1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Modules tree lookup
4 *
5 * Copyright (C) 2015 Peter Zijlstra
6 * Copyright (C) 2015 Rusty Russell
7 */
8
9#include <linux/module.h>
10#include <linux/rbtree_latch.h>
11#include "internal.h"
12
13/*
14 * Use a latched RB-tree for __module_address(); this allows us to use
15 * RCU lookups of the address from any context.
16 *
17 * This is conditional on PERF_EVENTS || TRACING || CFI because those can
18 * really hit __module_address() hard by doing a lot of stack unwinding;
19 * potentially from NMI context.
20 */
21
22static __always_inline unsigned long __mod_tree_val(struct latch_tree_node *n)
23{
24 struct module_memory *mod_mem = container_of(n, struct module_memory, mtn.node);
25
26 return (unsigned long)mod_mem->base;
27}
28
29static __always_inline unsigned long __mod_tree_size(struct latch_tree_node *n)
30{
31 struct module_memory *mod_mem = container_of(n, struct module_memory, mtn.node);
32
33 return (unsigned long)mod_mem->size;
34}
35
36static __always_inline bool
37mod_tree_less(struct latch_tree_node *a, struct latch_tree_node *b)
38{
39 return __mod_tree_val(n: a) < __mod_tree_val(n: b);
40}
41
42static __always_inline int
43mod_tree_comp(void *key, struct latch_tree_node *n)
44{
45 unsigned long val = (unsigned long)key;
46 unsigned long start, end;
47
48 start = __mod_tree_val(n);
49 if (val < start)
50 return -1;
51
52 end = start + __mod_tree_size(n);
53 if (val >= end)
54 return 1;
55
56 return 0;
57}
58
59static const struct latch_tree_ops mod_tree_ops = {
60 .less = mod_tree_less,
61 .comp = mod_tree_comp,
62};
63
64static noinline void __mod_tree_insert(struct mod_tree_node *node, struct mod_tree_root *tree)
65{
66 latch_tree_insert(node: &node->node, root: &tree->root, ops: &mod_tree_ops);
67}
68
69static void __mod_tree_remove(struct mod_tree_node *node, struct mod_tree_root *tree)
70{
71 latch_tree_erase(node: &node->node, root: &tree->root, ops: &mod_tree_ops);
72}
73
74/*
75 * These modifications: insert, remove_init and remove; are serialized by the
76 * module_mutex.
77 */
78void mod_tree_insert(struct module *mod)
79{
80 for_each_mod_mem_type(type) {
81 mod->mem[type].mtn.mod = mod;
82 if (mod->mem[type].size)
83 __mod_tree_insert(node: &mod->mem[type].mtn, tree: &mod_tree);
84 }
85}
86
87void mod_tree_remove_init(struct module *mod)
88{
89 for_class_mod_mem_type(type, init) {
90 if (mod->mem[type].size)
91 __mod_tree_remove(node: &mod->mem[type].mtn, tree: &mod_tree);
92 }
93}
94
95void mod_tree_remove(struct module *mod)
96{
97 for_each_mod_mem_type(type) {
98 if (mod->mem[type].size)
99 __mod_tree_remove(node: &mod->mem[type].mtn, tree: &mod_tree);
100 }
101}
102
103struct module *mod_find(unsigned long addr, struct mod_tree_root *tree)
104{
105 struct latch_tree_node *ltn;
106
107 ltn = latch_tree_find(key: (void *)addr, root: &tree->root, ops: &mod_tree_ops);
108 if (!ltn)
109 return NULL;
110
111 return container_of(ltn, struct mod_tree_node, node)->mod;
112}
113

source code of linux/kernel/module/tree_lookup.c