Messages in this thread | | | Date | Wed, 10 Jan 2018 19:26:11 +0000 | From | Will Deacon <> | Subject | Re: [PATCH v3 02/13] arm64: Kconfig: Reword UNMAP_KERNEL_AT_EL0 kconfig entry |
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On Tue, Jan 09, 2018 at 09:17:00AM -0800, Christoph Hellwig wrote: > On Mon, Jan 08, 2018 at 05:32:27PM +0000, Will Deacon wrote: > > Although CONFIG_UNMAP_KERNEL_AT_EL0 does make KASLR more robust, it's > > actually more useful as a mitigation against speculation attacks that > > can leak arbitrary kernel data to userspace through speculation. > > > > Reword the Kconfig help message to reflect this, and make the option > > depend on EXPERT so that it is on by default for the majority of users. > > I still haven't heard an anwer on why this isn't using > CONFIG_PAGE_TABLE_ISOLATION but instead reinvents its own symbol.
Mainly because this code was written before CONFIG_PAGE_TABLE_ISOLATION had been proposed and I wanted to avoid confusion with the ongoing backports just to align on the naming for an arch-specific config option. We could CONFIG_PAGE_TABLE_ISOLATION and make it select CONFIG_UNMAP_KERNEL_AT_EL) if you like, but worth noting that this is default 'y' anyway and depends on EXPERT.
Will
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