linux-kernel - Re: [PATCH v3 0/6] implement KASLR for powerpc/fsl

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Message-ID: <636f16fd-cc7b-ee2e-7496-c06bdc10c7af@huawei.com>
Date:   Thu, 13 Feb 2020 11:00:13 +0800
From:   Jason Yan <yanaijie@...wei.com>
To:     <mpe@...erman.id.au>, <linuxppc-dev@...ts.ozlabs.org>,
        <diana.craciun@....com>, <christophe.leroy@....fr>,
        <benh@...nel.crashing.org>, <paulus@...ba.org>,
        <npiggin@...il.com>, <keescook@...omium.org>,
        <kernel-hardening@...ts.openwall.com>, <oss@...error.net>
CC:     <linux-kernel@...r.kernel.org>, <zhaohongjiang@...wei.com>
Subject: Re: [PATCH v3 0/6] implement KASLR for powerpc/fsl_booke/64

Hi everyone, any comments or suggestions?

Thanks,
Jason

on 2020/2/6 10:58, Jason Yan wrote:
> This is a try to implement KASLR for Freescale BookE64 which is based on
> my earlier implementation for Freescale BookE32:
> https://patchwork.ozlabs.org/project/linuxppc-dev/list/?series=131718
> 
> The implementation for Freescale BookE64 is similar as BookE32. One
> difference is that Freescale BookE64 set up a TLB mapping of 1G during
> booting. Another difference is that ppc64 needs the kernel to be
> 64K-aligned. So we can randomize the kernel in this 1G mapping and make
> it 64K-aligned. This can save some code to creat another TLB map at
> early boot. The disadvantage is that we only have about 1G/64K = 16384
> slots to put the kernel in.
> 
>      KERNELBASE
> 
>            64K                     |--> kernel <--|
>             |                      |              |
>          +--+--+--+    +--+--+--+--+--+--+--+--+--+    +--+--+
>          |  |  |  |....|  |  |  |  |  |  |  |  |  |....|  |  |
>          +--+--+--+    +--+--+--+--+--+--+--+--+--+    +--+--+
>          |                         |                        1G
>          |----->   offset    <-----|
> 
>                                kernstart_virt_addr
> 
> I'm not sure if the slot numbers is enough or the design has any
> defects. If you have some better ideas, I would be happy to hear that.
> 
> Thank you all.
> 
> v2->v3:
>    Fix build error when KASLR is disabled.
> v1->v2:
>    Add __kaslr_offset for the secondary cpu boot up.
> 
> Jason Yan (6):
>    powerpc/fsl_booke/kaslr: refactor kaslr_legal_offset() and
>      kaslr_early_init()
>    powerpc/fsl_booke/64: introduce reloc_kernel_entry() helper
>    powerpc/fsl_booke/64: implement KASLR for fsl_booke64
>    powerpc/fsl_booke/64: do not clear the BSS for the second pass
>    powerpc/fsl_booke/64: clear the original kernel if randomized
>    powerpc/fsl_booke/kaslr: rename kaslr-booke32.rst to kaslr-booke.rst
>      and add 64bit part
> 
>   .../{kaslr-booke32.rst => kaslr-booke.rst}    | 35 +++++++--
>   arch/powerpc/Kconfig                          |  2 +-
>   arch/powerpc/kernel/exceptions-64e.S          | 23 ++++++
>   arch/powerpc/kernel/head_64.S                 | 14 ++++
>   arch/powerpc/kernel/setup_64.c                |  4 +-
>   arch/powerpc/mm/mmu_decl.h                    | 19 ++---
>   arch/powerpc/mm/nohash/kaslr_booke.c          | 71 +++++++++++++------
>   7 files changed, 132 insertions(+), 36 deletions(-)
>   rename Documentation/powerpc/{kaslr-booke32.rst => kaslr-booke.rst} (59%)
>