linux-kernel - Re: [PATCH v8 0/2] x86/boot/KASLR: Restrict kernel to be randomized in mirror regions

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Date:   Fri, 4 Aug 2017 17:22:41 +0800
From:   Baoquan He <bhe@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     mingo@...nel.org, matt@...eblueprint.co.uk, keescook@...omium.org,
        tglx@...utronix.de, hpa@...or.com, izumi.taku@...fujitsu.com,
        fanc.fnst@...fujitsu.com, thgarnie@...gle.com,
        n-horiguchi@...jp.nec.com, ard.biesheuvel@...aro.org,
        linux-efi@...r.kernel.org, x86@...nel.org
Subject: Re: [PATCH v8 0/2] x86/boot/KASLR: Restrict kernel to be randomized
 in mirror regions

On 08/04/17 at 03:52pm, Baoquan He wrote:
> Sorry, NACK this series, there's error to hang system. Before I just
> halt system intentionally with error() to check the efi memmap printing,
> didn't notice this. Checking the cause.

I rebuilt the code or change the one of the replacement back, hang never
seen again. Not sure if I copied the wrong kernel or any other mistakes.
Have got a hardware system with efi enabled to try again, see if
anything wrong will happen. It's really weird. And Chao also is helping
to try on his side.

> 
> On 08/04/17 at 03:26pm, Baoquan He wrote:
> > Patch 1/2 is newly added to add efi_memdesc_ptr helper to wrap the
> > open code which gets the start of efi memmap descriptor and also
> > explain why it need be done like that, Ingo suggested it. 
> > 
> > And also replace several places of the open code with efi_memdesc_ptr
> > helper.
> > 
> > And also use efi_memdesc_ptr in process_efi_entries() which handle efi
> > mirror issue during KASLR.
> > 
> > 
> > Change:
> > v7->v8:
> >     Add efi_memdesc_ptr helper to wrap the open code which gets the
> >     start of map descriptor according to Ingo's suggestion.
> > 
> > v6->v7:
> >   Ingo pointed out several incorrect line break issues and unclear
> >   description of patch log. Correct them and rewrite patch log.
> > 
> >   And also rewrite the EFI warning message that if EFI memmap is above
> >   4G in 32bit system since 32bit system can not handle data above 4G at
> >   kernel decompression stage. This is suggested by Ingo too.
> > 
> > v5->v6:
> >   Code style issue fix according to Kees's comment.
> > 
> >   This is based on tip/x86/boot, patch 1,2,3/4 in v5 post has
> >   been put into tip/x86/boot now.
> > 
> > 
> > 
> > Baoquan He (2):
> >   efi: Introduce efi_memdesc_ptr to get pointer to memmap descriptor
> >   x86/boot/KASLR: Restrict kernel to be randomized in mirror regions
> > 
> >  arch/x86/boot/compressed/eboot.c               |  2 +-
> >  arch/x86/boot/compressed/kaslr.c               | 68 +++++++++++++++++++++++++-
> >  drivers/firmware/efi/libstub/efi-stub-helper.c |  4 +-
> >  include/linux/efi.h                            | 19 +++++++
> >  4 files changed, 88 insertions(+), 5 deletions(-)
> > 
> > -- 
> > 2.5.5
> >