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
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
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
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