Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/livepatching

Pull livepatching update from Jiri Kosina:

 - cleanup of module notifiers; this depends on a module.c cleanup which
   has been acked by Rusty; from Jessica Yu

 - small assorted fixes and MAINTAINERS update

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/livepatching:
  livepatch/module: remove livepatch module notifier
  modules: split part of complete_formation() into prepare_coming_module()
  livepatch: Update maintainers
  livepatch: Fix the error message about unresolvable ambiguity
  klp: remove CONFIG_LIVEPATCH dependency from klp headers
  klp: remove superfluous errors in asm/livepatch.h

6 files changed, 113 insertions, 96 deletions

diff --git a/MAINTAINERS b/MAINTAINERS
index e32f4847e251..94ea42b76b30 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -6596,9 +6596,10 @@ F:	drivers/platform/x86/hp_accel.c
 
 LIVE PATCHING
 M:      Josh Poimboeuf <jpoimboe@redhat.com>
-M:      Seth Jennings <sjenning@redhat.com>
+M:      Jessica Yu <jeyu@redhat.com>
 M:      Jiri Kosina <jikos@kernel.org>
-M:      Vojtech Pavlik <vojtech@suse.com>
+M:      Miroslav Benes <mbenes@suse.cz>
+R:      Petr Mladek <pmladek@suse.com>
 S:      Maintained
 F:      kernel/livepatch/
 F:      include/linux/livepatch.h
diff --git a/arch/s390/include/asm/livepatch.h b/arch/s390/include/asm/livepatch.h
index a52b6cca873d..d5427c78b1b3 100644
--- a/arch/s390/include/asm/livepatch.h
+++ b/arch/s390/include/asm/livepatch.h
@@ -19,7 +19,6 @@
 
 #include <linux/module.h>
 
-#ifdef CONFIG_LIVEPATCH
 static inline int klp_check_compiler_support(void)
 {
         return 0;
@@ -36,8 +35,5 @@ static inline void klp_arch_set_pc(struct pt_regs *regs, unsigned long ip)
 {
         regs->psw.addr = ip;
 }
-#else
-#error Include linux/livepatch.h, not asm/livepatch.h
-#endif
 
 #endif
diff --git a/arch/x86/include/asm/livepatch.h b/arch/x86/include/asm/livepatch.h
index e795f5274217..7e68f9558552 100644
--- a/arch/x86/include/asm/livepatch.h
+++ b/arch/x86/include/asm/livepatch.h
@@ -25,7 +25,6 @@
 #include <linux/module.h>
 #include <linux/ftrace.h>
 
-#ifdef CONFIG_LIVEPATCH
 static inline int klp_check_compiler_support(void)
 {
 #ifndef CC_USING_FENTRY
@@ -40,8 +39,5 @@ static inline void klp_arch_set_pc(struct pt_regs *regs, unsigned long ip)
 {
         regs->ip = ip;
 }
-#else
-#error Include linux/livepatch.h, not asm/livepatch.h
-#endif
 
 #endif /* _ASM_X86_LIVEPATCH_H */
diff --git a/include/linux/livepatch.h b/include/linux/livepatch.h
index a8828652f794..bd830d590465 100644
--- a/include/linux/livepatch.h
+++ b/include/linux/livepatch.h
@@ -134,6 +134,15 @@ int klp_unregister_patch(struct klp_patch *);
 int klp_enable_patch(struct klp_patch *);
 int klp_disable_patch(struct klp_patch *);
 
+/* Called from the module loader during module coming/going states */
+int klp_module_coming(struct module *mod);
+void klp_module_going(struct module *mod);
+
+#else /* !CONFIG_LIVEPATCH */
+
+static inline int klp_module_coming(struct module *mod) { return 0; }
+static inline void klp_module_going(struct module *mod) { }
+
 #endif /* CONFIG_LIVEPATCH */
 
 #endif /* _LINUX_LIVEPATCH_H_ */
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index bc2c85c064c1..d68fbf63b083 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -99,12 +99,12 @@ static void klp_find_object_module(struct klp_object *obj)
         /*
          * We do not want to block removal of patched modules and therefore
          * we do not take a reference here. The patches are removed by
-         * a going module handler instead.
+         * klp_module_going() instead.
          */
         mod = find_module(obj->name);
         /*
-         * Do not mess work of the module coming and going notifiers.
-         * Note that the patch might still be needed before the going handler
+         * Do not mess work of klp_module_coming() and klp_module_going().
+         * Note that the patch might still be needed before klp_module_going()
          * is called. Module functions can be called even in the GOING state
          * until mod->exit() finishes. This is especially important for
          * patches that modify semantic of the functions.
@@ -190,8 +190,8 @@ static int klp_find_object_symbol(const char *objname, const char *name,
         if (args.addr == 0)
                 pr_err("symbol '%s' not found in symbol table\n", name);
         else if (args.count > 1 && sympos == 0) {
-                pr_err("unresolvable ambiguity (%lu matches) on symbol '%s' in object '%s'\n",
-                       args.count, name, objname);
+                pr_err("unresolvable ambiguity for symbol '%s' in object '%s'\n",
+                       name, objname);
         } else if (sympos != args.count && sympos > 0) {
                 pr_err("symbol position %lu for symbol '%s' in object '%s' not found\n",
                        sympos, name, objname ? objname : "vmlinux");
@@ -866,103 +866,108 @@ int klp_register_patch(struct klp_patch *patch)
 }
 EXPORT_SYMBOL_GPL(klp_register_patch);
 
-static int klp_module_notify_coming(struct klp_patch *patch,
-                                     struct klp_object *obj)
+int klp_module_coming(struct module *mod)
 {
-        struct module *pmod = patch->mod;
-        struct module *mod = obj->mod;
         int ret;
+        struct klp_patch *patch;
+        struct klp_object *obj;
 
-        ret = klp_init_object_loaded(patch, obj);
-        if (ret) {
-                pr_warn("failed to initialize patch '%s' for module '%s' (%d)\n",
-                        pmod->name, mod->name, ret);
-                return ret;
-        }
+        if (WARN_ON(mod->state != MODULE_STATE_COMING))
+                return -EINVAL;
 
-        if (patch->state == KLP_DISABLED)
-                return 0;
+        mutex_lock(&klp_mutex);
+        /*
+         * Each module has to know that klp_module_coming()
+         * has been called. We never know what module will
+         * get patched by a new patch.
+         */
+        mod->klp_alive = true;
 
-        pr_notice("applying patch '%s' to loading module '%s'\n",
-                  pmod->name, mod->name);
+        list_for_each_entry(patch, &klp_patches, list) {
+                klp_for_each_object(patch, obj) {
+                        if (!klp_is_module(obj) || strcmp(obj->name, mod->name))
+                                continue;
 
-        ret = klp_enable_object(obj);
-        if (ret)
-                pr_warn("failed to apply patch '%s' to module '%s' (%d)\n",
-                        pmod->name, mod->name, ret);
-        return ret;
-}
+                        obj->mod = mod;
 
-static void klp_module_notify_going(struct klp_patch *patch,
-                                    struct klp_object *obj)
-{
-        struct module *pmod = patch->mod;
-        struct module *mod = obj->mod;
+                        ret = klp_init_object_loaded(patch, obj);
+                        if (ret) {
+                                pr_warn("failed to initialize patch '%s' for module '%s' (%d)\n",
+                                        patch->mod->name, obj->mod->name, ret);
+                                goto err;
+                        }
 
-        if (patch->state == KLP_DISABLED)
-                goto disabled;
+                        if (patch->state == KLP_DISABLED)
+                                break;
+
+                        pr_notice("applying patch '%s' to loading module '%s'\n",
+                                  patch->mod->name, obj->mod->name);
+
+                        ret = klp_enable_object(obj);
+                        if (ret) {
+                                pr_warn("failed to apply patch '%s' to module '%s' (%d)\n",
+                                        patch->mod->name, obj->mod->name, ret);
+                                goto err;
+                        }
+
+                        break;
+                }
+        }
 
-        pr_notice("reverting patch '%s' on unloading module '%s'\n",
-                  pmod->name, mod->name);
+        mutex_unlock(&klp_mutex);
 
-        klp_disable_object(obj);
+        return 0;
 
-disabled:
+err:
+        /*
+         * If a patch is unsuccessfully applied, return
+         * error to the module loader.
+         */
+        pr_warn("patch '%s' failed for module '%s', refusing to load module '%s'\n",
+                patch->mod->name, obj->mod->name, obj->mod->name);
+        mod->klp_alive = false;
         klp_free_object_loaded(obj);
+        mutex_unlock(&klp_mutex);
+
+        return ret;
 }
 
-static int klp_module_notify(struct notifier_block *nb, unsigned long action,
-                             void *data)
+void klp_module_going(struct module *mod)
 {
-        int ret;
-        struct module *mod = data;
         struct klp_patch *patch;
         struct klp_object *obj;
 
-        if (action != MODULE_STATE_COMING && action != MODULE_STATE_GOING)
-                return 0;
+        if (WARN_ON(mod->state != MODULE_STATE_GOING &&
+                    mod->state != MODULE_STATE_COMING))
+                return;
 
         mutex_lock(&klp_mutex);
-
         /*
-         * Each module has to know that the notifier has been called.
-         * We never know what module will get patched by a new patch.
+         * Each module has to know that klp_module_going()
+         * has been called. We never know what module will
+         * get patched by a new patch.
          */
-        if (action == MODULE_STATE_COMING)
-                mod->klp_alive = true;
-        else /* MODULE_STATE_GOING */
-                mod->klp_alive = false;
+        mod->klp_alive = false;
 
         list_for_each_entry(patch, &klp_patches, list) {
                 klp_for_each_object(patch, obj) {
                         if (!klp_is_module(obj) || strcmp(obj->name, mod->name))
                                 continue;
 
-                        if (action == MODULE_STATE_COMING) {
-                                obj->mod = mod;
-                                ret = klp_module_notify_coming(patch, obj);
-                                if (ret) {
-                                        obj->mod = NULL;
-                                        pr_warn("patch '%s' is in an inconsistent state!\n",
-                                                patch->mod->name);
-                                }
-                        } else /* MODULE_STATE_GOING */
-                                klp_module_notify_going(patch, obj);
+                        if (patch->state != KLP_DISABLED) {
+                                pr_notice("reverting patch '%s' on unloading module '%s'\n",
+                                          patch->mod->name, obj->mod->name);
+                                klp_disable_object(obj);
+                        }
 
+                        klp_free_object_loaded(obj);
                         break;
                 }
         }
 
         mutex_unlock(&klp_mutex);
-
-        return 0;
 }
 
-static struct notifier_block klp_module_nb = {
-        .notifier_call = klp_module_notify,
-        .priority = INT_MIN+1, /* called late but before ftrace notifier */
-};
-
 static int __init klp_init(void)
 {
         int ret;
@@ -973,21 +978,11 @@ static int __init klp_init(void)
                 return -EINVAL;
         }
 
-        ret = register_module_notifier(&klp_module_nb);
-        if (ret)
-                return ret;
-
         klp_root_kobj = kobject_create_and_add("livepatch", kernel_kobj);
-        if (!klp_root_kobj) {
-                ret = -ENOMEM;
-                goto unregister;
-        }
+        if (!klp_root_kobj)
+                return -ENOMEM;
 
         return 0;
-
-unregister:
-        unregister_module_notifier(&klp_module_nb);
-        return ret;
 }
 
 module_init(klp_init);
diff --git a/kernel/module.c b/kernel/module.c
index 87cfeb25cf65..041200ca4a2d 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -53,6 +53,7 @@
 #include <asm/sections.h>
 #include <linux/tracepoint.h>
 #include <linux/ftrace.h>
+#include <linux/livepatch.h>
 #include <linux/async.h>
 #include <linux/percpu.h>
 #include <linux/kmemleak.h>
@@ -984,6 +985,7 @@ SYSCALL_DEFINE2(delete_module, const char __user *, name_user,
                 mod->exit();
         blocking_notifier_call_chain(&module_notify_list,
                                      MODULE_STATE_GOING, mod);
+        klp_module_going(mod);
         ftrace_release_mod(mod);
 
         async_synchronize_full();
@@ -3258,6 +3260,7 @@ fail:
         module_put(mod);
         blocking_notifier_call_chain(&module_notify_list,
                                      MODULE_STATE_GOING, mod);
+        klp_module_going(mod);
         ftrace_release_mod(mod);
         free_module(mod);
         wake_up_all(&module_wq);
@@ -3335,9 +3338,6 @@ static int complete_formation(struct module *mod, struct load_info *info)
         mod->state = MODULE_STATE_COMING;
         mutex_unlock(&module_mutex);
 
-        ftrace_module_enable(mod);
-        blocking_notifier_call_chain(&module_notify_list,
-                                     MODULE_STATE_COMING, mod);
         return 0;
 
 out:
@@ -3345,6 +3345,20 @@ out:
         return err;
 }
 
+static int prepare_coming_module(struct module *mod)
+{
+        int err;
+
+        ftrace_module_enable(mod);
+        err = klp_module_coming(mod);
+        if (err)
+                return err;
+
+        blocking_notifier_call_chain(&module_notify_list,
+                                     MODULE_STATE_COMING, mod);
+        return 0;
+}
+
 static int unknown_module_param_cb(char *param, char *val, const char *modname,
                                    void *arg)
 {
@@ -3459,13 +3473,17 @@ static int load_module(struct load_info *info, const char __user *uargs,
         if (err)
                 goto ddebug_cleanup;
 
+        err = prepare_coming_module(mod);
+        if (err)
+                goto bug_cleanup;
+
         /* Module is ready to execute: parsing args may do that. */
         after_dashes = parse_args(mod->name, mod->args, mod->kp, mod->num_kp,
                                   -32768, 32767, mod,
                                   unknown_module_param_cb);
         if (IS_ERR(after_dashes)) {
                 err = PTR_ERR(after_dashes);
-                goto bug_cleanup;
+                goto coming_cleanup;
         } else if (after_dashes) {
                 pr_warn("%s: parameters '%s' after `--' ignored\n",
                        mod->name, after_dashes);
@@ -3474,7 +3492,7 @@ static int load_module(struct load_info *info, const char __user *uargs,
         /* Link in to syfs. */
         err = mod_sysfs_setup(mod, info, mod->kp, mod->num_kp);
         if (err < 0)
-                goto bug_cleanup;
+                goto coming_cleanup;
 
         /* Get rid of temporary copy. */
         free_copy(info);
@@ -3484,15 +3502,17 @@ static int load_module(struct load_info *info, const char __user *uargs,
 
         return do_init_module(mod);
 
+ coming_cleanup:
+        blocking_notifier_call_chain(&module_notify_list,
+                                     MODULE_STATE_GOING, mod);
+        klp_module_going(mod);
+
  bug_cleanup:
         /* module_bug_cleanup needs module_mutex protection */
         mutex_lock(&module_mutex);
         module_bug_cleanup(mod);
         mutex_unlock(&module_mutex);
 
-        blocking_notifier_call_chain(&module_notify_list,
-                                     MODULE_STATE_GOING, mod);
-
         /* we can't deallocate the module until we clear memory protection */
         module_disable_ro(mod);
         module_disable_nx(mod);