[PATCH 5/8] module: introduce MODULE_STATE_GONE

[Mike Rapoport <rppt@kernel.org>]

From: "Mike Rapoport (Microsoft)" <rppt@kernel.org>

In order to use execmem's API for temporal remapping of the memory
allocated from ROX cache as writable, there is a need to distinguish
between the state when the module is being formed and the state when it is
deconstructed and freed so that when module_memory_free() is called from
error paths during module loading it could restore ROX mappings.

Replace open coded checks for MODULE_STATE_UNFORMED with a helper
function module_is_formed() and add a new MODULE_STATE_GONE that will be
set when the module is deconstructed and freed.

Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
---
 include/linux/module.h                        |  6 ++++++
 kernel/module/kallsyms.c                      |  8 ++++----
 kernel/module/kdb.c                           |  2 +-
 kernel/module/main.c                          | 19 +++++++++----------
 kernel/module/procfs.c                        |  2 +-
 kernel/tracepoint.c                           |  2 ++
 lib/kunit/test.c                              |  2 ++
 samples/livepatch/livepatch-callbacks-demo.c  |  1 +
 .../test_modules/test_klp_callbacks_demo.c    |  1 +
 .../test_modules/test_klp_callbacks_demo2.c   |  1 +
 .../livepatch/test_modules/test_klp_state.c   |  1 +
 .../livepatch/test_modules/test_klp_state2.c  |  1 +
 12 files changed, 30 insertions(+), 16 deletions(-)

diff --git a/include/linux/module.h b/include/linux/module.h
index 94acbacdcdf1..bd8cf93d32c8 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -320,6 +320,7 @@ enum module_state {
 	MODULE_STATE_COMING,	/* Full formed, running module_init. */
 	MODULE_STATE_GOING,	/* Going away. */
 	MODULE_STATE_UNFORMED,	/* Still setting it up. */
+	MODULE_STATE_GONE,	/* Deconstructing and freeing. */
 };
 
 struct mod_tree_node {
@@ -620,6 +621,11 @@ static inline bool module_is_coming(struct module *mod)
         return mod->state == MODULE_STATE_COMING;
 }
 
+static inline bool module_is_formed(struct module *mod)
+{
+	return mod->state < MODULE_STATE_UNFORMED;
+}
+
 struct module *__module_text_address(unsigned long addr);
 struct module *__module_address(unsigned long addr);
 bool is_module_address(unsigned long addr);
diff --git a/kernel/module/kallsyms.c b/kernel/module/kallsyms.c
index bf65e0c3c86f..daf9a9b3740f 100644
--- a/kernel/module/kallsyms.c
+++ b/kernel/module/kallsyms.c
@@ -361,7 +361,7 @@ int lookup_module_symbol_name(unsigned long addr, char *symname)
 
 	preempt_disable();
 	list_for_each_entry_rcu(mod, &modules, list) {
-		if (mod->state == MODULE_STATE_UNFORMED)
+		if (!module_is_formed(mod))
 			continue;
 		if (within_module(addr, mod)) {
 			const char *sym;
@@ -389,7 +389,7 @@ int module_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
 	list_for_each_entry_rcu(mod, &modules, list) {
 		struct mod_kallsyms *kallsyms;
 
-		if (mod->state == MODULE_STATE_UNFORMED)
+		if (!module_is_formed(mod))
 			continue;
 		kallsyms = rcu_dereference_sched(mod->kallsyms);
 		if (symnum < kallsyms->num_symtab) {
@@ -441,7 +441,7 @@ static unsigned long __module_kallsyms_lookup_name(const char *name)
 	list_for_each_entry_rcu(mod, &modules, list) {
 		unsigned long ret;
 
-		if (mod->state == MODULE_STATE_UNFORMED)
+		if (!module_is_formed(mod))
 			continue;
 		ret = __find_kallsyms_symbol_value(mod, name);
 		if (ret)
@@ -484,7 +484,7 @@ int module_kallsyms_on_each_symbol(const char *modname,
 	list_for_each_entry(mod, &modules, list) {
 		struct mod_kallsyms *kallsyms;
 
-		if (mod->state == MODULE_STATE_UNFORMED)
+		if (!module_is_formed(mod))
 			continue;
 
 		if (modname && strcmp(modname, mod->name))
diff --git a/kernel/module/kdb.c b/kernel/module/kdb.c
index 995c32d3698f..14f14700ffc2 100644
--- a/kernel/module/kdb.c
+++ b/kernel/module/kdb.c
@@ -23,7 +23,7 @@ int kdb_lsmod(int argc, const char **argv)
 
 	kdb_printf("Module                  Size  modstruct     Used by\n");
 	list_for_each_entry(mod, &modules, list) {
-		if (mod->state == MODULE_STATE_UNFORMED)
+		if (!module_is_formed(mod))
 			continue;
 
 		kdb_printf("%-20s%8u", mod->name, mod->mem[MOD_TEXT].size);
diff --git a/kernel/module/main.c b/kernel/module/main.c
index 5399c182b3cb..ad8ef20c120f 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -153,7 +153,7 @@ EXPORT_SYMBOL(unregister_module_notifier);
  */
 static inline int strong_try_module_get(struct module *mod)
 {
-	BUG_ON(mod && mod->state == MODULE_STATE_UNFORMED);
+	BUG_ON(mod && !module_is_formed(mod));
 	if (mod && mod->state == MODULE_STATE_COMING)
 		return -EBUSY;
 	if (try_module_get(mod))
@@ -361,7 +361,7 @@ bool find_symbol(struct find_symbol_arg *fsa)
 			  GPL_ONLY },
 		};
 
-		if (mod->state == MODULE_STATE_UNFORMED)
+		if (!module_is_formed(mod))
 			continue;
 
 		for (i = 0; i < ARRAY_SIZE(arr); i++)
@@ -386,7 +386,7 @@ struct module *find_module_all(const char *name, size_t len,
 
 	list_for_each_entry_rcu(mod, &modules, list,
 				lockdep_is_held(&module_mutex)) {
-		if (!even_unformed && mod->state == MODULE_STATE_UNFORMED)
+		if (!even_unformed && !module_is_formed(mod))
 			continue;
 		if (strlen(mod->name) == len && !memcmp(mod->name, name, len))
 			return mod;
@@ -457,7 +457,7 @@ bool __is_module_percpu_address(unsigned long addr, unsigned long *can_addr)
 	preempt_disable();
 
 	list_for_each_entry_rcu(mod, &modules, list) {
-		if (mod->state == MODULE_STATE_UNFORMED)
+		if (!module_is_formed(mod))
 			continue;
 		if (!mod->percpu_size)
 			continue;
@@ -1326,7 +1326,7 @@ static void free_module(struct module *mod)
 	 * that noone uses it while it's being deconstructed.
 	 */
 	mutex_lock(&module_mutex);
-	mod->state = MODULE_STATE_UNFORMED;
+	mod->state = MODULE_STATE_GONE;
 	mutex_unlock(&module_mutex);
 
 	/* Arch-specific cleanup. */
@@ -3048,8 +3048,7 @@ static int module_patient_check_exists(const char *name,
 	if (old == NULL)
 		return 0;
 
-	if (old->state == MODULE_STATE_COMING ||
-	    old->state == MODULE_STATE_UNFORMED) {
+	if (old->state == MODULE_STATE_COMING || !module_is_formed(old)) {
 		/* Wait in case it fails to load. */
 		mutex_unlock(&module_mutex);
 		err = wait_event_interruptible(module_wq,
@@ -3608,7 +3607,7 @@ char *module_flags(struct module *mod, char *buf, bool show_state)
 {
 	int bx = 0;
 
-	BUG_ON(mod->state == MODULE_STATE_UNFORMED);
+	BUG_ON(!module_is_formed(mod));
 	if (!mod->taints && !show_state)
 		goto out;
 	if (mod->taints ||
@@ -3702,7 +3701,7 @@ struct module *__module_address(unsigned long addr)
 	mod = mod_find(addr, &mod_tree);
 	if (mod) {
 		BUG_ON(!within_module(addr, mod));
-		if (mod->state == MODULE_STATE_UNFORMED)
+		if (!module_is_formed(mod))
 			mod = NULL;
 	}
 	return mod;
@@ -3756,7 +3755,7 @@ void print_modules(void)
 	/* Most callers should already have preempt disabled, but make sure */
 	preempt_disable();
 	list_for_each_entry_rcu(mod, &modules, list) {
-		if (mod->state == MODULE_STATE_UNFORMED)
+		if (!module_is_formed(mod))
 			continue;
 		pr_cont(" %s%s", mod->name, module_flags(mod, buf, true));
 	}
diff --git a/kernel/module/procfs.c b/kernel/module/procfs.c
index 0a4841e88adb..2c617e6f8bc0 100644
--- a/kernel/module/procfs.c
+++ b/kernel/module/procfs.c
@@ -79,7 +79,7 @@ static int m_show(struct seq_file *m, void *p)
 	unsigned int size;
 
 	/* We always ignore unformed modules. */
-	if (mod->state == MODULE_STATE_UNFORMED)
+	if (!module_is_formed(mod))
 		return 0;
 
 	size = module_total_size(mod);
diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
index 1848ce7e2976..e94247afb2c6 100644
--- a/kernel/tracepoint.c
+++ b/kernel/tracepoint.c
@@ -668,6 +668,8 @@ static int tracepoint_module_notify(struct notifier_block *self,
 		break;
 	case MODULE_STATE_UNFORMED:
 		break;
+	case MODULE_STATE_GONE:
+		break;
 	}
 	return notifier_from_errno(ret);
 }
diff --git a/lib/kunit/test.c b/lib/kunit/test.c
index 089c832e3cdb..54eaed92a2d3 100644
--- a/lib/kunit/test.c
+++ b/lib/kunit/test.c
@@ -836,6 +836,8 @@ static int kunit_module_notify(struct notifier_block *nb, unsigned long val,
 		break;
 	case MODULE_STATE_UNFORMED:
 		break;
+	case MODULE_STATE_GONE:
+		break;
 	}
 
 	return 0;
diff --git a/samples/livepatch/livepatch-callbacks-demo.c b/samples/livepatch/livepatch-callbacks-demo.c
index 11c3f4357812..324bddaef9a6 100644
--- a/samples/livepatch/livepatch-callbacks-demo.c
+++ b/samples/livepatch/livepatch-callbacks-demo.c
@@ -93,6 +93,7 @@ static const char *const module_state[] = {
 	[MODULE_STATE_COMING]	= "[MODULE_STATE_COMING] Full formed, running module_init",
 	[MODULE_STATE_GOING]	= "[MODULE_STATE_GOING] Going away",
 	[MODULE_STATE_UNFORMED]	= "[MODULE_STATE_UNFORMED] Still setting it up",
+	[MODULE_STATE_GONE]	= "[MODULE_STATE_GONE] Deconstructing and freeing",
 };
 
 static void callback_info(const char *callback, struct klp_object *obj)
diff --git a/tools/testing/selftests/livepatch/test_modules/test_klp_callbacks_demo.c b/tools/testing/selftests/livepatch/test_modules/test_klp_callbacks_demo.c
index 3fd8fe1cd1cc..8435e3254f85 100644
--- a/tools/testing/selftests/livepatch/test_modules/test_klp_callbacks_demo.c
+++ b/tools/testing/selftests/livepatch/test_modules/test_klp_callbacks_demo.c
@@ -16,6 +16,7 @@ static const char *const module_state[] = {
 	[MODULE_STATE_COMING]	= "[MODULE_STATE_COMING] Full formed, running module_init",
 	[MODULE_STATE_GOING]	= "[MODULE_STATE_GOING] Going away",
 	[MODULE_STATE_UNFORMED]	= "[MODULE_STATE_UNFORMED] Still setting it up",
+	[MODULE_STATE_GONE]	= "[MODULE_STATE_GONE] Deconstructing and freeing",
 };
 
 static void callback_info(const char *callback, struct klp_object *obj)
diff --git a/tools/testing/selftests/livepatch/test_modules/test_klp_callbacks_demo2.c b/tools/testing/selftests/livepatch/test_modules/test_klp_callbacks_demo2.c
index 5417573e80af..78c1fff5d977 100644
--- a/tools/testing/selftests/livepatch/test_modules/test_klp_callbacks_demo2.c
+++ b/tools/testing/selftests/livepatch/test_modules/test_klp_callbacks_demo2.c
@@ -16,6 +16,7 @@ static const char *const module_state[] = {
 	[MODULE_STATE_COMING]	= "[MODULE_STATE_COMING] Full formed, running module_init",
 	[MODULE_STATE_GOING]	= "[MODULE_STATE_GOING] Going away",
 	[MODULE_STATE_UNFORMED]	= "[MODULE_STATE_UNFORMED] Still setting it up",
+	[MODULE_STATE_GONE]	= "[MODULE_STATE_GONE] Deconstructing and freeing",
 };
 
 static void callback_info(const char *callback, struct klp_object *obj)
diff --git a/tools/testing/selftests/livepatch/test_modules/test_klp_state.c b/tools/testing/selftests/livepatch/test_modules/test_klp_state.c
index 57a4253acb01..bdebf1d24c98 100644
--- a/tools/testing/selftests/livepatch/test_modules/test_klp_state.c
+++ b/tools/testing/selftests/livepatch/test_modules/test_klp_state.c
@@ -18,6 +18,7 @@ static const char *const module_state[] = {
 	[MODULE_STATE_COMING]	= "[MODULE_STATE_COMING] Full formed, running module_init",
 	[MODULE_STATE_GOING]	= "[MODULE_STATE_GOING] Going away",
 	[MODULE_STATE_UNFORMED]	= "[MODULE_STATE_UNFORMED] Still setting it up",
+	[MODULE_STATE_GONE]	= "[MODULE_STATE_GONE] Deconstructing and freeing",
 };
 
 static void callback_info(const char *callback, struct klp_object *obj)
diff --git a/tools/testing/selftests/livepatch/test_modules/test_klp_state2.c b/tools/testing/selftests/livepatch/test_modules/test_klp_state2.c
index c978ea4d5e67..1a55f84a8eb3 100644
--- a/tools/testing/selftests/livepatch/test_modules/test_klp_state2.c
+++ b/tools/testing/selftests/livepatch/test_modules/test_klp_state2.c
@@ -18,6 +18,7 @@ static const char *const module_state[] = {
 	[MODULE_STATE_COMING]	= "[MODULE_STATE_COMING] Full formed, running module_init",
 	[MODULE_STATE_GOING]	= "[MODULE_STATE_GOING] Going away",
 	[MODULE_STATE_UNFORMED]	= "[MODULE_STATE_UNFORMED] Still setting it up",
+	[MODULE_STATE_GONE]	= "[MODULE_STATE_GONE] Deconstructing and freeing",
 };
 
 static void callback_info(const char *callback, struct klp_object *obj)
-- 
2.45.2