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 */
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", "");
33 return (char *)e;
34 }
35
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", "");
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
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
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
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", "");
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
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
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", "");
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
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
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
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", "");
226 return ret;
227 }
228 EXPORT_SYMBOL(strcmp);
229 #endif
230
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
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
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", "");
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
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
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", "");
345 return (void *)ret;
346 }
347 EXPORT_SYMBOL(memscan);
348 #endif
349
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