1 files changed, 75 insertions, 0 deletions
diff --git a/arch/s390/kernel/alternative.c b/arch/s390/kernel/alternative.c
new file mode 100644
index 000000000..e7bca29f9
--- /dev/null
+++ b/arch/s390/kernel/alternative.c
@@ -0,0 +1,75 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/module.h>
+#include <linux/cpu.h>
+#include <linux/smp.h>
+#include <asm/text-patching.h>
+#include <asm/alternative.h>
+#include <asm/facility.h>
+#include <asm/nospec-branch.h>
+
+static int __initdata_or_module alt_instr_disabled;
+
+static int __init disable_alternative_instructions(char *str)
+{
+	alt_instr_disabled = 1;
+	return 0;
+}
+
+early_param("noaltinstr", disable_alternative_instructions);
+
+static void __init_or_module __apply_alternatives(struct alt_instr *start,
+						  struct alt_instr *end)
+{
+	struct alt_instr *a;
+	u8 *instr, *replacement;
+
+	/*
+	 * The scan order should be from start to end. A later scanned
+	 * alternative code can overwrite previously scanned alternative code.
+	 */
+	for (a = start; a < end; a++) {
+		instr = (u8 *)&a->instr_offset + a->instr_offset;
+		replacement = (u8 *)&a->repl_offset + a->repl_offset;
+
+		if (!__test_facility(a->facility, alt_stfle_fac_list))
+			continue;
+
+		if (unlikely(a->instrlen % 2)) {
+			WARN_ONCE(1, "cpu alternatives instructions length is "
+				     "odd, skipping patching\n");
+			continue;
+		}
+
+		s390_kernel_write(instr, replacement, a->instrlen);
+	}
+}
+
+void __init_or_module apply_alternatives(struct alt_instr *start,
+					 struct alt_instr *end)
+{
+	if (!alt_instr_disabled)
+		__apply_alternatives(start, end);
+}
+
+extern struct alt_instr __alt_instructions[], __alt_instructions_end[];
+void __init apply_alternative_instructions(void)
+{
+	apply_alternatives(__alt_instructions, __alt_instructions_end);
+}
+
+static void do_sync_core(void *info)
+{
+	sync_core();
+}
+
+void text_poke_sync(void)
+{
+	on_each_cpu(do_sync_core, NULL, 1);
+}
+
+void text_poke_sync_lock(void)
+{
+	cpus_read_lock();
+	text_poke_sync();
+	cpus_read_unlock();
+}