// 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;}