diff mbox series

[v2,11/27] ftrace: Allow subops filtering to be modified

Message ID 20240602033832.870736657@goodmis.org (mailing list archive)
State Not Applicable
Delegated to: BPF
Headers show
Series function_graph: Allow multiple users for function graph tracing | expand

Checks

Context Check Description
netdev/tree_selection success Not a local patch

Commit Message

Steven Rostedt June 2, 2024, 3:37 a.m. UTC 
From: "Steven Rostedt (Google)" <rostedt@goodmis.org>

The subops filters use a "manager" ops to enable and disable its filters.
The manager ops can handle more than one subops, and its filter is what
controls what functions get set. Add a ftrace_hash_move_and_update_subops()
function that will update the manager ops when the subops filters change.

Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 include/linux/ftrace.h |  3 ++
 kernel/trace/ftrace.c  | 96 ++++++++++++++++++++++++++++++++++++++----
 2 files changed, 90 insertions(+), 9 deletions(-)

Comments

Masami Hiramatsu (Google) June 3, 2024, 2:37 a.m. UTC | #1 
On Sat, 01 Jun 2024 23:37:55 -0400
Steven Rostedt <rostedt@goodmis.org> wrote:

[...]
>  
> +static int ftrace_hash_move_and_update_subops(struct ftrace_ops *subops,
> +					      struct ftrace_hash **orig_subhash,
> +					      struct ftrace_hash *hash,
> +					      int enable)
> +{
> +	struct ftrace_ops *ops = subops->managed;
> +	struct ftrace_hash **orig_hash;
> +	struct ftrace_hash *save_hash;
> +	struct ftrace_hash *new_hash;
> +	int ret;
> +
> +	/* Manager ops can not be subops (yet) */
> +	if (WARN_ON_ONCE(!ops || ops->flags & FTRACE_OPS_FL_SUBOP))
> +		return -EINVAL;

This does return if ops->flags & FTRACE_OPS_FL_SUBOP, but --> (1)

> +
> +	/* Move the new hash over to the subops hash */
> +	save_hash = *orig_subhash;
> +	*orig_subhash = __ftrace_hash_move(hash);
> +	if (!*orig_subhash) {
> +		*orig_subhash = save_hash;
> +		return -ENOMEM;
> +	}
> +
> +	/* Create a new_hash to hold the ops new functions */
> +	if (enable) {
> +		orig_hash = &ops->func_hash->filter_hash;
> +		new_hash = append_hashes(ops);
> +	} else {
> +		orig_hash = &ops->func_hash->notrace_hash;
> +		new_hash = intersect_hashes(ops);
> +	}
> +
> +	/* Move the hash over to the new hash */
> +	ret = ftrace_hash_move_and_update_ops(ops, orig_hash, new_hash, enable);

This also a bit wired to me. maybe we need simple version like

`__ftrace_hash_move_and_update_ops()`

And call it from ftrace_hash_move_and_update_ops() and here?

> +
> +	free_ftrace_hash(new_hash);
> +
> +	if (ret) {
> +		/* Put back the original hash */
> +		free_ftrace_hash_rcu(*orig_subhash);
> +		*orig_subhash = save_hash;
> +	} else {
> +		free_ftrace_hash_rcu(save_hash);
> +	}
> +	return ret;
> +}
> +
> +
>  static u64		ftrace_update_time;
>  unsigned long		ftrace_update_tot_cnt;
>  unsigned long		ftrace_number_of_pages;
> @@ -4770,8 +4823,33 @@ static int ftrace_hash_move_and_update_ops(struct ftrace_ops *ops,
>  {
>  	struct ftrace_ops_hash old_hash_ops;
>  	struct ftrace_hash *old_hash;
> +	struct ftrace_ops *op;
>  	int ret;
>  
> +	if (ops->flags & FTRACE_OPS_FL_SUBOP)
> +		return ftrace_hash_move_and_update_subops(ops, orig_hash, hash, enable);

(1) This calls ftrace_hash_move_and_update_subops() if ops->flags & FTRACE_OPS_FL_SUBOP ?

Thank you,

> +
> +	/*
> +	 * If this ops is not enabled, it could be sharing its filters
> +	 * with a subop. If that's the case, update the subop instead of
> +	 * this ops. Shared filters are only allowed to have one ops set
> +	 * at a time, and if we update the ops that is not enabled,
> +	 * it will not affect subops that share it.
> +	 */
> +	if (!(ops->flags & FTRACE_OPS_FL_ENABLED)) {
> +		/* Check if any other manager subops maps to this hash */
> +		do_for_each_ftrace_op(op, ftrace_ops_list) {
> +			struct ftrace_ops *subops;
> +
> +			list_for_each_entry(subops, &op->subop_list, list) {
> +				if ((subops->flags & FTRACE_OPS_FL_ENABLED) &&
> +				     subops->func_hash == ops->func_hash) {
> +					return ftrace_hash_move_and_update_subops(subops, orig_hash, hash, enable);
> +				}
> +			}
> +		} while_for_each_ftrace_op(op);
> +	}
> +
>  	old_hash = *orig_hash;
>  	old_hash_ops.filter_hash = ops->func_hash->filter_hash;
>  	old_hash_ops.notrace_hash = ops->func_hash->notrace_hash;
> -- 
> 2.43.0
> 
>
Steven Rostedt June 3, 2024, 2:52 p.m. UTC | #2 
On Mon, 3 Jun 2024 11:37:23 +0900
Masami Hiramatsu (Google) <mhiramat@kernel.org> wrote:

> On Sat, 01 Jun 2024 23:37:55 -0400
> Steven Rostedt <rostedt@goodmis.org> wrote:
> 
> [...]
> >  
> > +static int ftrace_hash_move_and_update_subops(struct ftrace_ops *subops,
> > +					      struct ftrace_hash **orig_subhash,
> > +					      struct ftrace_hash *hash,
> > +					      int enable)
> > +{
> > +	struct ftrace_ops *ops = subops->managed;
> > +	struct ftrace_hash **orig_hash;
> > +	struct ftrace_hash *save_hash;
> > +	struct ftrace_hash *new_hash;
> > +	int ret;
> > +
> > +	/* Manager ops can not be subops (yet) */
> > +	if (WARN_ON_ONCE(!ops || ops->flags & FTRACE_OPS_FL_SUBOP))
> > +		return -EINVAL;  
> 
> This does return if ops->flags & FTRACE_OPS_FL_SUBOP, but --> (1)

Yes, because what is passed in is "subops" and "ops" is subops->managed.

> 
> > +
> > +	/* Move the new hash over to the subops hash */
> > +	save_hash = *orig_subhash;
> > +	*orig_subhash = __ftrace_hash_move(hash);
> > +	if (!*orig_subhash) {
> > +		*orig_subhash = save_hash;
> > +		return -ENOMEM;
> > +	}
> > +
> > +	/* Create a new_hash to hold the ops new functions */
> > +	if (enable) {
> > +		orig_hash = &ops->func_hash->filter_hash;
> > +		new_hash = append_hashes(ops);
> > +	} else {
> > +		orig_hash = &ops->func_hash->notrace_hash;
> > +		new_hash = intersect_hashes(ops);
> > +	}
> > +
> > +	/* Move the hash over to the new hash */
> > +	ret = ftrace_hash_move_and_update_ops(ops, orig_hash, new_hash, enable);  
> 
> This also a bit wired to me. maybe we need simple version like
> 
> `__ftrace_hash_move_and_update_ops()`
> 
> And call it from ftrace_hash_move_and_update_ops() and here?

We could do that. I almost did due to other issues but I reworked the code
where I didn't need to.

> 
> > +
> > +	free_ftrace_hash(new_hash);
> > +
> > +	if (ret) {
> > +		/* Put back the original hash */
> > +		free_ftrace_hash_rcu(*orig_subhash);
> > +		*orig_subhash = save_hash;
> > +	} else {
> > +		free_ftrace_hash_rcu(save_hash);
> > +	}
> > +	return ret;
> > +}
> > +
> > +
> >  static u64		ftrace_update_time;
> >  unsigned long		ftrace_update_tot_cnt;
> >  unsigned long		ftrace_number_of_pages;
> > @@ -4770,8 +4823,33 @@ static int ftrace_hash_move_and_update_ops(struct ftrace_ops *ops,
> >  {
> >  	struct ftrace_ops_hash old_hash_ops;
> >  	struct ftrace_hash *old_hash;
> > +	struct ftrace_ops *op;
> >  	int ret;
> >  
> > +	if (ops->flags & FTRACE_OPS_FL_SUBOP)
> > +		return ftrace_hash_move_and_update_subops(ops, orig_hash, hash, enable);  
> 
> (1) This calls ftrace_hash_move_and_update_subops() if ops->flags & FTRACE_OPS_FL_SUBOP ?

Yes, because ops turns into subops, and the ops above it is its manager ops.

-- Steve
Masami Hiramatsu (Google) June 3, 2024, 11:12 p.m. UTC | #3 
On Mon, 3 Jun 2024 10:52:50 -0400
Steven Rostedt <rostedt@goodmis.org> wrote:

> On Mon, 3 Jun 2024 11:37:23 +0900
> Masami Hiramatsu (Google) <mhiramat@kernel.org> wrote:
> 
> > On Sat, 01 Jun 2024 23:37:55 -0400
> > Steven Rostedt <rostedt@goodmis.org> wrote:
> > 
> > [...]
> > >  
> > > +static int ftrace_hash_move_and_update_subops(struct ftrace_ops *subops,
> > > +					      struct ftrace_hash **orig_subhash,
> > > +					      struct ftrace_hash *hash,
> > > +					      int enable)
> > > +{
> > > +	struct ftrace_ops *ops = subops->managed;
> > > +	struct ftrace_hash **orig_hash;
> > > +	struct ftrace_hash *save_hash;
> > > +	struct ftrace_hash *new_hash;
> > > +	int ret;
> > > +
> > > +	/* Manager ops can not be subops (yet) */
> > > +	if (WARN_ON_ONCE(!ops || ops->flags & FTRACE_OPS_FL_SUBOP))
> > > +		return -EINVAL;  
> > 
> > This does return if ops->flags & FTRACE_OPS_FL_SUBOP, but --> (1)
> 
> Yes, because what is passed in is "subops" and "ops" is subops->managed.

Ah, I missed that point. OK, I got it.


> 
> > 
> > > +
> > > +	/* Move the new hash over to the subops hash */
> > > +	save_hash = *orig_subhash;
> > > +	*orig_subhash = __ftrace_hash_move(hash);
> > > +	if (!*orig_subhash) {
> > > +		*orig_subhash = save_hash;
> > > +		return -ENOMEM;
> > > +	}
> > > +
> > > +	/* Create a new_hash to hold the ops new functions */
> > > +	if (enable) {
> > > +		orig_hash = &ops->func_hash->filter_hash;
> > > +		new_hash = append_hashes(ops);
> > > +	} else {
> > > +		orig_hash = &ops->func_hash->notrace_hash;
> > > +		new_hash = intersect_hashes(ops);
> > > +	}
> > > +
> > > +	/* Move the hash over to the new hash */
> > > +	ret = ftrace_hash_move_and_update_ops(ops, orig_hash, new_hash, enable);  

So this `ops` is managed ops of this subops.

> > 
> > This also a bit wired to me. maybe we need simple version like
> > 
> > `__ftrace_hash_move_and_update_ops()`
> > 
> > And call it from ftrace_hash_move_and_update_ops() and here?
> 
> We could do that. I almost did due to other issues but I reworked the code
> where I didn't need to.
> 
> > 
> > > +
> > > +	free_ftrace_hash(new_hash);
> > > +
> > > +	if (ret) {
> > > +		/* Put back the original hash */
> > > +		free_ftrace_hash_rcu(*orig_subhash);
> > > +		*orig_subhash = save_hash;
> > > +	} else {
> > > +		free_ftrace_hash_rcu(save_hash);
> > > +	}
> > > +	return ret;
> > > +}
> > > +
> > > +
> > >  static u64		ftrace_update_time;
> > >  unsigned long		ftrace_update_tot_cnt;
> > >  unsigned long		ftrace_number_of_pages;
> > > @@ -4770,8 +4823,33 @@ static int ftrace_hash_move_and_update_ops(struct ftrace_ops *ops,
> > >  {
> > >  	struct ftrace_ops_hash old_hash_ops;
> > >  	struct ftrace_hash *old_hash;
> > > +	struct ftrace_ops *op;
> > >  	int ret;
> > >  
> > > +	if (ops->flags & FTRACE_OPS_FL_SUBOP)
> > > +		return ftrace_hash_move_and_update_subops(ops, orig_hash, hash, enable);  
> > 
> > (1) This calls ftrace_hash_move_and_update_subops() if ops->flags & FTRACE_OPS_FL_SUBOP ?
> 
> Yes, because ops turns into subops, and the ops above it is its manager ops.

Ah, OK. This `ops` is a subops. 


Thank you,

> 
> -- Steve
>
diff mbox series

Patch

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 978a1d3b270a..63238a9a9270 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -227,6 +227,7 @@  ftrace_func_t ftrace_ops_get_func(struct ftrace_ops *ops);
  *             ftrace_enabled.
  * DIRECT - Used by the direct ftrace_ops helper for direct functions
  *            (internal ftrace only, should not be used by others)
+ * SUBOP  - Is controlled by another op in field managed.
  */
 enum {
 	FTRACE_OPS_FL_ENABLED			= BIT(0),
@@ -247,6 +248,7 @@  enum {
 	FTRACE_OPS_FL_TRACE_ARRAY		= BIT(15),
 	FTRACE_OPS_FL_PERMANENT                 = BIT(16),
 	FTRACE_OPS_FL_DIRECT			= BIT(17),
+	FTRACE_OPS_FL_SUBOP			= BIT(18),
 };
 
 #ifndef CONFIG_DYNAMIC_FTRACE_WITH_ARGS
@@ -336,6 +338,7 @@  struct ftrace_ops {
 	struct list_head		list;
 	struct list_head		subop_list;
 	ftrace_ops_func_t		ops_func;
+	struct ftrace_ops		*managed;
 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
 	unsigned long			direct_call;
 #endif
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 38fb2a634b04..e447b04c0c9c 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -3424,7 +3424,8 @@  int ftrace_startup_subops(struct ftrace_ops *ops, struct ftrace_ops *subops, int
 		} else {
 			free_ftrace_hash(save_filter_hash);
 			free_ftrace_hash(save_notrace_hash);
-			subops->flags |= FTRACE_OPS_FL_ENABLED;
+			subops->flags |= FTRACE_OPS_FL_ENABLED | FTRACE_OPS_FL_SUBOP;
+			subops->managed = ops;
 		}
 		return ret;
 	}
@@ -3478,11 +3479,12 @@  int ftrace_startup_subops(struct ftrace_ops *ops, struct ftrace_ops *subops, int
 	ret = ftrace_update_ops(ops, filter_hash, notrace_hash);
 	free_ftrace_hash(filter_hash);
 	free_ftrace_hash(notrace_hash);
-	if (ret < 0)
+	if (ret < 0) {
 		list_del(&subops->list);
-	else
-		subops->flags |= FTRACE_OPS_FL_ENABLED;
-
+	} else {
+		subops->flags |= FTRACE_OPS_FL_ENABLED | FTRACE_OPS_FL_SUBOP;
+		subops->managed = ops;
+	}
 	return ret;
 }
 
@@ -3527,6 +3529,8 @@  int ftrace_shutdown_subops(struct ftrace_ops *ops, struct ftrace_ops *subops, in
 		free_ftrace_hash(ops->func_hash->notrace_hash);
 		ops->func_hash->filter_hash = EMPTY_HASH;
 		ops->func_hash->notrace_hash = EMPTY_HASH;
+		subops->flags &= ~(FTRACE_OPS_FL_ENABLED | FTRACE_OPS_FL_SUBOP);
+		subops->managed = NULL;
 
 		return 0;
 	}
@@ -3542,16 +3546,65 @@  int ftrace_shutdown_subops(struct ftrace_ops *ops, struct ftrace_ops *subops, in
 	}
 
 	ret = ftrace_update_ops(ops, filter_hash, notrace_hash);
-	if (ret < 0)
+	if (ret < 0) {
 		list_add(&subops->list, &ops->subop_list);
-	else
-		subops->flags &= ~FTRACE_OPS_FL_ENABLED;
-
+	} else {
+		subops->flags &= ~(FTRACE_OPS_FL_ENABLED | FTRACE_OPS_FL_SUBOP);
+		subops->managed = NULL;
+	}
 	free_ftrace_hash(filter_hash);
 	free_ftrace_hash(notrace_hash);
 	return ret;
 }
 
+static int ftrace_hash_move_and_update_subops(struct ftrace_ops *subops,
+					      struct ftrace_hash **orig_subhash,
+					      struct ftrace_hash *hash,
+					      int enable)
+{
+	struct ftrace_ops *ops = subops->managed;
+	struct ftrace_hash **orig_hash;
+	struct ftrace_hash *save_hash;
+	struct ftrace_hash *new_hash;
+	int ret;
+
+	/* Manager ops can not be subops (yet) */
+	if (WARN_ON_ONCE(!ops || ops->flags & FTRACE_OPS_FL_SUBOP))
+		return -EINVAL;
+
+	/* Move the new hash over to the subops hash */
+	save_hash = *orig_subhash;
+	*orig_subhash = __ftrace_hash_move(hash);
+	if (!*orig_subhash) {
+		*orig_subhash = save_hash;
+		return -ENOMEM;
+	}
+
+	/* Create a new_hash to hold the ops new functions */
+	if (enable) {
+		orig_hash = &ops->func_hash->filter_hash;
+		new_hash = append_hashes(ops);
+	} else {
+		orig_hash = &ops->func_hash->notrace_hash;
+		new_hash = intersect_hashes(ops);
+	}
+
+	/* Move the hash over to the new hash */
+	ret = ftrace_hash_move_and_update_ops(ops, orig_hash, new_hash, enable);
+
+	free_ftrace_hash(new_hash);
+
+	if (ret) {
+		/* Put back the original hash */
+		free_ftrace_hash_rcu(*orig_subhash);
+		*orig_subhash = save_hash;
+	} else {
+		free_ftrace_hash_rcu(save_hash);
+	}
+	return ret;
+}
+
+
 static u64		ftrace_update_time;
 unsigned long		ftrace_update_tot_cnt;
 unsigned long		ftrace_number_of_pages;
@@ -4770,8 +4823,33 @@  static int ftrace_hash_move_and_update_ops(struct ftrace_ops *ops,
 {
 	struct ftrace_ops_hash old_hash_ops;
 	struct ftrace_hash *old_hash;
+	struct ftrace_ops *op;
 	int ret;
 
+	if (ops->flags & FTRACE_OPS_FL_SUBOP)
+		return ftrace_hash_move_and_update_subops(ops, orig_hash, hash, enable);
+
+	/*
+	 * If this ops is not enabled, it could be sharing its filters
+	 * with a subop. If that's the case, update the subop instead of
+	 * this ops. Shared filters are only allowed to have one ops set
+	 * at a time, and if we update the ops that is not enabled,
+	 * it will not affect subops that share it.
+	 */
+	if (!(ops->flags & FTRACE_OPS_FL_ENABLED)) {
+		/* Check if any other manager subops maps to this hash */
+		do_for_each_ftrace_op(op, ftrace_ops_list) {
+			struct ftrace_ops *subops;
+
+			list_for_each_entry(subops, &op->subop_list, list) {
+				if ((subops->flags & FTRACE_OPS_FL_ENABLED) &&
+				     subops->func_hash == ops->func_hash) {
+					return ftrace_hash_move_and_update_subops(subops, orig_hash, hash, enable);
+				}
+			}
+		} while_for_each_ftrace_op(op);
+	}
+
 	old_hash = *orig_hash;
 	old_hash_ops.filter_hash = ops->func_hash->filter_hash;
 	old_hash_ops.notrace_hash = ops->func_hash->notrace_hash;