virt_to_phys on 5.4 kernel
virt_to_phys on 5.4 kernel
5.4\arch\arm64\include\asm\Memory.h static inline phys_addr_t virt_to_phys(const volatile void *x) { return __virt_to_phys((unsigned long)(x)); }
#define __is_lm_address(addr) (((u64)(addr) ^ PAGE_OFFSET) < (PAGE_END - PAGE_OFFSET)) #define __lm_to_phys(addr) (((addr) & ~PAGE_OFFSET) + PHYS_OFFSET) #define __kimg_to_phys(addr) ((addr) - kimage_voffset) #define __virt_to_phys_nodebug(x) ({ \ phys_addr_t __x = (phys_addr_t)(__tag_reset(x)); \ __is_lm_address(__x) ? __lm_to_phys(__x) : __kimg_to_phys(__x); \ })
PAGE_OFFSET is 0xffffff8000000000, PHYS_OFFSET: 0x0
PAGE_END is 0xffffffc000000000, (PAGE_END - PAGE_OFFSET) is 0x4000000000
kimage_voffset计算
arch/arm64/kernel/head.S
ENTRY(kimage_vaddr)
.quad _text - TEXT_OFFSET
EXPORT_SYMBOL(kimage_vaddr)
#define __PHYS_OFFSET (KERNEL_START - TEXT_OFFSET)
ldr x8, =__primary_switched
adrp x0, __PHYS_OFFSET
blr x8
__primary_switched: ldr_l x4, kimage_vaddr // Save the offset between sub x4, x4, x0 // the kernel virtual and str_l x4, kimage_voffset, x5 // physical mappings
x0是调用__primary_switched的第一个参数,为__PHYS_OFFSET,它表示kernel起始物理地址
kernel链接常见macro定义
. KERNEL_START
arch\arm64\include\asm\Memory.h
#define KERNEL_START _text
#define KERNEL_END _end
. TEXT_OFFSET
arch/arm64/Makefile
# The byte offset of the kernel image in RAM from the start of RAM. ifeq ($(CONFIG_ARM64_RANDOMIZE_TEXT_OFFSET), y) TEXT_OFFSET := $(shell awk "BEGIN {srand(); printf \"0x%06x\n\", \ int(2 * 1024 * 1024 / (2 ^ $(CONFIG_ARM64_PAGE_SHIFT)) * \ rand()) * (2 ^ $(CONFIG_ARM64_PAGE_SHIFT))}") else TEXT_OFFSET := 0x00080000 endif
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