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 static struct page *um_vdso;
16
17 extern unsigned long task_size;
18 extern char vdso_start[], vdso_end[];
19
init_vdso(void)20 static int __init init_vdso(void)
21 {
22 BUG_ON(vdso_end - vdso_start > PAGE_SIZE);
23
24 um_vdso_addr = task_size - PAGE_SIZE;
25
26 um_vdso = alloc_page(GFP_KERNEL);
27 if (!um_vdso)
28 goto oom;
29
30 copy_page(page_address(um_vdso), vdso_start);
31
32 return 0;
33
34 oom:
35 printk(KERN_ERR "Cannot allocate vdso\n");
36 vdso_enabled = 0;
37
38 return -ENOMEM;
39 }
40 subsys_initcall(init_vdso);
41
arch_setup_additional_pages(struct linux_binprm * bprm,int uses_interp)42 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
43 {
44 struct vm_area_struct *vma;
45 struct mm_struct *mm = current->mm;
46 static struct vm_special_mapping vdso_mapping = {
47 .name = "[vdso]",
48 .pages = &um_vdso,
49 };
50
51 if (!vdso_enabled)
52 return 0;
53
54 if (mmap_write_lock_killable(mm))
55 return -EINTR;
56
57 vma = _install_special_mapping(mm, um_vdso_addr, PAGE_SIZE,
58 VM_READ|VM_EXEC|
59 VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
60 &vdso_mapping);
61
62 mmap_write_unlock(mm);
63
64 return IS_ERR(vma) ? PTR_ERR(vma) : 0;
65 }
66