[0/6] implement KASLR for powerpc/fsl_booke/64
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Message ID 20191115093209.26434-1-yanaijie@huawei.com
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  • implement KASLR for powerpc/fsl_booke/64
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Jason Yan Nov. 15, 2019, 9:32 a.m. UTC
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.

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          | 13 ++++
 arch/powerpc/kernel/head_64.S                 |  7 ++
 arch/powerpc/kernel/setup_64.c                |  4 +-
 arch/powerpc/mm/mmu_decl.h                    |  3 +-
 arch/powerpc/mm/nohash/kaslr_booke.c          | 67 +++++++++++++------
 7 files changed, 104 insertions(+), 27 deletions(-)
 rename Documentation/powerpc/{kaslr-booke32.rst => kaslr-booke.rst} (59%)

Comments

Kees Cook Nov. 20, 2019, 6:51 p.m. UTC | #1
On Fri, Nov 15, 2019 at 05:32:03PM +0800, 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

Whee! :) I've updated https://github.com/KSPP/linux/issues/3 with a link
to this current series.