Re: [PATCH v4 0/4] E0PD support
From: Will Deacon <will@kernel.org>
Date: 2019-10-31 12:42:31
On Thu, Oct 31, 2019 at 12:13:35PM +0000, John Garry wrote:
On 31/10/2019 11:26, Will Deacon wrote:quoted
On Thu, Oct 24, 2019 at 10:42:03PM +0100, Mark Brown wrote:quoted
This series adds support for E0PD. We enable E0PD unconditionally where present on systems where all the CPUs in the system support E0PD and change to not enabling KPTI by default on systems where we have enabled E0PD. It also converts the runtime checks for use of non-global mappings into a variable.Although I welcome the simplification introduced by this patch set, I'm worried that we might be removing a significant optimisation to KASLR boot-time on machines with large memory. John reported issues with this in the past, so I'm looping him in in case he has a chance to test this (branch here [1]). Of course, I could just be missing something since this code was really subtle to begin with.I booted our D05 and D06 boards with that branch and did not experience the pauses which we reported some time ago.
Hmm. So I annotated the code locally and I see that we do rewrite swapper in this case, so I'm surprised you're not seeing the performance issue you ran into with this before. Have you got KASLR enabled and are you passing a non-zero seed? Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel