1 files changed, 397 insertions, 0 deletions
diff --git a/drivers/firmware/efi/efi-pstore.c b/drivers/firmware/efi/efi-pstore.c
new file mode 100644
index 000000000..0f7d97917
--- /dev/null
+++ b/drivers/firmware/efi/efi-pstore.c
@@ -0,0 +1,397 @@
+#include <linux/efi.h>
+#include <linux/module.h>
+#include <linux/pstore.h>
+#include <linux/slab.h>
+#include <linux/ucs2_string.h>
+
+#define DUMP_NAME_LEN 66
+
+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)
+{
+	psi->data = NULL;
+	return 0;
+}
+
+static int efi_pstore_close(struct pstore_info *psi)
+{
+	psi->data = NULL;
+	return 0;
+}
+
+static inline u64 generic_id(u64 timestamp, unsigned int part, int count)
+{
+	return (timestamp * 100 + part) * 1000 + count;
+}
+
+static int efi_pstore_read_func(struct efivar_entry *entry,
+				struct pstore_record *record)
+{
+	efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
+	char name[DUMP_NAME_LEN], data_type;
+	int i;
+	int cnt;
+	unsigned int part;
+	unsigned long size;
+	u64 time;
+
+	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-%llu-%c",
+		   &record->type, &part, &cnt, &time, &data_type) == 5) {
+		record->id = generic_id(time, part, cnt);
+		record->part = part;
+		record->count = cnt;
+		record->time.tv_sec = time;
+		record->time.tv_nsec = 0;
+		if (data_type == 'C')
+			record->compressed = true;
+		else
+			record->compressed = false;
+		record->ecc_notice_size = 0;
+	} else if (sscanf(name, "dump-type%u-%u-%d-%llu",
+		   &record->type, &part, &cnt, &time) == 4) {
+		record->id = generic_id(time, part, cnt);
+		record->part = part;
+		record->count = cnt;
+		record->time.tv_sec = time;
+		record->time.tv_nsec = 0;
+		record->compressed = false;
+		record->ecc_notice_size = 0;
+	} else if (sscanf(name, "dump-type%u-%u-%llu",
+			  &record->type, &part, &time) == 3) {
+		/*
+		 * Check if an old format,
+		 * which doesn't support holding
+		 * multiple logs, remains.
+		 */
+		record->id = generic_id(time, part, 0);
+		record->part = part;
+		record->count = 0;
+		record->time.tv_sec = time;
+		record->time.tv_nsec = 0;
+		record->compressed = false;
+		record->ecc_notice_size = 0;
+	} else
+		return 0;
+
+	entry->var.DataSize = 1024;
+	__efivar_entry_get(entry, &entry->var.Attributes,
+			   &entry->var.DataSize, entry->var.Data);
+	size = entry->var.DataSize;
+	memcpy(record->buf, entry->var.Data,
+	       (size_t)min_t(unsigned long, EFIVARS_DATA_SIZE_MAX, size));
+
+	return size;
+}
+
+/**
+ * efi_pstore_scan_sysfs_enter
+ * @pos: scanning entry
+ * @next: next entry
+ * @head: list head
+ */
+static void efi_pstore_scan_sysfs_enter(struct efivar_entry *pos,
+					struct efivar_entry *next,
+					struct list_head *head)
+{
+	pos->scanning = true;
+	if (&next->list != head)
+		next->scanning = true;
+}
+
+/**
+ * __efi_pstore_scan_sysfs_exit
+ * @entry: deleting entry
+ * @turn_off_scanning: Check if a scanning flag should be turned off
+ */
+static inline int __efi_pstore_scan_sysfs_exit(struct efivar_entry *entry,
+						bool turn_off_scanning)
+{
+	if (entry->deleting) {
+		list_del(&entry->list);
+		efivar_entry_iter_end();
+		efivar_unregister(entry);
+		if (efivar_entry_iter_begin())
+			return -EINTR;
+	} else if (turn_off_scanning)
+		entry->scanning = false;
+
+	return 0;
+}
+
+/**
+ * efi_pstore_scan_sysfs_exit
+ * @pos: scanning entry
+ * @next: next entry
+ * @head: list head
+ * @stop: a flag checking if scanning will stop
+ */
+static int efi_pstore_scan_sysfs_exit(struct efivar_entry *pos,
+				       struct efivar_entry *next,
+				       struct list_head *head, bool stop)
+{
+	int ret = __efi_pstore_scan_sysfs_exit(pos, true);
+
+	if (ret)
+		return ret;
+
+	if (stop)
+		ret = __efi_pstore_scan_sysfs_exit(next, &next->list != head);
+	return ret;
+}
+
+/**
+ * efi_pstore_sysfs_entry_iter
+ *
+ * @record: pstore record to pass to callback
+ *
+ * You MUST call efivar_enter_iter_begin() before this function, and
+ * efivar_entry_iter_end() afterwards.
+ *
+ */
+static int efi_pstore_sysfs_entry_iter(struct pstore_record *record)
+{
+	struct efivar_entry **pos = (struct efivar_entry **)&record->psi->data;
+	struct efivar_entry *entry, *n;
+	struct list_head *head = &efivar_sysfs_list;
+	int size = 0;
+	int ret;
+
+	if (!*pos) {
+		list_for_each_entry_safe(entry, n, head, list) {
+			efi_pstore_scan_sysfs_enter(entry, n, head);
+
+			size = efi_pstore_read_func(entry, record);
+			ret = efi_pstore_scan_sysfs_exit(entry, n, head,
+							 size < 0);
+			if (ret)
+				return ret;
+			if (size)
+				break;
+		}
+		*pos = n;
+		return size;
+	}
+
+	list_for_each_entry_safe_from((*pos), n, head, list) {
+		efi_pstore_scan_sysfs_enter((*pos), n, head);
+
+		size = efi_pstore_read_func((*pos), record);
+		ret = efi_pstore_scan_sysfs_exit((*pos), n, head, size < 0);
+		if (ret)
+			return ret;
+		if (size)
+			break;
+	}
+	*pos = n;
+	return size;
+}
+
+/**
+ * efi_pstore_read
+ *
+ * This function returns a size of NVRAM entry logged via efi_pstore_write().
+ * The meaning and behavior of efi_pstore/pstore are as below.
+ *
+ * size > 0: Got data of an entry logged via efi_pstore_write() successfully,
+ *           and pstore filesystem will continue reading subsequent entries.
+ * size == 0: Entry was not logged via efi_pstore_write(),
+ *            and efi_pstore driver will continue reading subsequent entries.
+ * size < 0: Failed to get data of entry logging via efi_pstore_write(),
+ *           and pstore will stop reading entry.
+ */
+static ssize_t efi_pstore_read(struct pstore_record *record)
+{
+	ssize_t size;
+
+	record->buf = kzalloc(EFIVARS_DATA_SIZE_MAX, GFP_KERNEL);
+	if (!record->buf)
+		return -ENOMEM;
+
+	if (efivar_entry_iter_begin()) {
+		size = -EINTR;
+		goto out;
+	}
+	size = efi_pstore_sysfs_entry_iter(record);
+	efivar_entry_iter_end();
+
+out:
+	if (size <= 0) {
+		kfree(record->buf);
+		record->buf = NULL;
+	}
+	return size;
+}
+
+static int efi_pstore_write(struct pstore_record *record)
+{
+	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;
+
+	record->id = generic_id(record->time.tv_sec, record->part,
+				record->count);
+
+	/* Since we copy the entire length of name, make sure it is wiped. */
+	memset(name, 0, sizeof(name));
+
+	snprintf(name, sizeof(name), "dump-type%u-%u-%d-%lld-%c",
+		 record->type, record->part, record->count,
+		 (long long)record->time.tv_sec,
+		 record->compressed ? 'C' : 'D');
+
+	for (i = 0; i < DUMP_NAME_LEN; i++)
+		efi_name[i] = name[i];
+
+	ret = efivar_entry_set_safe(efi_name, vendor, PSTORE_EFI_ATTRIBUTES,
+			      preemptible(), record->size, record->psi->buf);
+
+	if (record->reason == KMSG_DUMP_OOPS)
+		efivar_run_worker();
+
+	return ret;
+};
+
+/*
+ * Clean up an entry with the same name
+ */
+static int efi_pstore_erase_func(struct efivar_entry *entry, void *data)
+{
+	efi_char16_t *efi_name = data;
+	efi_guid_t vendor = LINUX_EFI_CRASH_GUID;
+	unsigned long ucs2_len = ucs2_strlen(efi_name);
+
+	if (efi_guidcmp(entry->var.VendorGuid, vendor))
+		return 0;
+
+	if (ucs2_strncmp(entry->var.VariableName, efi_name, (size_t)ucs2_len))
+		return 0;
+
+	if (entry->scanning) {
+		/*
+		 * Skip deletion because this entry will be deleted
+		 * after scanning is completed.
+		 */
+		entry->deleting = true;
+	} else
+		list_del(&entry->list);
+
+	/* found */
+	__efivar_entry_delete(entry);
+
+	return 1;
+}
+
+static int efi_pstore_erase_name(const char *name)
+{
+	struct efivar_entry *entry = NULL;
+	efi_char16_t efi_name[DUMP_NAME_LEN];
+	int found, i;
+
+	for (i = 0; i < DUMP_NAME_LEN; i++) {
+		efi_name[i] = name[i];
+		if (name[i] == '\0')
+			break;
+	}
+
+	if (efivar_entry_iter_begin())
+		return -EINTR;
+
+	found = __efivar_entry_iter(efi_pstore_erase_func, &efivar_sysfs_list,
+				    efi_name, &entry);
+	efivar_entry_iter_end();
+
+	if (found && !entry->scanning)
+		efivar_unregister(entry);
+
+	return found ? 0 : -ENOENT;
+}
+
+static int efi_pstore_erase(struct pstore_record *record)
+{
+	char name[DUMP_NAME_LEN];
+	int ret;
+
+	snprintf(name, sizeof(name), "dump-type%u-%u-%d-%lld",
+		 record->type, record->part, record->count,
+		 (long long)record->time.tv_sec);
+	ret = efi_pstore_erase_name(name);
+	if (ret != -ENOENT)
+		return ret;
+
+	snprintf(name, sizeof(name), "dump-type%u-%u-%lld",
+		record->type, record->part, (long long)record->time.tv_sec);
+	ret = efi_pstore_erase_name(name);
+
+	return ret;
+}
+
+static struct pstore_info efi_pstore_info = {
+	.owner		= THIS_MODULE,
+	.name		= "efi",
+	.flags		= PSTORE_FLAGS_DMESG,
+	.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;
+
+	if (pstore_register(&efi_pstore_info)) {
+		kfree(efi_pstore_info.buf);
+		efi_pstore_info.buf = NULL;
+		efi_pstore_info.bufsize = 0;
+	}
+
+	return 0;
+}
+
+static __exit void efivars_pstore_exit(void)
+{
+	if (!efi_pstore_info.bufsize)
+		return;
+
+	pstore_unregister(&efi_pstore_info);
+	kfree(efi_pstore_info.buf);
+	efi_pstore_info.buf = NULL;
+	efi_pstore_info.bufsize = 0;
+}
+
+module_init(efivars_pstore_init);
+module_exit(efivars_pstore_exit);
+
+MODULE_DESCRIPTION("EFI variable backend for pstore");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:efivars");