Messages in this thread | | | Date | Wed, 08 Mar 2000 18:21:32 +0100 | From | Artur Skawina <> | Subject | Re: [patch] vsyscall feature |
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Jamie Lokier wrote: > > > > is a downside to doing this. If, for example, timeofday is > > > available in a raw form on one of these data pages, and user-space > > > code can read that page at will (without going to the kernel), you
> > preventing a rogue process from accessing the info directly might be a bit > > harder, w/o giving up the main benefit -- speed. There certainly seems to > > be a market for a runtime (global) on/off switch at least. > > If you switch it off, the process knows you've switched it off and > may behave differently. > > It's probably possible to lie to the process for gettimeofday and signal > operations though -- have the kernel unmap the page for those processes,
[for _all_ processes, as this is supposed to be a global mapping]
> and have a ptrace SEGV handler which provides results as if the page > were still mapped.
hmm, might work. since it would be detectable anyway (eg timing) the question is would it be worth the extra complexity...
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