Re: [crash, bisected] Re: [PATCH 3/4] x86_64: Fold pda into per cpu area

Jeremy Fitzhardinge wrote:

Yes, and there's no reason we couldn't do the same on 64-bit, aside from the stack-protector's use of %gs:40. There's no code-size cost in large offsets, since they're always 32-bits anyway (there's no short absolute addressing mode).

If we manually generate %gs-relative references to percpu data, then it's no different to what we do with 32-bit, whether it be a specific symbol address or using the TLS relocations.


If we think the problem is the zero-basing triggering linker bugs, we should probably just use a small offset, like 64 (put a small dummy section before the .percpu.data section to occupy this section.)

I'm going to play with this a bit and see if I come up with something sanish.

-hpa
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