linux-kernel - Re: [PATCH] tracing/profile: Fix profile_disable vs module

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Date:	Wed, 26 Aug 2009 08:52:42 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Li Zefan <lizf@...fujitsu.com>
Cc:	Ingo Molnar <mingo@...e.hu>, Steven Rostedt <rostedt@...dmis.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>,
	rusty <rusty@...tcorp.com.au>
Subject: Re: [PATCH] tracing/profile: Fix profile_disable vs module_unload

On Wed, 2009-08-26 at 08:46 +0200, Peter Zijlstra wrote:

> Aahh, I see the bug, its only ftrace that knows about the module, not
> tracepoints themselves, _that_ needs fixing.

These are the bits I hacked up until I figured out the above bug.

---
 include/linux/ftrace_event.h |    2 +-
 include/linux/module.h       |   18 ++++++++++++++----
 kernel/module.c              |    9 +--------
 3 files changed, 16 insertions(+), 13 deletions(-)

diff --git a/include/linux/ftrace_event.h b/include/linux/ftrace_event.h
index df5b085..d86d60c 100644
--- a/include/linux/ftrace_event.h
+++ b/include/linux/ftrace_event.h
@@ -122,7 +122,7 @@ struct ftrace_event_call {
 	struct list_head	fields;
 	int			filter_active;
 	struct event_filter	*filter;
-	void			*mod;
+	struct module		*mod;
 	void			*data;
 
 	atomic_t		profile_count;
diff --git a/include/linux/module.h b/include/linux/module.h
index 86863cd..09e2b88 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -409,16 +409,26 @@ struct module *__module_address(unsigned long addr);
 bool is_module_address(unsigned long addr);
 bool is_module_text_address(unsigned long addr);
 
+static inline 
+int __within_module(unsigned long addr, void *start, unsigned long size)
+{
+	return ((void *)addr >= start && (void *)addr < start + size);
+}
+
 static inline int within_module_core(unsigned long addr, struct module *mod)
 {
-	return (unsigned long)mod->module_core <= addr &&
-	       addr < (unsigned long)mod->module_core + mod->core_size;
+	return __within_module(addr, mod->module_core, mod->core_size);
 }
 
 static inline int within_module_init(unsigned long addr, struct module *mod)
 {
-	return (unsigned long)mod->module_init <= addr &&
-	       addr < (unsigned long)mod->module_init + mod->init_size;
+	return __within_module(addr, mod->module_init, mod->init_size);
+}
+
+static inline int within_module_text(unsigned long addr, struct module *mod)
+{
+	return __within_module(addr, mod->module_init, mod->init_text_size) ||
+	       __within_module(addr, mod->core_init, mod->core_text_size);
 }
 
 /* Search for module by name: must hold module_mutex. */
diff --git a/kernel/module.c b/kernel/module.c
index b182143..822adb6 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2493,11 +2493,6 @@ SYSCALL_DEFINE3(init_module, void __user *, umod,
 	return 0;
 }
 
-static inline int within(unsigned long addr, void *start, unsigned long size)
-{
-	return ((void *)addr >= start && (void *)addr < start + size);
-}
-
 #ifdef CONFIG_KALLSYMS
 /*
  * This ignores the intensely annoying "mapping symbols" found
@@ -2912,9 +2907,7 @@ struct module *__module_text_address(unsigned long addr)
 {
 	struct module *mod = __module_address(addr);
 	if (mod) {
-		/* Make sure it's within the text section. */
-		if (!within(addr, mod->module_init, mod->init_text_size)
-		    && !within(addr, mod->module_core, mod->core_text_size))
+		if (!within_module_text(addr, mod))
 			mod = NULL;
 	}
 	return mod;

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