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", "0"); 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", "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 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", "0"); 98 return ret; 99 } 100 EXPORT_SYMBOL(strcpy); 101 #endif 102 103 /** 104 * strlcpy - Copy a %NUL terminated string into a sized buffer 105 * @dest: Where to copy the string to 106 * @src: Where to copy the string from 107 * @size: size of destination buffer 108 * 109 * Compatible with *BSD: the result is always a valid 110 * NUL-terminated string that fits in the buffer (unless, 111 * of course, the buffer size is zero). It does not pad 112 * out the result like strncpy() does. 113 */ 114 #ifdef __HAVE_ARCH_STRLCPY 115 size_t strlcpy(char *dest, const char *src, size_t size) 116 { 117 size_t ret = __strend(src) - src; 118 119 if (size) { 120 size_t len = (ret >= size) ? size-1 : ret; 121 dest[len] = '\0'; 122 memcpy(dest, src, len); 123 } 124 return ret; 125 } 126 EXPORT_SYMBOL(strlcpy); 127 #endif 128 129 /** 130 * strncpy - Copy a length-limited, %NUL-terminated string 131 * @dest: Where to copy the string to 132 * @src: Where to copy the string from 133 * @n: The maximum number of bytes to copy 134 * 135 * The result is not %NUL-terminated if the source exceeds 136 * @n bytes. 137 */ 138 #ifdef __HAVE_ARCH_STRNCPY 139 char *strncpy(char *dest, const char *src, size_t n) 140 { 141 size_t len = __strnend(src, n) - src; 142 memset(dest + len, 0, n - len); 143 memcpy(dest, src, len); 144 return dest; 145 } 146 EXPORT_SYMBOL(strncpy); 147 #endif 148 149 /** 150 * strcat - Append one %NUL-terminated string to another 151 * @dest: The string to be appended to 152 * @src: The string to append to it 153 * 154 * returns a pointer to @dest 155 */ 156 #ifdef __HAVE_ARCH_STRCAT 157 char *strcat(char *dest, const char *src) 158 { 159 unsigned long dummy = 0; 160 char *ret = dest; 161 162 asm volatile( 163 " lghi 0,0\n" 164 "0: srst %[dummy],%[dest]\n" 165 " jo 0b\n" 166 "1: mvst %[dummy],%[src]\n" 167 " jo 1b\n" 168 : [dummy] "+&a" (dummy), [dest] "+&a" (dest), [src] "+&a" (src) 169 : 170 : "cc", "memory", "0"); 171 return ret; 172 } 173 EXPORT_SYMBOL(strcat); 174 #endif 175 176 /** 177 * strlcat - 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 size of the destination buffer. 181 */ 182 #ifdef __HAVE_ARCH_STRLCAT 183 size_t strlcat(char *dest, const char *src, size_t n) 184 { 185 size_t dsize = __strend(dest) - dest; 186 size_t len = __strend(src) - src; 187 size_t res = dsize + len; 188 189 if (dsize < n) { 190 dest += dsize; 191 n -= dsize; 192 if (len >= n) 193 len = n - 1; 194 dest[len] = '\0'; 195 memcpy(dest, src, len); 196 } 197 return res; 198 } 199 EXPORT_SYMBOL(strlcat); 200 #endif 201 202 /** 203 * strncat - Append a length-limited, %NUL-terminated string to another 204 * @dest: The string to be appended to 205 * @src: The string to append to it 206 * @n: The maximum numbers of bytes to copy 207 * 208 * returns a pointer to @dest 209 * 210 * Note that in contrast to strncpy, strncat ensures the result is 211 * terminated. 212 */ 213 #ifdef __HAVE_ARCH_STRNCAT 214 char *strncat(char *dest, const char *src, size_t n) 215 { 216 size_t len = __strnend(src, n) - src; 217 char *p = __strend(dest); 218 219 p[len] = '\0'; 220 memcpy(p, src, len); 221 return dest; 222 } 223 EXPORT_SYMBOL(strncat); 224 #endif 225 226 /** 227 * strcmp - Compare two strings 228 * @s1: One string 229 * @s2: Another string 230 * 231 * returns 0 if @s1 and @s2 are equal, 232 * < 0 if @s1 is less than @s2 233 * > 0 if @s1 is greater than @s2 234 */ 235 #ifdef __HAVE_ARCH_STRCMP 236 int strcmp(const char *s1, const char *s2) 237 { 238 int ret = 0; 239 240 asm volatile( 241 " lghi 0,0\n" 242 "0: clst %[s1],%[s2]\n" 243 " jo 0b\n" 244 " je 1f\n" 245 " ic %[ret],0(%[s1])\n" 246 " ic 0,0(%[s2])\n" 247 " sr %[ret],0\n" 248 "1:" 249 : [ret] "+&d" (ret), [s1] "+&a" (s1), [s2] "+&a" (s2) 250 : 251 : "cc", "memory", "0"); 252 return ret; 253 } 254 EXPORT_SYMBOL(strcmp); 255 #endif 256 257 /** 258 * strrchr - Find the last occurrence of a character in a string 259 * @s: The string to be searched 260 * @c: The character to search for 261 */ 262 #ifdef __HAVE_ARCH_STRRCHR 263 char *strrchr(const char *s, int c) 264 { 265 ssize_t len = __strend(s) - s; 266 267 do { 268 if (s[len] == (char)c) 269 return (char *)s + len; 270 } while (--len >= 0); 271 return NULL; 272 } 273 EXPORT_SYMBOL(strrchr); 274 #endif 275 276 static inline int clcle(const char *s1, unsigned long l1, 277 const char *s2, unsigned long l2) 278 { 279 union register_pair r1 = { .even = (unsigned long)s1, .odd = l1, }; 280 union register_pair r3 = { .even = (unsigned long)s2, .odd = l2, }; 281 int cc; 282 283 asm volatile( 284 "0: clcle %[r1],%[r3],0\n" 285 " jo 0b\n" 286 " ipm %[cc]\n" 287 " srl %[cc],28\n" 288 : [cc] "=&d" (cc), [r1] "+&d" (r1.pair), [r3] "+&d" (r3.pair) 289 : 290 : "cc", "memory"); 291 return cc; 292 } 293 294 /** 295 * strstr - Find the first substring in a %NUL terminated string 296 * @s1: The string to be searched 297 * @s2: The string to search for 298 */ 299 #ifdef __HAVE_ARCH_STRSTR 300 char *strstr(const char *s1, const char *s2) 301 { 302 int l1, l2; 303 304 l2 = __strend(s2) - s2; 305 if (!l2) 306 return (char *) s1; 307 l1 = __strend(s1) - s1; 308 while (l1-- >= l2) { 309 int cc; 310 311 cc = clcle(s1, l2, s2, l2); 312 if (!cc) 313 return (char *) s1; 314 s1++; 315 } 316 return NULL; 317 } 318 EXPORT_SYMBOL(strstr); 319 #endif 320 321 /** 322 * memchr - Find a character in an area of memory. 323 * @s: The memory area 324 * @c: The byte to search for 325 * @n: The size of the area. 326 * 327 * returns the address of the first occurrence of @c, or %NULL 328 * if @c is not found 329 */ 330 #ifdef __HAVE_ARCH_MEMCHR 331 void *memchr(const void *s, int c, size_t n) 332 { 333 const void *ret = s + n; 334 335 asm volatile( 336 " lgr 0,%[c]\n" 337 "0: srst %[ret],%[s]\n" 338 " jo 0b\n" 339 " jl 1f\n" 340 " la %[ret],0\n" 341 "1:" 342 : [ret] "+&a" (ret), [s] "+&a" (s) 343 : [c] "d" (c) 344 : "cc", "memory", "0"); 345 return (void *) ret; 346 } 347 EXPORT_SYMBOL(memchr); 348 #endif 349 350 /** 351 * memcmp - Compare two areas of memory 352 * @s1: One area of memory 353 * @s2: Another area of memory 354 * @n: The size of the area. 355 */ 356 #ifdef __HAVE_ARCH_MEMCMP 357 int memcmp(const void *s1, const void *s2, size_t n) 358 { 359 int ret; 360 361 ret = clcle(s1, n, s2, n); 362 if (ret) 363 ret = ret == 1 ? -1 : 1; 364 return ret; 365 } 366 EXPORT_SYMBOL(memcmp); 367 #endif 368 369 /** 370 * memscan - Find a character in an area of memory. 371 * @s: The memory area 372 * @c: The byte to search for 373 * @n: The size of the area. 374 * 375 * returns the address of the first occurrence of @c, or 1 byte past 376 * the area if @c is not found 377 */ 378 #ifdef __HAVE_ARCH_MEMSCAN 379 void *memscan(void *s, int c, size_t n) 380 { 381 const void *ret = s + n; 382 383 asm volatile( 384 " lgr 0,%[c]\n" 385 "0: srst %[ret],%[s]\n" 386 " jo 0b\n" 387 : [ret] "+&a" (ret), [s] "+&a" (s) 388 : [c] "d" (c) 389 : "cc", "memory", "0"); 390 return (void *)ret; 391 } 392 EXPORT_SYMBOL(memscan); 393 #endif 394