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Re: PATCH: Add AVX support to x86-64 _dl_runtime_profile
On Wed, Jul 15, 2009 at 6:15 PM, Ulrich Drepper<drepper@redhat.com> wrote:
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> I think I got your patches applied.
>
> But then I changed the whole approach quite a bit. ?The problem is that
> your patches create a writable code pointer. ?That's bad security-wise.
> ?Instead I opted for the slightly slower test of a flag and just one
> code path. ?This is a tad slower but safer.
>
> I also fixed a few problems:
>
> - - the decision whether to use xmm or ymm content is not all or nothing.
> ?it's per register
What happens when both xmm1 and ymm1 are modified?
> - - you didn't restore the FP stack correctly after pltexit
>
>
> There are two more things to do:
>
> - - the test for AVX availability should be done only once. ?It should
> ?move into the code which selected which trampoline code to use
Can't we extend IFUNC support to ld.so?
> - - the XMM restoration when YMM is available is not enough. ?If there
> ?are stacked audit modules we have to check whether the XMM part is
> ?modified, propagate the new content if necessary into the YMM
> ?element, and update the "old value" field
>
Do you have a testcase?
Thanks.
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H.J.