disable enable all interrupts (critical code zone)

I work with the AT91 controller from atmel, which managed all interrups by the Advanced Interrupt Controller (AIC).

I've critical code zone, where no interrups should be occured.

unsigned int mask; //disable interrupts
mask = AT91C_BASE_AIC->AIC_IMR;
AT91C_BASE_AIC->AIC_IDCR = 0xFFFFFFFF;

//critical code
//critical code

//enable interrupts
AT91C_BASE_AIC->AIC_IECR = mask;

If an interrupt occurs just before the AIC is disabled
but not processed until just afterwards, I will get
a suprious interrupt.

If I only disable the AIC - without saving the mask register - I have to enable all interrupts step by step.

What's the best way to do that?

Thomas