arm64: asm: Override SYM_FUNC_START when building the kernel with BTI

#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 ;

#define BTI_J hint 36 ;

/*

 * When using in-kernel BTI we need to ensure that 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

#define SYM_INNER_LABEL(name, linkage)			\

	.type name SYM_T_NONE ASM_NL			\

	SYM_ENTRY(name, linkage, SYM_A_NONE)		\

	BTI_J

#endif

/*

 * Annotate a function as position independent, i.e., safe to be called before

 * the kernel virtual mapping is activated.