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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2019-11-25 19:43:48 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2019-11-25 19:43:48 -0800 |
| commit | f838767555d40f29bc4771c5c8cc63193094b7cc (patch) | |
| tree | 50d126b8fd20a8f50e13263529805e8eaea73db3 /kernel/livepatch/state.c | |
| parent | 436b2a8039ac00f8dc6ae8f3bd2be83748f72312 (diff) | |
| parent | 0e672adc87e5ae1758b6e0571b42d743a8324327 (diff) | |
| download | linux-f838767555d40f29bc4771c5c8cc63193094b7cc.tar.gz linux-f838767555d40f29bc4771c5c8cc63193094b7cc.tar.bz2 linux-f838767555d40f29bc4771c5c8cc63193094b7cc.zip | |
Merge tag 'livepatching-for-5.5' of git://git.kernel.org/pub/scm/linux/kernel/git/livepatching/livepatching
Pull livepatching updates from Petr Mladek:
- New API to track system state changes done be livepatch callbacks. It
helps to maintain compatibility between livepatches.
- Update Kconfig help text. ORC is another reliable unwinder.
- Disable generic selftest timeout. Livepatch selftests have their own
per-operation fine-grained timeouts.
* tag 'livepatching-for-5.5' of git://git.kernel.org/pub/scm/linux/kernel/git/livepatching/livepatching:
x86/stacktrace: update kconfig help text for reliable unwinders
livepatch: Selftests of the API for tracking system state changes
livepatch: Documentation of the new API for tracking system state changes
livepatch: Allow to distinguish different version of system state changes
livepatch: Basic API to track system state changes
livepatch: Keep replaced patches until post_patch callback is called
selftests/livepatch: Disable the timeout
Diffstat (limited to 'kernel/livepatch/state.c')
| -rw-r--r-- | kernel/livepatch/state.c | 119 |
1 files changed, 119 insertions, 0 deletions
diff --git a/kernel/livepatch/state.c b/kernel/livepatch/state.c new file mode 100644 index 000000000000..7ee19476de9d --- /dev/null +++ b/kernel/livepatch/state.c @@ -0,0 +1,119 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * system_state.c - State of the system modified by livepatches + * + * Copyright (C) 2019 SUSE + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/livepatch.h> +#include "core.h" +#include "state.h" +#include "transition.h" + +#define klp_for_each_state(patch, state) \ + for (state = patch->states; state && state->id; state++) + +/** + * klp_get_state() - get information about system state modified by + * the given patch + * @patch: livepatch that modifies the given system state + * @id: custom identifier of the modified system state + * + * Checks whether the given patch modifies the given system state. + * + * The function can be called either from pre/post (un)patch + * callbacks or from the kernel code added by the livepatch. + * + * Return: pointer to struct klp_state when found, otherwise NULL. + */ +struct klp_state *klp_get_state(struct klp_patch *patch, unsigned long id) +{ + struct klp_state *state; + + klp_for_each_state(patch, state) { + if (state->id == id) + return state; + } + + return NULL; +} +EXPORT_SYMBOL_GPL(klp_get_state); + +/** + * klp_get_prev_state() - get information about system state modified by + * the already installed livepatches + * @id: custom identifier of the modified system state + * + * Checks whether already installed livepatches modify the given + * system state. + * + * The same system state can be modified by more non-cumulative + * livepatches. It is expected that the latest livepatch has + * the most up-to-date information. + * + * The function can be called only during transition when a new + * livepatch is being enabled or when such a transition is reverted. + * It is typically called only from from pre/post (un)patch + * callbacks. + * + * Return: pointer to the latest struct klp_state from already + * installed livepatches, NULL when not found. + */ +struct klp_state *klp_get_prev_state(unsigned long id) +{ + struct klp_patch *patch; + struct klp_state *state, *last_state = NULL; + + if (WARN_ON_ONCE(!klp_transition_patch)) + return NULL; + + klp_for_each_patch(patch) { + if (patch == klp_transition_patch) + goto out; + + state = klp_get_state(patch, id); + if (state) + last_state = state; + } + +out: + return last_state; +} +EXPORT_SYMBOL_GPL(klp_get_prev_state); + +/* Check if the patch is able to deal with the existing system state. */ +static bool klp_is_state_compatible(struct klp_patch *patch, + struct klp_state *old_state) +{ + struct klp_state *state; + + state = klp_get_state(patch, old_state->id); + + /* A cumulative livepatch must handle all already modified states. */ + if (!state) + return !patch->replace; + + return state->version >= old_state->version; +} + +/* + * Check that the new livepatch will not break the existing system states. + * Cumulative patches must handle all already modified states. + * Non-cumulative patches can touch already modified states. + */ +bool klp_is_patch_compatible(struct klp_patch *patch) +{ + struct klp_patch *old_patch; + struct klp_state *old_state; + + klp_for_each_patch(old_patch) { + klp_for_each_state(old_patch, old_state) { + if (!klp_is_state_compatible(patch, old_state)) + return false; + } + } + + return true; +} |