1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * arch/arm/boot/compressed/string.c
4 *
5 * Small subset of simple string routines
6 */
7
8 #define __NO_FORTIFY
9 #include <linux/string.h>
10
11 /*
12 * The decompressor is built without KASan but uses the same redirects as the
13 * rest of the kernel when CONFIG_KASAN is enabled, defining e.g. memcpy()
14 * to __memcpy() but since we are not linking with the main kernel string
15 * library in the decompressor, that will lead to link failures.
16 *
17 * Undefine KASan's versions, define the wrapped functions and alias them to
18 * the right names so that when e.g. __memcpy() appear in the code, it will
19 * still be linked to this local version of memcpy().
20 */
21 #ifdef CONFIG_KASAN
22 #undef memcpy
23 #undef memmove
24 #undef memset
25 void *__memcpy(void *__dest, __const void *__src, size_t __n) __alias(memcpy);
26 void *__memmove(void *__dest, __const void *__src, size_t count) __alias(memmove);
27 void *__memset(void *s, int c, size_t count) __alias(memset);
28 #endif
29
30 void *memcpy(void *__dest, __const void *__src, size_t __n)
31 {
32 int i = 0;
33 unsigned char *d = (unsigned char *)__dest, *s = (unsigned char *)__src;
34
35 for (i = __n >> 3; i > 0; i--) {
36 *d++ = *s++;
37 *d++ = *s++;
38 *d++ = *s++;
39 *d++ = *s++;
40 *d++ = *s++;
41 *d++ = *s++;
42 *d++ = *s++;
43 *d++ = *s++;
44 }
45
46 if (__n & 1 << 2) {
47 *d++ = *s++;
48 *d++ = *s++;
49 *d++ = *s++;
50 *d++ = *s++;
51 }
52
53 if (__n & 1 << 1) {
54 *d++ = *s++;
55 *d++ = *s++;
56 }
57
58 if (__n & 1)
59 *d++ = *s++;
60
61 return __dest;
62 }
63
64 void *memmove(void *__dest, __const void *__src, size_t count)
65 {
66 unsigned char *d = __dest;
67 const unsigned char *s = __src;
68
69 if (__dest == __src)
70 return __dest;
71
72 if (__dest < __src)
73 return memcpy(__dest, __src, count);
74
75 while (count--)
76 d[count] = s[count];
77 return __dest;
78 }
79
80 size_t strlen(const char *s)
81 {
82 const char *sc = s;
83
84 while (*sc != '\0')
85 sc++;
86 return sc - s;
87 }
88
89 size_t strnlen(const char *s, size_t count)
90 {
91 const char *sc;
92
93 for (sc = s; count-- && *sc != '\0'; ++sc)
94 /* nothing */;
95 return sc - s;
96 }
97
98 int memcmp(const void *cs, const void *ct, size_t count)
99 {
100 const unsigned char *su1 = cs, *su2 = ct, *end = su1 + count;
101 int res = 0;
102
103 while (su1 < end) {
104 res = *su1++ - *su2++;
105 if (res)
106 break;
107 }
108 return res;
109 }
110
111 int strcmp(const char *cs, const char *ct)
112 {
113 unsigned char c1, c2;
114 int res = 0;
115
116 do {
117 c1 = *cs++;
118 c2 = *ct++;
119 res = c1 - c2;
120 if (res)
121 break;
122 } while (c1);
123 return res;
124 }
125
126 void *memchr(const void *s, int c, size_t count)
127 {
128 const unsigned char *p = s;
129
130 while (count--)
131 if ((unsigned char)c == *p++)
132 return (void *)(p - 1);
133 return NULL;
134 }
135
136 char *strchr(const char *s, int c)
137 {
138 while (*s != (char)c)
139 if (*s++ == '\0')
140 return NULL;
141 return (char *)s;
142 }
143
144 char *strrchr(const char *s, int c)
145 {
146 const char *last = NULL;
147 do {
148 if (*s == (char)c)
149 last = s;
150 } while (*s++);
151 return (char *)last;
152 }
153
154 #undef memset
155
156 void *memset(void *s, int c, size_t count)
157 {
158 char *xs = s;
159 while (count--)
160 *xs++ = c;
161 return s;
162 }
163
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