1. 根目录:
2. arch
3. arm
4. include
5. asm
6. idmap.h

#ifndef __ASM_IDMAP_H
#define __ASM_IDMAP_H

#include <linux/compiler.h>
#include <asm/pgtable.h>

/* Tag a function as requiring to be executed via an identity mapping. */
#define __idmap __section(.idmap.text) noinline notrace

extern pgd_t *idmap_pgd;

void setup_mm_for_reboot(void);

#endif	/* __ASM_IDMAP_H */