[PATCH v2] tracing: Ignore mmiotrace from kernel commandline

[PATCH v2] tracing: Ignore mmiotrace from kernel commandline

[Ziqian SUN (Zamir)]

From: "Ziqian SUN (Zamir)" <zsun@redhat.com>

The mmiotrace tracer cannot be enabled with ftrace=mmiotrace in
kernel commandline. With this patch, a trace_noboot_tracer_list
is implemented and will be checked during system boot. If the
tracer declares itself as not for boot up, system will print out
a message and continue booting.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=196557
Signed-off-by: Ziqian SUN (Zamir) <zsun@redhat.com>
---
 kernel/trace/trace.c           | 34 +++++++++++++++++++++++++++++++++-
 kernel/trace/trace.h           | 11 +++++++++++
 kernel/trace/trace_mmiotrace.c |  4 ++++
 3 files changed, 48 insertions(+), 1 deletion(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 44004d8..0d25b1e 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -319,6 +319,33 @@ void trace_free_pid_list(struct trace_pid_list *pid_list)
 	kfree(pid_list);
 }
 
+struct mutex trace_noboot_tracer_lock;
+
+DEFINE_MUTEX(trace_noboot_tracer_lock);
+LIST_HEAD(trace_noboot_tracer_list);
+
+void trace_noboot_tracer_put(struct tracer_noboot *noboot_tracer)
+{
+	mutex_lock(&trace_noboot_tracer_lock);
+	list_add(&noboot_tracer->list, &trace_noboot_tracer_list);
+	mutex_unlock(&trace_noboot_tracer_lock);
+}
+
+bool trace_noboot_tracer_find(const char *str)
+{
+	mutex_lock(&trace_noboot_tracer_lock);
+	struct tracer_noboot *ptr = NULL;
+
+	list_for_each_entry(ptr, &trace_noboot_tracer_list, list) {
+		if (strcmp(ptr->name, str) == 0) {
+			mutex_unlock(&trace_noboot_tracer_lock);
+			return true;
+		}
+	}
+	mutex_unlock(&trace_noboot_tracer_lock);
+	return false;
+}
+
 /**
  * trace_find_filtered_pid - check if a pid exists in a filtered_pid list
  * @filtered_pids: The list of pids to check
@@ -1641,8 +1668,13 @@ int __init register_tracer(struct tracer *type)
 	if (strncmp(default_bootup_tracer, type->name, MAX_TRACER_SIZE))
 		goto out_unlock;
 
+	/* If the tracer should not be enabled by kernel parameter */
+	if (trace_noboot_tracer_find(type->name)) {
+		pr_warn("Tracer '%s' cannot be enabled during boot\n", type->name);
+		goto out_unlock;
+	}
+
 	printk(KERN_INFO "Starting tracer '%s'\n", type->name);
-	/* Do we want this tracer to start on bootup? */
 	tracing_set_tracer(&global_trace, type->name);
 	default_bootup_tracer = NULL;
 
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 490ba22..23bc668 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -502,6 +502,17 @@ enum {
 	TRACE_IRQ_BIT,
 };
 
+/*
+ * For tracer that cannot be enabled during boot time.
+ */
+
+struct tracer_noboot {
+	const char		*name;
+	struct list_head	list;
+};
+
+void trace_noboot_tracer_put(struct tracer_noboot *noboot_tracer);
+
 #define trace_recursion_set(bit)	do { (current)->trace_recursion |= (1<<(bit)); } while (0)
 #define trace_recursion_clear(bit)	do { (current)->trace_recursion &= ~(1<<(bit)); } while (0)
 #define trace_recursion_test(bit)	((current)->trace_recursion & (1<<(bit)))
diff --git a/kernel/trace/trace_mmiotrace.c b/kernel/trace/trace_mmiotrace.c
index cd7480d..06aa0a5 100644
--- a/kernel/trace/trace_mmiotrace.c
+++ b/kernel/trace/trace_mmiotrace.c
@@ -286,6 +286,10 @@ static enum print_line_t mmio_print_line(struct trace_iterator *iter)
 
 __init static int init_mmio_trace(void)
 {
+	struct tracer_noboot mmio_notrace;
+
+	mmio_notrace.name = "mmiotrace";
+	trace_noboot_tracer_put(&mmio_notrace);
 	return register_tracer(&mmio_tracer);
 }
 device_initcall(init_mmio_trace);
-- 
1.8.3.1

Re: [PATCH v2] tracing: Ignore mmiotrace from kernel commandline

[Ziqian SUN (Zamir)]

Hi Steve,

Is this solution acceptable? Any suggestions?

Thanks.

----- Original Message -----
> From: "Ziqian SUN (Zamir)" <zsun@redhat.com>
> 
> The mmiotrace tracer cannot be enabled with ftrace=mmiotrace in
> kernel commandline. With this patch, a trace_noboot_tracer_list
> is implemented and will be checked during system boot. If the
> tracer declares itself as not for boot up, system will print out
> a message and continue booting.
> 
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=196557
> Signed-off-by: Ziqian SUN (Zamir) <zsun@redhat.com>
> ---
>  kernel/trace/trace.c           | 34 +++++++++++++++++++++++++++++++++-
>  kernel/trace/trace.h           | 11 +++++++++++
>  kernel/trace/trace_mmiotrace.c |  4 ++++
>  3 files changed, 48 insertions(+), 1 deletion(-)
> 
> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index 44004d8..0d25b1e 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -319,6 +319,33 @@ void trace_free_pid_list(struct trace_pid_list
> *pid_list)
>  	kfree(pid_list);
>  }
>  
> +struct mutex trace_noboot_tracer_lock;
> +
> +DEFINE_MUTEX(trace_noboot_tracer_lock);
> +LIST_HEAD(trace_noboot_tracer_list);
> +
> +void trace_noboot_tracer_put(struct tracer_noboot *noboot_tracer)
> +{
> +	mutex_lock(&trace_noboot_tracer_lock);
> +	list_add(&noboot_tracer->list, &trace_noboot_tracer_list);
> +	mutex_unlock(&trace_noboot_tracer_lock);
> +}
> +
> +bool trace_noboot_tracer_find(const char *str)
> +{
> +	mutex_lock(&trace_noboot_tracer_lock);
> +	struct tracer_noboot *ptr = NULL;
> +
> +	list_for_each_entry(ptr, &trace_noboot_tracer_list, list) {
> +		if (strcmp(ptr->name, str) == 0) {
> +			mutex_unlock(&trace_noboot_tracer_lock);
> +			return true;
> +		}
> +	}
> +	mutex_unlock(&trace_noboot_tracer_lock);
> +	return false;
> +}
> +
>  /**
>   * trace_find_filtered_pid - check if a pid exists in a filtered_pid list
>   * @filtered_pids: The list of pids to check
> @@ -1641,8 +1668,13 @@ int __init register_tracer(struct tracer *type)
>  	if (strncmp(default_bootup_tracer, type->name, MAX_TRACER_SIZE))
>  		goto out_unlock;
>  
> +	/* If the tracer should not be enabled by kernel parameter */
> +	if (trace_noboot_tracer_find(type->name)) {
> +		pr_warn("Tracer '%s' cannot be enabled during boot\n", type->name);
> +		goto out_unlock;
> +	}
> +
>  	printk(KERN_INFO "Starting tracer '%s'\n", type->name);
> -	/* Do we want this tracer to start on bootup? */
>  	tracing_set_tracer(&global_trace, type->name);
>  	default_bootup_tracer = NULL;
>  
> diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
> index 490ba22..23bc668 100644
> --- a/kernel/trace/trace.h
> +++ b/kernel/trace/trace.h
> @@ -502,6 +502,17 @@ enum {
>  	TRACE_IRQ_BIT,
>  };
>  
> +/*
> + * For tracer that cannot be enabled during boot time.
> + */
> +
> +struct tracer_noboot {
> +	const char		*name;
> +	struct list_head	list;
> +};
> +
> +void trace_noboot_tracer_put(struct tracer_noboot *noboot_tracer);
> +
>  #define trace_recursion_set(bit)	do { (current)->trace_recursion |=
>  (1<<(bit)); } while (0)
>  #define trace_recursion_clear(bit)	do { (current)->trace_recursion &=
>  ~(1<<(bit)); } while (0)
>  #define trace_recursion_test(bit)	((current)->trace_recursion & (1<<(bit)))
> diff --git a/kernel/trace/trace_mmiotrace.c b/kernel/trace/trace_mmiotrace.c
> index cd7480d..06aa0a5 100644
> --- a/kernel/trace/trace_mmiotrace.c
> +++ b/kernel/trace/trace_mmiotrace.c
> @@ -286,6 +286,10 @@ static enum print_line_t mmio_print_line(struct
> trace_iterator *iter)
>  
>  __init static int init_mmio_trace(void)
>  {
> +	struct tracer_noboot mmio_notrace;
> +
> +	mmio_notrace.name = "mmiotrace";
> +	trace_noboot_tracer_put(&mmio_notrace);
>  	return register_tracer(&mmio_tracer);
>  }
>  device_initcall(init_mmio_trace);
> --
> 1.8.3.1
> 
> 

-- 
Ziqian SUN (Zamir)
Red Hat Red Hat Software (Beijing) Co.,Ltd
1D86 6D4A 49CE 4BBD 72CF FCF5 D856 6E11 F2A0 525E

Re: [PATCH v2] tracing: Ignore mmiotrace from kernel commandline

[Steven Rostedt]

On Fri, 8 Sep 2017 10:02:04 -0400 (EDT)
"Ziqian SUN (Zamir)" <zsun@redhat.com> wrote:

> Hi Steve,
> 
> Is this solution acceptable? Any suggestions?
> 

Sorry this patch got buried in other email. I'll take a look at it now.

-- Steve

Re: [PATCH v2] tracing: Ignore mmiotrace from kernel commandline

[Steven Rostedt]

On Wed, 30 Aug 2017 12:19:30 +0800
"Ziqian SUN (Zamir)" <zsun@redhat.com> wrote:

> From: "Ziqian SUN (Zamir)" <zsun@redhat.com>
> 
> The mmiotrace tracer cannot be enabled with ftrace=mmiotrace in
> kernel commandline. With this patch, a trace_noboot_tracer_list
> is implemented and will be checked during system boot. If the
> tracer declares itself as not for boot up, system will print out
> a message and continue booting.
> 
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=196557
> Signed-off-by: Ziqian SUN (Zamir) <zsun@redhat.com>
> ---
>  kernel/trace/trace.c           | 34 +++++++++++++++++++++++++++++++++-
>  kernel/trace/trace.h           | 11 +++++++++++
>  kernel/trace/trace_mmiotrace.c |  4 ++++
>  3 files changed, 48 insertions(+), 1 deletion(-)
> 
> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index 44004d8..0d25b1e 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -319,6 +319,33 @@ void trace_free_pid_list(struct trace_pid_list *pid_list)
>  	kfree(pid_list);
>  }
>  
> +struct mutex trace_noboot_tracer_lock;
> +
> +DEFINE_MUTEX(trace_noboot_tracer_lock);
> +LIST_HEAD(trace_noboot_tracer_list);
> +
> +void trace_noboot_tracer_put(struct tracer_noboot *noboot_tracer)
> +{
> +	mutex_lock(&trace_noboot_tracer_lock);
> +	list_add(&noboot_tracer->list, &trace_noboot_tracer_list);
> +	mutex_unlock(&trace_noboot_tracer_lock);
> +}
> +
> +bool trace_noboot_tracer_find(const char *str)
> +{
> +	mutex_lock(&trace_noboot_tracer_lock);
> +	struct tracer_noboot *ptr = NULL;
> +
> +	list_for_each_entry(ptr, &trace_noboot_tracer_list, list) {
> +		if (strcmp(ptr->name, str) == 0) {
> +			mutex_unlock(&trace_noboot_tracer_lock);
> +			return true;
> +		}
> +	}
> +	mutex_unlock(&trace_noboot_tracer_lock);
> +	return false;
> +}
> +
>  /**
>   * trace_find_filtered_pid - check if a pid exists in a filtered_pid list
>   * @filtered_pids: The list of pids to check
> @@ -1641,8 +1668,13 @@ int __init register_tracer(struct tracer *type)
>  	if (strncmp(default_bootup_tracer, type->name, MAX_TRACER_SIZE))
>  		goto out_unlock;
>  
> +	/* If the tracer should not be enabled by kernel parameter */
> +	if (trace_noboot_tracer_find(type->name)) {
> +		pr_warn("Tracer '%s' cannot be enabled during boot\n", type->name);
> +		goto out_unlock;
> +	}
> +
>  	printk(KERN_INFO "Starting tracer '%s'\n", type->name);
> -	/* Do we want this tracer to start on bootup? */
>  	tracing_set_tracer(&global_trace, type->name);
>  	default_bootup_tracer = NULL;
>  
> diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
> index 490ba22..23bc668 100644
> --- a/kernel/trace/trace.h
> +++ b/kernel/trace/trace.h
> @@ -502,6 +502,17 @@ enum {
>  	TRACE_IRQ_BIT,
>  };
>  
> +/*
> + * For tracer that cannot be enabled during boot time.
> + */
> +
> +struct tracer_noboot {
> +	const char		*name;
> +	struct list_head	list;
> +};
> +
> +void trace_noboot_tracer_put(struct tracer_noboot *noboot_tracer);
> +
>  #define trace_recursion_set(bit)	do { (current)->trace_recursion |= (1<<(bit)); } while (0)
>  #define trace_recursion_clear(bit)	do { (current)->trace_recursion &= ~(1<<(bit)); } while (0)
>  #define trace_recursion_test(bit)	((current)->trace_recursion & (1<<(bit)))
> diff --git a/kernel/trace/trace_mmiotrace.c b/kernel/trace/trace_mmiotrace.c
> index cd7480d..06aa0a5 100644
> --- a/kernel/trace/trace_mmiotrace.c
> +++ b/kernel/trace/trace_mmiotrace.c
> @@ -286,6 +286,10 @@ static enum print_line_t mmio_print_line(struct trace_iterator *iter)
>  
>  __init static int init_mmio_trace(void)
>  {
> +	struct tracer_noboot mmio_notrace;
> +
> +	mmio_notrace.name = "mmiotrace";
> +	trace_noboot_tracer_put(&mmio_notrace);
>  	return register_tracer(&mmio_tracer);
>  }
>  device_initcall(init_mmio_trace);

This is way overkill. Just add

	bool		noboot;

to struct tracer in trace.h and then to the mmiotracer:

struct tracer mmio_tracer = {
	[..]
	.noboot		= true,
};


And then in tracing_set_tracer() add after:

	if (t == tr->current_trace)
		goto out;

this:

	if (system_state < SYSTEM_RUNNING && t->noboot) {
		WARN(1, "Tracer %s not allowed on command line",
			t->name);
		goto out;
	}

That's it. No need for locking or anything else.

-- Steve

		

Re: [PATCH v2] tracing: Ignore mmiotrace from kernel commandline

[Ziqian SUN (Zamir)]

> On Wed, 30 Aug 2017 12:19:30 +0800
> "Ziqian SUN (Zamir)" <zsun@redhat.com> wrote:
> 
> > From: "Ziqian SUN (Zamir)" <zsun@redhat.com>
> > 
> > The mmiotrace tracer cannot be enabled with ftrace=mmiotrace in
> > kernel commandline. With this patch, a trace_noboot_tracer_list
> > is implemented and will be checked during system boot. If the
> > tracer declares itself as not for boot up, system will print out
> > a message and continue booting.
> > 
> > Link: https://bugzilla.kernel.org/show_bug.cgi?id=196557
> > Signed-off-by: Ziqian SUN (Zamir) <zsun@redhat.com>
> > ---
> >  kernel/trace/trace.c           | 34 +++++++++++++++++++++++++++++++++-
> >  kernel/trace/trace.h           | 11 +++++++++++
> >  kernel/trace/trace_mmiotrace.c |  4 ++++
> >  3 files changed, 48 insertions(+), 1 deletion(-)
> > 
> > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> > index 44004d8..0d25b1e 100644
> > --- a/kernel/trace/trace.c
> > +++ b/kernel/trace/trace.c
> > @@ -319,6 +319,33 @@ void trace_free_pid_list(struct trace_pid_list
> > *pid_list)
> >  	kfree(pid_list);
> >  }
> >  
> > +struct mutex trace_noboot_tracer_lock;
> > +
> > +DEFINE_MUTEX(trace_noboot_tracer_lock);
> > +LIST_HEAD(trace_noboot_tracer_list);
> > +
> > +void trace_noboot_tracer_put(struct tracer_noboot *noboot_tracer)
> > +{
> > +	mutex_lock(&trace_noboot_tracer_lock);
> > +	list_add(&noboot_tracer->list, &trace_noboot_tracer_list);
> > +	mutex_unlock(&trace_noboot_tracer_lock);
> > +}
> > +
> > +bool trace_noboot_tracer_find(const char *str)
> > +{
> > +	mutex_lock(&trace_noboot_tracer_lock);
> > +	struct tracer_noboot *ptr = NULL;
> > +
> > +	list_for_each_entry(ptr, &trace_noboot_tracer_list, list) {
> > +		if (strcmp(ptr->name, str) == 0) {
> > +			mutex_unlock(&trace_noboot_tracer_lock);
> > +			return true;
> > +		}
> > +	}
> > +	mutex_unlock(&trace_noboot_tracer_lock);
> > +	return false;
> > +}
> > +
> >  /**
> >   * trace_find_filtered_pid - check if a pid exists in a filtered_pid list
> >   * @filtered_pids: The list of pids to check
> > @@ -1641,8 +1668,13 @@ int __init register_tracer(struct tracer *type)
> >  	if (strncmp(default_bootup_tracer, type->name, MAX_TRACER_SIZE))
> >  		goto out_unlock;
> >  
> > +	/* If the tracer should not be enabled by kernel parameter */
> > +	if (trace_noboot_tracer_find(type->name)) {
> > +		pr_warn("Tracer '%s' cannot be enabled during boot\n", type->name);
> > +		goto out_unlock;
> > +	}
> > +
> >  	printk(KERN_INFO "Starting tracer '%s'\n", type->name);
> > -	/* Do we want this tracer to start on bootup? */
> >  	tracing_set_tracer(&global_trace, type->name);
> >  	default_bootup_tracer = NULL;
> >  
> > diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
> > index 490ba22..23bc668 100644
> > --- a/kernel/trace/trace.h
> > +++ b/kernel/trace/trace.h
> > @@ -502,6 +502,17 @@ enum {
> >  	TRACE_IRQ_BIT,
> >  };
> >  
> > +/*
> > + * For tracer that cannot be enabled during boot time.
> > + */
> > +
> > +struct tracer_noboot {
> > +	const char		*name;
> > +	struct list_head	list;
> > +};
> > +
> > +void trace_noboot_tracer_put(struct tracer_noboot *noboot_tracer);
> > +
> >  #define trace_recursion_set(bit)	do { (current)->trace_recursion |=
> >  (1<<(bit)); } while (0)
> >  #define trace_recursion_clear(bit)	do { (current)->trace_recursion &=
> >  ~(1<<(bit)); } while (0)
> >  #define trace_recursion_test(bit)	((current)->trace_recursion &
> >  (1<<(bit)))
> > diff --git a/kernel/trace/trace_mmiotrace.c
> > b/kernel/trace/trace_mmiotrace.c
> > index cd7480d..06aa0a5 100644
> > --- a/kernel/trace/trace_mmiotrace.c
> > +++ b/kernel/trace/trace_mmiotrace.c
> > @@ -286,6 +286,10 @@ static enum print_line_t mmio_print_line(struct
> > trace_iterator *iter)
> >  
> >  __init static int init_mmio_trace(void)
> >  {
> > +	struct tracer_noboot mmio_notrace;
> > +
> > +	mmio_notrace.name = "mmiotrace";
> > +	trace_noboot_tracer_put(&mmio_notrace);
> >  	return register_tracer(&mmio_tracer);
> >  }
> >  device_initcall(init_mmio_trace);
> 
> This is way overkill. Just add
> 
> 	bool		noboot;
> 
> to struct tracer in trace.h and then to the mmiotracer:
> 
> struct tracer mmio_tracer = {
> 	[..]
> 	.noboot		= true,
> };
> 
> 
> And then in tracing_set_tracer() add after:
> 
> 	if (t == tr->current_trace)
> 		goto out;
> 
> this:
> 
> 	if (system_state < SYSTEM_RUNNING && t->noboot) {
> 		WARN(1, "Tracer %s not allowed on command line",
> 			t->name);
> 		goto out;
> 	}
> 
> That's it. No need for locking or anything else.
> 

Thanks for the suggestions. I will send a patch v3 after testing.

> -- Steve
> 
> 		
> 

-- 
Ziqian SUN