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
12 #include <linux/types.h>
13 #include <linux/string.h>
14 #include <linux/export.h>
15
16 /*
17 * Helper functions to find the end of a string
18 */
__strend(const char * s)19 static inline char *__strend(const char *s)
20 {
21 unsigned long e = 0;
22
23 asm volatile(
24 " lghi 0,0\n"
25 "0: srst %[e],%[s]\n"
26 " jo 0b\n"
27 : [e] "+&a" (e), [s] "+&a" (s)
28 :
29 : "cc", "memory", "0");
30 return (char *)e;
31 }
32
__strnend(const char * s,size_t n)33 static inline char *__strnend(const char *s, size_t n)
34 {
35 const char *p = s + n;
36
37 asm volatile(
38 " lghi 0,0\n"
39 "0: srst %[p],%[s]\n"
40 " jo 0b\n"
41 : [p] "+&d" (p), [s] "+&a" (s)
42 :
43 : "cc", "memory", "0");
44 return (char *)p;
45 }
46
47 /**
48 * strlen - Find the length of a string
49 * @s: The string to be sized
50 *
51 * returns the length of @s
52 */
53 #ifdef __HAVE_ARCH_STRLEN
strlen(const char * s)54 size_t strlen(const char *s)
55 {
56 return __strend(s) - s;
57 }
58 EXPORT_SYMBOL(strlen);
59 #endif
60
61 /**
62 * strnlen - Find the length of a length-limited string
63 * @s: The string to be sized
64 * @n: The maximum number of bytes to search
65 *
66 * returns the minimum of the length of @s and @n
67 */
68 #ifdef __HAVE_ARCH_STRNLEN
strnlen(const char * s,size_t n)69 size_t strnlen(const char *s, size_t n)
70 {
71 return __strnend(s, n) - s;
72 }
73 EXPORT_SYMBOL(strnlen);
74 #endif
75
76 /**
77 * strcpy - Copy a %NUL terminated string
78 * @dest: Where to copy the string to
79 * @src: Where to copy the string from
80 *
81 * returns a pointer to @dest
82 */
83 #ifdef __HAVE_ARCH_STRCPY
strcpy(char * dest,const char * src)84 char *strcpy(char *dest, const char *src)
85 {
86 char *ret = dest;
87
88 asm volatile(
89 " lghi 0,0\n"
90 "0: mvst %[dest],%[src]\n"
91 " jo 0b\n"
92 : [dest] "+&a" (dest), [src] "+&a" (src)
93 :
94 : "cc", "memory", "0");
95 return ret;
96 }
97 EXPORT_SYMBOL(strcpy);
98 #endif
99
100 /**
101 * strlcpy - Copy a %NUL terminated string into a sized buffer
102 * @dest: Where to copy the string to
103 * @src: Where to copy the string from
104 * @size: size of destination buffer
105 *
106 * Compatible with *BSD: the result is always a valid
107 * NUL-terminated string that fits in the buffer (unless,
108 * of course, the buffer size is zero). It does not pad
109 * out the result like strncpy() does.
110 */
111 #ifdef __HAVE_ARCH_STRLCPY
strlcpy(char * dest,const char * src,size_t size)112 size_t strlcpy(char *dest, const char *src, size_t size)
113 {
114 size_t ret = __strend(src) - src;
115
116 if (size) {
117 size_t len = (ret >= size) ? size-1 : ret;
118 dest[len] = '\0';
119 memcpy(dest, src, len);
120 }
121 return ret;
122 }
123 EXPORT_SYMBOL(strlcpy);
124 #endif
125
126 /**
127 * strncpy - Copy a length-limited, %NUL-terminated string
128 * @dest: Where to copy the string to
129 * @src: Where to copy the string from
130 * @n: The maximum number of bytes to copy
131 *
132 * The result is not %NUL-terminated if the source exceeds
133 * @n bytes.
134 */
135 #ifdef __HAVE_ARCH_STRNCPY
strncpy(char * dest,const char * src,size_t n)136 char *strncpy(char *dest, const char *src, size_t n)
137 {
138 size_t len = __strnend(src, n) - src;
139 memset(dest + len, 0, n - len);
140 memcpy(dest, src, len);
141 return dest;
142 }
143 EXPORT_SYMBOL(strncpy);
144 #endif
145
146 /**
147 * strcat - Append one %NUL-terminated string to another
148 * @dest: The string to be appended to
149 * @src: The string to append to it
150 *
151 * returns a pointer to @dest
152 */
153 #ifdef __HAVE_ARCH_STRCAT
strcat(char * dest,const char * src)154 char *strcat(char *dest, const char *src)
155 {
156 unsigned long dummy = 0;
157 char *ret = dest;
158
159 asm volatile(
160 " lghi 0,0\n"
161 "0: srst %[dummy],%[dest]\n"
162 " jo 0b\n"
163 "1: mvst %[dummy],%[src]\n"
164 " jo 1b\n"
165 : [dummy] "+&a" (dummy), [dest] "+&a" (dest), [src] "+&a" (src)
166 :
167 : "cc", "memory", "0");
168 return ret;
169 }
170 EXPORT_SYMBOL(strcat);
171 #endif
172
173 /**
174 * strlcat - Append a length-limited, %NUL-terminated string to another
175 * @dest: The string to be appended to
176 * @src: The string to append to it
177 * @n: The size of the destination buffer.
178 */
179 #ifdef __HAVE_ARCH_STRLCAT
strlcat(char * dest,const char * src,size_t n)180 size_t strlcat(char *dest, const char *src, size_t n)
181 {
182 size_t dsize = __strend(dest) - dest;
183 size_t len = __strend(src) - src;
184 size_t res = dsize + len;
185
186 if (dsize < n) {
187 dest += dsize;
188 n -= dsize;
189 if (len >= n)
190 len = n - 1;
191 dest[len] = '\0';
192 memcpy(dest, src, len);
193 }
194 return res;
195 }
196 EXPORT_SYMBOL(strlcat);
197 #endif
198
199 /**
200 * strncat - Append a length-limited, %NUL-terminated string to another
201 * @dest: The string to be appended to
202 * @src: The string to append to it
203 * @n: The maximum numbers of bytes to copy
204 *
205 * returns a pointer to @dest
206 *
207 * Note that in contrast to strncpy, strncat ensures the result is
208 * terminated.
209 */
210 #ifdef __HAVE_ARCH_STRNCAT
strncat(char * dest,const char * src,size_t n)211 char *strncat(char *dest, const char *src, size_t n)
212 {
213 size_t len = __strnend(src, n) - src;
214 char *p = __strend(dest);
215
216 p[len] = '\0';
217 memcpy(p, src, len);
218 return dest;
219 }
220 EXPORT_SYMBOL(strncat);
221 #endif
222
223 /**
224 * strcmp - Compare two strings
225 * @s1: One string
226 * @s2: Another string
227 *
228 * returns 0 if @s1 and @s2 are equal,
229 * < 0 if @s1 is less than @s2
230 * > 0 if @s1 is greater than @s2
231 */
232 #ifdef __HAVE_ARCH_STRCMP
strcmp(const char * s1,const char * s2)233 int strcmp(const char *s1, const char *s2)
234 {
235 int ret = 0;
236
237 asm volatile(
238 " lghi 0,0\n"
239 "0: clst %[s1],%[s2]\n"
240 " jo 0b\n"
241 " je 1f\n"
242 " ic %[ret],0(%[s1])\n"
243 " ic 0,0(%[s2])\n"
244 " sr %[ret],0\n"
245 "1:"
246 : [ret] "+&d" (ret), [s1] "+&a" (s1), [s2] "+&a" (s2)
247 :
248 : "cc", "memory", "0");
249 return ret;
250 }
251 EXPORT_SYMBOL(strcmp);
252 #endif
253
254 /**
255 * strrchr - Find the last occurrence of a character in a string
256 * @s: The string to be searched
257 * @c: The character to search for
258 */
259 #ifdef __HAVE_ARCH_STRRCHR
strrchr(const char * s,int c)260 char *strrchr(const char *s, int c)
261 {
262 ssize_t len = __strend(s) - s;
263
264 do {
265 if (s[len] == (char)c)
266 return (char *)s + len;
267 } while (--len >= 0);
268 return NULL;
269 }
270 EXPORT_SYMBOL(strrchr);
271 #endif
272
clcle(const char * s1,unsigned long l1,const char * s2,unsigned long l2)273 static inline int clcle(const char *s1, unsigned long l1,
274 const char *s2, unsigned long l2)
275 {
276 union register_pair r1 = { .even = (unsigned long)s1, .odd = l1, };
277 union register_pair r3 = { .even = (unsigned long)s2, .odd = l2, };
278 int cc;
279
280 asm volatile(
281 "0: clcle %[r1],%[r3],0\n"
282 " jo 0b\n"
283 " ipm %[cc]\n"
284 " srl %[cc],28\n"
285 : [cc] "=&d" (cc), [r1] "+&d" (r1.pair), [r3] "+&d" (r3.pair)
286 :
287 : "cc", "memory");
288 return cc;
289 }
290
291 /**
292 * strstr - Find the first substring in a %NUL terminated string
293 * @s1: The string to be searched
294 * @s2: The string to search for
295 */
296 #ifdef __HAVE_ARCH_STRSTR
strstr(const char * s1,const char * s2)297 char *strstr(const char *s1, const char *s2)
298 {
299 int l1, l2;
300
301 l2 = __strend(s2) - s2;
302 if (!l2)
303 return (char *) s1;
304 l1 = __strend(s1) - s1;
305 while (l1-- >= l2) {
306 int cc;
307
308 cc = clcle(s1, l2, s2, l2);
309 if (!cc)
310 return (char *) s1;
311 s1++;
312 }
313 return NULL;
314 }
315 EXPORT_SYMBOL(strstr);
316 #endif
317
318 /**
319 * memchr - Find a character in an area of memory.
320 * @s: The memory area
321 * @c: The byte to search for
322 * @n: The size of the area.
323 *
324 * returns the address of the first occurrence of @c, or %NULL
325 * if @c is not found
326 */
327 #ifdef __HAVE_ARCH_MEMCHR
memchr(const void * s,int c,size_t n)328 void *memchr(const void *s, int c, size_t n)
329 {
330 const void *ret = s + n;
331
332 asm volatile(
333 " lgr 0,%[c]\n"
334 "0: srst %[ret],%[s]\n"
335 " jo 0b\n"
336 " jl 1f\n"
337 " la %[ret],0\n"
338 "1:"
339 : [ret] "+&a" (ret), [s] "+&a" (s)
340 : [c] "d" (c)
341 : "cc", "memory", "0");
342 return (void *) ret;
343 }
344 EXPORT_SYMBOL(memchr);
345 #endif
346
347 /**
348 * memcmp - Compare two areas of memory
349 * @s1: One area of memory
350 * @s2: Another area of memory
351 * @n: The size of the area.
352 */
353 #ifdef __HAVE_ARCH_MEMCMP
memcmp(const void * s1,const void * s2,size_t n)354 int memcmp(const void *s1, const void *s2, size_t n)
355 {
356 int ret;
357
358 ret = clcle(s1, n, s2, n);
359 if (ret)
360 ret = ret == 1 ? -1 : 1;
361 return ret;
362 }
363 EXPORT_SYMBOL(memcmp);
364 #endif
365
366 /**
367 * memscan - Find a character in an area of memory.
368 * @s: The memory area
369 * @c: The byte to search for
370 * @n: The size of the area.
371 *
372 * returns the address of the first occurrence of @c, or 1 byte past
373 * the area if @c is not found
374 */
375 #ifdef __HAVE_ARCH_MEMSCAN
memscan(void * s,int c,size_t n)376 void *memscan(void *s, int c, size_t n)
377 {
378 const void *ret = s + n;
379
380 asm volatile(
381 " lgr 0,%[c]\n"
382 "0: srst %[ret],%[s]\n"
383 " jo 0b\n"
384 : [ret] "+&a" (ret), [s] "+&a" (s)
385 : [c] "d" (c)
386 : "cc", "memory", "0");
387 return (void *)ret;
388 }
389 EXPORT_SYMBOL(memscan);
390 #endif
391