On 29.10.20 г. 14:42 ч., Nikolay Borisov wrote:
 Hello,
 
 I haven't been able to open a crashdump generated by 'dump-guest-memory
 -z' option. When I run crash -d10 vmlinux dump.img last thing I get is:
 
 kaslr_helper: failed to determine which kernel was running at crash,
 kaslr_helper: asssuming the kdump 1st kernel.
 calc_kaslr_offset: kaslr_offset=ffffffff9ba00810
 calc_kaslr_offset: phys_base=19a5ff7f0
 crash: pv_ops exists: ARCH_PVOPS
 <readmem: 137e001e0, PHYSADDR, "linux_banner verify", 13, (ROE|Q),
 7ffffe50ff50>
 <read_diskdump: addr: 137e001e0 paddr: 137e001e0 cnt: 13>
 read_diskdump: paddr/pfn: 137e001e0/137e00 -> cache physical page: 137e00000
 gdb vmlinux
 GNU gdb (GDB) 7.6
 Copyright (C) 2013 Free Software Foundation, Inc.
 License GPLv3+: GNU GPL version 3 or later
 <
http://gnu.org/licenses/gpl.html>
 This is free software: you are free to change and redistribute it.
 There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
 and "show warranty" for details.
 This GDB was configured as "x86_64-unknown-linux-gnu"...
 GETBUF(328 -> 0)
   GETBUF(1500 -> 1)
 
 WARNING: kernel relocated [1605MB]: patching 97581 gdb minimal_symbol values
 
   FREEBUF(1)
 FREEBUF(0)
 <readmem: ffffffff1db75260, KVADDR, "page_offset_base", 8, (FOE|Q),
 55bcc3a177e8>
 <read_diskdump: addr: ffffffff1db75260 paddr: 77ff1db75260 cnt: 8>
 read_diskdump: SEEK_ERROR: paddr/pfn: 77ff1db75260/77ff1db75 max_mapnr:
 140000
 crash: seek error: kernel virtual address: ffffffff1db75260  type:
 "page_offset_base"
 
 That kernel has RANDOMIZE_BASE set to y
 
 I get same error when I take an image dump of a kernel booted with
 nokaslr.
 
 My crash is freshly compiled, with HEAD commit : 915cc069ec03 x86_64:
 Perform EFRAME_VERIFY always if set in x86_64_exception_frame (7 weeks
 ago) <David Mair>
  
Ok, the porblem is that divide_error is no longer in the kernel as of
upstream kernel commit  9d06c4027f21 ("x86/entry: Convert Divide Error
to IDTENTRY") the correct symbol following this commit is
'asm_exc_divide_error'. I will be sending in a fix soon.