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-rw-r--r--Documentation/livepatch/callbacks.txt489
1 files changed, 5 insertions, 484 deletions
diff --git a/Documentation/livepatch/callbacks.txt b/Documentation/livepatch/callbacks.txt
index c9776f48e458..182e31d4abce 100644
--- a/Documentation/livepatch/callbacks.txt
+++ b/Documentation/livepatch/callbacks.txt
@@ -118,488 +118,9 @@ similar change to their hw_features value. (Client functions of the
value may need to be updated accordingly.)
-Test cases
-==========
-
-What follows is not an exhaustive test suite of every possible livepatch
-pre/post-(un)patch combination, but a selection that demonstrates a few
-important concepts. Each test case uses the kernel modules located in
-the samples/livepatch/ and assumes that no livepatches are loaded at the
-beginning of the test.
-
-
-Test 1
-------
-
-Test a combination of loading a kernel module and a livepatch that
-patches a function in the first module. (Un)load the target module
-before the livepatch module:
-
-- load target module
-- load livepatch
-- disable livepatch
-- unload target module
-- unload livepatch
-
-First load a target module:
-
- % insmod samples/livepatch/livepatch-callbacks-mod.ko
- [ 34.475708] livepatch_callbacks_mod: livepatch_callbacks_mod_init
-
-On livepatch enable, before the livepatch transition starts, pre-patch
-callbacks are executed for vmlinux and livepatch_callbacks_mod (those
-klp_objects currently loaded). After klp_objects are patched according
-to the klp_patch, their post-patch callbacks run and the transition
-completes:
-
- % insmod samples/livepatch/livepatch-callbacks-demo.ko
- [ 36.503719] livepatch: enabling patch 'livepatch_callbacks_demo'
- [ 36.504213] livepatch: 'livepatch_callbacks_demo': initializing patching transition
- [ 36.504238] livepatch_callbacks_demo: pre_patch_callback: vmlinux
- [ 36.504721] livepatch_callbacks_demo: pre_patch_callback: livepatch_callbacks_mod -> [MODULE_STATE_LIVE] Normal state
- [ 36.505849] livepatch: 'livepatch_callbacks_demo': starting patching transition
- [ 37.727133] livepatch: 'livepatch_callbacks_demo': completing patching transition
- [ 37.727232] livepatch_callbacks_demo: post_patch_callback: vmlinux
- [ 37.727860] livepatch_callbacks_demo: post_patch_callback: livepatch_callbacks_mod -> [MODULE_STATE_LIVE] Normal state
- [ 37.728792] livepatch: 'livepatch_callbacks_demo': patching complete
-
-Similarly, on livepatch disable, pre-patch callbacks run before the
-unpatching transition starts. klp_objects are reverted, post-patch
-callbacks execute and the transition completes:
-
- % echo 0 > /sys/kernel/livepatch/livepatch_callbacks_demo/enabled
- [ 38.510209] livepatch: 'livepatch_callbacks_demo': initializing unpatching transition
- [ 38.510234] livepatch_callbacks_demo: pre_unpatch_callback: vmlinux
- [ 38.510982] livepatch_callbacks_demo: pre_unpatch_callback: livepatch_callbacks_mod -> [MODULE_STATE_LIVE] Normal state
- [ 38.512209] livepatch: 'livepatch_callbacks_demo': starting unpatching transition
- [ 39.711132] livepatch: 'livepatch_callbacks_demo': completing unpatching transition
- [ 39.711210] livepatch_callbacks_demo: post_unpatch_callback: vmlinux
- [ 39.711779] livepatch_callbacks_demo: post_unpatch_callback: livepatch_callbacks_mod -> [MODULE_STATE_LIVE] Normal state
- [ 39.712735] livepatch: 'livepatch_callbacks_demo': unpatching complete
-
- % rmmod samples/livepatch/livepatch-callbacks-demo.ko
- % rmmod samples/livepatch/livepatch-callbacks-mod.ko
- [ 42.534183] livepatch_callbacks_mod: livepatch_callbacks_mod_exit
-
-
-Test 2
-------
-
-This test is similar to the previous test, but (un)load the livepatch
-module before the target kernel module. This tests the livepatch core's
-module_coming handler:
-
-- load livepatch
-- load target module
-- disable livepatch
-- unload livepatch
-- unload target module
-
-
-On livepatch enable, only pre/post-patch callbacks are executed for
-currently loaded klp_objects, in this case, vmlinux:
-
- % insmod samples/livepatch/livepatch-callbacks-demo.ko
- [ 44.553328] livepatch: enabling patch 'livepatch_callbacks_demo'
- [ 44.553997] livepatch: 'livepatch_callbacks_demo': initializing patching transition
- [ 44.554049] livepatch_callbacks_demo: pre_patch_callback: vmlinux
- [ 44.554845] livepatch: 'livepatch_callbacks_demo': starting patching transition
- [ 45.727128] livepatch: 'livepatch_callbacks_demo': completing patching transition
- [ 45.727212] livepatch_callbacks_demo: post_patch_callback: vmlinux
- [ 45.727961] livepatch: 'livepatch_callbacks_demo': patching complete
-
-When a targeted module is subsequently loaded, only its pre/post-patch
-callbacks are executed:
-
- % insmod samples/livepatch/livepatch-callbacks-mod.ko
- [ 46.560845] livepatch: applying patch 'livepatch_callbacks_demo' to loading module 'livepatch_callbacks_mod'
- [ 46.561988] livepatch_callbacks_demo: pre_patch_callback: livepatch_callbacks_mod -> [MODULE_STATE_COMING] Full formed, running module_init
- [ 46.563452] livepatch_callbacks_demo: post_patch_callback: livepatch_callbacks_mod -> [MODULE_STATE_COMING] Full formed, running module_init
- [ 46.565495] livepatch_callbacks_mod: livepatch_callbacks_mod_init
-
-On livepatch disable, all currently loaded klp_objects' (vmlinux and
-livepatch_callbacks_mod) pre/post-unpatch callbacks are executed:
-
- % echo 0 > /sys/kernel/livepatch/livepatch_callbacks_demo/enabled
- [ 48.568885] livepatch: 'livepatch_callbacks_demo': initializing unpatching transition
- [ 48.568910] livepatch_callbacks_demo: pre_unpatch_callback: vmlinux
- [ 48.569441] livepatch_callbacks_demo: pre_unpatch_callback: livepatch_callbacks_mod -> [MODULE_STATE_LIVE] Normal state
- [ 48.570502] livepatch: 'livepatch_callbacks_demo': starting unpatching transition
- [ 49.759091] livepatch: 'livepatch_callbacks_demo': completing unpatching transition
- [ 49.759171] livepatch_callbacks_demo: post_unpatch_callback: vmlinux
- [ 49.759742] livepatch_callbacks_demo: post_unpatch_callback: livepatch_callbacks_mod -> [MODULE_STATE_LIVE] Normal state
- [ 49.760690] livepatch: 'livepatch_callbacks_demo': unpatching complete
-
- % rmmod samples/livepatch/livepatch-callbacks-demo.ko
- % rmmod samples/livepatch/livepatch-callbacks-mod.ko
- [ 52.592283] livepatch_callbacks_mod: livepatch_callbacks_mod_exit
-
-
-Test 3
-------
-
-Test loading the livepatch after a targeted kernel module, then unload
-the kernel module before disabling the livepatch. This tests the
-livepatch core's module_going handler:
-
-- load target module
-- load livepatch
-- unload target module
-- disable livepatch
-- unload livepatch
-
-First load a target module, then the livepatch:
-
- % insmod samples/livepatch/livepatch-callbacks-mod.ko
- [ 54.607948] livepatch_callbacks_mod: livepatch_callbacks_mod_init
-
- % insmod samples/livepatch/livepatch-callbacks-demo.ko
- [ 56.613919] livepatch: enabling patch 'livepatch_callbacks_demo'
- [ 56.614411] livepatch: 'livepatch_callbacks_demo': initializing patching transition
- [ 56.614436] livepatch_callbacks_demo: pre_patch_callback: vmlinux
- [ 56.614818] livepatch_callbacks_demo: pre_patch_callback: livepatch_callbacks_mod -> [MODULE_STATE_LIVE] Normal state
- [ 56.615656] livepatch: 'livepatch_callbacks_demo': starting patching transition
- [ 57.759070] livepatch: 'livepatch_callbacks_demo': completing patching transition
- [ 57.759147] livepatch_callbacks_demo: post_patch_callback: vmlinux
- [ 57.759621] livepatch_callbacks_demo: post_patch_callback: livepatch_callbacks_mod -> [MODULE_STATE_LIVE] Normal state
- [ 57.760307] livepatch: 'livepatch_callbacks_demo': patching complete
-
-When a target module is unloaded, the livepatch is only reverted from
-that klp_object (livepatch_callbacks_mod). As such, only its pre and
-post-unpatch callbacks are executed when this occurs:
-
- % rmmod samples/livepatch/livepatch-callbacks-mod.ko
- [ 58.623409] livepatch_callbacks_mod: livepatch_callbacks_mod_exit
- [ 58.623903] livepatch_callbacks_demo: pre_unpatch_callback: livepatch_callbacks_mod -> [MODULE_STATE_GOING] Going away
- [ 58.624658] livepatch: reverting patch 'livepatch_callbacks_demo' on unloading module 'livepatch_callbacks_mod'
- [ 58.625305] livepatch_callbacks_demo: post_unpatch_callback: livepatch_callbacks_mod -> [MODULE_STATE_GOING] Going away
-
-When the livepatch is disabled, pre and post-unpatch callbacks are run
-for the remaining klp_object, vmlinux:
-
- % echo 0 > /sys/kernel/livepatch/livepatch_callbacks_demo/enabled
- [ 60.638420] livepatch: 'livepatch_callbacks_demo': initializing unpatching transition
- [ 60.638444] livepatch_callbacks_demo: pre_unpatch_callback: vmlinux
- [ 60.638996] livepatch: 'livepatch_callbacks_demo': starting unpatching transition
- [ 61.727088] livepatch: 'livepatch_callbacks_demo': completing unpatching transition
- [ 61.727165] livepatch_callbacks_demo: post_unpatch_callback: vmlinux
- [ 61.727985] livepatch: 'livepatch_callbacks_demo': unpatching complete
-
- % rmmod samples/livepatch/livepatch-callbacks-demo.ko
-
-
-Test 4
-------
-
-This test is similar to the previous test, however the livepatch is
-loaded first. This tests the livepatch core's module_coming and
-module_going handlers:
-
-- load livepatch
-- load target module
-- unload target module
-- disable livepatch
-- unload livepatch
-
-First load the livepatch:
-
- % insmod samples/livepatch/livepatch-callbacks-demo.ko
- [ 64.661552] livepatch: enabling patch 'livepatch_callbacks_demo'
- [ 64.662147] livepatch: 'livepatch_callbacks_demo': initializing patching transition
- [ 64.662175] livepatch_callbacks_demo: pre_patch_callback: vmlinux
- [ 64.662850] livepatch: 'livepatch_callbacks_demo': starting patching transition
- [ 65.695056] livepatch: 'livepatch_callbacks_demo': completing patching transition
- [ 65.695147] livepatch_callbacks_demo: post_patch_callback: vmlinux
- [ 65.695561] livepatch: 'livepatch_callbacks_demo': patching complete
-
-When a targeted kernel module is subsequently loaded, only its
-pre/post-patch callbacks are executed:
-
- % insmod samples/livepatch/livepatch-callbacks-mod.ko
- [ 66.669196] livepatch: applying patch 'livepatch_callbacks_demo' to loading module 'livepatch_callbacks_mod'
- [ 66.669882] livepatch_callbacks_demo: pre_patch_callback: livepatch_callbacks_mod -> [MODULE_STATE_COMING] Full formed, running module_init
- [ 66.670744] livepatch_callbacks_demo: post_patch_callback: livepatch_callbacks_mod -> [MODULE_STATE_COMING] Full formed, running module_init
- [ 66.672873] livepatch_callbacks_mod: livepatch_callbacks_mod_init
-
-When the target module is unloaded, the livepatch is only reverted from
-the livepatch_callbacks_mod klp_object. As such, only pre and
-post-unpatch callbacks are executed when this occurs:
-
- % rmmod samples/livepatch/livepatch-callbacks-mod.ko
- [ 68.680065] livepatch_callbacks_mod: livepatch_callbacks_mod_exit
- [ 68.680688] livepatch_callbacks_demo: pre_unpatch_callback: livepatch_callbacks_mod -> [MODULE_STATE_GOING] Going away
- [ 68.681452] livepatch: reverting patch 'livepatch_callbacks_demo' on unloading module 'livepatch_callbacks_mod'
- [ 68.682094] livepatch_callbacks_demo: post_unpatch_callback: livepatch_callbacks_mod -> [MODULE_STATE_GOING] Going away
-
- % echo 0 > /sys/kernel/livepatch/livepatch_callbacks_demo/enabled
- [ 70.689225] livepatch: 'livepatch_callbacks_demo': initializing unpatching transition
- [ 70.689256] livepatch_callbacks_demo: pre_unpatch_callback: vmlinux
- [ 70.689882] livepatch: 'livepatch_callbacks_demo': starting unpatching transition
- [ 71.711080] livepatch: 'livepatch_callbacks_demo': completing unpatching transition
- [ 71.711481] livepatch_callbacks_demo: post_unpatch_callback: vmlinux
- [ 71.711988] livepatch: 'livepatch_callbacks_demo': unpatching complete
-
- % rmmod samples/livepatch/livepatch-callbacks-demo.ko
-
-
-Test 5
-------
-
-A simple test of loading a livepatch without one of its patch target
-klp_objects ever loaded (livepatch_callbacks_mod):
-
-- load livepatch
-- disable livepatch
-- unload livepatch
-
-Load the livepatch:
-
- % insmod samples/livepatch/livepatch-callbacks-demo.ko
- [ 74.711081] livepatch: enabling patch 'livepatch_callbacks_demo'
- [ 74.711595] livepatch: 'livepatch_callbacks_demo': initializing patching transition
- [ 74.711639] livepatch_callbacks_demo: pre_patch_callback: vmlinux
- [ 74.712272] livepatch: 'livepatch_callbacks_demo': starting patching transition
- [ 75.743137] livepatch: 'livepatch_callbacks_demo': completing patching transition
- [ 75.743219] livepatch_callbacks_demo: post_patch_callback: vmlinux
- [ 75.743867] livepatch: 'livepatch_callbacks_demo': patching complete
-
-As expected, only pre/post-(un)patch handlers are executed for vmlinux:
-
- % echo 0 > /sys/kernel/livepatch/livepatch_callbacks_demo/enabled
- [ 76.716254] livepatch: 'livepatch_callbacks_demo': initializing unpatching transition
- [ 76.716278] livepatch_callbacks_demo: pre_unpatch_callback: vmlinux
- [ 76.716666] livepatch: 'livepatch_callbacks_demo': starting unpatching transition
- [ 77.727089] livepatch: 'livepatch_callbacks_demo': completing unpatching transition
- [ 77.727194] livepatch_callbacks_demo: post_unpatch_callback: vmlinux
- [ 77.727907] livepatch: 'livepatch_callbacks_demo': unpatching complete
+Other Examples
+==============
- % rmmod samples/livepatch/livepatch-callbacks-demo.ko
-
-
-Test 6
-------
-
-Test a scenario where a vmlinux pre-patch callback returns a non-zero
-status (ie, failure):
-
-- load target module
-- load livepatch -ENODEV
-- unload target module
-
-First load a target module:
-
- % insmod samples/livepatch/livepatch-callbacks-mod.ko
- [ 80.740520] livepatch_callbacks_mod: livepatch_callbacks_mod_init
-
-Load the livepatch module, setting its 'pre_patch_ret' value to -19
-(-ENODEV). When its vmlinux pre-patch callback executed, this status
-code will propagate back to the module-loading subsystem. The result is
-that the insmod command refuses to load the livepatch module:
-
- % insmod samples/livepatch/livepatch-callbacks-demo.ko pre_patch_ret=-19
- [ 82.747326] livepatch: enabling patch 'livepatch_callbacks_demo'
- [ 82.747743] livepatch: 'livepatch_callbacks_demo': initializing patching transition
- [ 82.747767] livepatch_callbacks_demo: pre_patch_callback: vmlinux
- [ 82.748237] livepatch: pre-patch callback failed for object 'vmlinux'
- [ 82.748637] livepatch: failed to enable patch 'livepatch_callbacks_demo'
- [ 82.749059] livepatch: 'livepatch_callbacks_demo': canceling transition, going to unpatch
- [ 82.749060] livepatch: 'livepatch_callbacks_demo': completing unpatching transition
- [ 82.749868] livepatch: 'livepatch_callbacks_demo': unpatching complete
- [ 82.765809] insmod: ERROR: could not insert module samples/livepatch/livepatch-callbacks-demo.ko: No such device
-
- % rmmod samples/livepatch/livepatch-callbacks-mod.ko
- [ 84.774238] livepatch_callbacks_mod: livepatch_callbacks_mod_exit
-
-
-Test 7
-------
-
-Similar to the previous test, setup a livepatch such that its vmlinux
-pre-patch callback returns success. However, when a targeted kernel
-module is later loaded, have the livepatch return a failing status code:
-
-- load livepatch
-- setup -ENODEV
-- load target module
-- disable livepatch
-- unload livepatch
-
-Load the livepatch, notice vmlinux pre-patch callback succeeds:
-
- % insmod samples/livepatch/livepatch-callbacks-demo.ko
- [ 86.787845] livepatch: enabling patch 'livepatch_callbacks_demo'
- [ 86.788325] livepatch: 'livepatch_callbacks_demo': initializing patching transition
- [ 86.788427] livepatch_callbacks_demo: pre_patch_callback: vmlinux
- [ 86.788821] livepatch: 'livepatch_callbacks_demo': starting patching transition
- [ 87.711069] livepatch: 'livepatch_callbacks_demo': completing patching transition
- [ 87.711143] livepatch_callbacks_demo: post_patch_callback: vmlinux
- [ 87.711886] livepatch: 'livepatch_callbacks_demo': patching complete
-
-Set a trap so subsequent pre-patch callbacks to this livepatch will
-return -ENODEV:
-
- % echo -19 > /sys/module/livepatch_callbacks_demo/parameters/pre_patch_ret
-
-The livepatch pre-patch callback for subsequently loaded target modules
-will return failure, so the module loader refuses to load the kernel
-module. Notice that no post-patch or pre/post-unpatch callbacks are
-executed for this klp_object:
-
- % insmod samples/livepatch/livepatch-callbacks-mod.ko
- [ 90.796976] livepatch: applying patch 'livepatch_callbacks_demo' to loading module 'livepatch_callbacks_mod'
- [ 90.797834] livepatch_callbacks_demo: pre_patch_callback: livepatch_callbacks_mod -> [MODULE_STATE_COMING] Full formed, running module_init
- [ 90.798900] livepatch: pre-patch callback failed for object 'livepatch_callbacks_mod'
- [ 90.799652] livepatch: patch 'livepatch_callbacks_demo' failed for module 'livepatch_callbacks_mod', refusing to load module 'livepatch_callbacks_mod'
- [ 90.819737] insmod: ERROR: could not insert module samples/livepatch/livepatch-callbacks-mod.ko: No such device
-
-However, pre/post-unpatch callbacks run for the vmlinux klp_object:
-
- % echo 0 > /sys/kernel/livepatch/livepatch_callbacks_demo/enabled
- [ 92.823547] livepatch: 'livepatch_callbacks_demo': initializing unpatching transition
- [ 92.823573] livepatch_callbacks_demo: pre_unpatch_callback: vmlinux
- [ 92.824331] livepatch: 'livepatch_callbacks_demo': starting unpatching transition
- [ 93.727128] livepatch: 'livepatch_callbacks_demo': completing unpatching transition
- [ 93.727327] livepatch_callbacks_demo: post_unpatch_callback: vmlinux
- [ 93.727861] livepatch: 'livepatch_callbacks_demo': unpatching complete
-
- % rmmod samples/livepatch/livepatch-callbacks-demo.ko
-
-
-Test 8
-------
-
-Test loading multiple targeted kernel modules. This test-case is
-mainly for comparing with the next test-case.
-
-- load busy target module (0s sleep),
-- load livepatch
-- load target module
-- unload target module
-- disable livepatch
-- unload livepatch
-- unload busy target module
-
-
-Load a target "busy" kernel module which kicks off a worker function
-that immediately exits:
-
- % insmod samples/livepatch/livepatch-callbacks-busymod.ko sleep_secs=0
- [ 96.910107] livepatch_callbacks_busymod: livepatch_callbacks_mod_init
- [ 96.910600] livepatch_callbacks_busymod: busymod_work_func, sleeping 0 seconds ...
- [ 96.913024] livepatch_callbacks_busymod: busymod_work_func exit
-
-Proceed with loading the livepatch and another ordinary target module,
-notice that the post-patch callbacks are executed and the transition
-completes quickly:
-
- % insmod samples/livepatch/livepatch-callbacks-demo.ko
- [ 98.917892] livepatch: enabling patch 'livepatch_callbacks_demo'
- [ 98.918426] livepatch: 'livepatch_callbacks_demo': initializing patching transition
- [ 98.918453] livepatch_callbacks_demo: pre_patch_callback: vmlinux
- [ 98.918955] livepatch_callbacks_demo: pre_patch_callback: livepatch_callbacks_busymod -> [MODULE_STATE_LIVE] Normal state
- [ 98.923835] livepatch: 'livepatch_callbacks_demo': starting patching transition
- [ 99.743104] livepatch: 'livepatch_callbacks_demo': completing patching transition
- [ 99.743156] livepatch_callbacks_demo: post_patch_callback: vmlinux
- [ 99.743679] livepatch_callbacks_demo: post_patch_callback: livepatch_callbacks_busymod -> [MODULE_STATE_LIVE] Normal state
- [ 99.744616] livepatch: 'livepatch_callbacks_demo': patching complete
-
- % insmod samples/livepatch/livepatch-callbacks-mod.ko
- [ 100.930955] livepatch: applying patch 'livepatch_callbacks_demo' to loading module 'livepatch_callbacks_mod'
- [ 100.931668] livepatch_callbacks_demo: pre_patch_callback: livepatch_callbacks_mod -> [MODULE_STATE_COMING] Full formed, running module_init
- [ 100.932645] livepatch_callbacks_demo: post_patch_callback: livepatch_callbacks_mod -> [MODULE_STATE_COMING] Full formed, running module_init
- [ 100.934125] livepatch_callbacks_mod: livepatch_callbacks_mod_init
-
- % rmmod samples/livepatch/livepatch-callbacks-mod.ko
- [ 102.942805] livepatch_callbacks_mod: livepatch_callbacks_mod_exit
- [ 102.943640] livepatch_callbacks_demo: pre_unpatch_callback: livepatch_callbacks_mod -> [MODULE_STATE_GOING] Going away
- [ 102.944585] livepatch: reverting patch 'livepatch_callbacks_demo' on unloading module 'livepatch_callbacks_mod'
- [ 102.945455] livepatch_callbacks_demo: post_unpatch_callback: livepatch_callbacks_mod -> [MODULE_STATE_GOING] Going away
-
- % echo 0 > /sys/kernel/livepatch/livepatch_callbacks_demo/enabled
- [ 104.953815] livepatch: 'livepatch_callbacks_demo': initializing unpatching transition
- [ 104.953838] livepatch_callbacks_demo: pre_unpatch_callback: vmlinux
- [ 104.954431] livepatch_callbacks_demo: pre_unpatch_callback: livepatch_callbacks_busymod -> [MODULE_STATE_LIVE] Normal state
- [ 104.955426] livepatch: 'livepatch_callbacks_demo': starting unpatching transition
- [ 106.719073] livepatch: 'livepatch_callbacks_demo': completing unpatching transition
- [ 106.722633] livepatch_callbacks_demo: post_unpatch_callback: vmlinux
- [ 106.723282] livepatch_callbacks_demo: post_unpatch_callback: livepatch_callbacks_busymod -> [MODULE_STATE_LIVE] Normal state
- [ 106.724279] livepatch: 'livepatch_callbacks_demo': unpatching complete
-
- % rmmod samples/livepatch/livepatch-callbacks-demo.ko
- % rmmod samples/livepatch/livepatch-callbacks-busymod.ko
- [ 108.975660] livepatch_callbacks_busymod: livepatch_callbacks_mod_exit
-
-
-Test 9
-------
-
-A similar test as the previous one, but force the "busy" kernel module
-to do longer work.
-
-The livepatching core will refuse to patch a task that is currently
-executing a to-be-patched function -- the consistency model stalls the
-current patch transition until this safety-check is met. Test a
-scenario where one of a livepatch's target klp_objects sits on such a
-function for a long time. Meanwhile, load and unload other target
-kernel modules while the livepatch transition is in progress.
-
-- load busy target module (30s sleep)
-- load livepatch
-- load target module
-- unload target module
-- disable livepatch
-- unload livepatch
-- unload busy target module
-
-
-Load the "busy" kernel module, this time make it do 30 seconds worth of
-work:
-
- % insmod samples/livepatch/livepatch-callbacks-busymod.ko sleep_secs=30
- [ 110.993362] livepatch_callbacks_busymod: livepatch_callbacks_mod_init
- [ 110.994059] livepatch_callbacks_busymod: busymod_work_func, sleeping 30 seconds ...
-
-Meanwhile, the livepatch is loaded. Notice that the patch transition
-does not complete as the targeted "busy" module is sitting on a
-to-be-patched function:
-
- % insmod samples/livepatch/livepatch-callbacks-demo.ko
- [ 113.000309] livepatch: enabling patch 'livepatch_callbacks_demo'
- [ 113.000764] livepatch: 'livepatch_callbacks_demo': initializing patching transition
- [ 113.000791] livepatch_callbacks_demo: pre_patch_callback: vmlinux
- [ 113.001289] livepatch_callbacks_demo: pre_patch_callback: livepatch_callbacks_busymod -> [MODULE_STATE_LIVE] Normal state
- [ 113.005208] livepatch: 'livepatch_callbacks_demo': starting patching transition
-
-Load a second target module (this one is an ordinary idle kernel
-module). Note that *no* post-patch callbacks will be executed while the
-livepatch is still in transition:
-
- % insmod samples/livepatch/livepatch-callbacks-mod.ko
- [ 115.012740] livepatch: applying patch 'livepatch_callbacks_demo' to loading module 'livepatch_callbacks_mod'
- [ 115.013406] livepatch_callbacks_demo: pre_patch_callback: livepatch_callbacks_mod -> [MODULE_STATE_COMING] Full formed, running module_init
- [ 115.015315] livepatch_callbacks_mod: livepatch_callbacks_mod_init
-
-Request an unload of the simple kernel module. The patch is still
-transitioning, so its pre-unpatch callbacks are skipped:
-
- % rmmod samples/livepatch/livepatch-callbacks-mod.ko
- [ 117.022626] livepatch_callbacks_mod: livepatch_callbacks_mod_exit
- [ 117.023376] livepatch: reverting patch 'livepatch_callbacks_demo' on unloading module 'livepatch_callbacks_mod'
- [ 117.024533] livepatch_callbacks_demo: post_unpatch_callback: livepatch_callbacks_mod -> [MODULE_STATE_GOING] Going away
-
-Finally the livepatch is disabled. Since none of the patch's
-klp_object's post-patch callbacks executed, the remaining klp_object's
-pre-unpatch callbacks are skipped:
-
- % echo 0 > /sys/kernel/livepatch/livepatch_callbacks_demo/enabled
- [ 119.035408] livepatch: 'livepatch_callbacks_demo': reversing transition from patching to unpatching
- [ 119.035485] livepatch: 'livepatch_callbacks_demo': starting unpatching transition
- [ 119.711166] livepatch: 'livepatch_callbacks_demo': completing unpatching transition
- [ 119.714179] livepatch_callbacks_demo: post_unpatch_callback: vmlinux
- [ 119.714653] livepatch_callbacks_demo: post_unpatch_callback: livepatch_callbacks_busymod -> [MODULE_STATE_LIVE] Normal state
- [ 119.715437] livepatch: 'livepatch_callbacks_demo': unpatching complete
-
- % rmmod samples/livepatch/livepatch-callbacks-demo.ko
- % rmmod samples/livepatch/livepatch-callbacks-busymod.ko
- [ 141.279111] livepatch_callbacks_busymod: busymod_work_func exit
- [ 141.279760] livepatch_callbacks_busymod: livepatch_callbacks_mod_exit
+Sample livepatch modules demonstrating the callback API can be found in
+samples/livepatch/ directory. These samples were modified for use in
+kselftests and can be found in the lib/livepatch directory.