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6#include <linux/err.h>
7#include <linux/highmem.h>
8#include <linux/mm.h>
9#include <linux/module.h>
10#include <linux/sched.h>
11#include <asm/current.h>
12#include <asm/page.h>
13#include <asm/pgtable.h>
14#include <kern_util.h>
15#include <os.h>
16
17pte_t *virt_to_pte(struct mm_struct *mm, unsigned long addr)
18{
19 pgd_t *pgd;
20 pud_t *pud;
21 pmd_t *pmd;
22
23 if (mm == NULL)
24 return NULL;
25
26 pgd = pgd_offset(mm, addr);
27 if (!pgd_present(*pgd))
28 return NULL;
29
30 pud = pud_offset(pgd, addr);
31 if (!pud_present(*pud))
32 return NULL;
33
34 pmd = pmd_offset(pud, addr);
35 if (!pmd_present(*pmd))
36 return NULL;
37
38 return pte_offset_kernel(pmd, addr);
39}
40
41static pte_t *maybe_map(unsigned long virt, int is_write)
42{
43 pte_t *pte = virt_to_pte(current->mm, virt);
44 int err, dummy_code;
45
46 if ((pte == NULL) || !pte_present(*pte) ||
47 (is_write && !pte_write(*pte))) {
48 err = handle_page_fault(virt, 0, is_write, 1, &dummy_code);
49 if (err)
50 return NULL;
51 pte = virt_to_pte(current->mm, virt);
52 }
53 if (!pte_present(*pte))
54 pte = NULL;
55
56 return pte;
57}
58
59static int do_op_one_page(unsigned long addr, int len, int is_write,
60 int (*op)(unsigned long addr, int len, void *arg), void *arg)
61{
62 jmp_buf buf;
63 struct page *page;
64 pte_t *pte;
65 int n, faulted;
66
67 pte = maybe_map(addr, is_write);
68 if (pte == NULL)
69 return -1;
70
71 page = pte_page(*pte);
72 addr = (unsigned long) kmap_atomic(page) +
73 (addr & ~PAGE_MASK);
74
75 current->thread.fault_catcher = &buf;
76
77 faulted = UML_SETJMP(&buf);
78 if (faulted == 0)
79 n = (*op)(addr, len, arg);
80 else
81 n = -1;
82
83 current->thread.fault_catcher = NULL;
84
85 kunmap_atomic((void *)addr);
86
87 return n;
88}
89
90static long buffer_op(unsigned long addr, int len, int is_write,
91 int (*op)(unsigned long, int, void *), void *arg)
92{
93 long size, remain, n;
94
95 size = min(PAGE_ALIGN(addr) - addr, (unsigned long) len);
96 remain = len;
97
98 n = do_op_one_page(addr, size, is_write, op, arg);
99 if (n != 0) {
100 remain = (n < 0 ? remain : 0);
101 goto out;
102 }
103
104 addr += size;
105 remain -= size;
106 if (remain == 0)
107 goto out;
108
109 while (addr < ((addr + remain) & PAGE_MASK)) {
110 n = do_op_one_page(addr, PAGE_SIZE, is_write, op, arg);
111 if (n != 0) {
112 remain = (n < 0 ? remain : 0);
113 goto out;
114 }
115
116 addr += PAGE_SIZE;
117 remain -= PAGE_SIZE;
118 }
119 if (remain == 0)
120 goto out;
121
122 n = do_op_one_page(addr, remain, is_write, op, arg);
123 if (n != 0) {
124 remain = (n < 0 ? remain : 0);
125 goto out;
126 }
127
128 return 0;
129 out:
130 return remain;
131}
132
133static int copy_chunk_from_user(unsigned long from, int len, void *arg)
134{
135 unsigned long *to_ptr = arg, to = *to_ptr;
136
137 memcpy((void *) to, (void *) from, len);
138 *to_ptr += len;
139 return 0;
140}
141
142unsigned long raw_copy_from_user(void *to, const void __user *from, unsigned long n)
143{
144 if (uaccess_kernel()) {
145 memcpy(to, (__force void*)from, n);
146 return 0;
147 }
148
149 return buffer_op((unsigned long) from, n, 0, copy_chunk_from_user, &to);
150}
151EXPORT_SYMBOL(raw_copy_from_user);
152
153static int copy_chunk_to_user(unsigned long to, int len, void *arg)
154{
155 unsigned long *from_ptr = arg, from = *from_ptr;
156
157 memcpy((void *) to, (void *) from, len);
158 *from_ptr += len;
159 return 0;
160}
161
162unsigned long raw_copy_to_user(void __user *to, const void *from, unsigned long n)
163{
164 if (uaccess_kernel()) {
165 memcpy((__force void *) to, from, n);
166 return 0;
167 }
168
169 return buffer_op((unsigned long) to, n, 1, copy_chunk_to_user, &from);
170}
171EXPORT_SYMBOL(raw_copy_to_user);
172
173static int strncpy_chunk_from_user(unsigned long from, int len, void *arg)
174{
175 char **to_ptr = arg, *to = *to_ptr;
176 int n;
177
178 strncpy(to, (void *) from, len);
179 n = strnlen(to, len);
180 *to_ptr += n;
181
182 if (n < len)
183 return 1;
184 return 0;
185}
186
187long __strncpy_from_user(char *dst, const char __user *src, long count)
188{
189 long n;
190 char *ptr = dst;
191
192 if (uaccess_kernel()) {
193 strncpy(dst, (__force void *) src, count);
194 return strnlen(dst, count);
195 }
196
197 n = buffer_op((unsigned long) src, count, 0, strncpy_chunk_from_user,
198 &ptr);
199 if (n != 0)
200 return -EFAULT;
201 return strnlen(dst, count);
202}
203EXPORT_SYMBOL(__strncpy_from_user);
204
205static int clear_chunk(unsigned long addr, int len, void *unused)
206{
207 memset((void *) addr, 0, len);
208 return 0;
209}
210
211unsigned long __clear_user(void __user *mem, unsigned long len)
212{
213 if (uaccess_kernel()) {
214 memset((__force void*)mem, 0, len);
215 return 0;
216 }
217
218 return buffer_op((unsigned long) mem, len, 1, clear_chunk, NULL);
219}
220EXPORT_SYMBOL(__clear_user);
221
222static int strnlen_chunk(unsigned long str, int len, void *arg)
223{
224 int *len_ptr = arg, n;
225
226 n = strnlen((void *) str, len);
227 *len_ptr += n;
228
229 if (n < len)
230 return 1;
231 return 0;
232}
233
234long __strnlen_user(const void __user *str, long len)
235{
236 int count = 0, n;
237
238 if (uaccess_kernel())
239 return strnlen((__force char*)str, len) + 1;
240
241 n = buffer_op((unsigned long) str, len, 0, strnlen_chunk, &count);
242 if (n == 0)
243 return count + 1;
244 return 0;
245}
246EXPORT_SYMBOL(__strnlen_user);
247
