vma.c

 1// SPDX-License-Identifier: GPL-2.0-only
 2/*
 3 * Copyright (C) 2011 Richard Weinberger <richrd@nod.at>
 4 */
 5
 6#include <linux/slab.h>
 7#include <linux/sched.h>
 8#include <linux/mm.h>
 9#include <asm/page.h>
10#include <asm/elf.h>
11#include <linux/init.h>
12
13unsigned long um_vdso_addr;
14static struct page *um_vdso;
15
16extern unsigned long task_size;
17extern char vdso_start[], vdso_end[];
18
19static int __init init_vdso(void)
20{
21	BUG_ON(vdso_end - vdso_start > PAGE_SIZE);
22
23	um_vdso_addr = task_size - PAGE_SIZE;
24
25	um_vdso = alloc_page(GFP_KERNEL);
26	if (!um_vdso)
27		panic("Cannot allocate vdso\n");
28
29	copy_page(page_address(um_vdso), vdso_start);
30
31	return 0;
32}
33subsys_initcall(init_vdso);
34
35int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
36{
37	struct vm_area_struct *vma;
38	struct mm_struct *mm = current->mm;
39	static struct vm_special_mapping vdso_mapping = {
40		.name = "[vdso]",
41		.pages = &um_vdso,
42	};
43
44	if (mmap_write_lock_killable(mm))
45		return -EINTR;
46
47	vma = _install_special_mapping(mm, um_vdso_addr, PAGE_SIZE,
48		VM_READ|VM_EXEC|
49		VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
50		&vdso_mapping);
51
52	mmap_write_unlock(mm);
53
54	return IS_ERR(vma) ? PTR_ERR(vma) : 0;
55}