1 files changed, 63 insertions, 0 deletions
diff --git a/arch/arm64/include/asm/linkage.h b/arch/arm64/include/asm/linkage.h
new file mode 100644
index 000000000..ba89a9af8
--- /dev/null
+++ b/arch/arm64/include/asm/linkage.h
@@ -0,0 +1,63 @@
+#ifndef __ASM_LINKAGE_H
+#define __ASM_LINKAGE_H
+
+#define __ALIGN		.align 2
+#define __ALIGN_STR	".align 2"
+
+#if defined(CONFIG_ARM64_BTI_KERNEL) && defined(__aarch64__)
+
+/*
+ * Since current versions of gas reject the BTI instruction unless we
+ * set the architecture version to v8.5 we use the hint instruction
+ * instead.
+ */
+#define BTI_C hint 34 ;
+
+/*
+ * When using in-kernel BTI we need to ensure that PCS-conformant assembly
+ * functions have suitable annotations.  Override SYM_FUNC_START to insert
+ * a BTI landing pad at the start of everything.
+ */
+#define SYM_FUNC_START(name)				\
+	SYM_START(name, SYM_L_GLOBAL, SYM_A_ALIGN)	\
+	BTI_C
+
+#define SYM_FUNC_START_NOALIGN(name)			\
+	SYM_START(name, SYM_L_GLOBAL, SYM_A_NONE)	\
+	BTI_C
+
+#define SYM_FUNC_START_LOCAL(name)			\
+	SYM_START(name, SYM_L_LOCAL, SYM_A_ALIGN)	\
+	BTI_C
+
+#define SYM_FUNC_START_LOCAL_NOALIGN(name)		\
+	SYM_START(name, SYM_L_LOCAL, SYM_A_NONE)	\
+	BTI_C
+
+#define SYM_FUNC_START_WEAK(name)			\
+	SYM_START(name, SYM_L_WEAK, SYM_A_ALIGN)	\
+	BTI_C
+
+#define SYM_FUNC_START_WEAK_NOALIGN(name)		\
+	SYM_START(name, SYM_L_WEAK, SYM_A_NONE)		\
+	BTI_C
+
+#endif
+
+/*
+ * Annotate a function as position independent, i.e., safe to be called before
+ * the kernel virtual mapping is activated.
+ */
+#define SYM_FUNC_START_PI(x)			\
+		SYM_FUNC_START_ALIAS(__pi_##x);	\
+		SYM_FUNC_START(x)
+
+#define SYM_FUNC_START_WEAK_PI(x)		\
+		SYM_FUNC_START_ALIAS(__pi_##x);	\
+		SYM_FUNC_START_WEAK(x)
+
+#define SYM_FUNC_END_PI(x)			\
+		SYM_FUNC_END(x);		\
+		SYM_FUNC_END_ALIAS(__pi_##x)
+
+#endif