xref: /openbmc/linux/kernel/module/tree_lookup.c (revision ac3b4328)
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_memory *mod_mem = container_of(n, struct module_memory, mtn.node);
25 
26 	return (unsigned long)mod_mem->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_memory *mod_mem = container_of(n, struct module_memory, mtn.node);
32 
33 	return (unsigned long)mod_mem->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 	for_each_mod_mem_type(type) {
81 		mod->mem[type].mtn.mod = mod;
82 		if (mod->mem[type].size)
83 			__mod_tree_insert(&mod->mem[type].mtn, &mod_tree);
84 	}
85 }
86 
mod_tree_remove_init(struct module * mod)87 void 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(&mod->mem[type].mtn, &mod_tree);
92 	}
93 }
94 
mod_tree_remove(struct module * mod)95 void mod_tree_remove(struct module *mod)
96 {
97 	for_each_mod_mem_type(type) {
98 		if (mod->mem[type].size)
99 			__mod_tree_remove(&mod->mem[type].mtn, &mod_tree);
100 	}
101 }
102 
mod_find(unsigned long addr,struct mod_tree_root * tree)103 struct module *mod_find(unsigned long addr, struct mod_tree_root *tree)
104 {
105 	struct latch_tree_node *ltn;
106 
107 	ltn = latch_tree_find((void *)addr, &tree->root, &mod_tree_ops);
108 	if (!ltn)
109 		return NULL;
110 
111 	return container_of(ltn, struct mod_tree_node, node)->mod;
112 }
113