3 files changed, 101 insertions, 0 deletions
diff --git a/arch/arm64/include/asm/asm-prototypes.h b/arch/arm64/include/asm/asm-prototypes.h
new file mode 100644
index 000000000000..930391c5cef7
--- /dev/null
+++ b/arch/arm64/include/asm/asm-prototypes.h
@@ -0,0 +1,41 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#include <asm-generic/asm-prototypes.h>
+
+#ifdef CONFIG_RETPOLINE
+#define INDIRECT_THUNK(reg) \
+extern asmlinkage void __aarch64_indirect_thunk_ ## reg(void);
+
+INDIRECT_THUNK(x0);
+INDIRECT_THUNK(x1);
+INDIRECT_THUNK(x2);
+INDIRECT_THUNK(x3);
+INDIRECT_THUNK(x4);
+INDIRECT_THUNK(x5);
+INDIRECT_THUNK(x6);
+INDIRECT_THUNK(x7);
+INDIRECT_THUNK(x8);
+INDIRECT_THUNK(x9);
+INDIRECT_THUNK(x10);
+INDIRECT_THUNK(x11);
+INDIRECT_THUNK(x12);
+INDIRECT_THUNK(x13);
+INDIRECT_THUNK(x14);
+INDIRECT_THUNK(x15);
+INDIRECT_THUNK(x16);
+INDIRECT_THUNK(x17);
+INDIRECT_THUNK(x18);
+INDIRECT_THUNK(x19);
+INDIRECT_THUNK(x20);
+INDIRECT_THUNK(x21);
+INDIRECT_THUNK(x22);
+INDIRECT_THUNK(x23);
+INDIRECT_THUNK(x24);
+INDIRECT_THUNK(x25);
+INDIRECT_THUNK(x26);
+INDIRECT_THUNK(x27);
+INDIRECT_THUNK(x28);
+INDIRECT_THUNK(x29);
+INDIRECT_THUNK(x30);
+
+#endif /* CONFIG_RETPOLINE */
+
diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h
index b05565dd50b6..863a03b96902 100644
--- a/arch/arm64/include/asm/assembler.h
+++ b/arch/arm64/include/asm/assembler.h
@@ -30,6 +30,7 @@
 #include <asm/pgtable-hwdef.h>
 #include <asm/ptrace.h>
 #include <asm/thread_info.h>
+#include <asm/nospec-branch.h>
 
 	.macro save_and_disable_daif, flags
 	mrs	\flags, daif
diff --git a/arch/arm64/include/asm/nospec-branch.h b/arch/arm64/include/asm/nospec-branch.h
new file mode 100644
index 000000000000..cc261d5f1afd
--- /dev/null
+++ b/arch/arm64/include/asm/nospec-branch.h
@@ -0,0 +1,59 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef _ASM_ARM64_NOSPEC_BRANCH_H_
+#define _ASM_ARM64_NOSPEC_BRANCH_H_
+
+#ifdef __ASSEMBLY__
+
+.macro retpoline
+	str	x30, [sp, #-16]!
+	bl	101f
+100: //speculation trap
+	wfe
+	b	100b
+101: //do ROP
+	adrp	x30, 102f
+	add	x30, x30, :lo12:102f
+	ret
+102: //non-spec code
+	ldr	x30, [sp], #16
+.endm
+
+.macro br_nospec reg
+#ifdef CONFIG_RETPOLINE
+	b	__aarch64_indirect_thunk_\reg
+#else
+	br	\reg
+#endif
+.endm
+
+.macro blr_nospec reg
+#ifdef CONFIG_RETPOLINE
+	bl	__aarch64_indirect_thunk_\reg
+#else
+	blr	\reg
+#endif
+.endm
+
+/*
+ * In case of "blr lr" we need to inline the retpoline
+ * as we cannot do a bl to the indirect_thunk, because
+ * it would destroy the contents of our link register.
+ */
+.macro blr_nospec_lr
+#ifdef CONFIG_RETPOLINE
+	retpoline
+	blr	lr
+#else
+	blr	lr
+#endif
+.endm
+
+#else /* __ASSEMBLY__ */
+
+extern char __indirect_thunk_start[];
+extern char __indirect_thunk_end[];
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* _ASM_ARM64_NOSPEC_BRANCH_H_ */