1 files changed, 269 insertions, 0 deletions
diff --git a/drivers/firmware/efi/efi-pstore.c b/drivers/firmware/efi/efi-pstore.c
new file mode 100644
index 0000000000..e7b9ec6f8a
--- /dev/null
+++ b/drivers/firmware/efi/efi-pstore.c
@@ -0,0 +1,269 @@
+// SPDX-License-Identifier: GPL-2.0+
+
+#include <linux/efi.h>
+#include <linux/module.h>
+#include <linux/pstore.h>
+#include <linux/slab.h>
+#include <linux/ucs2_string.h>
+
+MODULE_IMPORT_NS(EFIVAR);
+
+#define DUMP_NAME_LEN 66
+
+static unsigned int record_size = 1024;
+module_param(record_size, uint, 0444);
+MODULE_PARM_DESC(record_size, "size of each pstore UEFI var (in bytes, min/default=1024)");
+
+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)
+{
+	int err;
+
+	err = efivar_lock();
+	if (err)
+		return err;
+
+	psi->data = kzalloc(record_size, GFP_KERNEL);
+	if (!psi->data)
+		return -ENOMEM;
+
+	return 0;
+}
+
+static int efi_pstore_close(struct pstore_info *psi)
+{
+	efivar_unlock();
+	kfree(psi->data);
+	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 pstore_record *record,
+				efi_char16_t *varname)
+{
+	unsigned long wlen, size = record_size;
+	char name[DUMP_NAME_LEN], data_type;
+	efi_status_t status;
+	int cnt;
+	unsigned int part;
+	u64 time;
+
+	ucs2_as_utf8(name, varname, DUMP_NAME_LEN);
+
+	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;
+
+	record->buf = kmalloc(size, GFP_KERNEL);
+	if (!record->buf)
+		return -ENOMEM;
+
+	status = efivar_get_variable(varname, &LINUX_EFI_CRASH_GUID, NULL,
+				     &size, record->buf);
+	if (status != EFI_SUCCESS) {
+		kfree(record->buf);
+		return -EIO;
+	}
+
+	/*
+	 * Store the name of the variable in the pstore_record priv field, so
+	 * we can reuse it later if we need to delete the EFI variable from the
+	 * variable store.
+	 */
+	wlen = (ucs2_strnlen(varname, DUMP_NAME_LEN) + 1) * sizeof(efi_char16_t);
+	record->priv = kmemdup(varname, wlen, GFP_KERNEL);
+	if (!record->priv) {
+		kfree(record->buf);
+		return -ENOMEM;
+	}
+
+	return size;
+}
+
+static ssize_t efi_pstore_read(struct pstore_record *record)
+{
+	efi_char16_t *varname = record->psi->data;
+	efi_guid_t guid = LINUX_EFI_CRASH_GUID;
+	unsigned long varname_size;
+	efi_status_t status;
+
+	for (;;) {
+		varname_size = 1024;
+
+		/*
+		 * If this is the first read() call in the pstore enumeration,
+		 * varname will be the empty string, and the GetNextVariable()
+		 * runtime service call will return the first EFI variable in
+		 * its own enumeration order, ignoring the guid argument.
+		 *
+		 * Subsequent calls to GetNextVariable() must pass the name and
+		 * guid values returned by the previous call, which is why we
+		 * store varname in record->psi->data. Given that we only
+		 * enumerate variables with the efi-pstore GUID, there is no
+		 * need to record the guid return value.
+		 */
+		status = efivar_get_next_variable(&varname_size, varname, &guid);
+		if (status == EFI_NOT_FOUND)
+			return 0;
+
+		if (status != EFI_SUCCESS)
+			return -EIO;
+
+		/* skip variables that don't concern us */
+		if (efi_guidcmp(guid, LINUX_EFI_CRASH_GUID))
+			continue;
+
+		return efi_pstore_read_func(record, varname);
+	}
+}
+
+static int efi_pstore_write(struct pstore_record *record)
+{
+	char name[DUMP_NAME_LEN];
+	efi_char16_t efi_name[DUMP_NAME_LEN];
+	efi_status_t status;
+	int i;
+
+	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];
+
+	if (efivar_trylock())
+		return -EBUSY;
+	status = efivar_set_variable_locked(efi_name, &LINUX_EFI_CRASH_GUID,
+					    PSTORE_EFI_ATTRIBUTES,
+					    record->size, record->psi->buf,
+					    true);
+	efivar_unlock();
+	return status == EFI_SUCCESS ? 0 : -EIO;
+};
+
+static int efi_pstore_erase(struct pstore_record *record)
+{
+	efi_status_t status;
+
+	status = efivar_set_variable(record->priv, &LINUX_EFI_CRASH_GUID,
+				     PSTORE_EFI_ATTRIBUTES, 0, NULL);
+
+	if (status != EFI_SUCCESS && status != EFI_NOT_FOUND)
+		return -EIO;
+	return 0;
+}
+
+static struct pstore_info efi_pstore_info = {
+	.owner		= THIS_MODULE,
+	.name		= KBUILD_MODNAME,
+	.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 (!efivar_supports_writes())
+		return 0;
+
+	if (efivars_pstore_disable)
+		return 0;
+
+	/*
+	 * Notice that 1024 is the minimum here to prevent issues with
+	 * decompression algorithms that were spotted during tests;
+	 * even in the case of not using compression, smaller values would
+	 * just pollute more the pstore FS with many small collected files.
+	 */
+	if (record_size < 1024)
+		record_size = 1024;
+
+	efi_pstore_info.buf = kmalloc(record_size, GFP_KERNEL);
+	if (!efi_pstore_info.buf)
+		return -ENOMEM;
+
+	efi_pstore_info.bufsize = record_size;
+
+	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");