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