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 
memcpy(void * __dest,__const void * __src,size_t __n)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 
memmove(void * __dest,__const void * __src,size_t count)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 
strlen(const char * s)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 
strnlen(const char * s,size_t count)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 
memcmp(const void * cs,const void * ct,size_t count)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 
strcmp(const char * cs,const char * ct)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 
memchr(const void * s,int c,size_t count)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 
strchr(const char * s,int c)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 
strrchr(const char * s,int c)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 
memset(void * s,int c,size_t count)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