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 <asm/elf.h>
14#include <linux/init.h>
15
16static unsigned int __read_mostly vdso_enabled = 1;
17unsigned long um_vdso_addr;
18
19extern unsigned long task_size;
20extern char vdso_start[], vdso_end[];
21
22static struct page **vdsop;
23
24static int __init init_vdso(void)
25{
26	struct page *um_vdso;
27
28	BUG_ON(vdso_end - vdso_start > PAGE_SIZE);
29
30	um_vdso_addr = task_size - PAGE_SIZE;
31
32	vdsop = kmalloc(sizeof(struct page *), GFP_KERNEL);
33	if (!vdsop)
34		goto oom;
35
36	um_vdso = alloc_page(GFP_KERNEL);
37	if (!um_vdso) {
38		kfree(vdsop);
39
40		goto oom;
41	}
42
43	copy_page(page_address(um_vdso), vdso_start);
44	*vdsop = um_vdso;
45
46	return 0;
47
48oom:
49	printk(KERN_ERR "Cannot allocate vdso\n");
50	vdso_enabled = 0;
51
52	return -ENOMEM;
53}
54subsys_initcall(init_vdso);
55
56int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
57{
58	int err;
59	struct mm_struct *mm = current->mm;
60
61	if (!vdso_enabled)
62		return 0;
63
64	down_write(&mm->mmap_sem);
65
66	err = install_special_mapping(mm, um_vdso_addr, PAGE_SIZE,
67		VM_READ|VM_EXEC|
68		VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
69		vdsop);
70
71	up_write(&mm->mmap_sem);
72
73	return err;
74}
75