 attributes, } EXPORT_SYMBOL_GPL(efivar_entry_set); +/* + * efivar_entry_set_nonblocking - call set_variable_nonblocking() + * + * This function is guaranteed to not block and is suitable for calling + * from crash/panic handlers. + * + * Crucially, this function will not block if it cannot acquire + * __efivars->lock. Instead, it returns -EBUSY. + */ +static int +efivar_entry_set_nonblocking(efi_char16_t *name, efi_guid_t vendor, + u32 attributes, unsigned long size, void *data) +{ + const struct efivar_operations *ops = __efivars->ops; + unsigned long flags; + efi_status_t status; + + if (!spin_trylock_irqsave(&__efivars->lock, flags)) + return -EBUSY; + + status = check_var_size(attributes, size + ucs2_strsize(name, 1024)); + if (status != EFI_SUCCESS) { + spin_unlock_irqrestore(&__efivars->lock, flags); + return -ENOSPC; + } + + status = ops->set_variable_nonblocking(name, &vendor, attributes, + size, data); + + spin_unlock_irqrestore(&__efivars->lock, flags); + return efi_status_to_err(status); +} + /** * efivar_entry_set_safe - call set_variable() if enough space in firmware * @name: buffer containing the variable name @@ -622,6 +655,20 @@ int efivar_entry_set_safe(efi_char16_t *name, efi_guid_t vendor, u32 attributes, if (!ops->query_variable_store) return -ENOSYS; + /* + * If the EFI variable backend provides a non-blocking + * ->set_variable() operation and we're in a context where we + * cannot block, then we need to use it to avoid live-locks, + * since the implication is that the regular ->set_variable() + * will block. + * + * If no ->set_variable_nonblocking() is provided then + * ->set_variable() is assumed to be non-blocking. + */ + if (!block && ops->set_variable_nonblocking) + return efivar_entry_set_nonblocking(name, vendor, attributes, + size, data); + if (!block) { if (!spin_trylock_irqsave(&__efivars->lock, flags)) return -EBUSY; diff --git a/include/linux/efi.h b/include/linux/efi.h index 78b29b133e14..0949f9c7e872 100644 --- a/include/linux/efi.h +++ b/include/linux/efi.h @@ -503,6 +503,10 @@ typedef efi_status_t efi_get_next_variable_t (unsigned long *name_size, efi_char typedef efi_status_t efi_set_variable_t (efi_char16_t *name, efi_guid_t *vendor, u32 attr, unsigned long data_size, void *data); +typedef efi_status_t +efi_set_variable_nonblocking_t(efi_char16_t *name, efi_guid_t *vendor, + u32 attr, unsigned long data_size, void *data); + typedef efi_status_t efi_get_next_high_mono_count_t (u32 *count); typedef void efi_reset_system_t (int reset_type, efi_status_t status, unsigned long data_size, efi_char16_t *data); @@ -822,6 +826,7 @@ extern struct efi { efi_get_variable_t *get_variable; efi_get_next_variable_t *get_next_variable; efi_set_variable_t *set_variable; + efi_set_variable_nonblocking_t *set_variable_nonblocking; efi_query_variable_info_t *query_variable_info; efi_update_capsule_t *update_capsule; efi_query_capsule_caps_t *query_capsule_caps; @@ -1042,6 +1047,7 @@ struct efivar_operations { efi_get_variable_t *get_variable; efi_get_next_variable_t *get_next_variable; efi_set_variable_t *set_variable; + efi_set_variable_nonblocking_t *set_variable_nonblocking; efi_query_variable_store_t *query_variable_store; }; |