[PATCH v2 2/3] arm64: Bail out PIE builds early if load address is not 4K aligned

[Stephen Warren]

On 9/7/20 3:52 AM, Edgar E. Iglesias wrote:
> On Fri, Sep 04, 2020 at 12:43:57PM -0600, Stephen Warren wrote:
>> On 9/4/20 3:07 AM, Edgar E. Iglesias wrote:
>>> From: "Edgar E. Iglesias" <edgar.iglesias at xilinx.com>
>>>
>>> PIE requires a 4K aligned load address. If this is not met, trap
>>> the startup sequence in a WFI loop rather than running into obscure
>>> failures.
>>
>>> diff --git a/arch/arm/cpu/armv8/start.S b/arch/arm/cpu/armv8/start.S
>>>  #if CONFIG_POSITION_INDEPENDENT
>>> +	/* Verify that we're 4K aligned.  */
>>
>> Similar to the comment on the previous patch: I believe the code that
>> implements this check should be outside the #if check, since it's always
>> needed.
> 
> But a check for non-PIE would have to be stricter, wouldn't it?
> I.e the load address needs to exactly match the link-time address.

Oh yes, I guess that is true.