As Eric said,
 "what we need to do is move the variable vmcoreinfo_note out of the
  kernel's .bss section. And modify the code to regenerate and keep this
  information in something like the control page.

  Definitely something like this needs a page all to itself, and ideally
  far away from any other kernel data structures. I clearly was not
  watching closely the data someone decided to keep this silly thing in
  the kernel's .bss section."

This patch allocates extra pages for these vmcoreinfo_XXX variables, one
advantage is that it enhances some safety of vmcoreinfo, because
vmcoreinfo now is kept far away from other kernel data structures.

Link: http://lkml.kernel.org/r/1493281021-20737-1-git-send-email-xlpang@redhat.comSigned-off-by: NXunlei Pang <xlpang@redhat.com>
Tested-by: NMichael Holzheu <holzheu@linux.vnet.ibm.com>
Reviewed-by: NJuergen Gross <jgross@suse.com>
Suggested-by: NEric Biederman <ebiederm@xmission.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dave Young <dyoung@redhat.com>
Cc: Hari Bathini <hbathini@linux.vnet.ibm.com>
Cc: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Get rid of multiple definitions of append_elf_note() & final_note()
functions.  Reuse these functions compiled under CONFIG_CRASH_CORE Also,
define Elf_Word and use it instead of generic u32 or the more specific
Elf64_Word.

Link: http://lkml.kernel.org/r/149035342324.6881.11667840929850361402.stgit@hbathini.in.ibm.comSigned-off-by: NHari Bathini <hbathini@linux.vnet.ibm.com>
Acked-by: NDave Young <dyoung@redhat.com>
Acked-by: NTony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Patch series "kexec/fadump: remove dependency with CONFIG_KEXEC and
reuse crashkernel parameter for fadump", v4.

Traditionally, kdump is used to save vmcore in case of a crash.  Some
architectures like powerpc can save vmcore using architecture specific
support instead of kexec/kdump mechanism.  Such architecture specific
support also needs to reserve memory, to be used by dump capture kernel.
crashkernel parameter can be a reused, for memory reservation, by such
architecture specific infrastructure.

This patchset removes dependency with CONFIG_KEXEC for crashkernel
parameter and vmcoreinfo related code as it can be reused without kexec
support.  Also, crashkernel parameter is reused instead of
fadump_reserve_mem to reserve memory for fadump.

The first patch moves crashkernel parameter parsing and vmcoreinfo
related code under CONFIG_CRASH_CORE instead of CONFIG_KEXEC_CORE.  The
second patch reuses the definitions of append_elf_note() & final_note()
functions under CONFIG_CRASH_CORE in IA64 arch code.  The third patch
removes dependency on CONFIG_KEXEC for firmware-assisted dump (fadump)
in powerpc.  The next patch reuses crashkernel parameter for reserving
memory for fadump, instead of the fadump_reserve_mem parameter.  This
has the advantage of using all syntaxes crashkernel parameter supports,
for fadump as well.  The last patch updates fadump kernel documentation
about use of crashkernel parameter.

This patch (of 5):

Traditionally, kdump is used to save vmcore in case of a crash.  Some
architectures like powerpc can save vmcore using architecture specific
support instead of kexec/kdump mechanism.  Such architecture specific
support also needs to reserve memory, to be used by dump capture kernel.
crashkernel parameter can be a reused, for memory reservation, by such
architecture specific infrastructure.

But currently, code related to vmcoreinfo and parsing of crashkernel
parameter is built under CONFIG_KEXEC_CORE.  This patch introduces
CONFIG_CRASH_CORE and moves the above mentioned code under this config,
allowing code reuse without dependency on CONFIG_KEXEC.  There is no
functional change with this patch.

Link: http://lkml.kernel.org/r/149035338104.6881.4550894432615189948.stgit@hbathini.in.ibm.comSigned-off-by: NHari Bathini <hbathini@linux.vnet.ibm.com>
Acked-by: NDave Young <dyoung@redhat.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>