From mboxrd@z Thu Jan 1 00:00:00 1970 From: will.deacon@arm.com (Will Deacon) Date: Tue, 12 Dec 2017 10:28:27 +0000 Subject: [PATCH v2 17/18] arm64: Kconfig: Add CONFIG_UNMAP_KERNEL_AT_EL0 In-Reply-To: References: <1512059986-21325-1-git-send-email-will.deacon@arm.com> <1512059986-21325-18-git-send-email-will.deacon@arm.com> Message-ID: <20171212102826.GC28301@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Tue, Dec 12, 2017 at 09:44:09AM +0100, Geert Uytterhoeven wrote: > Hi Will, > > On Thu, Nov 30, 2017 at 5:39 PM, Will Deacon wrote: > > Add a Kconfig entry to control use of the entry trampoline, which allows > > us to unmap the kernel whilst running in userspace and improve the > > robustness of KASLR. > > > > Signed-off-by: Will Deacon > > This is now commit 084eb77cd3a81134 in arm64/for-next/core. > > > --- > > arch/arm64/Kconfig | 13 +++++++++++++ > > 1 file changed, 13 insertions(+) > > > > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > > index fdcc7b9bb15d..3af1657fcac3 100644 > > --- a/arch/arm64/Kconfig > > +++ b/arch/arm64/Kconfig > > @@ -833,6 +833,19 @@ config FORCE_MAX_ZONEORDER > > However for 4K, we choose a higher default value, 11 as opposed to 10, giving us > > 4M allocations matching the default size used by generic code. > > > > +config UNMAP_KERNEL_AT_EL0 > > + bool "Unmap kernel when running in userspace (aka \"KAISER\")" > > But I believe this is no longer called KAISER? That's right, but KAISER is the original name in the paper and so I figured it was worth mentioning just here to help people identify what this feature is. The command line option is "kpti" to align with x86. Will