3 files changed, 287 insertions, 0 deletions

diff --git a/drivers/firmware/efi/Kconfig b/drivers/firmware/efi/Kconfig
new file mode 100644
index 000000000000..b0fc7c79dfbb
--- /dev/null
+++ b/drivers/firmware/efi/Kconfig
@@ -0,0 +1,39 @@
+menu "EFI (Extensible Firmware Interface) Support"
+	depends on EFI
+
+config EFI_VARS
+	tristate "EFI Variable Support via sysfs"
+	depends on EFI
+	default n
+	help
+	  If you say Y here, you are able to get EFI (Extensible Firmware
+	  Interface) variable information via sysfs.  You may read,
+	  write, create, and destroy EFI variables through this interface.
+
+	  Note that using this driver in concert with efibootmgr requires
+	  at least test release version 0.5.0-test3 or later, which is
+	  available from Matt Domsch's website located at:
+	  <http://linux.dell.com/efibootmgr/testing/efibootmgr-0.5.0-test3.tar.gz>
+
+	  Subsequent efibootmgr releases may be found at:
+	  <http://linux.dell.com/efibootmgr>
+
+config EFI_VARS_PSTORE
+	tristate "Register efivars backend for pstore"
+	depends on EFI_VARS && PSTORE
+	default y
+	help
+	  Say Y here to enable use efivars as a backend to pstore. This
+	  will allow writing console messages, crash dumps, or anything
+	  else supported by pstore to EFI variables.
+
+config EFI_VARS_PSTORE_DEFAULT_DISABLE
+	bool "Disable using efivars as a pstore backend by default"
+	depends on EFI_VARS_PSTORE
+	default n
+	help
+	  Saying Y here will disable the use of efivars as a storage
+	  backend for pstore by default. This setting can be overridden
+	  using the efivars module's pstore_disable parameter.
+
+endmenu
diff --git a/drivers/firmware/efi/Makefile b/drivers/firmware/efi/Makefile
new file mode 100644
index 000000000000..e03cd51525c2
--- /dev/null
+++ b/drivers/firmware/efi/Makefile
@@ -0,0 +1,4 @@
+#
+# Makefile for linux kernel
+#
+obj-$(CONFIG_EFI_VARS_PSTORE)		+= efi-pstore.o
diff --git a/drivers/firmware/efi/efi-pstore.c b/drivers/firmware/efi/efi-pstore.c
new file mode 100644
index 000000000000..47ae712c9504
--- /dev/null
+++ b/drivers/firmware/efi/efi-pstore.c
@@ -0,0 +1,244 @@
+#include <linux/efi.h>
+#include <linux/module.h>
+#include <linux/pstore.h>
+
+#define DUMP_NAME_LEN 52
+
+static bool efivars_pstore_disable =
+	IS_ENABLED(CONFIG_EFI_VARS_PSTORE_DEFAULT_DISABLE);
+
+module_param_named(pstore_disable, efivars_pstore_disable, bool, 0644);
+
+#define PSTORE_EFI_ATTRIBUTES \
+	(EFI_VARIABLE_NON_VOLATILE | \
+	 EFI_VARIABLE_BOOTSERVICE_ACCESS | \
+	 EFI_VARIABLE_RUNTIME_ACCESS)
+
+static int efi_pstore_open(struct pstore_info *psi)
+{
+	efivar_entry_iter_begin();
+	psi->data = NULL;
+	return 0;
+}
+
+static int efi_pstore_close(struct pstore_info *psi)
+{
+	efivar_entry_iter_end();
+	psi->data = NULL;
+	return 0;
+}
+
+struct pstore_read_data {
+	u64 *id;
+	enum pstore_type_id *type;
+	int *count;
+	struct timespec *timespec;
+	char **buf;
+};
+
+static int efi_pstore_read_func(struct efivar_entry *entry, void *data)
+{
+	efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
+	struct pstore_read_data *cb_data = data;
+	char name[DUMP_NAME_LEN];
+	int i;
+	int cnt;
+	unsigned int part;
+	unsigned long time, size;
+
+	if (efi_guidcmp(entry->var.VendorGuid, vendor))
+		return 0;
+
+	for (i = 0; i < DUMP_NAME_LEN; i++)
+		name[i] = entry->var.VariableName[i];
+
+	if (sscanf(name, "dump-type%u-%u-%d-%lu",
+		   cb_data->type, &part, &cnt, &time) == 4) {
+		*cb_data->id = part;
+		*cb_data->count = cnt;
+		cb_data->timespec->tv_sec = time;
+		cb_data->timespec->tv_nsec = 0;
+	} else if (sscanf(name, "dump-type%u-%u-%lu",
+			  cb_data->type, &part, &time) == 3) {
+		/*
+		 * Check if an old format,
+		 * which doesn't support holding
+		 * multiple logs, remains.
+		 */
+		*cb_data->id = part;
+		*cb_data->count = 0;
+		cb_data->timespec->tv_sec = time;
+		cb_data->timespec->tv_nsec = 0;
+	} else
+		return 0;
+
+	__efivar_entry_size(entry, &size);
+	*cb_data->buf = kmalloc(size, GFP_KERNEL);
+	if (*cb_data->buf == NULL)
+		return -ENOMEM;
+	memcpy(*cb_data->buf, entry->var.Data, size);
+	return size;
+}
+
+static ssize_t efi_pstore_read(u64 *id, enum pstore_type_id *type,
+			       int *count, struct timespec *timespec,
+			       char **buf, struct pstore_info *psi)
+{
+	struct pstore_read_data data;
+
+	data.id = id;
+	data.type = type;
+	data.count = count;
+	data.timespec = timespec;
+	data.buf = buf;
+
+	return __efivar_entry_iter(efi_pstore_read_func, &efivar_sysfs_list, &data,
+				   (struct efivar_entry **)&psi->data);
+}
+
+static int efi_pstore_write(enum pstore_type_id type,
+		enum kmsg_dump_reason reason, u64 *id,
+		unsigned int part, int count, size_t size,
+		struct pstore_info *psi)
+{
+	char name[DUMP_NAME_LEN];
+	efi_char16_t efi_name[DUMP_NAME_LEN];
+	efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
+	int i, ret = 0;
+
+	sprintf(name, "dump-type%u-%u-%d-%lu", type, part, count,
+		get_seconds());
+
+	for (i = 0; i < DUMP_NAME_LEN; i++)
+		efi_name[i] = name[i];
+
+	efivar_entry_set_safe(efi_name, vendor, PSTORE_EFI_ATTRIBUTES,
+			      !pstore_cannot_block_path(reason),
+			      size, psi->buf);
+
+	if (reason == KMSG_DUMP_OOPS)
+		efivar_run_worker();
+
+	*id = part;
+	return ret;
+};
+
+struct pstore_erase_data {
+	u64 id;
+	enum pstore_type_id type;
+	int count;
+	struct timespec time;
+	efi_char16_t *name;
+};
+
+/*
+ * Clean up an entry with the same name
+ */
+static int efi_pstore_erase_func(struct efivar_entry *entry, void *data)
+{
+	struct pstore_erase_data *ed = data;
+	efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
+	efi_char16_t efi_name_old[DUMP_NAME_LEN];
+	efi_char16_t *efi_name = ed->name;
+	unsigned long utf16_len = utf16_strlen(ed->name);
+	char name_old[DUMP_NAME_LEN];
+	int i;
+
+	if (efi_guidcmp(entry->var.VendorGuid, vendor))
+		return 0;
+
+	if (utf16_strncmp(entry->var.VariableName,
+			  efi_name, (size_t)utf16_len)) {
+		/*
+		 * Check if an old format, which doesn't support
+		 * holding multiple logs, remains.
+		 */
+		sprintf(name_old, "dump-type%u-%u-%lu", ed->type,
+			(unsigned int)ed->id, ed->time.tv_sec);
+
+		for (i = 0; i < DUMP_NAME_LEN; i++)
+			efi_name_old[i] = name_old[i];
+
+		if (utf16_strncmp(entry->var.VariableName, efi_name_old,
+				  utf16_strlen(efi_name_old)))
+			return 0;
+	}
+
+	/* found */
+	__efivar_entry_delete(entry);
+	return 1;
+}
+
+static int efi_pstore_erase(enum pstore_type_id type, u64 id, int count,
+			    struct timespec time, struct pstore_info *psi)
+{
+	struct pstore_erase_data edata;
+	struct efivar_entry *entry;
+	char name[DUMP_NAME_LEN];
+	efi_char16_t efi_name[DUMP_NAME_LEN];
+	int found, i;
+
+	sprintf(name, "dump-type%u-%u-%d-%lu", type, (unsigned int)id, count,
+		time.tv_sec);
+
+	for (i = 0; i < DUMP_NAME_LEN; i++)
+		efi_name[i] = name[i];
+
+	edata.id = id;
+	edata.type = type;
+	edata.count = count;
+	edata.time = time;
+	edata.name = efi_name;
+
+	efivar_entry_iter_begin();
+	found = __efivar_entry_iter(efi_pstore_erase_func, &efivar_sysfs_list, &edata, &entry);
+	efivar_entry_iter_end();
+
+	if (found)
+		efivar_unregister(entry);
+
+	return 0;
+}
+
+static struct pstore_info efi_pstore_info = {
+	.owner		= THIS_MODULE,
+	.name		= "efi",
+	.open		= efi_pstore_open,
+	.close		= efi_pstore_close,
+	.read		= efi_pstore_read,
+	.write		= efi_pstore_write,
+	.erase		= efi_pstore_erase,
+};
+
+static __init int efivars_pstore_init(void)
+{
+	if (!efi_enabled(EFI_RUNTIME_SERVICES))
+		return 0;
+
+	if (!efivars_kobject())
+		return 0;
+
+	if (efivars_pstore_disable)
+		return 0;
+
+	efi_pstore_info.buf = kmalloc(4096, GFP_KERNEL);
+	if (!efi_pstore_info.buf)
+		return -ENOMEM;
+
+	efi_pstore_info.bufsize = 1024;
+	spin_lock_init(&efi_pstore_info.buf_lock);
+
+	pstore_register(&efi_pstore_info);
+
+	return 0;
+}
+
+static __exit void efivars_pstore_exit(void)
+{
+}
+
+module_init(efivars_pstore_init);
+module_exit(efivars_pstore_exit);
+
+MODULE_DESCRIPTION("EFI variable backend for pstore");
+MODULE_LICENSE("GPL");