timer_handler
extern void timer_handler(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs);
timer_handler(SIGALRM, NULL, ®s);
return timer_handler(ARCH_TIMER_VIRT_ACCESS, evt);
return timer_handler(ARCH_TIMER_PHYS_ACCESS, evt);
hrtimer_setup(&w->timer, timer_handler, CLOCK_MONOTONIC, HRTIMER_MODE_REL);