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

torvalds · torvalds · commit 705d43dbe10d · 2016-02-18T16:34:15.000-08:00
Pull livepatching fixes from Jiri Kosina:

 - regression (from 4.4) fix for ordering issue, introduced by an
   earlier ftrace change, that broke live patching of modules.

   The fix replaces the ftrace module notifier by direct call in order
   to make the ordering guaranteed and well-defined.  The patch, from
   Jessica Yu, has been acked both by Steven and Rusty

 - error message fix from Miroslav Benes

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/livepatching:
  ftrace/module: remove ftrace module notifier
  livepatch: change the error message in asm/livepatch.h header files
diff --git a/arch/s390/include/asm/livepatch.h b/arch/s390/include/asm/livepatch.h
@@ -37,7 +37,7 @@ 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
+#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
@@ -41,7 +41,7 @@ static inline void klp_arch_set_pc(struct pt_regs *regs, unsigned long ip)
 	regs->ip = ip;
 }
 #else
-#error Live patching support is disabled; check CONFIG_LIVEPATCH
+#error Include linux/livepatch.h, not asm/livepatch.h
 #endif
 
 #endif /* _ASM_X86_LIVEPATCH_H */
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
@@ -603,6 +603,7 @@ extern int ftrace_arch_read_dyn_info(char *buf, int size);
 
 extern int skip_trace(unsigned long ip);
 extern void ftrace_module_init(struct module *mod);
+extern void ftrace_module_enable(struct module *mod);
 extern void ftrace_release_mod(struct module *mod);
 
 extern void ftrace_disable_daemon(void);
@@ -612,8 +613,9 @@ static inline int skip_trace(unsigned long ip) { return 0; }
 static inline int ftrace_force_update(void) { return 0; }
 static inline void ftrace_disable_daemon(void) { }
 static inline void ftrace_enable_daemon(void) { }
-static inline void ftrace_release_mod(struct module *mod) {}
-static inline void ftrace_module_init(struct module *mod) {}
+static inline void ftrace_module_init(struct module *mod) { }
+static inline void ftrace_module_enable(struct module *mod) { }
+static inline void ftrace_release_mod(struct module *mod) { }
 static inline __init int register_ftrace_command(struct ftrace_func_command *cmd)
 {
 	return -EINVAL;
diff --git a/kernel/module.c b/kernel/module.c
@@ -984,6 +984,8 @@ SYSCALL_DEFINE2(delete_module, const char __user *, name_user,
 		mod->exit();
 	blocking_notifier_call_chain(&module_notify_list,
 				     MODULE_STATE_GOING, mod);
+	ftrace_release_mod(mod);
+
 	async_synchronize_full();
 
 	/* Store the name of the last unloaded module for diagnostic purposes */
@@ -3313,6 +3315,7 @@ static noinline int do_init_module(struct module *mod)
 	module_put(mod);
 	blocking_notifier_call_chain(&module_notify_list,
 				     MODULE_STATE_GOING, mod);
+	ftrace_release_mod(mod);
 	free_module(mod);
 	wake_up_all(&module_wq);
 	return ret;
@@ -3389,6 +3392,7 @@ 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;
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
@@ -4961,7 +4961,7 @@ void ftrace_release_mod(struct module *mod)
 	mutex_unlock(&ftrace_lock);
 }
 
-static void ftrace_module_enable(struct module *mod)
+void ftrace_module_enable(struct module *mod)
 {
 	struct dyn_ftrace *rec;
 	struct ftrace_page *pg;
@@ -5038,38 +5038,8 @@ void ftrace_module_init(struct module *mod)
 	ftrace_process_locs(mod, mod->ftrace_callsites,
 			    mod->ftrace_callsites + mod->num_ftrace_callsites);
 }
-
-static int ftrace_module_notify(struct notifier_block *self,
-				unsigned long val, void *data)
-{
-	struct module *mod = data;
-
-	switch (val) {
-	case MODULE_STATE_COMING:
-		ftrace_module_enable(mod);
-		break;
-	case MODULE_STATE_GOING:
-		ftrace_release_mod(mod);
-		break;
-	default:
-		break;
-	}
-
-	return 0;
-}
-#else
-static int ftrace_module_notify(struct notifier_block *self,
-				unsigned long val, void *data)
-{
-	return 0;
-}
 #endif /* CONFIG_MODULES */
 
-struct notifier_block ftrace_module_nb = {
-	.notifier_call = ftrace_module_notify,
-	.priority = INT_MIN,	/* Run after anything that can remove kprobes */
-};
-
 void __init ftrace_init(void)
 {
 	extern unsigned long __start_mcount_loc[];
@@ -5098,10 +5068,6 @@ void __init ftrace_init(void)
 				  __start_mcount_loc,
 				  __stop_mcount_loc);
 
-	ret = register_module_notifier(&ftrace_module_nb);
-	if (ret)
-		pr_warning("Failed to register trace ftrace module exit notifier\n");
-
 	set_ftrace_early_filters();
 
 	return;

Original file line number	Diff line number	Diff line change
`@@ -37,7 +37,7 @@ static inline void klp_arch_set_pc(struct pt_regs *regs, unsigned long ip)`
`37`	`37`	`regs->psw.addr = ip;`
`38`	`38`	`}`
`39`	`39`	`#else`
`40`		`-#error Live patching support is disabled; check CONFIG_LIVEPATCH`
	`40`	`+#error Include linux/livepatch.h, not asm/livepatch.h`
`41`	`41`	`#endif`
`42`	`42`
`43`	`43`	`#endif`
Original file line number	Diff line number	Diff line change
`@@ -41,7 +41,7 @@ static inline void klp_arch_set_pc(struct pt_regs *regs, unsigned long ip)`
`41`	`41`	`regs->ip = ip;`
`42`	`42`	`}`
`43`	`43`	`#else`
`44`		`-#error Live patching support is disabled; check CONFIG_LIVEPATCH`
	`44`	`+#error Include linux/livepatch.h, not asm/livepatch.h`
`45`	`45`	`#endif`
`46`	`46`
`47`	`47`	`#endif /* _ASM_X86_LIVEPATCH_H */`