Re: [PATCH v5 0/6] implement KASLR for powerpc/fsl_booke/64

From: Scott Wood
Date: Wed Apr 15 2020 - 15:35:04 EST


On Mon, 2020-03-30 at 10:20 +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&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%)
>

Acked-by: Scott Wood <oss@xxxxxxxxxxxx>

-Scott