module: Move latched RB-tree support to a separate file

No functional change.

This patch migrates module latched RB-tree support
(e.g. see __module_address()) from core module code
into kernel/module/tree_lookup.c.

Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Aaron Tomlin <atomlin@redhat.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>

1 files changed, 109 insertions, 0 deletions

diff --git a/kernel/module/tree_lookup.c b/kernel/module/tree_lookup.c
new file mode 100644
index 000000000000..0bc4ec3b22ce
--- /dev/null
+++ b/kernel/module/tree_lookup.c
@@ -0,0 +1,109 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Modules tree lookup
+ *
+ * Copyright (C) 2015 Peter Zijlstra
+ * Copyright (C) 2015 Rusty Russell
+ */
+
+#include <linux/module.h>
+#include <linux/rbtree_latch.h>
+#include "internal.h"
+
+/*
+ * Use a latched RB-tree for __module_address(); this allows us to use
+ * RCU-sched lookups of the address from any context.
+ *
+ * This is conditional on PERF_EVENTS || TRACING because those can really hit
+ * __module_address() hard by doing a lot of stack unwinding; potentially from
+ * NMI context.
+ */
+
+static __always_inline unsigned long __mod_tree_val(struct latch_tree_node *n)
+{
+	struct module_layout *layout = container_of(n, struct module_layout, mtn.node);
+
+	return (unsigned long)layout->base;
+}
+
+static __always_inline unsigned long __mod_tree_size(struct latch_tree_node *n)
+{
+	struct module_layout *layout = container_of(n, struct module_layout, mtn.node);
+
+	return (unsigned long)layout->size;
+}
+
+static __always_inline bool
+mod_tree_less(struct latch_tree_node *a, struct latch_tree_node *b)
+{
+	return __mod_tree_val(a) < __mod_tree_val(b);
+}
+
+static __always_inline int
+mod_tree_comp(void *key, struct latch_tree_node *n)
+{
+	unsigned long val = (unsigned long)key;
+	unsigned long start, end;
+
+	start = __mod_tree_val(n);
+	if (val < start)
+		return -1;
+
+	end = start + __mod_tree_size(n);
+	if (val >= end)
+		return 1;
+
+	return 0;
+}
+
+static const struct latch_tree_ops mod_tree_ops = {
+	.less = mod_tree_less,
+	.comp = mod_tree_comp,
+};
+
+static noinline void __mod_tree_insert(struct mod_tree_node *node)
+{
+	latch_tree_insert(&node->node, &mod_tree.root, &mod_tree_ops);
+}
+
+static void __mod_tree_remove(struct mod_tree_node *node)
+{
+	latch_tree_erase(&node->node, &mod_tree.root, &mod_tree_ops);
+}
+
+/*
+ * These modifications: insert, remove_init and remove; are serialized by the
+ * module_mutex.
+ */
+void mod_tree_insert(struct module *mod)
+{
+	mod->core_layout.mtn.mod = mod;
+	mod->init_layout.mtn.mod = mod;
+
+	__mod_tree_insert(&mod->core_layout.mtn);
+	if (mod->init_layout.size)
+		__mod_tree_insert(&mod->init_layout.mtn);
+}
+
+void mod_tree_remove_init(struct module *mod)
+{
+	if (mod->init_layout.size)
+		__mod_tree_remove(&mod->init_layout.mtn);
+}
+
+void mod_tree_remove(struct module *mod)
+{
+	__mod_tree_remove(&mod->core_layout.mtn);
+	mod_tree_remove_init(mod);
+}
+
+struct module *mod_find(unsigned long addr)
+{
+	struct latch_tree_node *ltn;
+
+	ltn = latch_tree_find((void *)addr, &mod_tree.root, &mod_tree_ops);
+	if (!ltn)
+		return NULL;
+
+	return container_of(ltn, struct mod_tree_node, node)->mod;
+}