1/*
2 * Copyright (C) 2011 Richard Weinberger <richrd@nod.at>
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 as
6 * published by the Free Software Foundation.
7 */
8
9#include <linux/slab.h>
10#include <linux/sched.h>
11#include <linux/mm.h>
12#include <asm/page.h>
13#include <linux/init.h>
14
15static unsigned int __read_mostly vdso_enabled = 1;
16unsigned long um_vdso_addr;
17
18extern unsigned long task_size;
19extern char vdso_start[], vdso_end[];
20
21static struct page **vdsop;
22
23static int __init init_vdso(void)
24{
25	struct page *um_vdso;
26
27	BUG_ON(vdso_end - vdso_start > PAGE_SIZE);
28
29	um_vdso_addr = task_size - PAGE_SIZE;
30
31	vdsop = kmalloc(sizeof(struct page *), GFP_KERNEL);
32	if (!vdsop)
33		goto oom;
34
35	um_vdso = alloc_page(GFP_KERNEL);
36	if (!um_vdso) {
37		kfree(vdsop);
38
39		goto oom;
40	}
41
42	copy_page(page_address(um_vdso), vdso_start);
43	*vdsop = um_vdso;
44
45	return 0;
46
47oom:
48	printk(KERN_ERR "Cannot allocate vdso\n");
49	vdso_enabled = 0;
50
51	return -ENOMEM;
52}
53subsys_initcall(init_vdso);
54
55int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
56{
57	int err;
58	struct mm_struct *mm = current->mm;
59
60	if (!vdso_enabled)
61		return 0;
62
63	down_write(&mm->mmap_sem);
64
65	err = install_special_mapping(mm, um_vdso_addr, PAGE_SIZE,
66		VM_READ|VM_EXEC|
67		VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
68		vdsop);
69
70	up_write(&mm->mmap_sem);
71
72	return err;
73}
74