Linux 内核 内存管理虚拟地址空间布局架构 ⑦ ( Linux 内核地址空间布局简介 )

Posted 2022-04-12 韩曙亮

文章目录

• 一、Linux 内核地址空间布局简介
• 二、Linux 内核地址空间布局 图示

一、Linux 内核地址空间布局简介

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" Linux 内核地址空间布局 " 对应代码在 Linux 内核源码的 linux-4.12\\arch\\arm64\\include\\asm\\memory.h#66 位置 ;

/*
 * PAGE_OFFSET - the virtual address of the start of the linear map (top
 *		 (VA_BITS - 1))
 * KIMAGE_VADDR - the virtual address of the start of the kernel image
 * VA_BITS - the maximum number of bits for virtual addresses.
 * VA_START - the first kernel virtual address.
 * TASK_SIZE - the maximum size of a user space task.
 * TASK_UNMAPPED_BASE - the lower boundary of the mmap VM area.
 */
#define VA_BITS			(CONFIG_ARM64_VA_BITS)
#define VA_START		(UL(0xffffffffffffffff) << VA_BITS)
#define PAGE_OFFSET		(UL(0xffffffffffffffff) << (VA_BITS - 1))
#define KIMAGE_VADDR		(MODULES_END)
#define MODULES_END		(MODULES_VADDR + MODULES_VSIZE)
#define MODULES_VADDR		(VA_START + KASAN_SHADOW_SIZE)
#define MODULES_VSIZE		(SZ_128M)
#define VMEMMAP_START		(PAGE_OFFSET - VMEMMAP_SIZE)
#define PCI_IO_END		(VMEMMAP_START - SZ_2M)
#define PCI_IO_START		(PCI_IO_END - PCI_IO_SIZE)
#define FIXADDR_TOP		(PCI_IO_START - SZ_2M)
#define TASK_SIZE_64		(UL(1) << VA_BITS)

#ifdef CONFIG_COMPAT
#define TASK_SIZE_32		UL(0x100000000)
#define TASK_SIZE		(test_thread_flag(TIF_32BIT) ? \\
				TASK_SIZE_32 : TASK_SIZE_64)
#define TASK_SIZE_OF(tsk)	(test_tsk_thread_flag(tsk, TIF_32BIT) ? \\
				TASK_SIZE_32 : TASK_SIZE_64)
#else
#define TASK_SIZE		TASK_SIZE_64
#endif /* CONFIG_COMPAT */

#define TASK_UNMAPPED_BASE	(PAGE_ALIGN(TASK_SIZE / 4))

#define KERNEL_START      _text
#define KERNEL_END        _end

二、Linux 内核地址空间布局 图示

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