123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119 |
- // 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 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;
- }
|