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.
Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
---
include/linux/ftrace.h | 6 ++++
kernel/trace/ftrace.c | 62 ++++++++++++++++++++++++++++++++++++++++++
2 files changed, 68 insertions(+)
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index ba5d02ba8166..c15b767f39cf 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -318,6 +318,8 @@ 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
@@ -357,6 +359,10 @@ 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
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index f9df7bffb770..d92f2591c3fc 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -5547,6 +5547,68 @@ 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 */
/**
--
2.31.1
