v4.19.13 snapshot.
diff --git a/fs/pstore/pmsg.c b/fs/pstore/pmsg.c
new file mode 100644
index 0000000..24db02d
--- /dev/null
+++ b/fs/pstore/pmsg.c
@@ -0,0 +1,102 @@
+/*
+ * Copyright 2014 Google, Inc.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/cdev.h>
+#include <linux/device.h>
+#include <linux/fs.h>
+#include <linux/uaccess.h>
+#include "internal.h"
+
+static DEFINE_MUTEX(pmsg_lock);
+
+static ssize_t write_pmsg(struct file *file, const char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ struct pstore_record record;
+ int ret;
+
+ if (!count)
+ return 0;
+
+ pstore_record_init(&record, psinfo);
+ record.type = PSTORE_TYPE_PMSG;
+ record.size = count;
+
+ /* check outside lock, page in any data. write_user also checks */
+ if (!access_ok(VERIFY_READ, buf, count))
+ return -EFAULT;
+
+ mutex_lock(&pmsg_lock);
+ ret = psinfo->write_user(&record, buf);
+ mutex_unlock(&pmsg_lock);
+ return ret ? ret : count;
+}
+
+static const struct file_operations pmsg_fops = {
+ .owner = THIS_MODULE,
+ .llseek = noop_llseek,
+ .write = write_pmsg,
+};
+
+static struct class *pmsg_class;
+static int pmsg_major;
+#define PMSG_NAME "pmsg"
+#undef pr_fmt
+#define pr_fmt(fmt) PMSG_NAME ": " fmt
+
+static char *pmsg_devnode(struct device *dev, umode_t *mode)
+{
+ if (mode)
+ *mode = 0220;
+ return NULL;
+}
+
+void pstore_register_pmsg(void)
+{
+ struct device *pmsg_device;
+
+ pmsg_major = register_chrdev(0, PMSG_NAME, &pmsg_fops);
+ if (pmsg_major < 0) {
+ pr_err("register_chrdev failed\n");
+ goto err;
+ }
+
+ pmsg_class = class_create(THIS_MODULE, PMSG_NAME);
+ if (IS_ERR(pmsg_class)) {
+ pr_err("device class file already in use\n");
+ goto err_class;
+ }
+ pmsg_class->devnode = pmsg_devnode;
+
+ pmsg_device = device_create(pmsg_class, NULL, MKDEV(pmsg_major, 0),
+ NULL, "%s%d", PMSG_NAME, 0);
+ if (IS_ERR(pmsg_device)) {
+ pr_err("failed to create device\n");
+ goto err_device;
+ }
+ return;
+
+err_device:
+ class_destroy(pmsg_class);
+err_class:
+ unregister_chrdev(pmsg_major, PMSG_NAME);
+err:
+ return;
+}
+
+void pstore_unregister_pmsg(void)
+{
+ device_destroy(pmsg_class, MKDEV(pmsg_major, 0));
+ class_destroy(pmsg_class);
+ unregister_chrdev(pmsg_major, PMSG_NAME);
+}