xref: /linux/arch/csky/kernel/vdso.c (revision 9208c05f9fdfd927ea160b97dfef3c379049fff2)
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 
12 extern char vdso_start[], vdso_end[];
13 
14 static unsigned int vdso_pages;
15 static struct page **vdso_pagelist;
16 
17 static int __init vdso_init(void)
18 {
19 	unsigned int i;
20 
21 	vdso_pages = (vdso_end - vdso_start) >> PAGE_SHIFT;
22 	vdso_pagelist =
23 		kcalloc(vdso_pages, sizeof(struct page *), GFP_KERNEL);
24 	if (unlikely(vdso_pagelist == NULL)) {
25 		pr_err("vdso: pagelist allocation failed\n");
26 		return -ENOMEM;
27 	}
28 
29 	for (i = 0; i < vdso_pages; i++) {
30 		struct page *pg;
31 
32 		pg = virt_to_page(vdso_start + (i << PAGE_SHIFT));
33 		vdso_pagelist[i] = pg;
34 	}
35 
36 	return 0;
37 }
38 arch_initcall(vdso_init);
39 
40 int arch_setup_additional_pages(struct linux_binprm *bprm,
41 	int uses_interp)
42 {
43 	struct vm_area_struct *vma;
44 	struct mm_struct *mm = current->mm;
45 	unsigned long vdso_base, vdso_len;
46 	int ret;
47 	static struct vm_special_mapping vdso_mapping = {
48 		.name = "[vdso]",
49 	};
50 
51 	vdso_len = vdso_pages << PAGE_SHIFT;
52 
53 	mmap_write_lock(mm);
54 	vdso_base = get_unmapped_area(NULL, 0, vdso_len, 0, 0);
55 	if (IS_ERR_VALUE(vdso_base)) {
56 		ret = vdso_base;
57 		goto end;
58 	}
59 
60 	/*
61 	 * Put vDSO base into mm struct. We need to do this before calling
62 	 * install_special_mapping or the perf counter mmap tracking code
63 	 * will fail to recognise it as a vDSO (since arch_vma_name fails).
64 	 */
65 	mm->context.vdso = (void *)vdso_base;
66 
67 	vdso_mapping.pages = vdso_pagelist;
68 	vma =
69 	   _install_special_mapping(mm, vdso_base, vdso_pages << PAGE_SHIFT,
70 		(VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC),
71 		&vdso_mapping);
72 
73 	if (IS_ERR(vma)) {
74 		ret = PTR_ERR(vma);
75 		mm->context.vdso = NULL;
76 		goto end;
77 	}
78 
79 	vdso_base += (vdso_pages << PAGE_SHIFT);
80 	ret = 0;
81 end:
82 	mmap_write_unlock(mm);
83 	return ret;
84 }
85