1 files changed, 54 insertions, 0 deletions
diff --git a/arch/s390/include/asm/jump_label.h b/arch/s390/include/asm/jump_label.h
new file mode 100644
index 000000000..dcb1bba4f
--- /dev/null
+++ b/arch/s390/include/asm/jump_label.h
@@ -0,0 +1,54 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_S390_JUMP_LABEL_H
+#define _ASM_S390_JUMP_LABEL_H
+
+#ifndef __ASSEMBLY__
+
+#include <linux/types.h>
+#include <linux/stringify.h>
+
+#define JUMP_LABEL_NOP_SIZE 6
+#define JUMP_LABEL_NOP_OFFSET 2
+
+#ifdef CONFIG_CC_IS_CLANG
+#define JUMP_LABEL_STATIC_KEY_CONSTRAINT "i"
+#elif __GNUC__ < 9
+#define JUMP_LABEL_STATIC_KEY_CONSTRAINT "X"
+#else
+#define JUMP_LABEL_STATIC_KEY_CONSTRAINT "jdd"
+#endif
+
+/*
+ * We use a brcl 0,2 instruction for jump labels at compile time so it
+ * can be easily distinguished from a hotpatch generated instruction.
+ */
+static __always_inline bool arch_static_branch(struct static_key *key, bool branch)
+{
+	asm_volatile_goto("0:	brcl	0,"__stringify(JUMP_LABEL_NOP_OFFSET)"\n"
+			  ".pushsection __jump_table,\"aw\"\n"
+			  ".balign	8\n"
+			  ".long	0b-.,%l[label]-.\n"
+			  ".quad	%0+%1-.\n"
+			  ".popsection\n"
+			  : : JUMP_LABEL_STATIC_KEY_CONSTRAINT (key), "i" (branch) : : label);
+	return false;
+label:
+	return true;
+}
+
+static __always_inline bool arch_static_branch_jump(struct static_key *key, bool branch)
+{
+	asm_volatile_goto("0:	brcl 15,%l[label]\n"
+			  ".pushsection __jump_table,\"aw\"\n"
+			  ".balign	8\n"
+			  ".long	0b-.,%l[label]-.\n"
+			  ".quad	%0+%1-.\n"
+			  ".popsection\n"
+			  : : JUMP_LABEL_STATIC_KEY_CONSTRAINT (key), "i" (branch) : : label);
+	return false;
+label:
+	return true;
+}
+
+#endif  /* __ASSEMBLY__ */
+#endif