stack_overflow_check

static inline void stack_overflow_check(struct pt_regs *regs)
{
#ifdef CONFIG_DEBUG_STACKOVERFLOW
#define STACK_TOP_MARGIN    128
    struct orig_ist *oist;
    u64 irq_stack_top, irq_stack_bottom;
    u64 estack_top, estack_bottom;
    u64 curbase = (u64)task_stack_page(current);

    if (user_mode_vm(regs))
        return;

    if (regs->sp >= curbase + sizeof(struct thread_info) +
                  sizeof(struct pt_regs) + STACK_TOP_MARGIN &&
        regs->sp <= curbase + THREAD_SIZE)
        return;

    irq_stack_top = (u64)__get_cpu_var(irq_stack_union.irq_stack) +
            STACK_TOP_MARGIN;
    irq_stack_bottom = (u64)__get_cpu_var(irq_stack_ptr);
    if (regs->sp >= irq_stack_top && regs->sp <= irq_stack_bottom)
        return;

    oist = &__get_cpu_var(orig_ist);
    estack_top = (u64)oist->ist[0] - EXCEPTION_STKSZ + STACK_TOP_MARGIN;
    estack_bottom = (u64)oist->ist[N_EXCEPTION_STACKS - 1];
    if (regs->sp >= estack_top && regs->sp <= estack_bottom)
        return;

    WARN_ONCE(1, "do_IRQ(): %s has overflown the kernel stack (cur:%Lx,sp:%lx,irq stk top-bottom:%Lx-%Lx,exception stk top-bottom:%Lx-%Lx)\n",
        current->comm, curbase, regs->sp,
        irq_stack_top, irq_stack_bottom,
        estack_top, estack_bottom);

    if (sysctl_panic_on_stackoverflow)
        panic("low stack detected by irq handler - check messages\n");
#endif
}