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

Pull livepatching updates from Jiri Kosina:

 - shadow variables support, allowing livepatches to associate new
   "shadow" fields to existing data structures, from Joe Lawrence

 - pre/post patch callbacks API, allowing livepatch writers to register
   callbacks to be called before and after patch application, from Joe
   Lawrence

* 'for-linus' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/jikos/livepatching:
  livepatch: __klp_disable_patch() should never be called for disabled patches
  livepatch: Correctly call klp_post_unpatch_callback() in error paths
  livepatch: add transition notices
  livepatch: move transition "complete" notice into klp_complete_transition()
  livepatch: add (un)patch callbacks
  livepatch: Small shadow variable documentation fixes
  livepatch: __klp_shadow_get_or_alloc() is local to shadow.c
  livepatch: introduce shadow variable API

1 files changed, 42 insertions, 10 deletions

diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index bf8c8fd72589..de9e45dca70f 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -54,11 +54,6 @@ static bool klp_is_module(struct klp_object *obj)
 	return obj->name;
 }
 
-static bool klp_is_object_loaded(struct klp_object *obj)
-{
-	return !obj->name || obj->mod;
-}
-
 /* sets obj->mod if object is not vmlinux and module is found */
 static void klp_find_object_module(struct klp_object *obj)
 {
@@ -285,6 +280,11 @@ static int klp_write_object_relocations(struct module *pmod,
 
 static int __klp_disable_patch(struct klp_patch *patch)
 {
+	struct klp_object *obj;
+
+	if (WARN_ON(!patch->enabled))
+		return -EINVAL;
+
 	if (klp_transition_patch)
 		return -EBUSY;
 
@@ -295,6 +295,10 @@ static int __klp_disable_patch(struct klp_patch *patch)
 
 	klp_init_transition(patch, KLP_UNPATCHED);
 
+	klp_for_each_object(patch, obj)
+		if (obj->patched)
+			klp_pre_unpatch_callback(obj);
+
 	/*
 	 * Enforce the order of the func->transition writes in
 	 * klp_init_transition() and the TIF_PATCH_PENDING writes in
@@ -388,13 +392,18 @@ static int __klp_enable_patch(struct klp_patch *patch)
 		if (!klp_is_object_loaded(obj))
 			continue;
 
-		ret = klp_patch_object(obj);
+		ret = klp_pre_patch_callback(obj);
 		if (ret) {
-			pr_warn("failed to enable patch '%s'\n",
-				patch->mod->name);
+			pr_warn("pre-patch callback failed for object '%s'\n",
+				klp_is_module(obj) ? obj->name : "vmlinux");
+			goto err;
+		}
 
-			klp_cancel_transition();
-			return ret;
+		ret = klp_patch_object(obj);
+		if (ret) {
+			pr_warn("failed to patch object '%s'\n",
+				klp_is_module(obj) ? obj->name : "vmlinux");
+			goto err;
 		}
 	}
 
@@ -403,6 +412,11 @@ static int __klp_enable_patch(struct klp_patch *patch)
 	patch->enabled = true;
 
 	return 0;
+err:
+	pr_warn("failed to enable patch '%s'\n", patch->mod->name);
+
+	klp_cancel_transition();
+	return ret;
 }
 
 /**
@@ -854,9 +868,15 @@ static void klp_cleanup_module_patches_limited(struct module *mod,
 			 * is in transition.
 			 */
 			if (patch->enabled || patch == klp_transition_patch) {
+
+				if (patch != klp_transition_patch)
+					klp_pre_unpatch_callback(obj);
+
 				pr_notice("reverting patch '%s' on unloading module '%s'\n",
 					  patch->mod->name, obj->mod->name);
 				klp_unpatch_object(obj);
+
+				klp_post_unpatch_callback(obj);
 			}
 
 			klp_free_object_loaded(obj);
@@ -906,13 +926,25 @@ int klp_module_coming(struct module *mod)
 			pr_notice("applying patch '%s' to loading module '%s'\n",
 				  patch->mod->name, obj->mod->name);
 
+			ret = klp_pre_patch_callback(obj);
+			if (ret) {
+				pr_warn("pre-patch callback failed for object '%s'\n",
+					obj->name);
+				goto err;
+			}
+
 			ret = klp_patch_object(obj);
 			if (ret) {
 				pr_warn("failed to apply patch '%s' to module '%s' (%d)\n",
 					patch->mod->name, obj->mod->name, ret);
+
+				klp_post_unpatch_callback(obj);
 				goto err;
 			}
 
+			if (patch != klp_transition_patch)
+				klp_post_patch_callback(obj);
+
 			break;
 		}
 	}