485 lines
11 KiB
C
485 lines
11 KiB
C
/*
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* jump label support
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*
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* Copyright (C) 2009 Jason Baron <jbaron@redhat.com>
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*
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*/
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#include <linux/jump_label.h>
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#include <linux/memory.h>
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#include <linux/uaccess.h>
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#include <linux/module.h>
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#include <linux/list.h>
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#include <linux/jhash.h>
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#include <linux/slab.h>
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#include <linux/sort.h>
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#include <linux/err.h>
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#ifdef HAVE_JUMP_LABEL
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#define JUMP_LABEL_HASH_BITS 6
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#define JUMP_LABEL_TABLE_SIZE (1 << JUMP_LABEL_HASH_BITS)
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static struct hlist_head jump_label_table[JUMP_LABEL_TABLE_SIZE];
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/* mutex to protect coming/going of the the jump_label table */
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static DEFINE_MUTEX(jump_label_mutex);
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struct jump_label_entry {
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struct hlist_node hlist;
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struct jump_entry *table;
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int nr_entries;
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/* hang modules off here */
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struct hlist_head modules;
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unsigned long key;
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};
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struct jump_label_module_entry {
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struct hlist_node hlist;
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struct jump_entry *table;
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int nr_entries;
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struct module *mod;
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};
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void jump_label_lock(void)
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{
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mutex_lock(&jump_label_mutex);
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}
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void jump_label_unlock(void)
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{
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mutex_unlock(&jump_label_mutex);
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}
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static int jump_label_cmp(const void *a, const void *b)
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{
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const struct jump_entry *jea = a;
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const struct jump_entry *jeb = b;
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if (jea->key < jeb->key)
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return -1;
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if (jea->key > jeb->key)
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return 1;
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return 0;
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}
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static void
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sort_jump_label_entries(struct jump_entry *start, struct jump_entry *stop)
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{
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unsigned long size;
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size = (((unsigned long)stop - (unsigned long)start)
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/ sizeof(struct jump_entry));
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sort(start, size, sizeof(struct jump_entry), jump_label_cmp, NULL);
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}
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static struct jump_label_entry *get_jump_label_entry(jump_label_t key)
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{
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struct hlist_head *head;
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struct hlist_node *node;
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struct jump_label_entry *e;
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u32 hash = jhash((void *)&key, sizeof(jump_label_t), 0);
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head = &jump_label_table[hash & (JUMP_LABEL_TABLE_SIZE - 1)];
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hlist_for_each_entry(e, node, head, hlist) {
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if (key == e->key)
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return e;
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}
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return NULL;
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}
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static struct jump_label_entry *
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add_jump_label_entry(jump_label_t key, int nr_entries, struct jump_entry *table)
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{
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struct hlist_head *head;
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struct jump_label_entry *e;
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u32 hash;
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e = get_jump_label_entry(key);
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if (e)
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return ERR_PTR(-EEXIST);
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e = kmalloc(sizeof(struct jump_label_entry), GFP_KERNEL);
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if (!e)
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return ERR_PTR(-ENOMEM);
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hash = jhash((void *)&key, sizeof(jump_label_t), 0);
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head = &jump_label_table[hash & (JUMP_LABEL_TABLE_SIZE - 1)];
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e->key = key;
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e->table = table;
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e->nr_entries = nr_entries;
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INIT_HLIST_HEAD(&(e->modules));
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hlist_add_head(&e->hlist, head);
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return e;
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}
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static int
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build_jump_label_hashtable(struct jump_entry *start, struct jump_entry *stop)
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{
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struct jump_entry *iter, *iter_begin;
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struct jump_label_entry *entry;
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int count;
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sort_jump_label_entries(start, stop);
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iter = start;
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while (iter < stop) {
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entry = get_jump_label_entry(iter->key);
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if (!entry) {
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iter_begin = iter;
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count = 0;
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while ((iter < stop) &&
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(iter->key == iter_begin->key)) {
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iter++;
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count++;
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}
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entry = add_jump_label_entry(iter_begin->key,
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count, iter_begin);
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if (IS_ERR(entry))
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return PTR_ERR(entry);
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} else {
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WARN_ONCE(1, KERN_ERR "build_jump_hashtable: unexpected entry!\n");
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return -1;
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}
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}
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return 0;
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}
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/***
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* jump_label_update - update jump label text
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* @key - key value associated with a a jump label
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* @type - enum set to JUMP_LABEL_ENABLE or JUMP_LABEL_DISABLE
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*
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* Will enable/disable the jump for jump label @key, depending on the
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* value of @type.
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*
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*/
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void jump_label_update(unsigned long key, enum jump_label_type type)
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{
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struct jump_entry *iter;
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struct jump_label_entry *entry;
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struct hlist_node *module_node;
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struct jump_label_module_entry *e_module;
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int count;
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jump_label_lock();
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entry = get_jump_label_entry((jump_label_t)key);
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if (entry) {
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count = entry->nr_entries;
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iter = entry->table;
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while (count--) {
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if (kernel_text_address(iter->code))
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arch_jump_label_transform(iter, type);
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iter++;
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}
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/* eanble/disable jump labels in modules */
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hlist_for_each_entry(e_module, module_node, &(entry->modules),
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hlist) {
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count = e_module->nr_entries;
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iter = e_module->table;
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while (count--) {
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if (iter->key &&
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kernel_text_address(iter->code))
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arch_jump_label_transform(iter, type);
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iter++;
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}
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}
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}
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jump_label_unlock();
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}
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static int addr_conflict(struct jump_entry *entry, void *start, void *end)
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{
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if (entry->code <= (unsigned long)end &&
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entry->code + JUMP_LABEL_NOP_SIZE > (unsigned long)start)
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return 1;
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return 0;
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}
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#ifdef CONFIG_MODULES
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static int module_conflict(void *start, void *end)
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{
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struct hlist_head *head;
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struct hlist_node *node, *node_next, *module_node, *module_node_next;
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struct jump_label_entry *e;
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struct jump_label_module_entry *e_module;
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struct jump_entry *iter;
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int i, count;
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int conflict = 0;
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for (i = 0; i < JUMP_LABEL_TABLE_SIZE; i++) {
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head = &jump_label_table[i];
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hlist_for_each_entry_safe(e, node, node_next, head, hlist) {
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hlist_for_each_entry_safe(e_module, module_node,
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module_node_next,
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&(e->modules), hlist) {
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count = e_module->nr_entries;
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iter = e_module->table;
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while (count--) {
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if (addr_conflict(iter, start, end)) {
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conflict = 1;
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goto out;
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}
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iter++;
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}
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}
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}
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}
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out:
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return conflict;
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}
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#endif
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/***
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* jump_label_text_reserved - check if addr range is reserved
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* @start: start text addr
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* @end: end text addr
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*
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* checks if the text addr located between @start and @end
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* overlaps with any of the jump label patch addresses. Code
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* that wants to modify kernel text should first verify that
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* it does not overlap with any of the jump label addresses.
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* Caller must hold jump_label_mutex.
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*
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* returns 1 if there is an overlap, 0 otherwise
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*/
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int jump_label_text_reserved(void *start, void *end)
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{
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struct jump_entry *iter;
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struct jump_entry *iter_start = __start___jump_table;
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struct jump_entry *iter_stop = __start___jump_table;
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int conflict = 0;
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iter = iter_start;
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while (iter < iter_stop) {
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if (addr_conflict(iter, start, end)) {
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conflict = 1;
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goto out;
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}
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iter++;
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}
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/* now check modules */
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#ifdef CONFIG_MODULES
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conflict = module_conflict(start, end);
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#endif
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out:
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return conflict;
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}
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/*
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* Not all archs need this.
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*/
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void __weak arch_jump_label_text_poke_early(jump_label_t addr)
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{
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}
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static __init int init_jump_label(void)
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{
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int ret;
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struct jump_entry *iter_start = __start___jump_table;
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struct jump_entry *iter_stop = __stop___jump_table;
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struct jump_entry *iter;
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jump_label_lock();
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ret = build_jump_label_hashtable(__start___jump_table,
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__stop___jump_table);
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iter = iter_start;
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while (iter < iter_stop) {
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arch_jump_label_text_poke_early(iter->code);
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iter++;
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}
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jump_label_unlock();
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return ret;
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}
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early_initcall(init_jump_label);
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#ifdef CONFIG_MODULES
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static struct jump_label_module_entry *
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add_jump_label_module_entry(struct jump_label_entry *entry,
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struct jump_entry *iter_begin,
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int count, struct module *mod)
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{
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struct jump_label_module_entry *e;
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e = kmalloc(sizeof(struct jump_label_module_entry), GFP_KERNEL);
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if (!e)
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return ERR_PTR(-ENOMEM);
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e->mod = mod;
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e->nr_entries = count;
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e->table = iter_begin;
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hlist_add_head(&e->hlist, &entry->modules);
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return e;
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}
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static int add_jump_label_module(struct module *mod)
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{
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struct jump_entry *iter, *iter_begin;
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struct jump_label_entry *entry;
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struct jump_label_module_entry *module_entry;
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int count;
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/* if the module doesn't have jump label entries, just return */
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if (!mod->num_jump_entries)
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return 0;
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sort_jump_label_entries(mod->jump_entries,
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mod->jump_entries + mod->num_jump_entries);
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iter = mod->jump_entries;
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while (iter < mod->jump_entries + mod->num_jump_entries) {
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entry = get_jump_label_entry(iter->key);
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iter_begin = iter;
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count = 0;
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while ((iter < mod->jump_entries + mod->num_jump_entries) &&
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(iter->key == iter_begin->key)) {
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iter++;
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count++;
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}
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if (!entry) {
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entry = add_jump_label_entry(iter_begin->key, 0, NULL);
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if (IS_ERR(entry))
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return PTR_ERR(entry);
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}
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module_entry = add_jump_label_module_entry(entry, iter_begin,
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count, mod);
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if (IS_ERR(module_entry))
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return PTR_ERR(module_entry);
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}
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return 0;
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}
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static void remove_jump_label_module(struct module *mod)
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{
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struct hlist_head *head;
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struct hlist_node *node, *node_next, *module_node, *module_node_next;
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struct jump_label_entry *e;
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struct jump_label_module_entry *e_module;
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int i;
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/* if the module doesn't have jump label entries, just return */
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if (!mod->num_jump_entries)
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return;
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for (i = 0; i < JUMP_LABEL_TABLE_SIZE; i++) {
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head = &jump_label_table[i];
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hlist_for_each_entry_safe(e, node, node_next, head, hlist) {
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hlist_for_each_entry_safe(e_module, module_node,
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module_node_next,
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&(e->modules), hlist) {
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if (e_module->mod == mod) {
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hlist_del(&e_module->hlist);
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kfree(e_module);
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}
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}
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if (hlist_empty(&e->modules) && (e->nr_entries == 0)) {
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hlist_del(&e->hlist);
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kfree(e);
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}
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}
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}
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}
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static void remove_jump_label_module_init(struct module *mod)
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{
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struct hlist_head *head;
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struct hlist_node *node, *node_next, *module_node, *module_node_next;
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struct jump_label_entry *e;
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struct jump_label_module_entry *e_module;
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struct jump_entry *iter;
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int i, count;
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/* if the module doesn't have jump label entries, just return */
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if (!mod->num_jump_entries)
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return;
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for (i = 0; i < JUMP_LABEL_TABLE_SIZE; i++) {
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head = &jump_label_table[i];
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hlist_for_each_entry_safe(e, node, node_next, head, hlist) {
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hlist_for_each_entry_safe(e_module, module_node,
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module_node_next,
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&(e->modules), hlist) {
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if (e_module->mod != mod)
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continue;
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count = e_module->nr_entries;
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iter = e_module->table;
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while (count--) {
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if (within_module_init(iter->code, mod))
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iter->key = 0;
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iter++;
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}
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}
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}
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}
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}
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static int
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jump_label_module_notify(struct notifier_block *self, unsigned long val,
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void *data)
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{
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struct module *mod = data;
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int ret = 0;
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switch (val) {
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case MODULE_STATE_COMING:
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jump_label_lock();
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ret = add_jump_label_module(mod);
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if (ret)
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remove_jump_label_module(mod);
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jump_label_unlock();
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break;
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case MODULE_STATE_GOING:
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jump_label_lock();
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remove_jump_label_module(mod);
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jump_label_unlock();
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break;
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case MODULE_STATE_LIVE:
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jump_label_lock();
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remove_jump_label_module_init(mod);
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jump_label_unlock();
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break;
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}
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return ret;
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}
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/***
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* apply_jump_label_nops - patch module jump labels with arch_get_jump_label_nop()
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* @mod: module to patch
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*
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* Allow for run-time selection of the optimal nops. Before the module
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* loads patch these with arch_get_jump_label_nop(), which is specified by
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* the arch specific jump label code.
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*/
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void jump_label_apply_nops(struct module *mod)
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{
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struct jump_entry *iter;
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/* if the module doesn't have jump label entries, just return */
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if (!mod->num_jump_entries)
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return;
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iter = mod->jump_entries;
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while (iter < mod->jump_entries + mod->num_jump_entries) {
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arch_jump_label_text_poke_early(iter->code);
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iter++;
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}
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}
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struct notifier_block jump_label_module_nb = {
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.notifier_call = jump_label_module_notify,
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.priority = 0,
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};
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static __init int init_jump_label_module(void)
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{
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return register_module_notifier(&jump_label_module_nb);
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}
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early_initcall(init_jump_label_module);
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#endif /* CONFIG_MODULES */
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#endif
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