[Crash-utility] Crash broken for latest upstream kernel

[Nikolay Borisov]

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.