xref: /openbmc/linux/arch/s390/lib/string.c (revision f492bac3)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  *    Optimized string functions
4  *
5  *  S390 version
6  *    Copyright IBM Corp. 2004
7  *    Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
8  */
9 
10 #define IN_ARCH_STRING_C 1
11 #ifndef __NO_FORTIFY
12 # define __NO_FORTIFY
13 #endif
14 
15 #include <linux/types.h>
16 #include <linux/string.h>
17 #include <linux/export.h>
18 
19 /*
20  * Helper functions to find the end of a string
21  */
__strend(const char * s)22 static inline char *__strend(const char *s)
23 {
24 	unsigned long e = 0;
25 
26 	asm volatile(
27 		"	lghi	0,0\n"
28 		"0:	srst	%[e],%[s]\n"
29 		"	jo	0b\n"
30 		: [e] "+&a" (e), [s] "+&a" (s)
31 		:
32 		: "cc", "memory", "0");
33 	return (char *)e;
34 }
35 
__strnend(const char * s,size_t n)36 static inline char *__strnend(const char *s, size_t n)
37 {
38 	const char *p = s + n;
39 
40 	asm volatile(
41 		"	lghi	0,0\n"
42 		"0:	srst	%[p],%[s]\n"
43 		"	jo	0b\n"
44 		: [p] "+&d" (p), [s] "+&a" (s)
45 		:
46 		: "cc", "memory", "0");
47 	return (char *)p;
48 }
49 
50 /**
51  * strlen - Find the length of a string
52  * @s: The string to be sized
53  *
54  * returns the length of @s
55  */
56 #ifdef __HAVE_ARCH_STRLEN
strlen(const char * s)57 size_t strlen(const char *s)
58 {
59 	return __strend(s) - s;
60 }
61 EXPORT_SYMBOL(strlen);
62 #endif
63 
64 /**
65  * strnlen - Find the length of a length-limited string
66  * @s: The string to be sized
67  * @n: The maximum number of bytes to search
68  *
69  * returns the minimum of the length of @s and @n
70  */
71 #ifdef __HAVE_ARCH_STRNLEN
strnlen(const char * s,size_t n)72 size_t strnlen(const char *s, size_t n)
73 {
74 	return __strnend(s, n) - s;
75 }
76 EXPORT_SYMBOL(strnlen);
77 #endif
78 
79 /**
80  * strcpy - Copy a %NUL terminated string
81  * @dest: Where to copy the string to
82  * @src: Where to copy the string from
83  *
84  * returns a pointer to @dest
85  */
86 #ifdef __HAVE_ARCH_STRCPY
strcpy(char * dest,const char * src)87 char *strcpy(char *dest, const char *src)
88 {
89 	char *ret = dest;
90 
91 	asm volatile(
92 		"	lghi	0,0\n"
93 		"0:	mvst	%[dest],%[src]\n"
94 		"	jo	0b\n"
95 		: [dest] "+&a" (dest), [src] "+&a" (src)
96 		:
97 		: "cc", "memory", "0");
98 	return ret;
99 }
100 EXPORT_SYMBOL(strcpy);
101 #endif
102 
103 /**
104  * strncpy - Copy a length-limited, %NUL-terminated string
105  * @dest: Where to copy the string to
106  * @src: Where to copy the string from
107  * @n: The maximum number of bytes to copy
108  *
109  * The result is not %NUL-terminated if the source exceeds
110  * @n bytes.
111  */
112 #ifdef __HAVE_ARCH_STRNCPY
strncpy(char * dest,const char * src,size_t n)113 char *strncpy(char *dest, const char *src, size_t n)
114 {
115 	size_t len = __strnend(src, n) - src;
116 	memset(dest + len, 0, n - len);
117 	memcpy(dest, src, len);
118 	return dest;
119 }
120 EXPORT_SYMBOL(strncpy);
121 #endif
122 
123 /**
124  * strcat - Append one %NUL-terminated string to another
125  * @dest: The string to be appended to
126  * @src: The string to append to it
127  *
128  * returns a pointer to @dest
129  */
130 #ifdef __HAVE_ARCH_STRCAT
strcat(char * dest,const char * src)131 char *strcat(char *dest, const char *src)
132 {
133 	unsigned long dummy = 0;
134 	char *ret = dest;
135 
136 	asm volatile(
137 		"	lghi	0,0\n"
138 		"0:	srst	%[dummy],%[dest]\n"
139 		"	jo	0b\n"
140 		"1:	mvst	%[dummy],%[src]\n"
141 		"	jo	1b\n"
142 		: [dummy] "+&a" (dummy), [dest] "+&a" (dest), [src] "+&a" (src)
143 		:
144 		: "cc", "memory", "0");
145 	return ret;
146 }
147 EXPORT_SYMBOL(strcat);
148 #endif
149 
150 /**
151  * strlcat - Append a length-limited, %NUL-terminated string to another
152  * @dest: The string to be appended to
153  * @src: The string to append to it
154  * @n: The size of the destination buffer.
155  */
156 #ifdef __HAVE_ARCH_STRLCAT
strlcat(char * dest,const char * src,size_t n)157 size_t strlcat(char *dest, const char *src, size_t n)
158 {
159 	size_t dsize = __strend(dest) - dest;
160 	size_t len = __strend(src) - src;
161 	size_t res = dsize + len;
162 
163 	if (dsize < n) {
164 		dest += dsize;
165 		n -= dsize;
166 		if (len >= n)
167 			len = n - 1;
168 		dest[len] = '\0';
169 		memcpy(dest, src, len);
170 	}
171 	return res;
172 }
173 EXPORT_SYMBOL(strlcat);
174 #endif
175 
176 /**
177  * strncat - Append a length-limited, %NUL-terminated string to another
178  * @dest: The string to be appended to
179  * @src: The string to append to it
180  * @n: The maximum numbers of bytes to copy
181  *
182  * returns a pointer to @dest
183  *
184  * Note that in contrast to strncpy, strncat ensures the result is
185  * terminated.
186  */
187 #ifdef __HAVE_ARCH_STRNCAT
strncat(char * dest,const char * src,size_t n)188 char *strncat(char *dest, const char *src, size_t n)
189 {
190 	size_t len = __strnend(src, n) - src;
191 	char *p = __strend(dest);
192 
193 	p[len] = '\0';
194 	memcpy(p, src, len);
195 	return dest;
196 }
197 EXPORT_SYMBOL(strncat);
198 #endif
199 
200 /**
201  * strcmp - Compare two strings
202  * @s1: One string
203  * @s2: Another string
204  *
205  * returns   0 if @s1 and @s2 are equal,
206  *	   < 0 if @s1 is less than @s2
207  *	   > 0 if @s1 is greater than @s2
208  */
209 #ifdef __HAVE_ARCH_STRCMP
strcmp(const char * s1,const char * s2)210 int strcmp(const char *s1, const char *s2)
211 {
212 	int ret = 0;
213 
214 	asm volatile(
215 		"	lghi	0,0\n"
216 		"0:	clst	%[s1],%[s2]\n"
217 		"	jo	0b\n"
218 		"	je	1f\n"
219 		"	ic	%[ret],0(%[s1])\n"
220 		"	ic	0,0(%[s2])\n"
221 		"	sr	%[ret],0\n"
222 		"1:"
223 		: [ret] "+&d" (ret), [s1] "+&a" (s1), [s2] "+&a" (s2)
224 		:
225 		: "cc", "memory", "0");
226 	return ret;
227 }
228 EXPORT_SYMBOL(strcmp);
229 #endif
230 
clcle(const char * s1,unsigned long l1,const char * s2,unsigned long l2)231 static inline int clcle(const char *s1, unsigned long l1,
232 			const char *s2, unsigned long l2)
233 {
234 	union register_pair r1 = { .even = (unsigned long)s1, .odd = l1, };
235 	union register_pair r3 = { .even = (unsigned long)s2, .odd = l2, };
236 	int cc;
237 
238 	asm volatile(
239 		"0:	clcle	%[r1],%[r3],0\n"
240 		"	jo	0b\n"
241 		"	ipm	%[cc]\n"
242 		"	srl	%[cc],28\n"
243 		: [cc] "=&d" (cc), [r1] "+&d" (r1.pair), [r3] "+&d" (r3.pair)
244 		:
245 		: "cc", "memory");
246 	return cc;
247 }
248 
249 /**
250  * strstr - Find the first substring in a %NUL terminated string
251  * @s1: The string to be searched
252  * @s2: The string to search for
253  */
254 #ifdef __HAVE_ARCH_STRSTR
strstr(const char * s1,const char * s2)255 char *strstr(const char *s1, const char *s2)
256 {
257 	int l1, l2;
258 
259 	l2 = __strend(s2) - s2;
260 	if (!l2)
261 		return (char *) s1;
262 	l1 = __strend(s1) - s1;
263 	while (l1-- >= l2) {
264 		int cc;
265 
266 		cc = clcle(s1, l2, s2, l2);
267 		if (!cc)
268 			return (char *) s1;
269 		s1++;
270 	}
271 	return NULL;
272 }
273 EXPORT_SYMBOL(strstr);
274 #endif
275 
276 /**
277  * memchr - Find a character in an area of memory.
278  * @s: The memory area
279  * @c: The byte to search for
280  * @n: The size of the area.
281  *
282  * returns the address of the first occurrence of @c, or %NULL
283  * if @c is not found
284  */
285 #ifdef __HAVE_ARCH_MEMCHR
memchr(const void * s,int c,size_t n)286 void *memchr(const void *s, int c, size_t n)
287 {
288 	const void *ret = s + n;
289 
290 	asm volatile(
291 		"	lgr	0,%[c]\n"
292 		"0:	srst	%[ret],%[s]\n"
293 		"	jo	0b\n"
294 		"	jl	1f\n"
295 		"	la	%[ret],0\n"
296 		"1:"
297 		: [ret] "+&a" (ret), [s] "+&a" (s)
298 		: [c] "d" (c)
299 		: "cc", "memory", "0");
300 	return (void *) ret;
301 }
302 EXPORT_SYMBOL(memchr);
303 #endif
304 
305 /**
306  * memcmp - Compare two areas of memory
307  * @s1: One area of memory
308  * @s2: Another area of memory
309  * @n: The size of the area.
310  */
311 #ifdef __HAVE_ARCH_MEMCMP
memcmp(const void * s1,const void * s2,size_t n)312 int memcmp(const void *s1, const void *s2, size_t n)
313 {
314 	int ret;
315 
316 	ret = clcle(s1, n, s2, n);
317 	if (ret)
318 		ret = ret == 1 ? -1 : 1;
319 	return ret;
320 }
321 EXPORT_SYMBOL(memcmp);
322 #endif
323 
324 /**
325  * memscan - Find a character in an area of memory.
326  * @s: The memory area
327  * @c: The byte to search for
328  * @n: The size of the area.
329  *
330  * returns the address of the first occurrence of @c, or 1 byte past
331  * the area if @c is not found
332  */
333 #ifdef __HAVE_ARCH_MEMSCAN
memscan(void * s,int c,size_t n)334 void *memscan(void *s, int c, size_t n)
335 {
336 	const void *ret = s + n;
337 
338 	asm volatile(
339 		"	lgr	0,%[c]\n"
340 		"0:	srst	%[ret],%[s]\n"
341 		"	jo	0b\n"
342 		: [ret] "+&a" (ret), [s] "+&a" (s)
343 		: [c] "d" (c)
344 		: "cc", "memory", "0");
345 	return (void *)ret;
346 }
347 EXPORT_SYMBOL(memscan);
348 #endif
349