arch/s390/lib/string.c

   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
  12 #include <linux/types.h>
  13 #include <linux/string.h>
  14 #include <linux/export.h>
  15
  16 /*
  17  * Helper functions to find the end of a string
  18  */
  19 static inline char *__strend(const char *s)
  20 {
  21         register unsigned long r0 asm("0") = 0;
  22
  23         asm volatile ("0: srst  %0,%1\n"
  24                       "   jo    0b"
  25                       : "+d" (r0), "+a" (s) :  : "cc", "memory");
  26         return (char *) r0;
  27 }
  28
  29 static inline char *__strnend(const char *s, size_t n)
  30 {
  31         register unsigned long r0 asm("0") = 0;
  32         const char *p = s + n;
  33
  34         asm volatile ("0: srst  %0,%1\n"
  35                       "   jo    0b"
  36                       : "+d" (p), "+a" (s) : "d" (r0) : "cc", "memory");
  37         return (char *) p;
  38 }
  39
  40 /**
  41  * strlen - Find the length of a string
  42  * @s: The string to be sized
  43  *
  44  * returns the length of @s
  45  */
  46 #ifdef __HAVE_ARCH_STRLEN
  47 size_t strlen(const char *s)
  48 {
  49         return __strend(s) - s;
  50 }
  51 EXPORT_SYMBOL(strlen);
  52 #endif
  53
  54 /**
  55  * strnlen - Find the length of a length-limited string
  56  * @s: The string to be sized
  57  * @n: The maximum number of bytes to search
  58  *
  59  * returns the minimum of the length of @s and @n
  60  */
  61 #ifdef __HAVE_ARCH_STRNLEN
  62 size_t strnlen(const char *s, size_t n)
  63 {
  64         return __strnend(s, n) - s;
  65 }
  66 EXPORT_SYMBOL(strnlen);
  67 #endif
  68
  69 /**
  70  * strcpy - Copy a %NUL terminated string
  71  * @dest: Where to copy the string to
  72  * @src: Where to copy the string from
  73  *
  74  * returns a pointer to @dest
  75  */
  76 #ifdef __HAVE_ARCH_STRCPY
  77 char *strcpy(char *dest, const char *src)
  78 {
  79         register int r0 asm("0") = 0;
  80         char *ret = dest;
  81
  82         asm volatile ("0: mvst  %0,%1\n"
  83                       "   jo    0b"
  84                       : "+&a" (dest), "+&a" (src) : "d" (r0)
  85                       : "cc", "memory" );
  86         return ret;
  87 }
  88 EXPORT_SYMBOL(strcpy);
  89 #endif
  90
  91 /**
  92  * strlcpy - Copy a %NUL terminated string into a sized buffer
  93  * @dest: Where to copy the string to
  94  * @src: Where to copy the string from
  95  * @size: size of destination buffer
  96  *
  97  * Compatible with *BSD: the result is always a valid
  98  * NUL-terminated string that fits in the buffer (unless,
  99  * of course, the buffer size is zero). It does not pad
 100  * out the result like strncpy() does.
 101  */
 102 #ifdef __HAVE_ARCH_STRLCPY
 103 size_t strlcpy(char *dest, const char *src, size_t size)
 104 {
 105         size_t ret = __strend(src) - src;
 106
 107         if (size) {
 108                 size_t len = (ret >= size) ? size-1 : ret;
 109                 dest[len] = '\0';
 110                 memcpy(dest, src, len);
 111         }
 112         return ret;
 113 }
 114 EXPORT_SYMBOL(strlcpy);
 115 #endif
 116
 117 /**
 118  * strncpy - Copy a length-limited, %NUL-terminated string
 119  * @dest: Where to copy the string to
 120  * @src: Where to copy the string from
 121  * @n: The maximum number of bytes to copy
 122  *
 123  * The result is not %NUL-terminated if the source exceeds
 124  * @n bytes.
 125  */
 126 #ifdef __HAVE_ARCH_STRNCPY
 127 char *strncpy(char *dest, const char *src, size_t n)
 128 {
 129         size_t len = __strnend(src, n) - src;
 130         memset(dest + len, 0, n - len);
 131         memcpy(dest, src, len);
 132         return dest;
 133 }
 134 EXPORT_SYMBOL(strncpy);
 135 #endif
 136
 137 /**
 138  * strcat - Append one %NUL-terminated string to another
 139  * @dest: The string to be appended to
 140  * @src: The string to append to it
 141  *
 142  * returns a pointer to @dest
 143  */
 144 #ifdef __HAVE_ARCH_STRCAT
 145 char *strcat(char *dest, const char *src)
 146 {
 147         register int r0 asm("0") = 0;
 148         unsigned long dummy;
 149         char *ret = dest;
 150
 151         asm volatile ("0: srst  %0,%1\n"
 152                       "   jo    0b\n"
 153                       "1: mvst  %0,%2\n"
 154                       "   jo    1b"
 155                       : "=&a" (dummy), "+a" (dest), "+a" (src)
 156                       : "d" (r0), "0" (0UL) : "cc", "memory" );
 157         return ret;
 158 }
 159 EXPORT_SYMBOL(strcat);
 160 #endif
 161
 162 /**
 163  * strlcat - Append a length-limited, %NUL-terminated string to another
 164  * @dest: The string to be appended to
 165  * @src: The string to append to it
 166  * @n: The size of the destination buffer.
 167  */
 168 #ifdef __HAVE_ARCH_STRLCAT
 169 size_t strlcat(char *dest, const char *src, size_t n)
 170 {
 171         size_t dsize = __strend(dest) - dest;
 172         size_t len = __strend(src) - src;
 173         size_t res = dsize + len;
 174
 175         if (dsize < n) {
 176                 dest += dsize;
 177                 n -= dsize;
 178                 if (len >= n)
 179                         len = n - 1;
 180                 dest[len] = '\0';
 181                 memcpy(dest, src, len);
 182         }
 183         return res;
 184 }
 185 EXPORT_SYMBOL(strlcat);
 186 #endif
 187
 188 /**
 189  * strncat - Append a length-limited, %NUL-terminated string to another
 190  * @dest: The string to be appended to
 191  * @src: The string to append to it
 192  * @n: The maximum numbers of bytes to copy
 193  *
 194  * returns a pointer to @dest
 195  *
 196  * Note that in contrast to strncpy, strncat ensures the result is
 197  * terminated.
 198  */
 199 #ifdef __HAVE_ARCH_STRNCAT
 200 char *strncat(char *dest, const char *src, size_t n)
 201 {
 202         size_t len = __strnend(src, n) - src;
 203         char *p = __strend(dest);
 204
 205         p[len] = '\0';
 206         memcpy(p, src, len);
 207         return dest;
 208 }
 209 EXPORT_SYMBOL(strncat);
 210 #endif
 211
 212 /**
 213  * strcmp - Compare two strings
 214  * @s1: One string
 215  * @s2: Another string
 216  *
 217  * returns   0 if @s1 and @s2 are equal,
 218  *         < 0 if @s1 is less than @s2
 219  *         > 0 if @s1 is greater than @s2
 220  */
 221 #ifdef __HAVE_ARCH_STRCMP
 222 int strcmp(const char *s1, const char *s2)
 223 {
 224         register int r0 asm("0") = 0;
 225         int ret = 0;
 226
 227         asm volatile ("0: clst %2,%3\n"
 228                       "   jo   0b\n"
 229                       "   je   1f\n"
 230                       "   ic   %0,0(%2)\n"
 231                       "   ic   %1,0(%3)\n"
 232                       "   sr   %0,%1\n"
 233                       "1:"
 234                       : "+d" (ret), "+d" (r0), "+a" (s1), "+a" (s2)
 235                       : : "cc", "memory");
 236         return ret;
 237 }
 238 EXPORT_SYMBOL(strcmp);
 239 #endif
 240
 241 /**
 242  * strrchr - Find the last occurrence of a character in a string
 243  * @s: The string to be searched
 244  * @c: The character to search for
 245  */
 246 #ifdef __HAVE_ARCH_STRRCHR
 247 char *strrchr(const char *s, int c)
 248 {
 249        size_t len = __strend(s) - s;
 250
 251        if (len)
 252                do {
 253                        if (s[len] == (char) c)
 254                                return (char *) s + len;
 255                } while (--len > 0);
 256        return NULL;
 257 }
 258 EXPORT_SYMBOL(strrchr);
 259 #endif
 260
 261 static inline int clcle(const char *s1, unsigned long l1,
 262                         const char *s2, unsigned long l2)
 263 {
 264         register unsigned long r2 asm("2") = (unsigned long) s1;
 265         register unsigned long r3 asm("3") = (unsigned long) l1;
 266         register unsigned long r4 asm("4") = (unsigned long) s2;
 267         register unsigned long r5 asm("5") = (unsigned long) l2;
 268         int cc;
 269
 270         asm volatile ("0: clcle %1,%3,0\n"
 271                       "   jo    0b\n"
 272                       "   ipm   %0\n"
 273                       "   srl   %0,28"
 274                       : "=&d" (cc), "+a" (r2), "+a" (r3),
 275                         "+a" (r4), "+a" (r5) : : "cc", "memory");
 276         return cc;
 277 }
 278
 279 /**
 280  * strstr - Find the first substring in a %NUL terminated string
 281  * @s1: The string to be searched
 282  * @s2: The string to search for
 283  */
 284 #ifdef __HAVE_ARCH_STRSTR
 285 char *strstr(const char *s1, const char *s2)
 286 {
 287         int l1, l2;
 288
 289         l2 = __strend(s2) - s2;
 290         if (!l2)
 291                 return (char *) s1;
 292         l1 = __strend(s1) - s1;
 293         while (l1-- >= l2) {
 294                 int cc;
 295
 296                 cc = clcle(s1, l2, s2, l2);
 297                 if (!cc)
 298                         return (char *) s1;
 299                 s1++;
 300         }
 301         return NULL;
 302 }
 303 EXPORT_SYMBOL(strstr);
 304 #endif
 305
 306 /**
 307  * memchr - Find a character in an area of memory.
 308  * @s: The memory area
 309  * @c: The byte to search for
 310  * @n: The size of the area.
 311  *
 312  * returns the address of the first occurrence of @c, or %NULL
 313  * if @c is not found
 314  */
 315 #ifdef __HAVE_ARCH_MEMCHR
 316 void *memchr(const void *s, int c, size_t n)
 317 {
 318         register int r0 asm("0") = (char) c;
 319         const void *ret = s + n;
 320
 321         asm volatile ("0: srst  %0,%1\n"
 322                       "   jo    0b\n"
 323                       "   jl    1f\n"
 324                       "   la    %0,0\n"
 325                       "1:"
 326                       : "+a" (ret), "+&a" (s) : "d" (r0) : "cc", "memory");
 327         return (void *) ret;
 328 }
 329 EXPORT_SYMBOL(memchr);
 330 #endif
 331
 332 /**
 333  * memcmp - Compare two areas of memory
 334  * @s1: One area of memory
 335  * @s2: Another area of memory
 336  * @n: The size of the area.
 337  */
 338 #ifdef __HAVE_ARCH_MEMCMP
 339 int memcmp(const void *s1, const void *s2, size_t n)
 340 {
 341         int ret;
 342
 343         ret = clcle(s1, n, s2, n);
 344         if (ret)
 345                 ret = ret == 1 ? -1 : 1;
 346         return ret;
 347 }
 348 EXPORT_SYMBOL(memcmp);
 349 #endif
 350
 351 /**
 352  * memscan - Find a character in an area of memory.
 353  * @s: The memory area
 354  * @c: The byte to search for
 355  * @n: The size of the area.
 356  *
 357  * returns the address of the first occurrence of @c, or 1 byte past
 358  * the area if @c is not found
 359  */
 360 #ifdef __HAVE_ARCH_MEMSCAN
 361 void *memscan(void *s, int c, size_t n)
 362 {
 363         register int r0 asm("0") = (char) c;
 364         const void *ret = s + n;
 365
 366         asm volatile ("0: srst  %0,%1\n"
 367                       "   jo    0b\n"
 368                       : "+a" (ret), "+&a" (s) : "d" (r0) : "cc", "memory");
 369         return (void *) ret;
 370 }
 371 EXPORT_SYMBOL(memscan);
 372 #endif