1 files changed, 65 insertions, 0 deletions
diff --git a/arch/um/kernel/kmsg_dump.c b/arch/um/kernel/kmsg_dump.c
new file mode 100644
index 0000000000..427dd5a61a
--- /dev/null
+++ b/arch/um/kernel/kmsg_dump.c
@@ -0,0 +1,65 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/kmsg_dump.h>
+#include <linux/spinlock.h>
+#include <linux/console.h>
+#include <linux/string.h>
+#include <shared/init.h>
+#include <shared/kern.h>
+#include <os.h>
+
+static void kmsg_dumper_stdout(struct kmsg_dumper *dumper,
+				enum kmsg_dump_reason reason)
+{
+	static struct kmsg_dump_iter iter;
+	static DEFINE_SPINLOCK(lock);
+	static char line[1024];
+	struct console *con;
+	unsigned long flags;
+	size_t len = 0;
+	int cookie;
+
+	/*
+	 * If no consoles are available to output crash information, dump
+	 * the kmsg buffer to stdout.
+	 */
+
+	cookie = console_srcu_read_lock();
+	for_each_console_srcu(con) {
+		/*
+		 * The ttynull console and disabled consoles are ignored
+		 * since they cannot output. All other consoles are
+		 * expected to output the crash information.
+		 */
+		if (strcmp(con->name, "ttynull") != 0 &&
+		    (console_srcu_read_flags(con) & CON_ENABLED)) {
+			break;
+		}
+	}
+	console_srcu_read_unlock(cookie);
+	if (con)
+		return;
+
+	if (!spin_trylock_irqsave(&lock, flags))
+		return;
+
+	kmsg_dump_rewind(&iter);
+
+	printf("kmsg_dump:\n");
+	while (kmsg_dump_get_line(&iter, true, line, sizeof(line), &len)) {
+		line[len] = '\0';
+		printf("%s", line);
+	}
+
+	spin_unlock_irqrestore(&lock, flags);
+}
+
+static struct kmsg_dumper kmsg_dumper = {
+	.dump = kmsg_dumper_stdout
+};
+
+int __init kmsg_dumper_stdout_init(void)
+{
+	return kmsg_dump_register(&kmsg_dumper);
+}
+
+__uml_postsetup(kmsg_dumper_stdout_init);