[Xen-devel] [PATCH v3] Livepatching patch set for 4.10

[Konrad Rzeszutek Wilk <konrad@xxxxxxxxxx>]

Hey,

As I was trying to port livepatch-build-tools.git to work under ARM32 and ARM64
(still ongoing, if somebody wants to help/take over would appreciate it)
I found some inconsistencies compared to the x86 and test-cases:
 - The .livepatch.funcs in the test-cases are in RW section but the 
livepatch-build-tools
   puts them in the RO sections. That works on x86 as arch_livepatch_quiesce
   turns of WP globally during the livepatching.
   But not on ARM.. and to make it work there I ended up using the vmap 
functionality.
   Which then I made common on x86 as well (so no more CR4 mucking).
   This meant however meant mucking with x86 code page walker to
   have a do_page_walk functionality.

 - Cross compiling ARM32 introduces subtle alignment issues. Mainly
   both .altinstructions and .livepatch.depends end up with the
   wrong alingment and the hypervisor blows up. Both fixes are
   in the patchset.

I am also including in this patchset:

 - Declare the livepatch supported on x86 (but not ARM). It has latest
   feedback from Andrew and George (I hope!)

 - Post the local/global symbol patchset functionality. Only Jan had
   commented and I would appreciate other folks feedback - perhaps
   folks have better ideas on this?

Lastly, I tested this on ARM32 (Cubietruck), ARM64 (HiKey960) and
on x86. All looked good until I enabled CONFIG_DEBUG_SCRUB - which
is reported in:
https://lists.xen.org/archives/html/xen-devel/2017-09/msg01147.html

Patches are in 

  git://xenbits.xen.org/people/konradwilk/xen.git staging-for-4.10.v3

 docs/features/livepatch.pandoc         | 106 ++++++++++++++++
 docs/misc/livepatch.markdown           |   4 +
 xen/arch/arm/arm32/livepatch.c         |  33 ++++-
 xen/arch/arm/arm64/livepatch.c         |  17 ++-
 xen/arch/arm/livepatch.c               |  49 +-------
 xen/arch/arm/xen.lds.S                 |   2 -
 xen/arch/x86/livepatch.c               |  36 ++++--
 xen/arch/x86/x86_64/mm.c               |  33 +++--
 xen/arch/x86/xen.lds.S                 |   1 -
 xen/common/Kconfig                     |   4 +-
 xen/common/livepatch.c                 | 219 +++++++++++++++++++++++++--------
 xen/common/livepatch_elf.c             |  13 ++
 xen/include/asm-arm/alternative.h      |   4 +
 xen/include/asm-arm/livepatch.h        |   6 -
 xen/include/asm-x86/alternative.h      |   1 +
 xen/include/asm-x86/mm.h               |   1 +
 xen/include/xen/elfstructs.h           |   2 +
 xen/include/xen/livepatch.h            |  23 +++-
 xen/include/xen/livepatch_elf.h        |   7 ++
 xen/test/livepatch/Makefile            |  76 +++++++-----
 xen/test/livepatch/xen_bye_world.c     |   1 +
 xen/test/livepatch/xen_hello_world.c   |   1 +
 xen/test/livepatch/xen_local_symbols.c |  53 ++++++++
 xen/test/livepatch/xen_nop.c           |   1 +
 xen/test/livepatch/xen_replace_world.c |   1 +
 25 files changed, 521 insertions(+), 173 deletions(-)

Konrad Rzeszutek Wilk (16):
      livepatch: Expand check for safe_for_reapply if livepatch has only 
.rodata.
      livepatch: Tighten alignment checks.
      livepatch: Include sizes when an mismatch occurs
      xen/livepatch/ARM32: Don't load and crash on livepatches loaded with 
wrong text alignment.
      alternative/x86/arm32: Align altinstructions (and altinstr_replacement) 
sections.
      xen/livepatch/x86/arm32: Force .livepatch.depends section to be uint32_t 
aligned.
      livepatch/arm/x86: Strip note_depends symbol from test-cases.
      livepatch/tests: Make sure all .livepatch.funcs sections are read-only
      livepatch/arm[32,64]: Modify livepatch_funcs
      livepatch/x86/arm[32,64]: Use common vmap code for applying.
      livepatch/x86/arm[32,64]: Unify arch_livepatch_revert
      livepatch: Expand spin_debug_disable in [apply|revert]_payload
      livepatch/x86/arm: arch/x86/mm: generalize do_page_walk() and implement 
arch_livepatch_lookup_mfn
      livepatch/x86/arm: Utilize the arch_livepatch_lookup_mfn
      livepatch: Add local and global symbol resolution.
      livepatch: Add xen_local_symbols test-case

Ross Lagerwall (1):
      livepatch: Declare live patching as a supported feature


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