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 ([email protected])
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 #include <asm/asm.h>
19
20 /*
21 * Helper functions to find the end of a string
22 */
__strend(const char * s)23 static inline char *__strend(const char *s)
24 {
25 unsigned long e = 0;
26
27 asm volatile(
28 " lghi 0,0\n"
29 "0: srst %[e],%[s]\n"
30 " jo 0b\n"
31 : [e] "+&a" (e), [s] "+&a" (s)
32 :
33 : "cc", "memory", "0");
34 return (char *)e;
35 }
36
__strnend(const char * s,size_t n)37 static inline char *__strnend(const char *s, size_t n)
38 {
39 const char *p = s + n;
40
41 asm volatile(
42 " lghi 0,0\n"
43 "0: srst %[p],%[s]\n"
44 " jo 0b\n"
45 : [p] "+&d" (p), [s] "+&a" (s)
46 :
47 : "cc", "memory", "0");
48 return (char *)p;
49 }
50
51 /**
52 * strlen - Find the length of a string
53 * @s: The string to be sized
54 *
55 * returns the length of @s
56 */
57 #ifdef __HAVE_ARCH_STRLEN
strlen(const char * s)58 size_t strlen(const char *s)
59 {
60 return __strend(s) - s;
61 }
62 EXPORT_SYMBOL(strlen);
63 #endif
64
65 /**
66 * strnlen - Find the length of a length-limited string
67 * @s: The string to be sized
68 * @n: The maximum number of bytes to search
69 *
70 * returns the minimum of the length of @s and @n
71 */
72 #ifdef __HAVE_ARCH_STRNLEN
strnlen(const char * s,size_t n)73 size_t strnlen(const char *s, size_t n)
74 {
75 return __strnend(s, n) - s;
76 }
77 EXPORT_SYMBOL(strnlen);
78 #endif
79
80 /**
81 * strcpy - Copy a %NUL terminated string
82 * @dest: Where to copy the string to
83 * @src: Where to copy the string from
84 *
85 * returns a pointer to @dest
86 */
87 #ifdef __HAVE_ARCH_STRCPY
strcpy(char * dest,const char * src)88 char *strcpy(char *dest, const char *src)
89 {
90 char *ret = dest;
91
92 asm volatile(
93 " lghi 0,0\n"
94 "0: mvst %[dest],%[src]\n"
95 " jo 0b\n"
96 : [dest] "+&a" (dest), [src] "+&a" (src)
97 :
98 : "cc", "memory", "0");
99 return ret;
100 }
101 EXPORT_SYMBOL(strcpy);
102 #endif
103
104 /**
105 * strncpy - Copy a length-limited, %NUL-terminated string
106 * @dest: Where to copy the string to
107 * @src: Where to copy the string from
108 * @n: The maximum number of bytes to copy
109 *
110 * The result is not %NUL-terminated if the source exceeds
111 * @n bytes.
112 */
113 #ifdef __HAVE_ARCH_STRNCPY
strncpy(char * dest,const char * src,size_t n)114 char *strncpy(char *dest, const char *src, size_t n)
115 {
116 size_t len = __strnend(src, n) - src;
117 memset(dest + len, 0, n - len);
118 memcpy(dest, src, len);
119 return dest;
120 }
121 EXPORT_SYMBOL(strncpy);
122 #endif
123
124 /**
125 * strcat - Append one %NUL-terminated string to another
126 * @dest: The string to be appended to
127 * @src: The string to append to it
128 *
129 * returns a pointer to @dest
130 */
131 #ifdef __HAVE_ARCH_STRCAT
strcat(char * dest,const char * src)132 char *strcat(char *dest, const char *src)
133 {
134 unsigned long dummy = 0;
135 char *ret = dest;
136
137 asm volatile(
138 " lghi 0,0\n"
139 "0: srst %[dummy],%[dest]\n"
140 " jo 0b\n"
141 "1: mvst %[dummy],%[src]\n"
142 " jo 1b\n"
143 : [dummy] "+&a" (dummy), [dest] "+&a" (dest), [src] "+&a" (src)
144 :
145 : "cc", "memory", "0");
146 return ret;
147 }
148 EXPORT_SYMBOL(strcat);
149 #endif
150
151 /**
152 * strlcat - Append a length-limited, %NUL-terminated string to another
153 * @dest: The string to be appended to
154 * @src: The string to append to it
155 * @n: The size of the destination buffer.
156 */
157 #ifdef __HAVE_ARCH_STRLCAT
strlcat(char * dest,const char * src,size_t n)158 size_t strlcat(char *dest, const char *src, size_t n)
159 {
160 size_t dsize = __strend(dest) - dest;
161 size_t len = __strend(src) - src;
162 size_t res = dsize + len;
163
164 if (dsize < n) {
165 dest += dsize;
166 n -= dsize;
167 if (len >= n)
168 len = n - 1;
169 dest[len] = '\0';
170 memcpy(dest, src, len);
171 }
172 return res;
173 }
174 EXPORT_SYMBOL(strlcat);
175 #endif
176
177 /**
178 * strncat - Append a length-limited, %NUL-terminated string to another
179 * @dest: The string to be appended to
180 * @src: The string to append to it
181 * @n: The maximum numbers of bytes to copy
182 *
183 * returns a pointer to @dest
184 *
185 * Note that in contrast to strncpy, strncat ensures the result is
186 * terminated.
187 */
188 #ifdef __HAVE_ARCH_STRNCAT
strncat(char * dest,const char * src,size_t n)189 char *strncat(char *dest, const char *src, size_t n)
190 {
191 size_t len = __strnend(src, n) - src;
192 char *p = __strend(dest);
193
194 p[len] = '\0';
195 memcpy(p, src, len);
196 return dest;
197 }
198 EXPORT_SYMBOL(strncat);
199 #endif
200
201 /**
202 * strcmp - Compare two strings
203 * @s1: One string
204 * @s2: Another string
205 *
206 * returns 0 if @s1 and @s2 are equal,
207 * < 0 if @s1 is less than @s2
208 * > 0 if @s1 is greater than @s2
209 */
210 #ifdef __HAVE_ARCH_STRCMP
strcmp(const char * s1,const char * s2)211 int strcmp(const char *s1, const char *s2)
212 {
213 int ret = 0;
214
215 asm volatile(
216 " lghi 0,0\n"
217 "0: clst %[s1],%[s2]\n"
218 " jo 0b\n"
219 " je 1f\n"
220 " ic %[ret],0(%[s1])\n"
221 " ic 0,0(%[s2])\n"
222 " sr %[ret],0\n"
223 "1:"
224 : [ret] "+&d" (ret), [s1] "+&a" (s1), [s2] "+&a" (s2)
225 :
226 : "cc", "memory", "0");
227 return ret;
228 }
229 EXPORT_SYMBOL(strcmp);
230 #endif
231
clcle(const char * s1,unsigned long l1,const char * s2,unsigned long l2)232 static inline int clcle(const char *s1, unsigned long l1,
233 const char *s2, unsigned long l2)
234 {
235 union register_pair r1 = { .even = (unsigned long)s1, .odd = l1, };
236 union register_pair r3 = { .even = (unsigned long)s2, .odd = l2, };
237 int cc;
238
239 asm volatile(
240 "0: clcle %[r1],%[r3],0\n"
241 " jo 0b\n"
242 CC_IPM(cc)
243 : CC_OUT(cc, cc), [r1] "+d" (r1.pair), [r3] "+d" (r3.pair)
244 :
245 : CC_CLOBBER_LIST("memory"));
246 return CC_TRANSFORM(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