linkage.h
#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