Messages in this thread | | | Date | Wed, 8 Jun 2011 12:39:06 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH v5 8/9] x86-64: Emulate legacy vsyscalls |
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* pageexec@freemail.hu <pageexec@freemail.hu> wrote:
> On 8 Jun 2011 at 12:06, Andi Kleen wrote: > > > > eventually may even go away as time progresses and linux > > > systems begin to fully rely on the vdso instead. > > > > That assumes that everyone uses glibc and also updates their > > userland. As pointed out many times that's a deeply flawed > > assumption. > > i think the assumption is not that everyone uses glibc but that > everyone else (as in, every other libc) can simply take the > necessary changes from glibc, provided they need such changes at > all (i.e., they're using the vsyscall entry points over the vdso > ones). > > i frankly didn't check any of the alternatives myself > (uclibc/klibc/bionic/etc) but i can't imagine that it'd be that > much harder to patch them than glibc.
Correct. Also, as i pointed it out in the previous mail, ABI does not mean 'will execute the same instructions', that would be silly. We *do* fix serious wide-scale performance regressions (obviously), but if it's about some weird crazy legacy path that we had good security reasons to change, and which is trivial to performance-improve in the library then we are well within our boundaries to keep the change.
> as i said, this was a compromise solution but then i think you > already made it clear that you didn't even think there was a > problem here to solve, so i guess we should work that out first, if > you want to ;).
Heh, indeed ;-)
Thanks,
Ingo
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