Re: [patch] vsyscall feature

From: Ingo Molnar (mingo@chiara.csoma.elte.hu)
Date: Thu Mar 09 2000 - 20:49:55 EST


On Wed, 8 Mar 2000, Jamie Lokier wrote:

> Good point. You can bet that some partial machine code evaluator
> would like to disassemble the vsyscall code and duplicate the
> equivalent in JIT generated code at some point, interleaved with
> caller optimisations...

yep - since kernel-entry-less vsyscalls are basically an extension to
glibc, it's perfectly possible to avoid the intended behavior via
user-space tricks. Just like it's possible currently to override the _time
libc function. So anyone who wants to do tricks must either do it at the
libc level if vsyscalls are use. Also, since this is fully under the
control of the kernel, it can be disabled (via a kernel recompile and/or
kernel patch) without impacting any application.

        Ingo

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