Another turn of the livepatch callback crank. This version cleans up
some minor issues found in v5 and was rebased on top of Jiri's branches
listed below.
Unfortunately, I didn't have time to test out Petr's suggestion to move
the pre-patch callback inside klp_patch_object() and the post-unpatch
callback into klp_unpatch_object()... let me know if this is a
deal-breaker (I think it would be possible to revisit this later if
need be.)
Thanks for all the feedback and suggestions thus far!
-- Joe
v6:
- Rebased on-top of jiri_livepatching/
- for-4.14/upstream-fixes
- for-4.15/shadow-variables
Rebasing changes:
- kernel/livepatch/core.c: code moved from klp_module_going() to
klp_cleanup_module_patches_limited()
- samples/livepatch/Makefile: patch context changes due to shadow
variable samples
- Documentation
- s/pare/pair
- add note about reversed transitions and post-patch/pre-unpatch
callbacks
- add Josh's extended text about which callbacks will run
- Debug messages
- Fix pr_debug at beginning of klp_init_transition() to display the
intended target state
- Expand "canceling patching transition" pr_debug message
- Misc
- s/callbacks_enabled/post_unpatch_enabled and moved to struct
klp_callbacks per Miroslav's suggestion
- Added Acked-by and Reviewed-by tags to patches 1 and 2
v5:
- Move code comments from kernel/livepatch/core.h to
include/linux/livepatch.h's struct klp_callbacks definition
- Change int klp_object.prepatch_callback_status to a bool
klp_object.callbacks_enabled
- fixes a hole where returned status=0 wasn't distinguished from
"never-ran" status=0
- Removed a few extraneous checks in the execute callback routines
- In the module-coming case, be sure to execute the post-unpatch
callback in the event that patching fails
- Moved my Signed-off-by line to the bottom in patches 2 and 3
v4:
- Move callback helpers into core.h
- Move klp_pre_patch_callback() and klp_pre_unpatch_callback()
invocations into __klp_enable_patch() and __klp_disable_patch()
- klp_patch_object() and klp_unpatch_objects()
- Do not run pre-unpatch callbacks from here
- Add a pre_patch_status member to klp_object so when a pre-patch
callback fails, the helpers can skip any post-patch, pre-unpatch,
post-unpatch callbacks
- klp_module_coming() and klp_module_going()
- Do not run post-patch or pre-unpatch callbacks for current
klp_transition_patch
- Documentation
- Add various test cases and provide commentary
- Samples
- Create two target modules: a simple one and another that invokes a
worker function that sleeps for a long time
- Added two follow-up patches:
- livepatch: move transition "complete" notice into
klp_complete_transition() - this pushes the "patching complete" message
after the post-patch callbacks
- livepatch: add transition notices - these were helpful during
debugging of the callback patch. The transaction annotations were
also used in the Documentation file tese cases to illustrate the
order of operations.
v3:
- livepatch.h
- drop obj->patched checks from pre/post-(un)patch funcs,
add preceding comment and note about obj->patched assumptions
- move core.c :: klp_is_module() to here
- klp_complete_transition()
- fix "else if (klp_target_state == KLP_UNPATCHED)" case
- combine conditional syntax when avoiding module_put for immediate
patches
- add check for klp_is_object_loaded to avoid callbacks for any
unloaded modules (necessary after removing obj->patched checks in
livepatch.h)
- Documentation
- added Josh's use-cases blurb in intro
- s/Callbacks are only executed/A callbacks is only executed/
- livepatch-callbacks-demo.c
- whitespace cleanup
v2:
- s/hooks/callbacks/g
- implemented pre-(un)patch and post-(un)patch callbacks
- pre-patch and pre-unpatch callbacks run from callers of
klp_patch_object() and klp_unpatch_object()
- post-patch and post-unpatch callbacks run from
klp_complete_transition() and klp_module_coming/going()
- reduce callbacks from a list to a single per-klp_object instance
- revamp the sample callback demo
- revamp documentation
Joe Lawrence (3):
livepatch: add (un)patch callbacks
livepatch: move transition "complete" notice into
klp_complete_transition()
livepatch: add transition notices
Documentation/livepatch/callbacks.txt | 605 ++++++++++++++++++++++++
include/linux/livepatch.h | 26 +
kernel/livepatch/core.c | 51 +-
kernel/livepatch/core.h | 38 ++
kernel/livepatch/patch.c | 1 +
kernel/livepatch/transition.c | 45 +-
samples/livepatch/Makefile | 3 +
samples/livepatch/livepatch-callbacks-busymod.c | 72 +++
samples/livepatch/livepatch-callbacks-demo.c | 234 +++++++++
samples/livepatch/livepatch-callbacks-mod.c | 53 +++
10 files changed, 1111 insertions(+), 17 deletions(-)
create mode 100644 Documentation/livepatch/callbacks.txt
create mode 100644 samples/livepatch/livepatch-callbacks-busymod.c
create mode 100644 samples/livepatch/livepatch-callbacks-demo.c
create mode 100644 samples/livepatch/livepatch-callbacks-mod.c
--
1.8.3.1
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