1 files changed, 65 insertions, 0 deletions
diff --git a/arch/s390/kernel/early_nobss.c b/arch/s390/kernel/early_nobss.c
new file mode 100644
index 000000000000..2d84fc48df3a
--- /dev/null
+++ b/arch/s390/kernel/early_nobss.c
@@ -0,0 +1,65 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *    Copyright IBM Corp. 2007, 2018
+ */
+
+/*
+ * Early setup functions which may not rely on an initialized bss
+ * section. The last thing that is supposed to happen here is
+ * initialization of the bss section.
+ */
+
+#include <linux/processor.h>
+#include <linux/string.h>
+#include <asm/sections.h>
+#include <asm/lowcore.h>
+#include <asm/setup.h>
+#include <asm/timex.h>
+#include "entry.h"
+
+static void __init reset_tod_clock(void)
+{
+	u64 time;
+
+	if (store_tod_clock(&time) == 0)
+		return;
+	/* TOD clock not running. Set the clock to Unix Epoch. */
+	if (set_tod_clock(TOD_UNIX_EPOCH) != 0 || store_tod_clock(&time) != 0)
+		disabled_wait(0);
+
+	memset(tod_clock_base, 0, 16);
+	*(__u64 *) &tod_clock_base[1] = TOD_UNIX_EPOCH;
+	S390_lowcore.last_update_clock = TOD_UNIX_EPOCH;
+}
+
+static void __init rescue_initrd(void)
+{
+	unsigned long min_initrd_addr = (unsigned long) _end + (4UL << 20);
+
+	/*
+	 * Just like in case of IPL from VM reader we make sure there is a
+	 * gap of 4MB between end of kernel and start of initrd.
+	 * That way we can also be sure that saving an NSS will succeed,
+	 * which however only requires different segments.
+	 */
+	if (!IS_ENABLED(CONFIG_BLK_DEV_INITRD))
+		return;
+	if (!INITRD_START || !INITRD_SIZE)
+		return;
+	if (INITRD_START >= min_initrd_addr)
+		return;
+	memmove((void *) min_initrd_addr, (void *) INITRD_START, INITRD_SIZE);
+	INITRD_START = min_initrd_addr;
+}
+
+static void __init clear_bss_section(void)
+{
+	memset(__bss_start, 0, __bss_stop - __bss_start);
+}
+
+void __init startup_init_nobss(void)
+{
+	reset_tod_clock();
+	rescue_initrd();
+	clear_bss_section();
+}