lkml.org 
[lkml]   [2018]   [Jun]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v2 0/2] x86/boot/KASLR: Skip specified number of 1GB huge pages when do physical randomization
On Mon, 25 Jun 2018 11:16:54 +0800
Baoquan He <bhe@redhat.com> wrote:

> This is a regression bug fix. Luiz's team reported that 1GB huge page
> allocation will get one less 1GB page randomly when KASLR is enabled. On
> their KVM guest with 4GB RAM, which only has one good 1GB huge page,
> they found the 1GB huge page allocation sometime failed with below
> kernel option adding.
>
> default_hugepagesz=1G hugepagesz=1G hugepages=1
>
> This is because kernel may be randomized into those good 1GB huge pages.
>
> And also on those bare-metal machines with larger memory, one less 1GB huge
> page might be seen with KASLR enabled than 'nokaslr' specified case. It's
> also because that kernel might be randomized into one of those good 1GB huge
> pages.
>
> The solution in this patchset is to skip specified number of GB huge
> pages when do kernel physical randomization. If the specified number of GB
> huge pages is bigger than amount of good GB huge pages which system can
> provide, it's consistent with the current huge page implementation.

Reviewed-and-Tested-by: Luiz Capitulino <lcapitulino@redhat.com>

>
> v1->v2:
> There are several code style problems and typos which were pointed out
> by Ingo, fix them in this patchset.
>
> Baoquan He (2):
> x86/boot/KASLR: Add two functions for 1GB huge pages handling
> x86/boot/KASLR: Skip specified number of 1GB huge pages when do
> physical randomization
>
> arch/x86/boot/compressed/kaslr.c | 96 +++++++++++++++++++++++++++++++++++++---
> 1 file changed, 91 insertions(+), 5 deletions(-)
>

\
 
 \ /
  Last update: 2018-06-26 17:26    [W:0.045 / U:0.064 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site