Messages in this thread | | | Date | Tue, 16 Jan 2018 21:19:13 +0000 | From | Marc Zyngier <> | Subject | Re: [PATCH RFC v1] arm64: Handle traps from accessing CNTVCT/CNTFRQ for CONFIG_COMPAT |
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On Tue, 16 Jan 2018 20:32:19 +0000, Nicolin Chen wrote: > > Hello Marc, > > On Thu, Jan 11, 2018 at 08:51:37AM +0000, Marc Zyngier wrote: > > > [ I also added cntfrq here for safety as theoretically it could > > > trigger the trap as well. However, my another test case (with > > > mrc insturction) doesn't seem to trigger a trap. So I would > > > drop it in the next version if someone can confirm it's not > > > required. Thanks -- Nicolin ] > > > > See my previous series on this very subject[1] as well as Will's reply. > > Thanks for the background. > > > > - for (hook = sys64_hooks; hook->handler; hook++) > > > + for (; hook && hook->handler; hook++) > > > if ((hook->esr_mask & esr) == hook->esr_val) { > > > hook->handler(esr, regs); > > > return; > > > > > > > Also, this code is fairly broken in its handling of conditional > > instructions. > > I understand that it should take care of the condition field as > a general instruction handler. Just for curiosity: If we confine > the topic to read access of CNTVCT/CNTFRQ, what'd be the penalty > by ignoring the condition field and executing it anyway?
Do you mean, apart from severely corrupting userspace execution? That's a rhetorical question, right?
M. -- Jazz is not dead, it just smell funny.
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