[Crash-utility] [PATCH 0/1] arm64: Fix missing offset for modules_vaddr with aarch64 guest dump

[Dave Anderson]

----- Original Message -----
...
> 
> Thanks, I didn't know qemu has '-device vmcoreinfo' option.
> 
> It seems that the vmcoreinfo option works for aarch64 as well.
> The KASLR issue and the modules_vaddr issue are gone with
> vmcoreinfo option. Great!
> 
> However, VA_BITS issue still remains the vmcoreinfo doesn't have
> 'NUMBER(tcr_el1_t1sz)'.
> I suppose we can use 'NUMBER(VA_BITS)' instead, so I'll post
> another patch later.

Right -- Bhupesh is still working on getting NUMBER(tcr_el1_t1sz) 
accepted upstream.  

> 
> BTW, could you merge the patch which I posted today
> in case the '-device vmcoreinfo' isn't set to qemu?
> https://www.redhat.com/archives/crash-utility/2020-January/msg00010.html

Honestly, I'm leaning against doing it, especially since the other two 
issues that you referenced (VA_BITS and KASLR) would still exist without
"-device vmcoreinfo".  

I'd prefer not to put in a bunch of patches for problems that would only exist
because a user has not properly configured QEMU.  The whole point of the 
vmcoreinfo device is specifically for its use by the crash utility.

Comments?

Dave


 
> Thanks,
> Masa
> 
> > 
> > Anyway, Daisuke should be able fill in the details.
> > 
> > Dave
> > 
> > 
> > > 
> > > Dave
> > >    
> > > 
> > > > 
> > > > - Masa
> > > > 
> > > > > 
> > > > > Dave
> > > > > 
> > > > > 
> > > > > > 
> > > > > > ./crash -d1 vmlinux-v5.4 dump.v5.4
> > > > > > ...
> > > > > > vmcore_data:
> > > > > >                   flags: c0 (KDUMP_LOCAL|KDUMP_ELF64)
> > > > > >                    ndfd: 3
> > > > > >                     ofp: ffffa5e81588
> > > > > >             header_size: 30896
> > > > > >    num_pt_load_segments: 1
> > > > > >      pt_load_segment[0]:
> > > > > >             file_offset: 78b0
> > > > > >              phys_start: 40000000
> > > > > >                phys_end: 260000000
> > > > > >               zero_fill: 0
> > > > > >              elf_header: 2ed6d4e0
> > > > > >                   elf32: 0
> > > > > >                 notes32: 0
> > > > > >                  load32: 0
> > > > > >                   elf64: 2ed6d4e0
> > > > > >                 notes64: 2ed6d520
> > > > > >                  load64: 2ed6d558
> > > > > >                sect0_64: 0
> > > > > >             nt_prstatus: 2ed6d590
> > > > > >             nt_prpsinfo: 0
> > > > > >           nt_taskstruct: 0
> > > > > >             task_struct: 0
> > > > > >              arch_data1: (unused)
> > > > > >              arch_data2: (unused)
> > > > > >            switch_stack: 0
> > > > > >               page_size: 0
> > > > > >          xen_kdump_data: (unused)
> > > > > >      num_prstatus_notes: 32
> > > > > >          num_qemu_notes: 0
> > > > > >              vmcoreinfo: 0
> > > > > >         size_vmcoreinfo: 0
> > > > > >      nt_prstatus_percpu:
> > > > > >         000000002ed6d590 000000002ed6d950 000000002ed6dd10
> > > > > >         000000002ed6e0d0
> > > > > >         000000002ed6e490 000000002ed6e850 000000002ed6ec10
> > > > > >         000000002ed6efd0
> > > > > >         000000002ed6f390 000000002ed6f750 000000002ed6fb10
> > > > > >         000000002ed6fed0
> > > > > >         000000002ed70290 000000002ed70650 000000002ed70a10
> > > > > >         000000002ed70dd0
> > > > > >         000000002ed71190 000000002ed71550 000000002ed71910
> > > > > >         000000002ed71cd0
> > > > > >         000000002ed72090 000000002ed72450 000000002ed72810
> > > > > >         000000002ed72bd0
> > > > > >         000000002ed72f90 000000002ed73350 000000002ed73710
> > > > > >         000000002ed73ad0
> > > > > >         000000002ed73e90 000000002ed74250 000000002ed74610
> > > > > >         000000002ed749d0
> > > > > >          nt_qemu_percpu:
> > > > > >        backup_src_start: 0
> > > > > >         backup_src_size: 0
> > > > > >           backup_offset: 0
> > > > > > ...
> > > > > > 
> > > > > > Thanks,
> > > > > > Masa
> > > > > > 
> > > > > > > 
> > > > > > > Dave
> > > > > > > 
> > > > > > >   I
> > > > > > > > 
> > > > > > > > 1. KASLR
> > > > > > > >    crash doesn't work in case KASLR is enabled on the guest.
> > > > > > > >    That is because the memory dump doesn't have vmcoreinfo, so
> > > > > > > >    we
> > > > > > > >    cannot get the relocation position.
> > > > > > > >    I suppose we need to implement calc_kaslr_offset() for
> > > > > > > >    aarch64.
> > > > > > > >    nokaslr with the guest kernel parameter is a workaround.
> > > > > > > > 
> > > > > > > > 2. VA_BITS
> > > > > > > >    crash doesn't work in case the guest kernel is v5.4 and
> > > > > > > >    later.
> > > > > > > >    That is because the memory dump doesn't have vmcoreinfo, so
> > > > > > > >    we
> > > > > > > >    cannot get vabits_actual.
> > > > > > > >    I think there's no workaround so far...
> > > > > > > > 
> > > > > > > > Masayoshi Mizuma (1):
> > > > > > > >   arm64: Fix missing offset for modules_vaddr with aarch64
> > > > > > > >   guest
> > > > > > > >   dump
> > > > > > > > 
> > > > > > > >  arm64.c | 2 ++
> > > > > > > >  defs.h  | 3 +++
> > > > > > > >  2 files changed, 5 insertions(+)
> > > > > > > > 
> > > > > > > > --
> > > > > > > > 2.18.1
> > > > > > > > 
> > > > > > > > 
> > > > > > > > --
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> > > > > > > > Crash-utility at redhat.com
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> > > > > > > > 
> > > > > > > 
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> > > > > > 
> > > > > > 
> > > > > 
> > > > 
> > > > 
> > > 
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