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