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 #include <asm/asm.h> 19 20 /* 21 * Helper functions to find the end of a string 22 */ 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 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 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 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 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 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 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 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 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 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 231 232 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 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