sys_brk
unsigned long retval = sys_brk(brk);
asmlinkage long sys_brk(unsigned long brk);
__SYSCALL(__NR_brk, sys_brk)
void *ret = sys_brk(NULL);
if (ret && sys_brk(ret + inc) == ret + inc)
void *ret = sys_brk(addr);
__SYSCALL(__NR_brk, sys_brk)