Re: [PATCH v4 0/6] implement KASLR for powerpc/fsl_booke/64

在 2020/3/20 11:19, Daniel Axtens 写道:

Hi Jason,

I tried to compile this series and got the following error:

/home/dja/dev/linux/linux/arch/powerpc/mm/nohash/kaslr_booke.c: In function ‘kaslr_early_init’:
/home/dja/dev/linux/linux/arch/powerpc/mm/nohash/kaslr_booke.c:357:33: error: ‘linear_sz’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
   357 |  regions.pa_end = memstart_addr + linear_sz;
       |                   ~~~~~~~~~~~~~~^~~~~~~~~~~
/home/dja/dev/linux/linux/arch/powerpc/mm/nohash/kaslr_booke.c:317:21: note: ‘linear_sz’ was declared here
   317 |  unsigned long ram, linear_sz;
       |                     ^~~~~~~~~
/home/dja/dev/linux/linux/arch/powerpc/mm/nohash/kaslr_booke.c:187:8: error: ‘ram’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
   187 |  ret = parse_crashkernel(boot_command_line, size, &crash_size,
       |        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   188 |     &crash_base);
       |     ~~~~~~~~~~~~
/home/dja/dev/linux/linux/arch/powerpc/mm/nohash/kaslr_booke.c:317:16: note: ‘ram’ was declared here
   317 |  unsigned long ram, linear_sz;
       |                ^~~
cc1: all warnings being treated as errors
make[4]: *** [/home/dja/dev/linux/linux/scripts/Makefile.build:268: arch/powerpc/mm/nohash/kaslr_booke.o] Error 1
make[3]: *** [/home/dja/dev/linux/linux/scripts/Makefile.build:505: arch/powerpc/mm/nohash] Error 2
make[2]: *** [/home/dja/dev/linux/linux/scripts/Makefile.build:505: arch/powerpc/mm] Error 2
make[2]: *** Waiting for unfinished jobs....

I have attached my .config file.

Thanks Daniel,

My config had CC_DISABLE_WARN_MAYBE_UNINITIALIZED=y enabled so I missed 
this warning. I will fix it.

Thanks again.

Jason

I'm using
powerpc64-linux-gnu-gcc (Ubuntu 9.2.1-9ubuntu1) 9.2.1 20191008

Regards,
Daniel

quoted

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.

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          | 88 +++++++++++++------
  8 files changed, 144 insertions(+), 45 deletions(-)
  rename Documentation/powerpc/{kaslr-booke32.rst => kaslr-booke.rst} (59%)

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