efi: pstore: disentangle from deprecated efivars module

The EFI pstore implementation relies on the 'efivars' abstraction,
which encapsulates the EFI variable store in a way that can be
overridden by other backing stores, like the Google SMI one.

On top of that, the EFI pstore implementation also relies on the
efivars.ko module, which is a separate layer built on top of the
'efivars' abstraction that exposes the [deprecated] sysfs entries
for each variable that exists in the backing store.

Since the efivars.ko module is deprecated, and all users appear to
have moved to the efivarfs file system instead, let's prepare for
its removal, by removing EFI pstore's dependency on it.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

1 files changed, 72 insertions, 4 deletions

diff --git a/drivers/firmware/efi/efi-pstore.c b/drivers/firmware/efi/efi-pstore.c
index feb7fe6f2da7..785f5e6b3a41 100644
--- a/drivers/firmware/efi/efi-pstore.c
+++ b/drivers/firmware/efi/efi-pstore.c
@@ -8,6 +8,8 @@
 
 #define DUMP_NAME_LEN 66
 
+#define EFIVARS_DATA_SIZE_MAX 1024
+
 static bool efivars_pstore_disable =
 	IS_ENABLED(CONFIG_EFI_VARS_PSTORE_DEFAULT_DISABLE);
 
@@ -18,6 +20,8 @@ module_param_named(pstore_disable, efivars_pstore_disable, bool, 0644);
 	 EFI_VARIABLE_BOOTSERVICE_ACCESS | \
 	 EFI_VARIABLE_RUNTIME_ACCESS)
 
+static LIST_HEAD(efi_pstore_list);
+
 static int efi_pstore_open(struct pstore_info *psi)
 {
 	psi->data = NULL;
@@ -126,7 +130,7 @@ static inline int __efi_pstore_scan_sysfs_exit(struct efivar_entry *entry,
 	if (entry->deleting) {
 		list_del(&entry->list);
 		efivar_entry_iter_end();
-		efivar_unregister(entry);
+		kfree(entry);
 		if (efivar_entry_iter_begin())
 			return -EINTR;
 	} else if (turn_off_scanning)
@@ -169,7 +173,7 @@ 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;
+	struct list_head *head = &efi_pstore_list;
 	int size = 0;
 	int ret;
 
@@ -314,12 +318,12 @@ static int efi_pstore_erase_name(const char *name)
 	if (efivar_entry_iter_begin())
 		return -EINTR;
 
-	found = __efivar_entry_iter(efi_pstore_erase_func, &efivar_sysfs_list,
+	found = __efivar_entry_iter(efi_pstore_erase_func, &efi_pstore_list,
 				    efi_name, &entry);
 	efivar_entry_iter_end();
 
 	if (found && !entry->scanning)
-		efivar_unregister(entry);
+		kfree(entry);
 
 	return found ? 0 : -ENOENT;
 }
@@ -354,14 +358,76 @@ static struct pstore_info efi_pstore_info = {
 	.erase		= efi_pstore_erase,
 };
 
+static int efi_pstore_callback(efi_char16_t *name, efi_guid_t vendor,
+			       unsigned long name_size, void *data)
+{
+	struct efivar_entry *entry;
+	int ret;
+
+	entry = kzalloc(sizeof(*entry), GFP_KERNEL);
+	if (!entry)
+		return -ENOMEM;
+
+	memcpy(entry->var.VariableName, name, name_size);
+	entry->var.VendorGuid = vendor;
+
+	ret = efivar_entry_add(entry, &efi_pstore_list);
+	if (ret)
+		kfree(entry);
+
+	return ret;
+}
+
+static int efi_pstore_update_entry(efi_char16_t *name, efi_guid_t vendor,
+				   unsigned long name_size, void *data)
+{
+	struct efivar_entry *entry = data;
+
+	if (efivar_entry_find(name, vendor, &efi_pstore_list, false))
+		return 0;
+
+	memcpy(entry->var.VariableName, name, name_size);
+	memcpy(&(entry->var.VendorGuid), &vendor, sizeof(efi_guid_t));
+
+	return 1;
+}
+
+static void efi_pstore_update_entries(struct work_struct *work)
+{
+	struct efivar_entry *entry;
+	int err;
+
+	/* Add new sysfs entries */
+	while (1) {
+		entry = kzalloc(sizeof(*entry), GFP_KERNEL);
+		if (!entry)
+			return;
+
+		err = efivar_init(efi_pstore_update_entry, entry,
+				  false, &efi_pstore_list);
+		if (!err)
+			break;
+
+		efivar_entry_add(entry, &efi_pstore_list);
+	}
+
+	kfree(entry);
+}
+
 static __init int efivars_pstore_init(void)
 {
+	int ret;
+
 	if (!efivars_kobject() || !efivar_supports_writes())
 		return 0;
 
 	if (efivars_pstore_disable)
 		return 0;
 
+	ret = efivar_init(efi_pstore_callback, NULL, true, &efi_pstore_list);
+	if (ret)
+		return ret;
+
 	efi_pstore_info.buf = kmalloc(4096, GFP_KERNEL);
 	if (!efi_pstore_info.buf)
 		return -ENOMEM;
@@ -374,6 +440,8 @@ static __init int efivars_pstore_init(void)
 		efi_pstore_info.bufsize = 0;
 	}
 
+	INIT_WORK(&efivar_work, efi_pstore_update_entries);
+
 	return 0;
 }