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

Pull livepatching updates from Jiri Kosina:
 "These are mostly smaller things that got accumulated during the
  development cycle.  The unified solution is still being worked on and
  is not mature enough for 4.1 yet.

   - s390 livepatching support, from Jiri Slaby (has Ack from s390
     maintainers)

   - error handling simplification, from Josh Poimboeuf

   - two minor code cleanups from Josh Poimboeuf and Miroslav Benes"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/livepatching:
  livepatch: add support on s390
  livepatch: remove unnecessary call to klp_find_object_module()
  livepatch: simplify disable error path
  livepatch: remove extern specifier from header files

arch/s390/Kconfig

@@ -133,6 +133,7 @@ config S390
 	select HAVE_KPROBES
 	select HAVE_KRETPROBES
 	select HAVE_KVM if 64BIT
+	select HAVE_LIVEPATCH
 	select HAVE_MEMBLOCK
 	select HAVE_MEMBLOCK_NODE_MAP
 	select HAVE_MEMBLOCK_PHYS_MAP
@@ -159,6 +160,8 @@ source "init/Kconfig"
 
 source "kernel/Kconfig.freezer"
 
+source "kernel/livepatch/Kconfig"
+
 menu "Processor type and features"
 
 config HAVE_MARCH_Z900_FEATURES

arch/s390/include/asm/livepatch.h

+/*
+ * livepatch.h - s390-specific Kernel Live Patching Core
+ *
+ *  Copyright (c) 2013-2015 SUSE
+ *   Authors: Jiri Kosina
+ *	      Vojtech Pavlik
+ *	      Jiri Slaby
+ */
+
+/*
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ */
+
+#ifndef ASM_LIVEPATCH_H
+#define ASM_LIVEPATCH_H
+
+#include <linux/module.h>
+
+#ifdef CONFIG_LIVEPATCH
+static inline int klp_check_compiler_support(void)
+{
+	return 0;
+}
+
+static inline int klp_write_module_reloc(struct module *mod, unsigned long
+		type, unsigned long loc, unsigned long value)
+{
+	/* not supported yet */
+	return -ENOSYS;
+}
+
+static inline void klp_arch_set_pc(struct pt_regs *regs, unsigned long ip)
+{
+	regs->psw.addr = ip;
+}
+#else
+#error Live patching support is disabled; check CONFIG_LIVEPATCH
+#endif
+
+#endif

arch/x86/include/asm/livepatch.h

@@ -32,8 +32,8 @@ static inline int klp_check_compiler_support(void)
 #endif
 	return 0;
 }
-extern int klp_write_module_reloc(struct module *mod, unsigned long type,
-				  unsigned long loc, unsigned long value);
+int klp_write_module_reloc(struct module *mod, unsigned long type,
+			   unsigned long loc, unsigned long value);
 
 static inline void klp_arch_set_pc(struct pt_regs *regs, unsigned long ip)
 {

include/linux/livepatch.h

@@ -123,10 +123,10 @@ struct klp_patch {
 	enum klp_state state;
 };
 
-extern int klp_register_patch(struct klp_patch *);
-extern int klp_unregister_patch(struct klp_patch *);
-extern int klp_enable_patch(struct klp_patch *);
-extern int klp_disable_patch(struct klp_patch *);
+int klp_register_patch(struct klp_patch *);
+int klp_unregister_patch(struct klp_patch *);
+int klp_enable_patch(struct klp_patch *);
+int klp_disable_patch(struct klp_patch *);
 
 #endif /* CONFIG_LIVEPATCH */
 

kernel/livepatch/core.c

@@ -335,32 +335,20 @@ static void notrace klp_ftrace_handler(unsigned long ip,
 	rcu_read_unlock();
 }
 
-static int klp_disable_func(struct klp_func *func)
+static void klp_disable_func(struct klp_func *func)
 {
 	struct klp_ops *ops;
-	int ret;
-
-	if (WARN_ON(func->state != KLP_ENABLED))
-		return -EINVAL;
 
-	if (WARN_ON(!func->old_addr))
-		return -EINVAL;
+	WARN_ON(func->state != KLP_ENABLED);
+	WARN_ON(!func->old_addr);
 
 	ops = klp_find_ops(func->old_addr);
 	if (WARN_ON(!ops))
-		return -EINVAL;
+		return;
 
 	if (list_is_singular(&ops->func_stack)) {
-		ret = unregister_ftrace_function(&ops->fops);
-		if (ret) {
-			pr_err("failed to unregister ftrace handler for function '%s' (%d)\n",
-			       func->old_name, ret);
-			return ret;
-		}
-
-		ret = ftrace_set_filter_ip(&ops->fops, func->old_addr, 1, 0);
-		if (ret)
-			pr_warn("function unregister succeeded but failed to clear the filter\n");
+		WARN_ON(unregister_ftrace_function(&ops->fops));
+		WARN_ON(ftrace_set_filter_ip(&ops->fops, func->old_addr, 1, 0));
 
 		list_del_rcu(&func->stack_node);
 		list_del(&ops->node);
@@ -370,8 +358,6 @@ static int klp_disable_func(struct klp_func *func)
 	}
 
 	func->state = KLP_DISABLED;
-
-	return 0;
 }
 
 static int klp_enable_func(struct klp_func *func)
@@ -432,23 +418,15 @@ static int klp_enable_func(struct klp_func *func)
 	return ret;
 }
 
-static int klp_disable_object(struct klp_object *obj)
+static void klp_disable_object(struct klp_object *obj)
 {
 	struct klp_func *func;
-	int ret;
 
-	for (func = obj->funcs; func->old_name; func++) {
-		if (func->state != KLP_ENABLED)
-			continue;
-
-		ret = klp_disable_func(func);
-		if (ret)
-			return ret;
-	}
+	for (func = obj->funcs; func->old_name; func++)
+		if (func->state == KLP_ENABLED)
+			klp_disable_func(func);
 
 	obj->state = KLP_DISABLED;
-
-	return 0;
 }
 
 static int klp_enable_object(struct klp_object *obj)
@@ -464,22 +442,19 @@ static int klp_enable_object(struct klp_object *obj)
 
 	for (func = obj->funcs; func->old_name; func++) {
 		ret = klp_enable_func(func);
-		if (ret)
-			goto unregister;
+		if (ret) {
+			klp_disable_object(obj);
+			return ret;
+		}
 	}
 	obj->state = KLP_ENABLED;
 
 	return 0;
-
-unregister:
-	WARN_ON(klp_disable_object(obj));
-	return ret;
 }
 
 static int __klp_disable_patch(struct klp_patch *patch)
 {
 	struct klp_object *obj;
-	int ret;
 
 	/* enforce stacking: only the last enabled patch can be disabled */
 	if (!list_is_last(&patch->list, &klp_patches) &&
@@ -489,12 +464,8 @@ static int __klp_disable_patch(struct klp_patch *patch)
 	pr_notice("disabling patch '%s'\n", patch->mod->name);
 
 	for (obj = patch->objs; obj->funcs; obj++) {
-		if (obj->state != KLP_ENABLED)
-			continue;
-
-		ret = klp_disable_object(obj);
-		if (ret)
-			return ret;
+		if (obj->state == KLP_ENABLED)
+			klp_disable_object(obj);
 	}
 
 	patch->state = KLP_DISABLED;
@@ -553,8 +524,6 @@ static int __klp_enable_patch(struct klp_patch *patch)
 	pr_notice("enabling patch '%s'\n", patch->mod->name);
 
 	for (obj = patch->objs; obj->funcs; obj++) {
-		klp_find_object_module(obj);
-
 		if (!klp_is_object_loaded(obj))
 			continue;
 
@@ -945,7 +914,6 @@ static void klp_module_notify_going(struct klp_patch *patch,
 {
 	struct module *pmod = patch->mod;
 	struct module *mod = obj->mod;
-	int ret;
 
 	if (patch->state == KLP_DISABLED)
 		goto disabled;
@@ -953,10 +921,7 @@ static void klp_module_notify_going(struct klp_patch *patch,
 	pr_notice("reverting patch '%s' on unloading module '%s'\n",
 		  pmod->name, mod->name);
 
-	ret = klp_disable_object(obj);
-	if (ret)
-		pr_warn("failed to revert patch '%s' on module '%s' (%d)\n",
-			pmod->name, mod->name, ret);
+	klp_disable_object(obj);
 
 disabled:
 	klp_free_object_loaded(obj);