[Crash-utility] arm64: doesn't work for kernel v5.4?

[Dave Anderson]

> ----- Original Message -----
> > Hi Dave,
> > 
> > I tried to use crash v7.2.7 with kernel v5.4-rc1 on arm64.
> > 
> > 1. VA_BITS_ACTUAL is missing in vmcoreinfo.
> >    Does anyone work on fixing it on kernel side?
> >    (just adding one or two lines though)
> > 
> > 2. With a tweak above, I still fail to run crash with vmcore
> >    seeing the following errors;
> >    (I didn't dig into details)
> > 
> >    crash-arm64: invalid kernel virtual address: ffff800010c689a8  type: "kernel_config_data"
> >    WARNING: cannot read kernel_config_data
> >    crash-arm64: invalid kernel virtual address: ffff80001177a160  type: "possible"
> >    WARNING: cannot read cpu_possible_map
> >    crash-arm64: invalid kernel virtual address: ffff80001177a140  type: "present"
> >    WARNING: cannot read cpu_present_map
> >    crash-arm64: invalid kernel virtual address: ffff80001177a120  type: "online"
> >    WARNING: cannot read cpu_online_map 
> >    crash-arm64: invalid kernel virtual address: ffff80001177a188  type: "active" 
> >    WARNING: cannot read cpu_active_map
> >    crash-arm64: invalid kernel virtual address: ffff80001196afe0  type: "shadow_timekeeper xtime_sec"
> >    crash-arm64: invalid kernel virtual address: ffff800011782b3c  type: "init_uts_ns"
> >    WARNING: invalid linux_banner pointer: ffff800010c500e8
> >    crash: vmlinux.1003 and vmcore.1003 do not match!
> > 
> > Have you noticed this issue?
> 
> I have been waiting for our internal 5.4-rc1 based ARK kernel to be built,
> and it looks like it should be available soon.  But I did not expect crash
> to work on arm64 in 5.4.    
> 
> I put in a bunch of 52-bit support into the crash utility last spring, but 
> it was based upon an early proposed patch-set from Steve Capper that Chris
> von Recklinghausen backported to our 4.18.0-80.el8 kernel at the time.
> I believe Chris may have added the VA_BITS_ACTUAL vmcoreinfo entry (?),
> and I'm presuming there will be other VM-related things that are 
> different from that original kernel patch.
> 
> Thanks,
>   Dave

I still haven't got a 5.4-rc1 kernel to test with, but Chris Von Recklinghausen
has backported the latest upstream 52-bit patch-set to a 4.18-based kernel.  
However, it did require one additional patch needed for crash to run live 
on /proc/kcore, which he posted on the arm list today:

  [PATCH] arm64: remove arm64 definitions of kc_vaddr_to_offset and kc_offset_to_vaddr.
  http://lists.infradead.org/pipermail/linux-arm-kernel/2019-October/685109.html

With his patch-set (including the above), crash-7.2.7 comes up unmodified on 
a live system -- albeit one which downgrades from 52 bits to 48 bits.  Chris is 
going to test crash running live on a 52 bit simulator tomorrow.

Dave