1 // SPDX-License-Identifier: GPL-2.0
2 // Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
3 
4 #include <linux/binfmts.h>
5 #include <linux/elf.h>
6 #include <linux/err.h>
7 #include <linux/mm.h>
8 #include <linux/slab.h>
9 
10 #include <asm/page.h>
11 #ifdef GENERIC_TIME_VSYSCALL
12 #include <vdso/datapage.h>
13 #else
14 #include <asm/vdso.h>
15 #endif
16 
17 extern char vdso_start[], vdso_end[];
18 
19 static unsigned int vdso_pages;
20 static struct page **vdso_pagelist;
21 
22 /*
23  * The vDSO data page.
24  */
25 static union {
26 	struct vdso_data	data;
27 	u8			page[PAGE_SIZE];
28 } vdso_data_store __page_aligned_data;
29 struct vdso_data *vdso_data = &vdso_data_store.data;
30 
vdso_init(void)31 static int __init vdso_init(void)
32 {
33 	unsigned int i;
34 
35 	vdso_pages = (vdso_end - vdso_start) >> PAGE_SHIFT;
36 	vdso_pagelist =
37 		kcalloc(vdso_pages + 1, sizeof(struct page *), GFP_KERNEL);
38 	if (unlikely(vdso_pagelist == NULL)) {
39 		pr_err("vdso: pagelist allocation failed\n");
40 		return -ENOMEM;
41 	}
42 
43 	for (i = 0; i < vdso_pages; i++) {
44 		struct page *pg;
45 
46 		pg = virt_to_page(vdso_start + (i << PAGE_SHIFT));
47 		vdso_pagelist[i] = pg;
48 	}
49 	vdso_pagelist[i] = virt_to_page(vdso_data);
50 
51 	return 0;
52 }
53 arch_initcall(vdso_init);
54 
arch_setup_additional_pages(struct linux_binprm * bprm,int uses_interp)55 int arch_setup_additional_pages(struct linux_binprm *bprm,
56 	int uses_interp)
57 {
58 	struct mm_struct *mm = current->mm;
59 	unsigned long vdso_base, vdso_len;
60 	int ret;
61 
62 	vdso_len = (vdso_pages + 1) << PAGE_SHIFT;
63 
64 	mmap_write_lock(mm);
65 	vdso_base = get_unmapped_area(NULL, 0, vdso_len, 0, 0);
66 	if (IS_ERR_VALUE(vdso_base)) {
67 		ret = vdso_base;
68 		goto end;
69 	}
70 
71 	/*
72 	 * Put vDSO base into mm struct. We need to do this before calling
73 	 * install_special_mapping or the perf counter mmap tracking code
74 	 * will fail to recognise it as a vDSO (since arch_vma_name fails).
75 	 */
76 	mm->context.vdso = (void *)vdso_base;
77 
78 	ret =
79 	   install_special_mapping(mm, vdso_base, vdso_pages << PAGE_SHIFT,
80 		(VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC),
81 		vdso_pagelist);
82 
83 	if (unlikely(ret)) {
84 		mm->context.vdso = NULL;
85 		goto end;
86 	}
87 
88 	vdso_base += (vdso_pages << PAGE_SHIFT);
89 	ret = install_special_mapping(mm, vdso_base, PAGE_SIZE,
90 		(VM_READ | VM_MAYREAD), &vdso_pagelist[vdso_pages]);
91 
92 	if (unlikely(ret))
93 		mm->context.vdso = NULL;
94 end:
95 	mmap_write_unlock(mm);
96 	return ret;
97 }
98 
arch_vma_name(struct vm_area_struct * vma)99 const char *arch_vma_name(struct vm_area_struct *vma)
100 {
101 	if (vma->vm_mm && (vma->vm_start == (long)vma->vm_mm->context.vdso))
102 		return "[vdso]";
103 	if (vma->vm_mm && (vma->vm_start ==
104 			   (long)vma->vm_mm->context.vdso + PAGE_SIZE))
105 		return "[vdso_data]";
106 	return NULL;
107 }
108