summaryrefslogtreecommitdiff
path: root/arch/arm/boot/compressed/string.c
blob: fcc678fce0459df5129a097ac94c3c88d38d198d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
// SPDX-License-Identifier: GPL-2.0
/*
 * arch/arm/boot/compressed/string.c
 *
 * Small subset of simple string routines
 */

#define __NO_FORTIFY
#include <linux/string.h>

/*
 * The decompressor is built without KASan but uses the same redirects as the
 * rest of the kernel when CONFIG_KASAN is enabled, defining e.g. memcpy()
 * to __memcpy() but since we are not linking with the main kernel string
 * library in the decompressor, that will lead to link failures.
 *
 * Undefine KASan's versions, define the wrapped functions and alias them to
 * the right names so that when e.g. __memcpy() appear in the code, it will
 * still be linked to this local version of memcpy().
 */
#ifdef CONFIG_KASAN
#undef memcpy
#undef memmove
#undef memset
void *__memcpy(void *__dest, __const void *__src, size_t __n) __alias(memcpy);
void *__memmove(void *__dest, __const void *__src, size_t count) __alias(memmove);
void *__memset(void *s, int c, size_t count) __alias(memset);
#endif

void *memcpy(void *__dest, __const void *__src, size_t __n)
{
	int i = 0;
	unsigned char *d = (unsigned char *)__dest, *s = (unsigned char *)__src;

	for (i = __n >> 3; i > 0; i--) {
		*d++ = *s++;
		*d++ = *s++;
		*d++ = *s++;
		*d++ = *s++;
		*d++ = *s++;
		*d++ = *s++;
		*d++ = *s++;
		*d++ = *s++;
	}

	if (__n & 1 << 2) {
		*d++ = *s++;
		*d++ = *s++;
		*d++ = *s++;
		*d++ = *s++;
	}

	if (__n & 1 << 1) {
		*d++ = *s++;
		*d++ = *s++;
	}

	if (__n & 1)
		*d++ = *s++;

	return __dest;
}

void *memmove(void *__dest, __const void *__src, size_t count)
{
	unsigned char *d = __dest;
	const unsigned char *s = __src;

	if (__dest == __src)
		return __dest;

	if (__dest < __src)
		return memcpy(__dest, __src, count);

	while (count--)
		d[count] = s[count];
	return __dest;
}

size_t strlen(const char *s)
{
	const char *sc = s;

	while (*sc != '\0')
		sc++;
	return sc - s;
}

size_t strnlen(const char *s, size_t count)
{
	const char *sc;

	for (sc = s; count-- && *sc != '\0'; ++sc)
		/* nothing */;
	return sc - s;
}

int memcmp(const void *cs, const void *ct, size_t count)
{
	const unsigned char *su1 = cs, *su2 = ct, *end = su1 + count;
	int res = 0;

	while (su1 < end) {
		res = *su1++ - *su2++;
		if (res)
			break;
	}
	return res;
}

int strcmp(const char *cs, const char *ct)
{
	unsigned char c1, c2;
	int res = 0;

	do {
		c1 = *cs++;
		c2 = *ct++;
		res = c1 - c2;
		if (res)
			break;
	} while (c1);
	return res;
}

void *memchr(const void *s, int c, size_t count)
{
	const unsigned char *p = s;

	while (count--)
		if ((unsigned char)c == *p++)
			return (void *)(p - 1);
	return NULL;
}

char *strchr(const char *s, int c)
{
	while (*s != (char)c)
		if (*s++ == '\0')
			return NULL;
	return (char *)s;
}

char *strrchr(const char *s, int c)
{
	const char *last = NULL;
	do {
		if (*s == (char)c)
			last = s;
	} while (*s++);
	return (char *)last;
}

#undef memset

void *memset(void *s, int c, size_t count)
{
	char *xs = s;
	while (count--)
		*xs++ = c;
	return s;
}