s390/lib/string.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 /*
0003  *    Optimized string functions
0004  *
0005  *  S390 version
0006  *    Copyright IBM Corp. 2004
0007  *    Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
0008  */
0009
0010 #define IN_ARCH_STRING_C 1
0011 #ifndef __NO_FORTIFY
0012 # define __NO_FORTIFY
0013 #endif
0014
0015 #include <linux/types.h>
0016 #include <linux/string.h>
0017 #include <linux/export.h>
0018
0019 /*
0020  * Helper functions to find the end of a string
0021  */
0022 static inline char *__strend(const char *s)
0023 {
0024     unsigned long e = 0;
0025
0026     asm volatile(
0027         "   lghi    0,0\n"
0028         "0: srst    %[e],%[s]\n"
0029         "   jo  0b\n"
0030         : [e] "+&a" (e), [s] "+&a" (s)
0031         :
0032         : "cc", "memory", "0");
0033     return (char *)e;
0034 }
0035
0036 static inline char *__strnend(const char *s, size_t n)
0037 {
0038     const char *p = s + n;
0039
0040     asm volatile(
0041         "   lghi    0,0\n"
0042         "0: srst    %[p],%[s]\n"
0043         "   jo  0b\n"
0044         : [p] "+&d" (p), [s] "+&a" (s)
0045         :
0046         : "cc", "memory", "0");
0047     return (char *)p;
0048 }
0049
0050 /**
0051  * strlen - Find the length of a string
0052  * @s: The string to be sized
0053  *
0054  * returns the length of @s
0055  */
0056 #ifdef __HAVE_ARCH_STRLEN
0057 size_t strlen(const char *s)
0058 {
0059     return __strend(s) - s;
0060 }
0061 EXPORT_SYMBOL(strlen);
0062 #endif
0063
0064 /**
0065  * strnlen - Find the length of a length-limited string
0066  * @s: The string to be sized
0067  * @n: The maximum number of bytes to search
0068  *
0069  * returns the minimum of the length of @s and @n
0070  */
0071 #ifdef __HAVE_ARCH_STRNLEN
0072 size_t strnlen(const char *s, size_t n)
0073 {
0074     return __strnend(s, n) - s;
0075 }
0076 EXPORT_SYMBOL(strnlen);
0077 #endif
0078
0079 /**
0080  * strcpy - Copy a %NUL terminated string
0081  * @dest: Where to copy the string to
0082  * @src: Where to copy the string from
0083  *
0084  * returns a pointer to @dest
0085  */
0086 #ifdef __HAVE_ARCH_STRCPY
0087 char *strcpy(char *dest, const char *src)
0088 {
0089     char *ret = dest;
0090
0091     asm volatile(
0092         "   lghi    0,0\n"
0093         "0: mvst    %[dest],%[src]\n"
0094         "   jo  0b\n"
0095         : [dest] "+&a" (dest), [src] "+&a" (src)
0096         :
0097         : "cc", "memory", "0");
0098     return ret;
0099 }
0100 EXPORT_SYMBOL(strcpy);
0101 #endif
0102
0103 /**
0104  * strncpy - Copy a length-limited, %NUL-terminated string
0105  * @dest: Where to copy the string to
0106  * @src: Where to copy the string from
0107  * @n: The maximum number of bytes to copy
0108  *
0109  * The result is not %NUL-terminated if the source exceeds
0110  * @n bytes.
0111  */
0112 #ifdef __HAVE_ARCH_STRNCPY
0113 char *strncpy(char *dest, const char *src, size_t n)
0114 {
0115     size_t len = __strnend(src, n) - src;
0116     memset(dest + len, 0, n - len);
0117     memcpy(dest, src, len);
0118     return dest;
0119 }
0120 EXPORT_SYMBOL(strncpy);
0121 #endif
0122
0123 /**
0124  * strcat - Append one %NUL-terminated string to another
0125  * @dest: The string to be appended to
0126  * @src: The string to append to it
0127  *
0128  * returns a pointer to @dest
0129  */
0130 #ifdef __HAVE_ARCH_STRCAT
0131 char *strcat(char *dest, const char *src)
0132 {
0133     unsigned long dummy = 0;
0134     char *ret = dest;
0135
0136     asm volatile(
0137         "   lghi    0,0\n"
0138         "0: srst    %[dummy],%[dest]\n"
0139         "   jo  0b\n"
0140         "1: mvst    %[dummy],%[src]\n"
0141         "   jo  1b\n"
0142         : [dummy] "+&a" (dummy), [dest] "+&a" (dest), [src] "+&a" (src)
0143         :
0144         : "cc", "memory", "0");
0145     return ret;
0146 }
0147 EXPORT_SYMBOL(strcat);
0148 #endif
0149
0150 /**
0151  * strlcat - Append a length-limited, %NUL-terminated string to another
0152  * @dest: The string to be appended to
0153  * @src: The string to append to it
0154  * @n: The size of the destination buffer.
0155  */
0156 #ifdef __HAVE_ARCH_STRLCAT
0157 size_t strlcat(char *dest, const char *src, size_t n)
0158 {
0159     size_t dsize = __strend(dest) - dest;
0160     size_t len = __strend(src) - src;
0161     size_t res = dsize + len;
0162
0163     if (dsize < n) {
0164         dest += dsize;
0165         n -= dsize;
0166         if (len >= n)
0167             len = n - 1;
0168         dest[len] = '\0';
0169         memcpy(dest, src, len);
0170     }
0171     return res;
0172 }
0173 EXPORT_SYMBOL(strlcat);
0174 #endif
0175
0176 /**
0177  * strncat - Append a length-limited, %NUL-terminated string to another
0178  * @dest: The string to be appended to
0179  * @src: The string to append to it
0180  * @n: The maximum numbers of bytes to copy
0181  *
0182  * returns a pointer to @dest
0183  *
0184  * Note that in contrast to strncpy, strncat ensures the result is
0185  * terminated.
0186  */
0187 #ifdef __HAVE_ARCH_STRNCAT
0188 char *strncat(char *dest, const char *src, size_t n)
0189 {
0190     size_t len = __strnend(src, n) - src;
0191     char *p = __strend(dest);
0192
0193     p[len] = '\0';
0194     memcpy(p, src, len);
0195     return dest;
0196 }
0197 EXPORT_SYMBOL(strncat);
0198 #endif
0199
0200 /**
0201  * strcmp - Compare two strings
0202  * @s1: One string
0203  * @s2: Another string
0204  *
0205  * returns   0 if @s1 and @s2 are equal,
0206  *     < 0 if @s1 is less than @s2
0207  *     > 0 if @s1 is greater than @s2
0208  */
0209 #ifdef __HAVE_ARCH_STRCMP
0210 int strcmp(const char *s1, const char *s2)
0211 {
0212     int ret = 0;
0213
0214     asm volatile(
0215         "   lghi    0,0\n"
0216         "0: clst    %[s1],%[s2]\n"
0217         "   jo  0b\n"
0218         "   je  1f\n"
0219         "   ic  %[ret],0(%[s1])\n"
0220         "   ic  0,0(%[s2])\n"
0221         "   sr  %[ret],0\n"
0222         "1:"
0223         : [ret] "+&d" (ret), [s1] "+&a" (s1), [s2] "+&a" (s2)
0224         :
0225         : "cc", "memory", "0");
0226     return ret;
0227 }
0228 EXPORT_SYMBOL(strcmp);
0229 #endif
0230
0231 static inline int clcle(const char *s1, unsigned long l1,
0232             const char *s2, unsigned long l2)
0233 {
0234     union register_pair r1 = { .even = (unsigned long)s1, .odd = l1, };
0235     union register_pair r3 = { .even = (unsigned long)s2, .odd = l2, };
0236     int cc;
0237
0238     asm volatile(
0239         "0: clcle   %[r1],%[r3],0\n"
0240         "   jo  0b\n"
0241         "   ipm %[cc]\n"
0242         "   srl %[cc],28\n"
0243         : [cc] "=&d" (cc), [r1] "+&d" (r1.pair), [r3] "+&d" (r3.pair)
0244         :
0245         : "cc", "memory");
0246     return cc;
0247 }
0248
0249 /**
0250  * strstr - Find the first substring in a %NUL terminated string
0251  * @s1: The string to be searched
0252  * @s2: The string to search for
0253  */
0254 #ifdef __HAVE_ARCH_STRSTR
0255 char *strstr(const char *s1, const char *s2)
0256 {
0257     int l1, l2;
0258
0259     l2 = __strend(s2) - s2;
0260     if (!l2)
0261         return (char *) s1;
0262     l1 = __strend(s1) - s1;
0263     while (l1-- >= l2) {
0264         int cc;
0265
0266         cc = clcle(s1, l2, s2, l2);
0267         if (!cc)
0268             return (char *) s1;
0269         s1++;
0270     }
0271     return NULL;
0272 }
0273 EXPORT_SYMBOL(strstr);
0274 #endif
0275
0276 /**
0277  * memchr - Find a character in an area of memory.
0278  * @s: The memory area
0279  * @c: The byte to search for
0280  * @n: The size of the area.
0281  *
0282  * returns the address of the first occurrence of @c, or %NULL
0283  * if @c is not found
0284  */
0285 #ifdef __HAVE_ARCH_MEMCHR
0286 void *memchr(const void *s, int c, size_t n)
0287 {
0288     const void *ret = s + n;
0289
0290     asm volatile(
0291         "   lgr 0,%[c]\n"
0292         "0: srst    %[ret],%[s]\n"
0293         "   jo  0b\n"
0294         "   jl  1f\n"
0295         "   la  %[ret],0\n"
0296         "1:"
0297         : [ret] "+&a" (ret), [s] "+&a" (s)
0298         : [c] "d" (c)
0299         : "cc", "memory", "0");
0300     return (void *) ret;
0301 }
0302 EXPORT_SYMBOL(memchr);
0303 #endif
0304
0305 /**
0306  * memcmp - Compare two areas of memory
0307  * @s1: One area of memory
0308  * @s2: Another area of memory
0309  * @n: The size of the area.
0310  */
0311 #ifdef __HAVE_ARCH_MEMCMP
0312 int memcmp(const void *s1, const void *s2, size_t n)
0313 {
0314     int ret;
0315
0316     ret = clcle(s1, n, s2, n);
0317     if (ret)
0318         ret = ret == 1 ? -1 : 1;
0319     return ret;
0320 }
0321 EXPORT_SYMBOL(memcmp);
0322 #endif
0323
0324 /**
0325  * memscan - Find a character in an area of memory.
0326  * @s: The memory area
0327  * @c: The byte to search for
0328  * @n: The size of the area.
0329  *
0330  * returns the address of the first occurrence of @c, or 1 byte past
0331  * the area if @c is not found
0332  */
0333 #ifdef __HAVE_ARCH_MEMSCAN
0334 void *memscan(void *s, int c, size_t n)
0335 {
0336     const void *ret = s + n;
0337
0338     asm volatile(
0339         "   lgr 0,%[c]\n"
0340         "0: srst    %[ret],%[s]\n"
0341         "   jo  0b\n"
0342         : [ret] "+&a" (ret), [s] "+&a" (s)
0343         : [c] "d" (c)
0344         : "cc", "memory", "0");
0345     return (void *)ret;
0346 }
0347 EXPORT_SYMBOL(memscan);
0348 #endif