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From:   Aaron Tomlin <atomlin@redhat.com>
To:     mcgrof@kernel.org
Cc:     cl@linux.com, pmladek@suse.com, mbenes@suse.cz,
        akpm@linux-foundation.org, jeyu@kernel.org,
        linux-kernel@vger.kernel.org, linux-modules@vger.kernel.org,
        live-patching@vger.kernel.org, atomlin@atomlin.com,
        ghalat@redhat.com, allen.lkml@gmail.com, void@manifault.com,
        joe@perches.com
Subject: [RFC PATCH v4 04/13] module: Move latched RB-tree support to a separate file
Date:   Sun, 30 Jan 2022 21:32:05 +0000
Message-Id: <20220130213214.1042497-5-atomlin@redhat.com>
In-Reply-To: <20220130213214.1042497-1-atomlin@redhat.com>
References: <20220130213214.1042497-1-atomlin@redhat.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

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.

Signed-off-by: Aaron Tomlin <atomlin@redhat.com>
---
 include/linux/module.h      |   4 +-
 kernel/module/Makefile      |   1 +
 kernel/module/internal.h    |  33 +++++++++
 kernel/module/main.c        | 129 +-----------------------------------
 kernel/module/tree_lookup.c | 109 ++++++++++++++++++++++++++++++
 5 files changed, 147 insertions(+), 129 deletions(-)
 create mode 100644 kernel/module/tree_lookup.c

diff --git a/include/linux/module.h b/include/linux/module.h
index c7daac4d16ee..faeb7ae49b89 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -342,9 +342,9 @@ struct module_layout {
 #ifdef CONFIG_MODULES_TREE_LOOKUP
 /* Only touch one cacheline for common rbtree-for-core-layout case. */
 #define __module_layout_align ____cacheline_aligned
-#else
+#else /* !CONFIG_MODULES_TREE_LOOKUP */
 #define __module_layout_align
-#endif
+#endif /* CONFIG_MODULES_TREE_LOOKUP */
 
 struct mod_kallsyms {
 	Elf_Sym *symtab;
diff --git a/kernel/module/Makefile b/kernel/module/Makefile
index ee20d864ad19..fc6d7a053a62 100644
--- a/kernel/module/Makefile
+++ b/kernel/module/Makefile
@@ -9,4 +9,5 @@ obj-$(CONFIG_MODULE_SIG) += signing.o
 obj-$(CONFIG_MODULE_SIG_FORMAT) += signature.o
 ifdef CONFIG_MODULES
 obj-$(CONFIG_LIVEPATCH) += livepatch.o
+obj-$(CONFIG_MODULES_TREE_LOOKUP) += tree_lookup.o
 endif
diff --git a/kernel/module/internal.h b/kernel/module/internal.h
index 6150ec5ae042..de28d6bb7b5b 100644
--- a/kernel/module/internal.h
+++ b/kernel/module/internal.h
@@ -81,3 +81,36 @@ static inline void module_decompress_cleanup(struct load_info *info)
 {
 }
 #endif
+
+#ifdef CONFIG_MODULES_TREE_LOOKUP
+struct mod_tree_root {
+	struct latch_tree_root root;
+	unsigned long addr_min;
+	unsigned long addr_max;
+};
+
+extern struct mod_tree_root mod_tree;
+
+extern void mod_tree_insert(struct module *mod);
+extern void mod_tree_remove_init(struct module *mod);
+extern void mod_tree_remove(struct module *mod);
+extern struct module *mod_find(unsigned long addr);
+#else /* !CONFIG_MODULES_TREE_LOOKUP */
+static unsigned long module_addr_min = -1UL, module_addr_max = 0;
+
+static void mod_tree_insert(struct module *mod) { }
+static void mod_tree_remove_init(struct module *mod) { }
+static void mod_tree_remove(struct module *mod) { }
+static struct module *mod_find(unsigned long addr)
+{
+	struct module *mod;
+
+	list_for_each_entry_rcu(mod, &modules, list,
+				lockdep_is_held(&module_mutex)) {
+		if (within_module(addr, mod))
+			return mod;
+	}
+
+	return NULL;
+}
+#endif /* CONFIG_MODULES_TREE_LOOKUP */
diff --git a/kernel/module/main.c b/kernel/module/main.c
index c91c7e57bca7..941be7788626 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -90,138 +90,13 @@ static DECLARE_WORK(init_free_wq, do_free_init);
 static LLIST_HEAD(init_free_list);
 
 #ifdef CONFIG_MODULES_TREE_LOOKUP
-
-/*
- * 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 struct mod_tree_root {
-	struct latch_tree_root root;
-	unsigned long addr_min;
-	unsigned long addr_max;
-} mod_tree __cacheline_aligned = {
+struct mod_tree_root mod_tree __cacheline_aligned = {
 	.addr_min = -1UL,
 };
 
 #define module_addr_min mod_tree.addr_min
 #define module_addr_max mod_tree.addr_max
-
-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.
- */
-static 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);
-}
-
-static void mod_tree_remove_init(struct module *mod)
-{
-	if (mod->init_layout.size)
-		__mod_tree_remove(&mod->init_layout.mtn);
-}
-
-static void mod_tree_remove(struct module *mod)
-{
-	__mod_tree_remove(&mod->core_layout.mtn);
-	mod_tree_remove_init(mod);
-}
-
-static 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;
-}
-
-#else /* MODULES_TREE_LOOKUP */
-
-static unsigned long module_addr_min = -1UL, module_addr_max = 0;
-
-static void mod_tree_insert(struct module *mod) { }
-static void mod_tree_remove_init(struct module *mod) { }
-static void mod_tree_remove(struct module *mod) { }
-
-static struct module *mod_find(unsigned long addr)
-{
-	struct module *mod;
-
-	list_for_each_entry_rcu(mod, &modules, list,
-				lockdep_is_held(&module_mutex)) {
-		if (within_module(addr, mod))
-			return mod;
-	}
-
-	return NULL;
-}
-
-#endif /* MODULES_TREE_LOOKUP */
+#endif
 
 /*
  * Bounds of module text, for speeding up __module_address.
diff --git a/kernel/module/tree_lookup.c b/kernel/module/tree_lookup.c
new file mode 100644
index 000000000000..037d6eb2f56f
--- /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.
+ */
+
+__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;
+}
+
+__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;
+}
+
+__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);
+}
+
+__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;
+}
+
+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;
+}
-- 
2.34.1