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

Pull livepatching updates from Jiri Kosina:

 - support for something we call 'atomic replace', and allows for much
   better handling of cumulative patches (which is something very useful
   for distros), from Jason Baron with help of Petr Mladek and Joe
   Lawrence

 - improvement of handling of tasks blocking finalization, from Miroslav
   Benes

 - update of MAINTAINERS file to reflect move towards group
   maintainership

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/livepatching/livepatching: (22 commits)
  livepatch/selftests: use "$@" to preserve argument list
  livepatch: Module coming and going callbacks can proceed with all listed patches
  livepatch: Proper error handling in the shadow variables selftest
  livepatch: return -ENOMEM on ptr_id() allocation failure
  livepatch: Introduce klp_for_each_patch macro
  livepatch: core: Return EOPNOTSUPP instead of ENOSYS
  selftests/livepatch: add DYNAMIC_DEBUG config dependency
  livepatch: samples: non static warnings fix
  livepatch: update MAINTAINERS
  livepatch: Remove signal sysfs attribute
  livepatch: Send a fake signal periodically
  selftests/livepatch: introduce tests
  livepatch: Remove ordering (stacking) of the livepatches
  livepatch: Atomic replace and cumulative patches documentation
  livepatch: Remove Nop structures when unused
  livepatch: Add atomic replace
  livepatch: Use lists to manage patches, objects and functions
  livepatch: Simplify API by removing registration step
  livepatch: Don't block the removal of patches loaded after a forced transition
  livepatch: Consolidate klp_free functions
  ...

1 files changed, 44 insertions, 13 deletions

diff --git a/kernel/livepatch/patch.c b/kernel/livepatch/patch.c
index 7702cb4064fc..99cb3ad05eb4 100644
--- a/kernel/livepatch/patch.c
+++ b/kernel/livepatch/patch.c
@@ -34,7 +34,7 @@
 
 static LIST_HEAD(klp_ops);
 
-struct klp_ops *klp_find_ops(unsigned long old_addr)
+struct klp_ops *klp_find_ops(void *old_func)
 {
 	struct klp_ops *ops;
 	struct klp_func *func;
@@ -42,7 +42,7 @@ struct klp_ops *klp_find_ops(unsigned long old_addr)
 	list_for_each_entry(ops, &klp_ops, node) {
 		func = list_first_entry(&ops->func_stack, struct klp_func,
 					stack_node);
-		if (func->old_addr == old_addr)
+		if (func->old_func == old_func)
 			return ops;
 	}
 
@@ -118,7 +118,15 @@ static void notrace klp_ftrace_handler(unsigned long ip,
 		}
 	}
 
+	/*
+	 * NOPs are used to replace existing patches with original code.
+	 * Do nothing! Setting pc would cause an infinite loop.
+	 */
+	if (func->nop)
+		goto unlock;
+
 	klp_arch_set_pc(regs, (unsigned long)func->new_func);
+
 unlock:
 	preempt_enable_notrace();
 }
@@ -142,17 +150,18 @@ static void klp_unpatch_func(struct klp_func *func)
 
 	if (WARN_ON(!func->patched))
 		return;
-	if (WARN_ON(!func->old_addr))
+	if (WARN_ON(!func->old_func))
 		return;
 
-	ops = klp_find_ops(func->old_addr);
+	ops = klp_find_ops(func->old_func);
 	if (WARN_ON(!ops))
 		return;
 
 	if (list_is_singular(&ops->func_stack)) {
 		unsigned long ftrace_loc;
 
-		ftrace_loc = klp_get_ftrace_location(func->old_addr);
+		ftrace_loc =
+			klp_get_ftrace_location((unsigned long)func->old_func);
 		if (WARN_ON(!ftrace_loc))
 			return;
 
@@ -174,17 +183,18 @@ static int klp_patch_func(struct klp_func *func)
 	struct klp_ops *ops;
 	int ret;
 
-	if (WARN_ON(!func->old_addr))
+	if (WARN_ON(!func->old_func))
 		return -EINVAL;
 
 	if (WARN_ON(func->patched))
 		return -EINVAL;
 
-	ops = klp_find_ops(func->old_addr);
+	ops = klp_find_ops(func->old_func);
 	if (!ops) {
 		unsigned long ftrace_loc;
 
-		ftrace_loc = klp_get_ftrace_location(func->old_addr);
+		ftrace_loc =
+			klp_get_ftrace_location((unsigned long)func->old_func);
 		if (!ftrace_loc) {
 			pr_err("failed to find location for function '%s'\n",
 				func->old_name);
@@ -236,15 +246,26 @@ err:
 	return ret;
 }
 
-void klp_unpatch_object(struct klp_object *obj)
+static void __klp_unpatch_object(struct klp_object *obj, bool nops_only)
 {
 	struct klp_func *func;
 
-	klp_for_each_func(obj, func)
+	klp_for_each_func(obj, func) {
+		if (nops_only && !func->nop)
+			continue;
+
 		if (func->patched)
 			klp_unpatch_func(func);
+	}
 
-	obj->patched = false;
+	if (obj->dynamic || !nops_only)
+		obj->patched = false;
+}
+
+
+void klp_unpatch_object(struct klp_object *obj)
+{
+	__klp_unpatch_object(obj, false);
 }
 
 int klp_patch_object(struct klp_object *obj)
@@ -267,11 +288,21 @@ int klp_patch_object(struct klp_object *obj)
 	return 0;
 }
 
-void klp_unpatch_objects(struct klp_patch *patch)
+static void __klp_unpatch_objects(struct klp_patch *patch, bool nops_only)
 {
 	struct klp_object *obj;
 
 	klp_for_each_object(patch, obj)
 		if (obj->patched)
-			klp_unpatch_object(obj);
+			__klp_unpatch_object(obj, nops_only);
+}
+
+void klp_unpatch_objects(struct klp_patch *patch)
+{
+	__klp_unpatch_objects(patch, false);
+}
+
+void klp_unpatch_objects_dynamic(struct klp_patch *patch)
+{
+	__klp_unpatch_objects(patch, true);
 }