1 /*
2 * User address space access functions.
3 *
4 * Copyright 1997 Andi Kleen <ak@muc.de>
5 * Copyright 1997 Linus Torvalds
6 * Copyright 2002 Andi Kleen <ak@suse.de>
7 */
8 #include <linux/export.h>
9 #include <linux/uaccess.h>
10 #include <linux/highmem.h>
11
12 /*
13 * Zero Userspace
14 */
15
__clear_user(void __user * addr,unsigned long size)16 unsigned long __clear_user(void __user *addr, unsigned long size)
17 {
18 long __d0;
19 might_fault();
20 /* no memory constraint because it doesn't change any memory gcc knows
21 about */
22 stac();
23 asm volatile(
24 " testq %[size8],%[size8]\n"
25 " jz 4f\n"
26 " .align 16\n"
27 "0: movq $0,(%[dst])\n"
28 " addq $8,%[dst]\n"
29 " decl %%ecx ; jnz 0b\n"
30 "4: movq %[size1],%%rcx\n"
31 " testl %%ecx,%%ecx\n"
32 " jz 2f\n"
33 "1: movb $0,(%[dst])\n"
34 " incq %[dst]\n"
35 " decl %%ecx ; jnz 1b\n"
36 "2:\n"
37 ".section .fixup,\"ax\"\n"
38 "3: lea 0(%[size1],%[size8],8),%[size8]\n"
39 " jmp 2b\n"
40 ".previous\n"
41 _ASM_EXTABLE(0b,3b)
42 _ASM_EXTABLE(1b,2b)
43 : [size8] "=&c"(size), [dst] "=&D" (__d0)
44 : [size1] "r"(size & 7), "[size8]" (size / 8), "[dst]"(addr));
45 clac();
46 return size;
47 }
48 EXPORT_SYMBOL(__clear_user);
49
clear_user(void __user * to,unsigned long n)50 unsigned long clear_user(void __user *to, unsigned long n)
51 {
52 if (access_ok(VERIFY_WRITE, to, n))
53 return __clear_user(to, n);
54 return n;
55 }
56 EXPORT_SYMBOL(clear_user);
57
58 /*
59 * Try to copy last bytes and clear the rest if needed.
60 * Since protection fault in copy_from/to_user is not a normal situation,
61 * it is not necessary to optimize tail handling.
62 */
63 __visible unsigned long
copy_user_handle_tail(char * to,char * from,unsigned len)64 copy_user_handle_tail(char *to, char *from, unsigned len)
65 {
66 for (; len; --len, to++) {
67 char c;
68
69 if (__get_user_nocheck(c, from++, sizeof(char)))
70 break;
71 if (__put_user_nocheck(c, to, sizeof(char)))
72 break;
73 }
74 clac();
75 return len;
76 }
77
78 /*
79 * Similar to copy_user_handle_tail, probe for the write fault point,
80 * but reuse __memcpy_mcsafe in case a new read error is encountered.
81 * clac() is handled in _copy_to_iter_mcsafe().
82 */
83 __visible unsigned long
mcsafe_handle_tail(char * to,char * from,unsigned len)84 mcsafe_handle_tail(char *to, char *from, unsigned len)
85 {
86 for (; len; --len, to++, from++) {
87 /*
88 * Call the assembly routine back directly since
89 * memcpy_mcsafe() may silently fallback to memcpy.
90 */
91 unsigned long rem = __memcpy_mcsafe(to, from, 1);
92
93 if (rem)
94 break;
95 }
96 return len;
97 }
98
99 #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
100 /**
101 * clean_cache_range - write back a cache range with CLWB
102 * @vaddr: virtual start address
103 * @size: number of bytes to write back
104 *
105 * Write back a cache range using the CLWB (cache line write back)
106 * instruction. Note that @size is internally rounded up to be cache
107 * line size aligned.
108 */
clean_cache_range(void * addr,size_t size)109 static void clean_cache_range(void *addr, size_t size)
110 {
111 u16 x86_clflush_size = boot_cpu_data.x86_clflush_size;
112 unsigned long clflush_mask = x86_clflush_size - 1;
113 void *vend = addr + size;
114 void *p;
115
116 for (p = (void *)((unsigned long)addr & ~clflush_mask);
117 p < vend; p += x86_clflush_size)
118 clwb(p);
119 }
120
arch_wb_cache_pmem(void * addr,size_t size)121 void arch_wb_cache_pmem(void *addr, size_t size)
122 {
123 clean_cache_range(addr, size);
124 }
125 EXPORT_SYMBOL_GPL(arch_wb_cache_pmem);
126
__copy_user_flushcache(void * dst,const void __user * src,unsigned size)127 long __copy_user_flushcache(void *dst, const void __user *src, unsigned size)
128 {
129 unsigned long flushed, dest = (unsigned long) dst;
130 long rc = __copy_user_nocache(dst, src, size, 0);
131
132 /*
133 * __copy_user_nocache() uses non-temporal stores for the bulk
134 * of the transfer, but we need to manually flush if the
135 * transfer is unaligned. A cached memory copy is used when
136 * destination or size is not naturally aligned. That is:
137 * - Require 8-byte alignment when size is 8 bytes or larger.
138 * - Require 4-byte alignment when size is 4 bytes.
139 */
140 if (size < 8) {
141 if (!IS_ALIGNED(dest, 4) || size != 4)
142 clean_cache_range(dst, size);
143 } else {
144 if (!IS_ALIGNED(dest, 8)) {
145 dest = ALIGN(dest, boot_cpu_data.x86_clflush_size);
146 clean_cache_range(dst, 1);
147 }
148
149 flushed = dest - (unsigned long) dst;
150 if (size > flushed && !IS_ALIGNED(size - flushed, 8))
151 clean_cache_range(dst + size - 1, 1);
152 }
153
154 return rc;
155 }
156
memcpy_flushcache(void * _dst,const void * _src,size_t size)157 void memcpy_flushcache(void *_dst, const void *_src, size_t size)
158 {
159 unsigned long dest = (unsigned long) _dst;
160 unsigned long source = (unsigned long) _src;
161
162 /* cache copy and flush to align dest */
163 if (!IS_ALIGNED(dest, 8)) {
164 unsigned len = min_t(unsigned, size, ALIGN(dest, 8) - dest);
165
166 memcpy((void *) dest, (void *) source, len);
167 clean_cache_range((void *) dest, len);
168 dest += len;
169 source += len;
170 size -= len;
171 if (!size)
172 return;
173 }
174
175 /* 4x8 movnti loop */
176 while (size >= 32) {
177 asm("movq (%0), %%r8\n"
178 "movq 8(%0), %%r9\n"
179 "movq 16(%0), %%r10\n"
180 "movq 24(%0), %%r11\n"
181 "movnti %%r8, (%1)\n"
182 "movnti %%r9, 8(%1)\n"
183 "movnti %%r10, 16(%1)\n"
184 "movnti %%r11, 24(%1)\n"
185 :: "r" (source), "r" (dest)
186 : "memory", "r8", "r9", "r10", "r11");
187 dest += 32;
188 source += 32;
189 size -= 32;
190 }
191
192 /* 1x8 movnti loop */
193 while (size >= 8) {
194 asm("movq (%0), %%r8\n"
195 "movnti %%r8, (%1)\n"
196 :: "r" (source), "r" (dest)
197 : "memory", "r8");
198 dest += 8;
199 source += 8;
200 size -= 8;
201 }
202
203 /* 1x4 movnti loop */
204 while (size >= 4) {
205 asm("movl (%0), %%r8d\n"
206 "movnti %%r8d, (%1)\n"
207 :: "r" (source), "r" (dest)
208 : "memory", "r8");
209 dest += 4;
210 source += 4;
211 size -= 4;
212 }
213
214 /* cache copy for remaining bytes */
215 if (size) {
216 memcpy((void *) dest, (void *) source, size);
217 clean_cache_range((void *) dest, size);
218 }
219 }
220 EXPORT_SYMBOL_GPL(memcpy_flushcache);
221
memcpy_page_flushcache(char * to,struct page * page,size_t offset,size_t len)222 void memcpy_page_flushcache(char *to, struct page *page, size_t offset,
223 size_t len)
224 {
225 char *from = kmap_atomic(page);
226
227 memcpy_flushcache(to, from + offset, len);
228 kunmap_atomic(from);
229 }
230 #endif
231