1
2
3
4
5
6
7
8
9
10
11
12#include <linux/kernel.h>
13#include <linux/ctype.h>
14#include <linux/uaccess.h>
15#include <linux/rwsem.h>
16#include <linux/mm.h>
17#include <linux/sched.h>
18#include <linux/hardirq.h>
19#include <asm/current.h>
20#include <asm/page.h>
21
22static int
23pin_page_for_write(const void __user *_addr, pte_t **ptep, spinlock_t **ptlp)
24{
25 unsigned long addr = (unsigned long)_addr;
26 pgd_t *pgd;
27 pmd_t *pmd;
28 pte_t *pte;
29 spinlock_t *ptl;
30
31 pgd = pgd_offset(current->mm, addr);
32 if (unlikely(pgd_none(*pgd) || pgd_bad(*pgd)))
33 return 0;
34
35 pmd = pmd_offset(pgd, addr);
36 if (unlikely(pmd_none(*pmd) || pmd_bad(*pmd)))
37 return 0;
38
39 pte = pte_offset_map_lock(current->mm, pmd, addr, &ptl);
40 if (unlikely(!pte_present(*pte) || !pte_young(*pte) ||
41 !pte_write(*pte) || !pte_dirty(*pte))) {
42 pte_unmap_unlock(pte, ptl);
43 return 0;
44 }
45
46 *ptep = pte;
47 *ptlp = ptl;
48
49 return 1;
50}
51
52static unsigned long noinline
53__copy_to_user_memcpy(void __user *to, const void *from, unsigned long n)
54{
55 int atomic;
56
57 if (unlikely(segment_eq(get_fs(), KERNEL_DS))) {
58 memcpy((void *)to, from, n);
59 return 0;
60 }
61
62
63 atomic = in_atomic();
64
65 if (!atomic)
66 down_read(¤t->mm->mmap_sem);
67 while (n) {
68 pte_t *pte;
69 spinlock_t *ptl;
70 int tocopy;
71
72 while (!pin_page_for_write(to, &pte, &ptl)) {
73 if (!atomic)
74 up_read(¤t->mm->mmap_sem);
75 if (__put_user(0, (char __user *)to))
76 goto out;
77 if (!atomic)
78 down_read(¤t->mm->mmap_sem);
79 }
80
81 tocopy = (~(unsigned long)to & ~PAGE_MASK) + 1;
82 if (tocopy > n)
83 tocopy = n;
84
85 memcpy((void *)to, from, tocopy);
86 to += tocopy;
87 from += tocopy;
88 n -= tocopy;
89
90 pte_unmap_unlock(pte, ptl);
91 }
92 if (!atomic)
93 up_read(¤t->mm->mmap_sem);
94
95out:
96 return n;
97}
98
99unsigned long
100__copy_to_user(void __user *to, const void *from, unsigned long n)
101{
102
103
104
105
106
107
108
109 if (n < 64)
110 return __copy_to_user_std(to, from, n);
111 return __copy_to_user_memcpy(to, from, n);
112}
113
114static unsigned long noinline
115__clear_user_memset(void __user *addr, unsigned long n)
116{
117 if (unlikely(segment_eq(get_fs(), KERNEL_DS))) {
118 memset((void *)addr, 0, n);
119 return 0;
120 }
121
122 down_read(¤t->mm->mmap_sem);
123 while (n) {
124 pte_t *pte;
125 spinlock_t *ptl;
126 int tocopy;
127
128 while (!pin_page_for_write(addr, &pte, &ptl)) {
129 up_read(¤t->mm->mmap_sem);
130 if (__put_user(0, (char __user *)addr))
131 goto out;
132 down_read(¤t->mm->mmap_sem);
133 }
134
135 tocopy = (~(unsigned long)addr & ~PAGE_MASK) + 1;
136 if (tocopy > n)
137 tocopy = n;
138
139 memset((void *)addr, 0, tocopy);
140 addr += tocopy;
141 n -= tocopy;
142
143 pte_unmap_unlock(pte, ptl);
144 }
145 up_read(¤t->mm->mmap_sem);
146
147out:
148 return n;
149}
150
151unsigned long __clear_user(void __user *addr, unsigned long n)
152{
153
154 if (n < 64)
155 return __clear_user_std(addr, n);
156 return __clear_user_memset(addr, n);
157}
158
159#if 0
160
161
162
163
164
165
166
167
168
169
170
171
172#include <linux/vmalloc.h>
173
174static int __init test_size_treshold(void)
175{
176 struct page *src_page, *dst_page;
177 void *user_ptr, *kernel_ptr;
178 unsigned long long t0, t1, t2;
179 int size, ret;
180
181 ret = -ENOMEM;
182 src_page = alloc_page(GFP_KERNEL);
183 if (!src_page)
184 goto no_src;
185 dst_page = alloc_page(GFP_KERNEL);
186 if (!dst_page)
187 goto no_dst;
188 kernel_ptr = page_address(src_page);
189 user_ptr = vmap(&dst_page, 1, VM_IOREMAP, __pgprot(__P010));
190 if (!user_ptr)
191 goto no_vmap;
192
193
194 ret = __copy_to_user_memcpy(user_ptr, kernel_ptr, PAGE_SIZE);
195
196 for (size = PAGE_SIZE; size >= 4; size /= 2) {
197 t0 = sched_clock();
198 ret |= __copy_to_user_memcpy(user_ptr, kernel_ptr, size);
199 t1 = sched_clock();
200 ret |= __copy_to_user_std(user_ptr, kernel_ptr, size);
201 t2 = sched_clock();
202 printk("copy_to_user: %d %llu %llu\n", size, t1 - t0, t2 - t1);
203 }
204
205 for (size = PAGE_SIZE; size >= 4; size /= 2) {
206 t0 = sched_clock();
207 ret |= __clear_user_memset(user_ptr, size);
208 t1 = sched_clock();
209 ret |= __clear_user_std(user_ptr, size);
210 t2 = sched_clock();
211 printk("clear_user: %d %llu %llu\n", size, t1 - t0, t2 - t1);
212 }
213
214 if (ret)
215 ret = -EFAULT;
216
217 vunmap(user_ptr);
218no_vmap:
219 put_page(dst_page);
220no_dst:
221 put_page(src_page);
222no_src:
223 return ret;
224}
225
226subsys_initcall(test_size_treshold);
227
228#endif
229