1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (C) 2004 Benjamin Herrenschmidt, IBM Corp.
4 * <benh@kernel.crashing.org>
5 * Copyright (C) 2012 ARM Limited
6 * Copyright (C) 2015 Regents of the University of California
7 */
8
9 #include <linux/elf.h>
10 #include <linux/mm.h>
11 #include <linux/slab.h>
12 #include <linux/binfmts.h>
13 #include <linux/err.h>
14 #include <asm/page.h>
15 #ifdef CONFIG_GENERIC_TIME_VSYSCALL
16 #include <vdso/datapage.h>
17 #else
18 #include <asm/vdso.h>
19 #endif
20
21 extern char vdso_start[], vdso_end[];
22
23 static unsigned int vdso_pages;
24 static struct page **vdso_pagelist;
25
26 /*
27 * The vDSO data page.
28 */
29 static union {
30 struct vdso_data data;
31 u8 page[PAGE_SIZE];
32 } vdso_data_store __page_aligned_data;
33 struct vdso_data *vdso_data = &vdso_data_store.data;
34
vdso_init(void)35 static int __init vdso_init(void)
36 {
37 unsigned int i;
38
39 vdso_pages = (vdso_end - vdso_start) >> PAGE_SHIFT;
40 vdso_pagelist =
41 kcalloc(vdso_pages + 1, sizeof(struct page *), GFP_KERNEL);
42 if (unlikely(vdso_pagelist == NULL)) {
43 pr_err("vdso: pagelist allocation failed\n");
44 return -ENOMEM;
45 }
46
47 for (i = 0; i < vdso_pages; i++) {
48 struct page *pg;
49
50 pg = virt_to_page(vdso_start + (i << PAGE_SHIFT));
51 vdso_pagelist[i] = pg;
52 }
53 vdso_pagelist[i] = virt_to_page(vdso_data);
54
55 return 0;
56 }
57 arch_initcall(vdso_init);
58
arch_setup_additional_pages(struct linux_binprm * bprm,int uses_interp)59 int arch_setup_additional_pages(struct linux_binprm *bprm,
60 int uses_interp)
61 {
62 struct mm_struct *mm = current->mm;
63 unsigned long vdso_base, vdso_len;
64 int ret;
65
66 vdso_len = (vdso_pages + 1) << PAGE_SHIFT;
67
68 if (mmap_write_lock_killable(mm))
69 return -EINTR;
70
71 vdso_base = get_unmapped_area(NULL, 0, vdso_len, 0, 0);
72 if (IS_ERR_VALUE(vdso_base)) {
73 ret = vdso_base;
74 goto end;
75 }
76
77 /*
78 * Put vDSO base into mm struct. We need to do this before calling
79 * install_special_mapping or the perf counter mmap tracking code
80 * will fail to recognise it as a vDSO (since arch_vma_name fails).
81 */
82 mm->context.vdso = (void *)vdso_base;
83
84 ret =
85 install_special_mapping(mm, vdso_base, vdso_pages << PAGE_SHIFT,
86 (VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC),
87 vdso_pagelist);
88
89 if (unlikely(ret)) {
90 mm->context.vdso = NULL;
91 goto end;
92 }
93
94 vdso_base += (vdso_pages << PAGE_SHIFT);
95 ret = install_special_mapping(mm, vdso_base, PAGE_SIZE,
96 (VM_READ | VM_MAYREAD), &vdso_pagelist[vdso_pages]);
97
98 if (unlikely(ret))
99 mm->context.vdso = NULL;
100 end:
101 mmap_write_unlock(mm);
102 return ret;
103 }
104
arch_vma_name(struct vm_area_struct * vma)105 const char *arch_vma_name(struct vm_area_struct *vma)
106 {
107 if (vma->vm_mm && (vma->vm_start == (long)vma->vm_mm->context.vdso))
108 return "[vdso]";
109 if (vma->vm_mm && (vma->vm_start ==
110 (long)vma->vm_mm->context.vdso + PAGE_SIZE))
111 return "[vdso_data]";
112 return NULL;
113 }
114