// SPDX-License-Identifier: GPL-2.0// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd. #include <linux/binfmts.h>#include <linux/elf.h>#include <linux/err.h>#include <linux/mm.h>#include <linux/slab.h> #include <asm/page.h> extern char vdso_start[], vdso_end[]; static unsigned int vdso_pages;static struct page **vdso_pagelist; static int __init vdso_init(void){	unsigned int i; 	vdso_pages = (vdso_end - vdso_start) >> PAGE_SHIFT;	vdso_pagelist =		kzalloc_objs(struct page *, vdso_pages);	if (unlikely(vdso_pagelist == NULL)) {		pr_err("vdso: pagelist allocation failed\n");		return -ENOMEM;	} 	for (i = 0; i < vdso_pages; i++) {		struct page *pg; 		pg = virt_to_page(vdso_start + (i << PAGE_SHIFT));		vdso_pagelist[i] = pg;	} 	return 0;}arch_initcall(vdso_init); int arch_setup_additional_pages(struct linux_binprm *bprm,	int uses_interp){	struct vm_area_struct *vma;	struct mm_struct *mm = current->mm;	unsigned long vdso_base, vdso_len;	int ret;	static struct vm_special_mapping vdso_mapping = {		.name = "[vdso]",	}; 	vdso_len = vdso_pages << PAGE_SHIFT; 	mmap_write_lock(mm);	vdso_base = get_unmapped_area(NULL, 0, vdso_len, 0, 0);	if (IS_ERR_VALUE(vdso_base)) {		ret = vdso_base;		goto end;	} 	/*	 * Put vDSO base into mm struct. We need to do this before calling	 * install_special_mapping or the perf counter mmap tracking code	 * will fail to recognise it as a vDSO (since arch_vma_name fails).	 */	mm->context.vdso = (void *)vdso_base; 	vdso_mapping.pages = vdso_pagelist;	vma =	   _install_special_mapping(mm, vdso_base, vdso_pages << PAGE_SHIFT,		(VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC),		&vdso_mapping); 	if (IS_ERR(vma)) {		ret = PTR_ERR(vma);		mm->context.vdso = NULL;		goto end;	} 	vdso_base += (vdso_pages << PAGE_SHIFT);	ret = 0;end:	mmap_write_unlock(mm);	return ret;}