[Crash-utility] Can't read stack contents from qemu dump

[Nikolay Borisov]

Hello,

I tried running crash-head (HEAD: 5d172b230cf4) against today's linus'
master on a dump obtained via dump-guest-memory in qemu. And I got the
following when the image is loaded:

please wait... (determining panic task)
bt: read error: kernel virtual address: fffffe0000007000  type: "stack
contents"

  KERNEL: vmlinux
    DUMPFILE: memory-verbatim.img
        CPUS: 1
        DATE: Wed Apr  4 16:36:47 2018
      UPTIME: 00:27:48
LOAD AVERAGE: 31.11, 17.80, 10.43
       TASKS: 145
    NODENAME: ubuntu-virtual
     RELEASE: 4.16.0-rc7-nbor
     VERSION: #570 SMP Wed Apr 4 16:03:44 EEST 2018
     MACHINE: x86_64  (3392 Mhz)
      MEMORY: 4 GB
       PANIC: ""
         PID: 0
     COMMAND: "swapper/0"
        TASK: ffffffff82016500  [THREAD_INFO: ffffffff82016500]
         CPU: 0
       STATE: TASK_RUNNING
     WARNING: panic task not found

crash> bt
PID: 0      TASK: ffffffff82016500  CPU: 0   COMMAND: "swapper/0"
 #0 [ffffffff82003dc8] __schedule at ffffffff817ea059
bt: invalid RSP: ffffffff82003dc8  bt->stackbase/stacktop:
ffffffff82000000/ffffffff82002000 cpu: 0


So the kernel has been compiled with : gcc (Ubuntu
5.4.0-6ubuntu1~16.04.9) 5.4.0 20160609 which has retpoline enabled.

I have KASLR disabled: # CONFIG_RANDOMIZE_BASE is not set and the kernel
is compiled with CONFIG_FRAME_POINTER=y .

This scenario used to work around the 4.10 timeline. Am I doing
something wrong or crash still needs time to work on the latest upstream
kernel code?