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

[Jason Yan]

å 2020/3/20 11:19, Daniel Axtens åé:
> 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 âkaslr_early_initâ:
> /home/dja/dev/linux/linux/arch/powerpc/mm/nohash/kaslr_booke.c:357:33: error: âlinear_szâ 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: âlinear_szâ was declared here
>    317 |  unsigned long ram, linear_sz;
>        |                     ^~~~~~~~~
> /home/dja/dev/linux/linux/arch/powerpc/mm/nohash/kaslr_booke.c:187:8: error: âramâ 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: âramâ 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
>
>
>
>
> > 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%)
> >
> > --
> > 2.17.2