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

[Daniel Axtens]

Hi Jason,

Apologies for the delay in testing.

I'm seeing this problem when I try to boot on a t4240rdb:

random: get_random_u64 called from .start_kernel+0x734/0x964 with crng_init=0                               [8/973]
clocksource: timebase: mask: 0xffffffffffffffff max_cycles: 0xa9210e89c, max_idle_ns: 440795203878 ns
clocksource: timebase mult[15d17460] shift[24] registered
Console: colour dummy device 80x25
pid_max: default: 32768 minimum: 301
Mount-cache hash table entries: 16384 (order: 5, 131072 bytes, linear)
Mountpoint-cache hash table entries: 16384 (order: 5, 131072 bytes, linear)
e6500 family performance monitor hardware support registered
rcu: Hierarchical SRCU implementation.
smp: Bringing up secondary CPUs ...
Processor 2 is stuck.
Processor 3 is stuck.
Processor 4 is stuck.
Processor 5 is stuck.
Processor 6 is stuck.
Processor 7 is stuck.
Processor 8 is stuck.
Processor 9 is stuck.
Processor 10 is stuck.
Processor 11 is stuck.
Processor 12 is stuck.
Processor 13 is stuck.
Processor 14 is stuck.
...
Processor 22 is stuck.                                                                                             
Processor 23 is stuck.                                                            
smp: Brought up 1 node, 2 CPUs                                                                              
Using standard scheduler topology                                                                                  
devtmpfs: initialized                                                                                              
clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 7645041785100000 ns                    
futex hash table entries: 8192 (order: 7, 524288 bytes, linear)                                             
NET: Registered protocol family 16                                                                        
audit: initializing netlink subsys (disabled)                                                       
audit: type=2000 audit(108.032:1): state=initialized audit_enabled=0 res=1                                         
Machine: fsl,T4240RDB                                                        
SoC family: QorIQ T4240                                                                   
SoC ID: svr:0x82480020, Revision: 2.0
... boot continues ...


If I boot with nokaslr, all the CPUs come up with no issue.

This is on top of powerpc/merge at
8299da600ad05b8aa0f15ec0f5f03bd40e37d6f0. If you'd like me to test any
debug patches I can do that.

I've attached my .config.

Regards,
Daniel

Attachment: .config
Description: Binary data

> 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