linux/arch
AKASHI Takahiro b799a09f63 kexec_file: make use of purgatory optional
Patch series "kexec_file, x86, powerpc: refactoring for other
architecutres", v2.

This is a preparatory patchset for adding kexec_file support on arm64.

It was originally included in a arm64 patch set[1], but Philipp is also
working on their kexec_file support on s390[2] and some changes are now
conflicting.

So these common parts were extracted and put into a separate patch set
for better integration.  What's more, my original patch#4 was split into
a few small chunks for easier review after Dave's comment.

As such, the resulting code is basically identical with my original, and
the only *visible* differences are:

 - renaming of _kexec_kernel_image_probe() and  _kimage_file_post_load_cleanup()

 - change one of types of arguments at prepare_elf64_headers()

Those, unfortunately, require a couple of trivial changes on the rest
(#1, #6 to #13) of my arm64 kexec_file patch set[1].

Patch #1 allows making a use of purgatory optional, particularly useful
for arm64.

Patch #2 commonalizes arch_kexec_kernel_{image_probe, image_load,
verify_sig}() and arch_kimage_file_post_load_cleanup() across
architectures.

Patches #3-#7 are also intended to generalize parse_elf64_headers(),
along with exclude_mem_range(), to be made best re-use of.

[1] http://lists.infradead.org/pipermail/linux-arm-kernel/2018-February/561182.html
[2] http://lkml.iu.edu//hypermail/linux/kernel/1802.1/02596.html

This patch (of 7):

On arm64, crash dump kernel's usable memory is protected by *unmapping*
it from kernel virtual space unlike other architectures where the region
is just made read-only.  It is highly unlikely that the region is
accidentally corrupted and this observation rationalizes that digest
check code can also be dropped from purgatory.  The resulting code is so
simple as it doesn't require a bit ugly re-linking/relocation stuff,
i.e.  arch_kexec_apply_relocations_add().

Please see:

   http://lists.infradead.org/pipermail/linux-arm-kernel/2017-December/545428.html

All that the purgatory does is to shuffle arguments and jump into a new
kernel, while we still need to have some space for a hash value
(purgatory_sha256_digest) which is never checked against.

As such, it doesn't make sense to have trampline code between old kernel
and new kernel on arm64.

This patch introduces a new configuration, ARCH_HAS_KEXEC_PURGATORY, and
allows related code to be compiled in only if necessary.

[takahiro.akashi@linaro.org: fix trivial screwup]
  Link: http://lkml.kernel.org/r/20180309093346.GF25863@linaro.org
Link: http://lkml.kernel.org/r/20180306102303.9063-2-takahiro.akashi@linaro.org
Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Acked-by: Dave Young <dyoung@redhat.com>
Tested-by: Dave Young <dyoung@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Baoquan He <bhe@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-13 17:10:27 -07:00
..
alpha mm: introduce MAP_FIXED_NOREPLACE 2018-04-11 10:28:38 -07:00
arc Merge branch 'akpm' (patches from Andrew) 2018-04-06 14:19:26 -07:00
arm ARM: SoC fixes for 4.17 2018-04-11 16:12:21 -07:00
arm64 arm64: turn flush_dcache_mmap_lock into a no-op 2018-04-11 10:28:39 -07:00
c6x c6x: pass endianness info to sparse 2018-04-10 09:58:58 -04:00
h8300 h8300: remove extraneous __BIG_ENDIAN definition 2018-03-22 17:07:01 -07:00
hexagon
ia64 pci-v4.17-changes 2018-04-06 18:31:06 -07:00
m68k Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gerg/m68knommu 2018-04-09 09:15:46 -07:00
microblaze Microblaze patches for 4.17-rc1 2018-04-12 10:18:02 -07:00
mips mm/gup.c: document return value 2018-04-13 17:10:27 -07:00
nds32 page cache: use xa_lock 2018-04-11 10:28:39 -07:00
nios2 nios2 update for v4.17-rc1 2018-04-11 16:02:18 -07:00
openrisc Merge branch 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-04-04 15:19:26 -07:00
parisc Merge branch 'parisc-4.17-2' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux 2018-04-12 17:07:04 -07:00
powerpc kexec_file: make use of purgatory optional 2018-04-13 17:10:27 -07:00
riscv RISC-V changes for 4.17 2018-04-04 16:43:47 -07:00
s390 mm/gup.c: document return value 2018-04-13 17:10:27 -07:00
sh mm/gup.c: document return value 2018-04-13 17:10:27 -07:00
sparc mm/gup.c: document return value 2018-04-13 17:10:27 -07:00
um Merge git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml 2018-04-11 16:36:47 -07:00
unicore32 unicore32: turn flush_dcache_mmap_lock into a no-op 2018-04-11 10:28:39 -07:00
x86 kexec_file: make use of purgatory optional 2018-04-13 17:10:27 -07:00
xtensa mm: introduce MAP_FIXED_NOREPLACE 2018-04-11 10:28:38 -07:00
.gitignore
Kconfig kbuild: remove incremental linking option 2018-03-26 02:01:19 +09:00