kernel/module/tree_lookup.c

   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
  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
  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
  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
  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
  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
  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  */
  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
  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
  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
 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 }