1 #include <stdio.h> 2 #include <stdlib.h> 3 4 int main(int argc, char **argv) 5 { 6 unsigned long sp1; 7 unsigned long sp2; 8 unsigned long sp3; 9 unsigned short fs1; 10 unsigned short fs2; 11 12 fs1 = 0x0003; 13 14 asm("movw %4, %%fs\n" 15 "movl %%esp, %0\n" 16 "pushw %%fs\n" 17 "movl %%esp, %1\n" 18 "popw %%fs\n" 19 "movl %%esp, %2\n" 20 "movw %%fs, %3\n" 21 : "=r" (sp1), "=r" (sp2), "=r" (sp3), "=r" (fs2) 22 : "r" (fs1) 23 : "ax" 24 ); 25 26 printf("sp change after push = %ld\n", sp2 - sp1); 27 printf("sp change after pop = %ld\n", sp3 - sp2); 28 printf("fs after push and pop = %04x\n", fs1); 29 30 asm("movw %4, %%fs\n" 31 "movl %%esp, %0\n" 32 "pushl %%fs\n" 33 "movl %%esp, %1\n" 34 "popl %%fs\n" 35 "movl %%esp, %2\n" 36 "movw %%fs, %3\n" 37 : "=r" (sp1), "=r" (sp2), "=r" (sp3), "=r" (fs2) 38 : "r" (fs1) 39 : "ax" 40 ); 41 42 printf("sp change after push = %ld\n", sp2 - sp1); 43 printf("sp change after pop = %ld\n", sp3 - sp2); 44 printf("fs after push and pop = %04x\n", fs1); 45 46 exit(0); 47 } 48
