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SubjectRe: [crash, bisected] Re: [PATCH 3/4] x86_64: Fold pda into per cpu area
Jeremy Fitzhardinge wrote:
>>
>> Its loaded at __per_cpu_load but the symbols have addresses starting
>> at 0.
>
> Yes, which leads to an odd-looking ELF file where the Phdrs aren't
> sorted by virtual address order. I'm wondering what would happen if a
> bootloader that actually understood ELF files tried to load it as an
> actual ELF file...
>

If it is implemented correctly, it will work. It might trigger bugs in
such loaders, however.

>> Hmmm.... we could add the relocation offset to __per_cpu_load?
>> __per_cpu_load is used very sparingly. Basically only useful during
>> early boot and when a new per cpu area has to be setup. In that case
>> we want to copy from __per_cpu_load to the newly allocated percpu area.
>
> Yes, it should be fairly easy to manually relocate it by applying the
> (load - link) offset to it.

Seems easy enough, and as already stated, this is not
performance-critical so a few extra instructions is pretty much a non-issue.

-hpa


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