linux-kernel - [PATCH v5 0/6] implement KASLR for powerpc/fsl

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Message-ID: <20200330022023.3691-1-yanaijie@huawei.com>
Date:   Mon, 30 Mar 2020 10:20:17 +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>,
        <dja@...ens.net>, Jason Yan <yanaijie@...wei.com>
Subject: [PATCH v5 0/6] implement KASLR for powerpc/fsl_booke/64

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&state=*

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.

v4->v5:
  Fix "-Werror=maybe-uninitialized" compile error.
  Fix typo "similar as" -> "similar to".
v3->v4:
  Do not define __kaslr_offset as a fixed symbol. Reference __run_at_load and
    __kaslr_offset by symbol instead of magic offsets.
  Use IS_ENABLED(CONFIG_PPC32) instead of #ifdef CONFIG_PPC32.
  Change kaslr-booke32 to kaslr-booke in index.rst
  Switch some instructions to 64-bit.
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

 Documentation/powerpc/index.rst               |  2 +-
 .../{kaslr-booke32.rst => kaslr-booke.rst}    | 35 ++++++-
 arch/powerpc/Kconfig                          |  2 +-
 arch/powerpc/kernel/exceptions-64e.S          | 23 +++++
 arch/powerpc/kernel/head_64.S                 | 13 +++
 arch/powerpc/kernel/setup_64.c                |  3 +
 arch/powerpc/mm/mmu_decl.h                    | 23 +++--
 arch/powerpc/mm/nohash/kaslr_booke.c          | 91 +++++++++++++------
 8 files changed, 147 insertions(+), 45 deletions(-)
 rename Documentation/powerpc/{kaslr-booke32.rst => kaslr-booke.rst} (59%)

-- 
2.17.2