summaryrefslogtreecommitdiff
path: root/arch/um/sys-x86/vdso/vma.c
blob: 9495c8d0ce37e9e3ca22c5645c4aef3d2135d0e9 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
/*
 * Copyright (C) 2011 Richard Weinberger <richrd@nod.at>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <asm/page.h>
#include <linux/init.h>

unsigned int __read_mostly vdso_enabled = 1;
unsigned long um_vdso_addr;

extern unsigned long task_size;
extern char vdso_start[], vdso_end[];

static struct page **vdsop;

static int __init init_vdso(void)
{
	struct page *um_vdso;

	BUG_ON(vdso_end - vdso_start > PAGE_SIZE);

	um_vdso_addr = task_size - PAGE_SIZE;

	vdsop = kmalloc(GFP_KERNEL, sizeof(struct page *));
	if (!vdsop)
		goto oom;

	um_vdso = alloc_page(GFP_KERNEL);
	if (!um_vdso) {
		kfree(vdsop);

		goto oom;
	}

	copy_page(page_address(um_vdso), vdso_start);
	*vdsop = um_vdso;

	return 0;

oom:
	printk(KERN_ERR "Cannot allocate vdso\n");
	vdso_enabled = 0;

	return -ENOMEM;
}
subsys_initcall(init_vdso);

int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
{
	int err;
	struct mm_struct *mm = current->mm;

	if (!vdso_enabled)
		return 0;

	down_write(&mm->mmap_sem);

	err = install_special_mapping(mm, um_vdso_addr, PAGE_SIZE,
		VM_READ|VM_EXEC|
		VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC|
		VM_ALWAYSDUMP,
		vdsop);

	up_write(&mm->mmap_sem);

	return err;
}