1*b2441318SGreg Kroah-Hartman // SPDX-License-Identifier: GPL-2.0
244f0257fSThomas Gleixner #include <linux/string.h>
3784d5699SAl Viro #include <linux/export.h>
444f0257fSThomas Gleixner
strstr(const char * cs,const char * ct)544f0257fSThomas Gleixner char *strstr(const char *cs, const char *ct)
644f0257fSThomas Gleixner {
744f0257fSThomas Gleixner int d0, d1;
844f0257fSThomas Gleixner register char *__res;
944f0257fSThomas Gleixner __asm__ __volatile__(
1044f0257fSThomas Gleixner "movl %6,%%edi\n\t"
1144f0257fSThomas Gleixner "repne\n\t"
1244f0257fSThomas Gleixner "scasb\n\t"
1344f0257fSThomas Gleixner "notl %%ecx\n\t"
1444f0257fSThomas Gleixner "decl %%ecx\n\t" /* NOTE! This also sets Z if searchstring='' */
1544f0257fSThomas Gleixner "movl %%ecx,%%edx\n"
1644f0257fSThomas Gleixner "1:\tmovl %6,%%edi\n\t"
1744f0257fSThomas Gleixner "movl %%esi,%%eax\n\t"
1844f0257fSThomas Gleixner "movl %%edx,%%ecx\n\t"
1944f0257fSThomas Gleixner "repe\n\t"
2044f0257fSThomas Gleixner "cmpsb\n\t"
2144f0257fSThomas Gleixner "je 2f\n\t" /* also works for empty string, see above */
2244f0257fSThomas Gleixner "xchgl %%eax,%%esi\n\t"
2344f0257fSThomas Gleixner "incl %%esi\n\t"
2444f0257fSThomas Gleixner "cmpb $0,-1(%%eax)\n\t"
2544f0257fSThomas Gleixner "jne 1b\n\t"
2644f0257fSThomas Gleixner "xorl %%eax,%%eax\n\t"
2744f0257fSThomas Gleixner "2:"
2844f0257fSThomas Gleixner : "=a" (__res), "=&c" (d0), "=&S" (d1)
2944f0257fSThomas Gleixner : "0" (0), "1" (0xffffffff), "2" (cs), "g" (ct)
3044f0257fSThomas Gleixner : "dx", "di");
3144f0257fSThomas Gleixner return __res;
3244f0257fSThomas Gleixner }
33784d5699SAl Viro EXPORT_SYMBOL(strstr);
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