Subject: [PATCH] arm: Prevent memory aliasing on non-LPAE kernels

From: [email-masked] (Stepan Moskovchenko)
Date: Fri, 31 May 2013 18:30:52 -0700

On 5/30/2013 3:24 PM, Arnd Bergmann wrote:
>> +       if (size > ((phys_addr_t)~0))
>> +               size = ((phys_addr_t)~0);
>> +
>> +       /* arm_add_memory() already checks for the case of base + size > 4GB */
>> +#endif
>>          arm_add_memory(base, size);
>>   }
>
> This looks wrong for the case where 'base' is between >0 and 4GB and 'size'
> makes it spill over the 4GB boundary. You need to set
> 'size = (phys_addr_t)~0 - base' then.
>

Ah. I believe arm_add_memory() already has the logic to handle this 
case. Here, we are just trying to shrink 'size' to fit into phys_addr_t, 
since it is currently u64 but arm_add_memory() uses phys_addr_t for its 
arguments. I did not want to have this logic in two places, but I can do 
what you said if you like.

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