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Message-Id: <20250528034712.138701-7-dongml2@chinatelecom.cn>
Date: Wed, 28 May 2025 11:46:53 +0800
From: Menglong Dong <menglong8.dong@...il.com>
To: alexei.starovoitov@...il.com,
rostedt@...dmis.org,
jolsa@...nel.org
Cc: bpf@...r.kernel.org,
Menglong Dong <dongml2@...natelecom.cn>,
linux-kernel@...r.kernel.org
Subject: [PATCH bpf-next 06/25] ftrace: factor out ftrace_direct_update from register_ftrace_direct
Factor out ftrace_direct_update() from register_ftrace_direct(), which is
used to add new entries to the direct_functions. This function will be
used in the later patch.
Signed-off-by: Menglong Dong <dongml2@...natelecom.cn>
---
kernel/trace/ftrace.c | 108 +++++++++++++++++++++++-------------------
1 file changed, 60 insertions(+), 48 deletions(-)
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 61130bb34d6c..a1028942e743 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -5910,53 +5910,18 @@ static void register_ftrace_direct_cb(struct rcu_head *rhp)
free_ftrace_hash(fhp);
}
-/**
- * register_ftrace_direct - Call a custom trampoline directly
- * for multiple functions registered in @ops
- * @ops: The address of the struct ftrace_ops object
- * @addr: The address of the trampoline to call at @ops functions
- *
- * This is used to connect a direct calls to @addr from the nop locations
- * of the functions registered in @ops (with by ftrace_set_filter_ip
- * function).
- *
- * The location that it calls (@addr) must be able to handle a direct call,
- * and save the parameters of the function being traced, and restore them
- * (or inject new ones if needed), before returning.
- *
- * Returns:
- * 0 on success
- * -EINVAL - The @ops object was already registered with this call or
- * when there are no functions in @ops object.
- * -EBUSY - Another direct function is already attached (there can be only one)
- * -ENODEV - @ip does not point to a ftrace nop location (or not supported)
- * -ENOMEM - There was an allocation failure.
- */
-int register_ftrace_direct(struct ftrace_ops *ops, unsigned long addr)
+static int ftrace_direct_update(struct ftrace_hash *hash, unsigned long addr)
{
- struct ftrace_hash *hash, *new_hash = NULL, *free_hash = NULL;
struct ftrace_func_entry *entry, *new;
+ struct ftrace_hash *new_hash = NULL;
int err = -EBUSY, size, i;
- if (ops->func || ops->trampoline)
- return -EINVAL;
- if (!(ops->flags & FTRACE_OPS_FL_INITIALIZED))
- return -EINVAL;
- if (ops->flags & FTRACE_OPS_FL_ENABLED)
- return -EINVAL;
-
- hash = ops->func_hash->filter_hash;
- if (ftrace_hash_empty(hash))
- return -EINVAL;
-
- mutex_lock(&direct_mutex);
-
/* Make sure requested entries are not already registered.. */
size = 1 << hash->size_bits;
for (i = 0; i < size; i++) {
hlist_for_each_entry(entry, &hash->buckets[i], hlist) {
if (ftrace_find_rec_direct(entry->ip))
- goto out_unlock;
+ goto out;
}
}
@@ -5969,7 +5934,7 @@ int register_ftrace_direct(struct ftrace_ops *ops, unsigned long addr)
size = FTRACE_HASH_MAX_BITS;
new_hash = alloc_ftrace_hash(size);
if (!new_hash)
- goto out_unlock;
+ goto out;
/* Now copy over the existing direct entries */
size = 1 << direct_functions->size_bits;
@@ -5977,7 +5942,7 @@ int register_ftrace_direct(struct ftrace_ops *ops, unsigned long addr)
hlist_for_each_entry(entry, &direct_functions->buckets[i], hlist) {
new = add_hash_entry(new_hash, entry->ip);
if (!new)
- goto out_unlock;
+ goto out;
new->direct = entry->direct;
}
}
@@ -5988,16 +5953,67 @@ int register_ftrace_direct(struct ftrace_ops *ops, unsigned long addr)
hlist_for_each_entry(entry, &hash->buckets[i], hlist) {
new = add_hash_entry(new_hash, entry->ip);
if (!new)
- goto out_unlock;
+ goto out;
/* Update both the copy and the hash entry */
new->direct = addr;
entry->direct = addr;
}
}
- free_hash = direct_functions;
rcu_assign_pointer(direct_functions, new_hash);
new_hash = NULL;
+ err = 0;
+out:
+ if (new_hash)
+ free_ftrace_hash(new_hash);
+
+ return err;
+}
+
+/**
+ * register_ftrace_direct - Call a custom trampoline directly
+ * for multiple functions registered in @ops
+ * @ops: The address of the struct ftrace_ops object
+ * @addr: The address of the trampoline to call at @ops functions
+ *
+ * This is used to connect a direct calls to @addr from the nop locations
+ * of the functions registered in @ops (with by ftrace_set_filter_ip
+ * function).
+ *
+ * The location that it calls (@addr) must be able to handle a direct call,
+ * and save the parameters of the function being traced, and restore them
+ * (or inject new ones if needed), before returning.
+ *
+ * Returns:
+ * 0 on success
+ * -EINVAL - The @ops object was already registered with this call or
+ * when there are no functions in @ops object.
+ * -EBUSY - Another direct function is already attached (there can be only one)
+ * -ENODEV - @ip does not point to a ftrace nop location (or not supported)
+ * -ENOMEM - There was an allocation failure.
+ */
+int register_ftrace_direct(struct ftrace_ops *ops, unsigned long addr)
+{
+ struct ftrace_hash *hash, *free_hash = NULL;
+ int err = -EBUSY;
+
+ if (ops->func || ops->trampoline)
+ return -EINVAL;
+ if (!(ops->flags & FTRACE_OPS_FL_INITIALIZED))
+ return -EINVAL;
+ if (ops->flags & FTRACE_OPS_FL_ENABLED)
+ return -EINVAL;
+
+ hash = ops->func_hash->filter_hash;
+ if (ftrace_hash_empty(hash))
+ return -EINVAL;
+
+ mutex_lock(&direct_mutex);
+
+ free_hash = direct_functions;
+ err = ftrace_direct_update(hash, addr);
+ if (err)
+ goto out_unlock;
ops->func = call_direct_funcs;
ops->flags = MULTI_FLAGS;
@@ -6005,15 +6021,11 @@ int register_ftrace_direct(struct ftrace_ops *ops, unsigned long addr)
ops->direct_call = addr;
err = register_ftrace_function_nolock(ops);
-
- out_unlock:
- mutex_unlock(&direct_mutex);
-
if (free_hash && free_hash != EMPTY_HASH)
call_rcu_tasks(&free_hash->rcu, register_ftrace_direct_cb);
- if (new_hash)
- free_ftrace_hash(new_hash);
+ out_unlock:
+ mutex_unlock(&direct_mutex);
return err;
}
--
2.39.5
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