1 // SPDX-License-Identifier: GPL-2.0 2 #include <linux/string.h> 3 #include <linux/export.h> 4 5 char *strstr(const char *cs, const char *ct) 6 { 7 int d0, d1; 8 register char *__res; 9 __asm__ __volatile__( 10 "movl %6,%%edi\n\t" 11 "repne scasb\n\t" 12 "notl %%ecx\n\t" 13 "decl %%ecx\n\t" /* NOTE! This also sets Z if searchstring='' */ 14 "movl %%ecx,%%edx\n" 15 "1:\tmovl %6,%%edi\n\t" 16 "movl %%esi,%%eax\n\t" 17 "movl %%edx,%%ecx\n\t" 18 "repe cmpsb\n\t" 19 "je 2f\n\t" /* also works for empty string, see above */ 20 "xchgl %%eax,%%esi\n\t" 21 "incl %%esi\n\t" 22 "cmpb $0,-1(%%eax)\n\t" 23 "jne 1b\n\t" 24 "xorl %%eax,%%eax\n\t" 25 "2:" 26 : "=a" (__res), "=&c" (d0), "=&S" (d1) 27 : "0" (0), "1" (0xffffffff), "2" (cs), "g" (ct) 28 : "dx", "di"); 29 return __res; 30 } 31 EXPORT_SYMBOL(strstr); 32