Commit ccf5a89e authored by Jiri Olsa's avatar Jiri Olsa Committed by Steven Rostedt (VMware)
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ftrace: Add multi direct modify interface 

Adding interface to modify registered direct function
for ftrace_ops. Adding following function:

   modify_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr)

The function changes the currently registered direct
function for all attached functions.

Link: https://lkml.kernel.org/r/20211008091336.33616-8-jolsa@kernel.org



Signed-off-by: default avatarJiri Olsa <jolsa@kernel.org>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent f64dd462

include/linux/ftrace.h

+6 −0
Original line number Diff line number Diff line
@@ -326,6 +326,8 @@ int ftrace_modify_direct_caller(struct ftrace_func_entry *entry, 
unsigned long ftrace_find_rec_direct(unsigned long ip);

int register_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr);

int unregister_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr);

int modify_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr);



#else

struct ftrace_ops;

# define ftrace_direct_func_count 0
@@ -365,6 +367,10 @@ static inline int unregister_ftrace_direct_multi(struct ftrace_ops *ops, unsigne 
{

	return -ENODEV;

}

static inline int modify_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr)

{

	return -ENODEV;

}

#endif /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */



#ifndef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS

kernel/trace/ftrace.c

+62 −0
Original line number Diff line number Diff line
@@ -5543,6 +5543,68 @@ int unregister_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr) 
	return err;

}

EXPORT_SYMBOL_GPL(unregister_ftrace_direct_multi);



/**

 * modify_ftrace_direct_multi - Modify an existing direct 'multi' call

 * to call something else

 * @ops: The address of the struct ftrace_ops object

 * @addr: The address of the new trampoline to call at @ops functions

 *

 * This is used to unregister currently registered direct caller and

 * register new one @addr on functions registered in @ops object.

 *

 * Note there's window between ftrace_shutdown and ftrace_startup calls

 * where there will be no callbacks called.

 *

 * Returns: zero on success. Non zero on error, which includes:

 *  -EINVAL - The @ops object was not properly registered.

 */

int modify_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr)

{

	struct ftrace_hash *hash = ops->func_hash->filter_hash;

	struct ftrace_func_entry *entry, *iter;

	int i, size;

	int err;



	if (check_direct_multi(ops))

		return -EINVAL;

	if (!(ops->flags & FTRACE_OPS_FL_ENABLED))

		return -EINVAL;



	mutex_lock(&direct_mutex);

	mutex_lock(&ftrace_lock);



	/*

	 * Shutdown the ops, change 'direct' pointer for each

	 * ops entry in direct_functions hash and startup the

	 * ops back again.

	 *

	 * Note there is no callback called for @ops object after

	 * this ftrace_shutdown call until ftrace_startup is called

	 * later on.

	 */

	err = ftrace_shutdown(ops, 0);

	if (err)

		goto out_unlock;



	size = 1 << hash->size_bits;

	for (i = 0; i < size; i++) {

		hlist_for_each_entry(iter, &hash->buckets[i], hlist) {

			entry = __ftrace_lookup_ip(direct_functions, iter->ip);

			if (!entry)

				continue;

			entry->direct = addr;

		}

	}



	err = ftrace_startup(ops, 0);



 out_unlock:

	mutex_unlock(&ftrace_lock);

	mutex_unlock(&direct_mutex);

	return err;

}

EXPORT_SYMBOL_GPL(modify_ftrace_direct_multi);

#endif /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */



/**