[PATCH v2 2/3] module: Add lock_modules() and unlock_modules()

[PATCH v2 2/3] module: Add lock_modules() and unlock_modules()

[Jarkko Sakkinen]

Add wrappers to take the modules "big lock" in order to encapsulate
conditional compilation (CONFIG_MODULES) inside the wrapper.

Cc: Andi Kleen <ak@linux.intel.com>
Suggested-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
---
 include/linux/module.h      | 15 ++++++++++
 kernel/kprobes.c            |  4 +--
 kernel/livepatch/core.c     |  8 ++---
 kernel/module.c             | 60 ++++++++++++++++++-------------------
 kernel/trace/trace_kprobe.c |  4 +--
 5 files changed, 53 insertions(+), 38 deletions(-)

diff --git a/include/linux/module.h b/include/linux/module.h
index 2e6670860d27..857b84bf9e90 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -902,4 +902,19 @@ static inline bool module_sig_ok(struct module *module)
 }
 #endif	/* CONFIG_MODULE_SIG */
 
+#ifdef CONFIG_MODULES
+static inline void lock_modules(void)
+{
+	mutex_lock(&module_mutex);
+}
+
+static inline void unlock_modules(void)
+{
+	mutex_unlock(&module_mutex);
+}
+#else
+static inline void lock_modules(void) { }
+static inline void unlock_modules(void) { }
+#endif
+
 #endif /* _LINUX_MODULE_H */
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index d1c354ec89de..bbe3423cb2b8 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -564,7 +564,7 @@ static void kprobe_optimizer(struct work_struct *work)
 	cpus_read_lock();
 	mutex_lock(&text_mutex);
 	/* Lock modules while optimizing kprobes */
-	mutex_lock(&module_mutex);
+	lock_modules();
 
 	/*
 	 * Step 1: Unoptimize kprobes and collect cleaned (unused and disarmed)
@@ -589,7 +589,7 @@ static void kprobe_optimizer(struct work_struct *work)
 	/* Step 4: Free cleaned kprobes after quiesence period */
 	do_free_cleaned_kprobes();
 
-	mutex_unlock(&module_mutex);
+	unlock_modules();
 	mutex_unlock(&text_mutex);
 	cpus_read_unlock();
 
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index f76fdb925532..d9d9d4973e6b 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -57,7 +57,7 @@ static void klp_find_object_module(struct klp_object *obj)
 	if (!klp_is_module(obj))
 		return;
 
-	mutex_lock(&module_mutex);
+	lock_modules();
 	/*
 	 * We do not want to block removal of patched modules and therefore
 	 * we do not take a reference here. The patches are removed by
@@ -74,7 +74,7 @@ static void klp_find_object_module(struct klp_object *obj)
 	if (mod && mod->klp_alive)
 		obj->mod = mod;
 
-	mutex_unlock(&module_mutex);
+	unlock_modules();
 }
 
 static bool klp_initialized(void)
@@ -163,12 +163,12 @@ static int klp_find_object_symbol(const char *objname, const char *name,
 		.pos = sympos,
 	};
 
-	mutex_lock(&module_mutex);
+	lock_modules();
 	if (objname)
 		module_kallsyms_on_each_symbol(klp_find_callback, &args);
 	else
 		kallsyms_on_each_symbol(klp_find_callback, &args);
-	mutex_unlock(&module_mutex);
+	unlock_modules();
 
 	/*
 	 * Ensure an address was found. If sympos is 0, ensure symbol is unique;
diff --git a/kernel/module.c b/kernel/module.c
index bdb3773f3668..3c7001cf754c 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -895,7 +895,7 @@ static void module_unload_free(struct module *mod)
 {
 	struct module_use *use, *tmp;
 
-	mutex_lock(&module_mutex);
+	lock_modules();
 	list_for_each_entry_safe(use, tmp, &mod->target_list, target_list) {
 		struct module *i = use->target;
 		pr_debug("%s unusing %s\n", mod->name, i->name);
@@ -904,7 +904,7 @@ static void module_unload_free(struct module *mod)
 		list_del(&use->target_list);
 		kfree(use);
 	}
-	mutex_unlock(&module_mutex);
+	unlock_modules();
 }
 
 #ifdef CONFIG_MODULE_FORCE_UNLOAD
@@ -1024,7 +1024,7 @@ SYSCALL_DEFINE2(delete_module, const char __user *, name_user,
 	if (ret != 0)
 		goto out;
 
-	mutex_unlock(&module_mutex);
+	unlock_modules();
 	/* Final destruction now no one is using it. */
 	if (mod->exit != NULL)
 		mod->exit();
@@ -1043,7 +1043,7 @@ SYSCALL_DEFINE2(delete_module, const char __user *, name_user,
 	wake_up_all(&module_wq);
 	return 0;
 out:
-	mutex_unlock(&module_mutex);
+	unlock_modules();
 	return ret;
 }
 
@@ -1448,7 +1448,7 @@ static const struct kernel_symbol *resolve_symbol(struct module *mod,
 	 * in the wait_event_interruptible(), which is harmless.
 	 */
 	sched_annotate_sleep();
-	mutex_lock(&module_mutex);
+	lock_modules();
 	sym = find_symbol(name, &owner, &crc,
 			  !(mod->taints & (1 << TAINT_PROPRIETARY_MODULE)), true);
 	if (!sym)
@@ -1475,7 +1475,7 @@ static const struct kernel_symbol *resolve_symbol(struct module *mod,
 	/* We must make copy under the lock if we failed to get ref. */
 	strncpy(ownername, module_name(owner), MODULE_NAME_LEN);
 unlock:
-	mutex_unlock(&module_mutex);
+	unlock_modules();
 	return sym;
 }
 
@@ -1727,10 +1727,10 @@ static void del_usage_links(struct module *mod)
 #ifdef CONFIG_MODULE_UNLOAD
 	struct module_use *use;
 
-	mutex_lock(&module_mutex);
+	lock_modules();
 	list_for_each_entry(use, &mod->target_list, target_list)
 		sysfs_remove_link(use->target->holders_dir, mod->name);
-	mutex_unlock(&module_mutex);
+	unlock_modules();
 #endif
 }
 
@@ -1740,14 +1740,14 @@ static int add_usage_links(struct module *mod)
 #ifdef CONFIG_MODULE_UNLOAD
 	struct module_use *use;
 
-	mutex_lock(&module_mutex);
+	lock_modules();
 	list_for_each_entry(use, &mod->target_list, target_list) {
 		ret = sysfs_create_link(use->target->holders_dir,
 					&mod->mkobj.kobj, mod->name);
 		if (ret)
 			break;
 	}
-	mutex_unlock(&module_mutex);
+	unlock_modules();
 	if (ret)
 		del_usage_links(mod);
 #endif
@@ -2158,9 +2158,9 @@ static void free_module(struct module *mod)
 
 	/* We leave it in list to prevent duplicate loads, but make sure
 	 * that noone uses it while it's being deconstructed. */
-	mutex_lock(&module_mutex);
+	lock_modules();
 	mod->state = MODULE_STATE_UNFORMED;
-	mutex_unlock(&module_mutex);
+	unlock_modules();
 
 	/* Remove dynamic debug info */
 	ddebug_remove_module(mod->name);
@@ -2178,7 +2178,7 @@ static void free_module(struct module *mod)
 		free_module_elf(mod);
 
 	/* Now we can delete it from the lists */
-	mutex_lock(&module_mutex);
+	lock_modules();
 	/* Unlink carefully: kallsyms could be walking list. */
 	list_del_rcu(&mod->list);
 	mod_tree_remove(mod);
@@ -2186,7 +2186,7 @@ static void free_module(struct module *mod)
 	module_bug_cleanup(mod);
 	/* Wait for RCU-sched synchronizing before releasing mod->list and buglist. */
 	synchronize_rcu();
-	mutex_unlock(&module_mutex);
+	unlock_modules();
 
 	/* This may be empty, but that's OK */
 	module_arch_freeing_init(mod);
@@ -3474,10 +3474,10 @@ static bool finished_loading(const char *name)
 	 * in the wait_event_interruptible(), which is harmless.
 	 */
 	sched_annotate_sleep();
-	mutex_lock(&module_mutex);
+	lock_modules();
 	mod = find_module_all(name, strlen(name), true);
 	ret = !mod || mod->state == MODULE_STATE_LIVE;
-	mutex_unlock(&module_mutex);
+	unlock_modules();
 
 	return ret;
 }
@@ -3589,7 +3589,7 @@ static noinline int do_init_module(struct module *mod)
 
 	ftrace_free_mem(mod, mod->init_layout.base, mod->init_layout.base +
 			mod->init_layout.size);
-	mutex_lock(&module_mutex);
+	lock_modules();
 	/* Drop initial reference. */
 	module_put(mod);
 	trim_init_extable(mod);
@@ -3621,7 +3621,7 @@ static noinline int do_init_module(struct module *mod)
 	if (llist_add(&freeinit->node, &init_free_list))
 		schedule_work(&init_free_wq);
 
-	mutex_unlock(&module_mutex);
+	unlock_modules();
 	wake_up_all(&module_wq);
 
 	return 0;
@@ -3663,12 +3663,12 @@ static int add_unformed_module(struct module *mod)
 	mod->state = MODULE_STATE_UNFORMED;
 
 again:
-	mutex_lock(&module_mutex);
+	lock_modules();
 	old = find_module_all(mod->name, strlen(mod->name), true);
 	if (old != NULL) {
 		if (old->state != MODULE_STATE_LIVE) {
 			/* Wait in case it fails to load. */
-			mutex_unlock(&module_mutex);
+			unlock_modules();
 			err = wait_event_interruptible(module_wq,
 					       finished_loading(mod->name));
 			if (err)
@@ -3684,7 +3684,7 @@ static int add_unformed_module(struct module *mod)
 	err = 0;
 
 out:
-	mutex_unlock(&module_mutex);
+	unlock_modules();
 out_unlocked:
 	return err;
 }
@@ -3693,7 +3693,7 @@ static int complete_formation(struct module *mod, struct load_info *info)
 {
 	int err;
 
-	mutex_lock(&module_mutex);
+	lock_modules();
 
 	/* Find duplicate symbols (must be called under lock). */
 	err = verify_exported_symbols(mod);
@@ -3710,12 +3710,12 @@ static int complete_formation(struct module *mod, struct load_info *info)
 	/* Mark state as coming so strong_try_module_get() ignores us,
 	 * but kallsyms etc. can see us. */
 	mod->state = MODULE_STATE_COMING;
-	mutex_unlock(&module_mutex);
+	unlock_modules();
 
 	return 0;
 
 out:
-	mutex_unlock(&module_mutex);
+	unlock_modules();
 	return err;
 }
 
@@ -3913,9 +3913,9 @@ static int load_module(struct load_info *info, const char __user *uargs,
 	klp_module_going(mod);
  bug_cleanup:
 	/* module_bug_cleanup needs module_mutex protection */
-	mutex_lock(&module_mutex);
+	lock_modules();
 	module_bug_cleanup(mod);
-	mutex_unlock(&module_mutex);
+	unlock_modules();
 
  ddebug_cleanup:
 	ftrace_release_mod(mod);
@@ -3929,14 +3929,14 @@ static int load_module(struct load_info *info, const char __user *uargs,
  free_unload:
 	module_unload_free(mod);
  unlink_mod:
-	mutex_lock(&module_mutex);
+	lock_modules();
 	/* Unlink carefully: kallsyms could be walking list. */
 	list_del_rcu(&mod->list);
 	mod_tree_remove(mod);
 	wake_up_all(&module_wq);
 	/* Wait for RCU-sched synchronizing before releasing mod->list. */
 	synchronize_rcu();
-	mutex_unlock(&module_mutex);
+	unlock_modules();
  free_module:
 	/* Free lock-classes; relies on the preceding sync_rcu() */
 	lockdep_free_key_range(mod->core_layout.base, mod->core_layout.size);
@@ -4292,7 +4292,7 @@ static char *module_flags(struct module *mod, char *buf)
 /* Called by the /proc file system to return a list of modules. */
 static void *m_start(struct seq_file *m, loff_t *pos)
 {
-	mutex_lock(&module_mutex);
+	lock_modules();
 	return seq_list_start(&modules, *pos);
 }
 
@@ -4303,7 +4303,7 @@ static void *m_next(struct seq_file *m, void *p, loff_t *pos)
 
 static void m_stop(struct seq_file *m, void *p)
 {
-	mutex_unlock(&module_mutex);
+	unlock_modules();
 }
 
 static int m_show(struct seq_file *m, void *p)
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index aefb6065b508..710ec6a6aa8f 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -122,9 +122,9 @@ static nokprobe_inline bool trace_kprobe_module_exist(struct trace_kprobe *tk)
 	if (!p)
 		return true;
 	*p = '\0';
-	mutex_lock(&module_mutex);
+	lock_modules();
 	ret = !!find_module(tk->symbol);
-	mutex_unlock(&module_mutex);
+	unlock_modules();
 	*p = ':';
 
 	return ret;
-- 
2.25.1

[PATCH v2 3/3] kprobes: Flag out CONFIG_MODULES dependent code

[Jarkko Sakkinen]

Remove CONFIG_MODULES dependency by flagging out the dependent code. This
allows to use kprobes in a kernel without support for loadable modules,
which could be useful for a test kernel or perhaps an embedded kernel.

Cc: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
---
 arch/Kconfig                |  1 -
 include/linux/module.h      | 14 +++++++-------
 kernel/kprobes.c            |  9 +++++++++
 kernel/trace/trace_kprobe.c | 16 +++++++++++++++-
 4 files changed, 31 insertions(+), 9 deletions(-)

diff --git a/arch/Kconfig b/arch/Kconfig
index 8cc35dc556c7..bb59cdf335ab 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -61,7 +61,6 @@ config OPROFILE_NMI_TIMER
 
 config KPROBES
 	bool "Kprobes"
-	depends on MODULES
 	depends on HAVE_KPROBES
 	select KALLSYMS
 	help
diff --git a/include/linux/module.h b/include/linux/module.h
index 857b84bf9e90..eaa8ad02f75c 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -290,6 +290,13 @@ extern typeof(name) __mod_##type##__##name##_device_table		\
 
 struct notifier_block;
 
+enum module_state {
+	MODULE_STATE_LIVE,	/* Normal state. */
+	MODULE_STATE_COMING,	/* Full formed, running module_init. */
+	MODULE_STATE_GOING,	/* Going away. */
+	MODULE_STATE_UNFORMED,	/* Still setting it up. */
+};
+
 #ifdef CONFIG_MODULES
 
 extern int modules_disabled; /* for sysctl */
@@ -305,13 +312,6 @@ struct module_use {
 	struct module *source, *target;
 };
 
-enum module_state {
-	MODULE_STATE_LIVE,	/* Normal state. */
-	MODULE_STATE_COMING,	/* Full formed, running module_init. */
-	MODULE_STATE_GOING,	/* Going away. */
-	MODULE_STATE_UNFORMED,	/* Still setting it up. */
-};
-
 struct mod_tree_node {
 	struct module *mod;
 	struct latch_tree_node node;
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index bbe3423cb2b8..047353008cb6 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -1608,6 +1608,7 @@ static int check_kprobe_address_safe(struct kprobe *p,
 			goto out;
 		}
 
+#ifdef CONFIG_MODULES
 		/*
 		 * If the module freed .init.text, we couldn't insert
 		 * kprobes in there.
@@ -1618,6 +1619,7 @@ static int check_kprobe_address_safe(struct kprobe *p,
 			*probed_mod = NULL;
 			ret = -ENOENT;
 		}
+#endif
 	}
 out:
 	preempt_enable();
@@ -2214,6 +2216,7 @@ int kprobe_add_area_blacklist(unsigned long start, unsigned long end)
 	return 0;
 }
 
+#ifdef CONFIG_MODULES
 /* Remove all symbols in given area from kprobe blacklist */
 static void kprobe_remove_area_blacklist(unsigned long start, unsigned long end)
 {
@@ -2231,6 +2234,7 @@ static void kprobe_remove_ksym_blacklist(unsigned long entry)
 {
 	kprobe_remove_area_blacklist(entry, entry + 1);
 }
+#endif
 
 int __init __weak arch_populate_kprobe_blacklist(void)
 {
@@ -2274,6 +2278,7 @@ static int __init populate_kprobe_blacklist(unsigned long *start,
 	return ret ? : arch_populate_kprobe_blacklist();
 }
 
+#ifdef CONFIG_MODULES
 static void add_module_kprobe_blacklist(struct module *mod)
 {
 	unsigned long start, end;
@@ -2319,6 +2324,10 @@ static void remove_module_kprobe_blacklist(struct module *mod)
 		kprobe_remove_area_blacklist(start, end);
 	}
 }
+#else
+static void add_module_kprobe_blacklist(struct module *mod) {}
+static void remove_module_kprobe_blacklist(struct module *mod) {}
+#endif /* CONFIG_MODULES */
 
 /* Module notifier call back, checking kprobes on the module */
 static int kprobes_module_callback(struct notifier_block *nb,
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 710ec6a6aa8f..7fcd1bf2d96e 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -103,8 +103,9 @@ static nokprobe_inline bool trace_kprobe_has_gone(struct trace_kprobe *tk)
 	return !!(kprobe_gone(&tk->rp.kp));
 }
 
+#ifdef CONFIG_MODULES
 static nokprobe_inline bool trace_kprobe_within_module(struct trace_kprobe *tk,
-						 struct module *mod)
+						       struct module *mod)
 {
 	int len = strlen(mod->name);
 	const char *name = trace_kprobe_symbol(tk);
@@ -129,6 +130,17 @@ static nokprobe_inline bool trace_kprobe_module_exist(struct trace_kprobe *tk)
 
 	return ret;
 }
+#else
+static nokprobe_inline bool trace_kprobe_within_module(struct trace_kprobe *tk,
+						       struct module *mod)
+{
+	return false;
+}
+static nokprobe_inline bool trace_kprobe_module_exist(struct trace_kprobe *tk)
+{
+	return false;
+}
+#endif
 
 static bool trace_kprobe_is_busy(struct dyn_event *ev)
 {
@@ -685,10 +697,12 @@ static int trace_kprobe_module_callback(struct notifier_block *nb,
 			/* Don't need to check busy - this should have gone. */
 			__unregister_trace_kprobe(tk);
 			ret = __register_trace_kprobe(tk);
+#ifdef CONFIG_MODULES
 			if (ret)
 				pr_warn("Failed to re-register probe %s on %s: %d\n",
 					trace_probe_name(&tk->tp),
 					mod->name, ret);
+#endif
 		}
 	}
 	mutex_unlock(&event_mutex);
-- 
2.25.1