Messages in this thread |  | | Date | Tue, 23 Feb 2021 12:49:52 +0000 | From | Will Deacon <> | Subject | Re: [PATCH v13 4/7] arm64: mte: Enable TCO in functions that can read beyond buffer limits |
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On Tue, Feb 23, 2021 at 12:05:32PM +0000, Catalin Marinas wrote: > On Tue, Feb 23, 2021 at 10:56:46AM +0000, Vincenzo Frascino wrote: > > On 2/22/21 5:58 PM, Catalin Marinas wrote: > > > We'll still have an issue with dynamically switching the async/sync mode > > > at run-time. Luckily kasan doesn't do this now. The problem is that > > > until the last CPU have been switched from async to sync, we can't > > > toggle the static label. When switching from sync to async, we need > > > to do it on the first CPU being switched. > > > > I totally agree on this point. In the case of runtime switching we might need > > the rethink completely the strategy and depends a lot on what we want to allow > > and what not. For the kernel I imagine we will need to expose something in sysfs > > that affects all the cores and then maybe stop_machine() to propagate it to all > > the cores. Do you think having some of the cores running in sync mode and some > > in async is a viable solution? > > stop_machine() is an option indeed. I think it's still possible to run > some cores in async while others in sync but the static key here would > only be toggled when no async CPUs are left.
Just as a general point, but if we expose stop_machine() via sysfs we probably want to limit that to privileged users so you can't DoS the system by spamming into the file.
Will
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