[PATCH v3] livepatch: shadow variables

[Joe Lawrence]

Hi all,

This is v3 of the livepatch shadow variable API.  v2 collected a bunch
of great feedback on terminology, use cases and concurrency notes which
I've tried to incorporate here.

Here's a high-level sketch of v2 changes:

- Overall
  
  - Squash into a one patch, makes for finding terms and code across
    docs/implementation/example easier
  
  - Variable naming:
    - obj, original data -> obj, parent object
    - num, numerical description of new data -> id, data identifier
    - new_data -> data
    - new_size -> size
  
- Documentation
  
  - API summary: s/klp_shadow_detach/klp_shadow_detach_all
  - describe uses for the data id (versions, class/type, etc)
  - clarify that shadow data is a copy
  - fix use-cases - use one upstream commit and steal Petr's example for
                    klp_shadow_get_or_attach()
  
- Implementation
  
  - Modify klp_shadow_get_or_attach() to WARN and return NULL if shadow
    variable already exists
  
  - Add klp_shadow_update_or_attach() to update if shadow variable already
    exists
  
  
- Sample modules
  
  - s/_thread/_work_func
  - use system workqueue, DECLARE_DELAYED_WORK
  - use XXX_PERIOD constants
  - overhaul usage/comments, drop the verbose dmesg logs

Joe Lawrence (1):
  livepatch: introduce shadow variable API

 Documentation/livepatch/shadow-vars.txt   | 217 +++++++++++++++++
 include/linux/livepatch.h                 |  10 +
 kernel/livepatch/Makefile                 |   2 +-
 kernel/livepatch/shadow.c                 | 383 ++++++++++++++++++++++++++++++
 samples/Kconfig                           |   5 +-
 samples/livepatch/Makefile                |   3 +
 samples/livepatch/livepatch-shadow-mod.c  | 222 +++++++++++++++++
 samples/livepatch/livepatch-shadow-fix1.c | 174 ++++++++++++++
 samples/livepatch/livepatch-shadow-fix2.c | 167 +++++++++++++
 9 files changed, 1179 insertions(+), 4 deletions(-)
 create mode 100644 Documentation/livepatch/shadow-vars.txt
 create mode 100644 kernel/livepatch/shadow.c
 create mode 100644 samples/livepatch/livepatch-shadow-mod.c
 create mode 100644 samples/livepatch/livepatch-shadow-fix1.c
 create mode 100644 samples/livepatch/livepatch-shadow-fix2.c

-- 
1.8.3.1