開啓kaslr後，kernel image 在vmalloc區域. 運行地址與鏈接地址會有一個offset
addr_run = addr_link + offset //開啓KASLR
addr_run = addr_link + _text - (KIMAG_VADDR+TEXT_OFFSET)//_text爲重定向後的值
addr_link = addr_run - _text_start + (vmalloc_start+TEX_OFFSET)//ARM64 KIMAGE_VADDR==vmalloc_start
kimage_vaddr= _text - TEXT_OFFSET //如果開啓KASLR後，_text會重定向，
kimage_voffset //kernel image虛擬地址-kernel image物理地址
kaslr_offset= kimage_vaddr - KIMAGE_VADDR
memstart_addr //the base of physical memory
#define KERNEL_START _text
#define KERNEL_END _end
#define PAGE_OFFSET ((-1)<<VA_BITS)//PAGE_OFFSET - the virtual address of the start of the linear map