paging_init

arch/arm64/mm/mmu.c
arch/arm64/kernel/setup.c
arch/arm64/kernel/smp.c

void __init paging_init(void)
{
	map_mem(swapper_pg_dir);

	memblock_allow_resize();

	create_idmap();
	declare_kernel_vmas();
}

	/*
	 * Take care not to create a writable alias for the
	 * read-only text and rodata sections of the kernel image.
	 * So temporarily mark them as NOMAP to skip mappings in
	 * the following for-loop
	 */
	memblock_mark_nomap(kernel_start, kernel_end - kernel_start);

	/* map all the memory banks */
	for_each_mem_range(i, &start, &end) {
		if (start >= end)
			break;
		/*
		 * The linear map must allow allocation tags reading/writing
		 * if MTE is present. Otherwise, it has the same attributes as
		 * PAGE_KERNEL.
		 */
		__map_memblock(pgdp, start, end, pgprot_tagged(PAGE_KERNEL),
			       flags);
	}

	/*
	 * Map the linear alias of the [_text, __init_begin) interval
	 * as non-executable now, and remove the write permission in
	 * mark_linear_text_alias_ro() below (which will be called after
	 * alternative patching has completed). This makes the contents
	 * of the region accessible to subsystems such as hibernate,
	 * but protects it from inadvertent modification or execution.
	 * Note that contiguous mappings cannot be remapped in this way,
	 * so we should avoid them here.
	 */
	__map_memblock(pgdp, kernel_start, kernel_end,
		       PAGE_KERNEL, NO_CONT_MAPPINGS);
	memblock_clear_nomap(kernel_start, kernel_end - kernel_start);
	arm64_kfence_map_pool(early_kfence_pool, pgdp);
}

void mark_rodata_ro(void)
{
	unsigned long section_size;

	/*
	 * mark .rodata as read only. Use __init_begin rather than __end_rodata
	 * to cover NOTES and EXCEPTION_TABLE.
	 */
	section_size = (unsigned long)__init_begin - (unsigned long)__start_rodata;
	WRITE_ONCE(rodata_is_rw, false);
	update_mapping_prot(__pa_symbol(__start_rodata), (unsigned long)__start_rodata,
			    section_size, PAGE_KERNEL_RO);
	/* mark the range between _text and _stext as read only. */
	update_mapping_prot(__pa_symbol(_text), (unsigned long)_text,
			    (unsigned long)_stext - (unsigned long)_text,
			    PAGE_KERNEL_RO);
}