----- Original Message -----
>
> Hi Sergio,
>
> I have one obvious question. Throughout the patch-set you are using
> KDUMP_DUMPFILE() as a qualifier, which is restricted to ELF vmcores
> only. While the use of ELF vmcores is an option, it's far more likely
> that the output format of "virsh dump --memory-only" will utilize one
> of the compressed kdump formats, using zlib, lzo or snappy.
>
> Dave
And aside from support for compressed kdumps, i.e., DISKDUMP_DUMPFILE(),
when I requested segregation of this QEMU-dumps-with-no-VMCOREINFO code,
here's what I meant.
Instead of using KDUMP_DUMPFILE() and/or DISKDUMP_DUMPFILE() as top-level
qualifiers for this patchset, the qualifier should restrict it to only
virsh dump generated dumpfiles that do not have VMCOREINFO notes. Note
that these pc->flags2 bits already exist:
QEMU_MEM_DUMP_ELF
QEMU_MEM_DUMP_COMPRESSED
VMCOREINFO
For this patchset, I suggest creating a new QEMU_MEM_DUMP_NO_VMCOREINFO()
macro that looks something like:
#define QEM_MEM_DUMP_NO_VMCOREINFO() \
((pc->flags2 & (QEMU_MEM_DUMP_ELF|QEMU_MEM_DUMP_COMPRESSED)) && !(pc->flags2 & VMCOREINFO))
Then after any "if (QEM_MEM_DUMP_NO_VMCOREINFO()" qualifier applies, you
can use KDUMP_DUMPFILE() or DISKDUMP_DUMPFILE() within that code section to
branch appropriately.
Dave
>
>
> ----- Original Message -----
> > Commit 45b74b89530d611b3fa95a1041e158fbb865fa84 added support for
> > calculating phys_base and kernel offset for KASLR-enabled kernels on
> > SADUMPs by using a technique developed by Takao Indoh. Originally, the
> > patchset included support for KDUMPs, but this was dropped in v2, as it
> > was deemed unnecessary due to the implementation of the vmcoreinfo
> > device in QEMU.
> >
> > Sadly, there are many reasons for which the vmcoreinfo device may not be
> > present in the moment of taking the memory dump from a VM, ranging from
> > a Host running older QEMU/libvirt versions, to misconfigured VMs or
> > environments running Hypervisors that doesn't support this device.
> >
> > This patchset generalizes the kaslr related functions from sadump.c
> > moving them to kaslr_helper.c, and makes KDUMP analysis fallback to
> > KASLR offset calculation if vmcoreinfo data is missing.
> >
> > These changes have been successfully tested with a 3.10.0-830.el7.x86_64
> > under the following conditions:
> >
> > - kdump with KASLR and vmcoreinfo
> >
> > - kdump with KASLR but no vmcoreinfo
> >
> > - kdump without KASLR ("nokaslr" kernel command line option)
> >
> > It was also tested that a "crash" patched with these changes still
> > builds and runs (live and kdump debugging) on an aarch64 machine.
> >
> > Sergio Lopez (2):
> > Move kaslr related functions from sadump.c to kaslr_helper.c
> > kdump: if vmcoreinfo is missing, try to infer kaslr offset
> >
> > Makefile | 7 +-
> > defs.h | 15 ++
> > kaslr_helper.c | 466
> > ++++++++++++++++++++++++++++++++++++++++++++++++++++++
> > netdump.c | 73 +++++++++
> > netdump.h | 1 +
> > sadump.c | 487
> > +++++----------------------------------------------------
> > symbols.c | 29 ++--
> > x86_64.c | 14 +-
> > 8 files changed, 629 insertions(+), 463 deletions(-)
> > create mode 100644 kaslr_helper.c
> >
> > --
> > 2.14.3
> >
> >
>
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