慢慢欣赏arm64内核启动11 primary_entry之__create_page_tables代码第一部分

代码分析

/*
 * Setup the initial page tables. We only setup the barest amount which is
 * required to get the kernel running. The following sections are required:
 *   - identity mapping to enable the MMU (low address, TTBR0)
 *   - first few MB of the kernel linear mapping to jump to once the MMU has
 *     been enabled
 */
SYM_FUNC_START_LOCAL(__create_page_tables)
	mov	x28, lr

	/*
	 * Invalidate the init page tables to avoid potential dirty cache lines
	 * being evicted. Other page tables are allocated in rodata as part of
	 * the kernel image, and thus are clean to the PoC per the boot
	 * protocol.
	 */
	adrp	x0, init_pg_dir
	adrp	x1, init_pg_end
	sub	x1, x1, x0
	bl	__inval_dcache_area

	/*
	 * Clear the init page tables.
	 */
	adrp	x0, init_pg_dir
	adrp	x1, init_pg_end
	sub	x1, x1, x0
1:	stp	xzr, xzr, [x0], #16
	stp	xzr, xzr, [x0], #16
	stp	xzr, xzr, [x0], #16
	stp	xzr, xzr, [x0], #16
	subs	x1, x1, #64
	b.ne	1b

	mov	x7, SWAPPER_MM_MMUFLAGS

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