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-sched lookups of the address from any context.
16 *
17 * This is conditional on PERF_EVENTS || TRACING because those can really hit
18 * __module_address() hard by doing a lot of stack unwinding; potentially from
19 * NMI context.
20 */
21
__mod_tree_val(struct latch_tree_node * n)22 static __always_inline unsigned long __mod_tree_val(struct latch_tree_node *n)
23 {
24 struct module_layout *layout = container_of(n, struct module_layout, mtn.node);
25
26 return (unsigned long)layout->base;
27 }
28
__mod_tree_size(struct latch_tree_node * n)29 static __always_inline unsigned long __mod_tree_size(struct latch_tree_node *n)
30 {
31 struct module_layout *layout = container_of(n, struct module_layout, mtn.node);
32
33 return (unsigned long)layout->size;
34 }
35
36 static __always_inline bool
mod_tree_less(struct latch_tree_node * a,struct latch_tree_node * b)37 mod_tree_less(struct latch_tree_node *a, struct latch_tree_node *b)
38 {
39 return __mod_tree_val(a) < __mod_tree_val(b);
40 }
41
42 static __always_inline int
mod_tree_comp(void * key,struct latch_tree_node * n)43 mod_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
59 static const struct latch_tree_ops mod_tree_ops = {
60 .less = mod_tree_less,
61 .comp = mod_tree_comp,
62 };
63
__mod_tree_insert(struct mod_tree_node * node,struct mod_tree_root * tree)64 static noinline void __mod_tree_insert(struct mod_tree_node *node, struct mod_tree_root *tree)
65 {
66 latch_tree_insert(&node->node, &tree->root, &mod_tree_ops);
67 }
68
__mod_tree_remove(struct mod_tree_node * node,struct mod_tree_root * tree)69 static void __mod_tree_remove(struct mod_tree_node *node, struct mod_tree_root *tree)
70 {
71 latch_tree_erase(&node->node, &tree->root, &mod_tree_ops);
72 }
73
74 /*
75 * These modifications: insert, remove_init and remove; are serialized by the
76 * module_mutex.
77 */
mod_tree_insert(struct module * mod)78 void mod_tree_insert(struct module *mod)
79 {
80 mod->core_layout.mtn.mod = mod;
81 mod->init_layout.mtn.mod = mod;
82
83 __mod_tree_insert(&mod->core_layout.mtn, &mod_tree);
84 if (mod->init_layout.size)
85 __mod_tree_insert(&mod->init_layout.mtn, &mod_tree);
86
87 #ifdef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
88 mod->data_layout.mtn.mod = mod;
89 __mod_tree_insert(&mod->data_layout.mtn, &mod_data_tree);
90 #endif
91 }
92
mod_tree_remove_init(struct module * mod)93 void mod_tree_remove_init(struct module *mod)
94 {
95 if (mod->init_layout.size)
96 __mod_tree_remove(&mod->init_layout.mtn, &mod_tree);
97 }
98
mod_tree_remove(struct module * mod)99 void mod_tree_remove(struct module *mod)
100 {
101 __mod_tree_remove(&mod->core_layout.mtn, &mod_tree);
102 mod_tree_remove_init(mod);
103 #ifdef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC
104 __mod_tree_remove(&mod->data_layout.mtn, &mod_data_tree);
105 #endif
106 }
107
mod_find(unsigned long addr,struct mod_tree_root * tree)108 struct module *mod_find(unsigned long addr, struct mod_tree_root *tree)
109 {
110 struct latch_tree_node *ltn;
111
112 ltn = latch_tree_find((void *)addr, &tree->root, &mod_tree_ops);
113 if (!ltn)
114 return NULL;
115
116 return container_of(ltn, struct mod_tree_node, node)->mod;
117 }
118
