v4.19.13 snapshot.
diff --git a/fs/proc/kmsg.c b/fs/proc/kmsg.c
new file mode 100644
index 0000000..4f4a2ab
--- /dev/null
+++ b/fs/proc/kmsg.c
@@ -0,0 +1,65 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * linux/fs/proc/kmsg.c
+ *
+ * Copyright (C) 1992 by Linus Torvalds
+ *
+ */
+
+#include <linux/types.h>
+#include <linux/errno.h>
+#include <linux/time.h>
+#include <linux/kernel.h>
+#include <linux/poll.h>
+#include <linux/proc_fs.h>
+#include <linux/fs.h>
+#include <linux/syslog.h>
+
+#include <linux/uaccess.h>
+#include <asm/io.h>
+
+extern wait_queue_head_t log_wait;
+
+static int kmsg_open(struct inode * inode, struct file * file)
+{
+ return do_syslog(SYSLOG_ACTION_OPEN, NULL, 0, SYSLOG_FROM_PROC);
+}
+
+static int kmsg_release(struct inode * inode, struct file * file)
+{
+ (void) do_syslog(SYSLOG_ACTION_CLOSE, NULL, 0, SYSLOG_FROM_PROC);
+ return 0;
+}
+
+static ssize_t kmsg_read(struct file *file, char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ if ((file->f_flags & O_NONBLOCK) &&
+ !do_syslog(SYSLOG_ACTION_SIZE_UNREAD, NULL, 0, SYSLOG_FROM_PROC))
+ return -EAGAIN;
+ return do_syslog(SYSLOG_ACTION_READ, buf, count, SYSLOG_FROM_PROC);
+}
+
+static __poll_t kmsg_poll(struct file *file, poll_table *wait)
+{
+ poll_wait(file, &log_wait, wait);
+ if (do_syslog(SYSLOG_ACTION_SIZE_UNREAD, NULL, 0, SYSLOG_FROM_PROC))
+ return EPOLLIN | EPOLLRDNORM;
+ return 0;
+}
+
+
+static const struct file_operations proc_kmsg_operations = {
+ .read = kmsg_read,
+ .poll = kmsg_poll,
+ .open = kmsg_open,
+ .release = kmsg_release,
+ .llseek = generic_file_llseek,
+};
+
+static int __init proc_kmsg_init(void)
+{
+ proc_create("kmsg", S_IRUSR, NULL, &proc_kmsg_operations);
+ return 0;
+}
+fs_initcall(proc_kmsg_init);