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 * 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", "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 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", "0"); 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", "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 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", "0"); 345 return (void *)ret; 346 } 347 EXPORT_SYMBOL(memscan); 348 #endif 349