linux-kernel - [RFC 08/10] ftrace: Factor ftrace_ops ops

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Message-ID: <20250729102813.1531457-9-jolsa@kernel.org>
Date: Tue, 29 Jul 2025 12:28:11 +0200
From: Jiri Olsa <jolsa@...nel.org>
To: Steven Rostedt <rostedt@...nel.org>,
	Florent Revest <revest@...gle.com>,
	Mark Rutland <mark.rutland@....com>
Cc: bpf@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-trace-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	Alexei Starovoitov <ast@...nel.org>,
	Daniel Borkmann <daniel@...earbox.net>,
	Andrii Nakryiko <andrii@...nel.org>,
	Menglong Dong <menglong8.dong@...il.com>
Subject: [RFC 08/10] ftrace: Factor ftrace_ops ops_func interface

We are going to remove "ftrace_ops->private == bpf_trampoline" setup
in following changes.

Adding ip argument to ftrace_ops_func_t callback function, so we can
use it to look up the trampoline.

Signed-off-by: Jiri Olsa <jolsa@...nel.org>
---
 include/linux/ftrace.h  |  2 +-
 kernel/bpf/trampoline.c | 26 ++++++++++++++++++++++++--
 kernel/trace/ftrace.c   |  6 +++---
 3 files changed, 28 insertions(+), 6 deletions(-)

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 85f4ab1a1e72..1a61f969550d 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -394,7 +394,7 @@ enum ftrace_ops_cmd {
  *        Negative on failure. The return value is dependent on the
  *        callback.
  */
-typedef int (*ftrace_ops_func_t)(struct ftrace_ops *op, enum ftrace_ops_cmd cmd);
+typedef int (*ftrace_ops_func_t)(struct ftrace_ops *op, unsigned long ip, enum ftrace_ops_cmd cmd);
 
 #ifdef CONFIG_DYNAMIC_FTRACE
 
diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c
index 84bcd9f6bd74..398c1a722d83 100644
--- a/kernel/bpf/trampoline.c
+++ b/kernel/bpf/trampoline.c
@@ -33,11 +33,33 @@ static DEFINE_MUTEX(trampoline_mutex);
 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
 static int bpf_trampoline_update(struct bpf_trampoline *tr, bool lock_direct_mutex);
 
-static int bpf_tramp_ftrace_ops_func(struct ftrace_ops *ops, enum ftrace_ops_cmd cmd)
+static struct bpf_trampoline *bpf_trampoline_ip_lookup(unsigned long ip)
 {
-	struct bpf_trampoline *tr = ops->private;
+	struct hlist_head *head_ip;
+	struct bpf_trampoline *tr;
+
+	mutex_lock(&trampoline_mutex);
+	head_ip = &trampoline_ip_table[hash_64(ip, TRAMPOLINE_HASH_BITS)];
+	hlist_for_each_entry(tr, head_ip, hlist_ip) {
+		if (tr->func.addr == (void *) ip)
+			goto out;
+	}
+	tr = NULL;
+out:
+	mutex_unlock(&trampoline_mutex);
+	return tr;
+}
+
+static int bpf_tramp_ftrace_ops_func(struct ftrace_ops *ops, unsigned long ip,
+				     enum ftrace_ops_cmd cmd)
+{
+	struct bpf_trampoline *tr;
 	int ret = 0;
 
+	tr = bpf_trampoline_ip_lookup(ip);
+	if (!tr)
+		return -EINVAL;
+
 	if (cmd == FTRACE_OPS_CMD_ENABLE_SHARE_IPMODIFY_SELF) {
 		/* This is called inside register_ftrace_direct_multi(), so
 		 * tr->mutex is already locked.
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 151ca94f496a..943feabdd5e6 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -2040,7 +2040,7 @@ static int __ftrace_hash_update_ipmodify(struct ftrace_ops *ops,
 				 */
 				if (!ops->ops_func)
 					return -EBUSY;
-				ret = ops->ops_func(ops, FTRACE_OPS_CMD_ENABLE_SHARE_IPMODIFY_SELF);
+				ret = ops->ops_func(ops, rec->ip, FTRACE_OPS_CMD_ENABLE_SHARE_IPMODIFY_SELF);
 				if (ret)
 					return ret;
 			} else if (is_ipmodify) {
@@ -8746,7 +8746,7 @@ static int prepare_direct_functions_for_ipmodify(struct ftrace_ops *ops)
 				if (!op->ops_func)
 					return -EBUSY;
 
-				ret = op->ops_func(op, FTRACE_OPS_CMD_ENABLE_SHARE_IPMODIFY_PEER);
+				ret = op->ops_func(op, ip, FTRACE_OPS_CMD_ENABLE_SHARE_IPMODIFY_PEER);
 				if (ret)
 					return ret;
 			}
@@ -8793,7 +8793,7 @@ static void cleanup_direct_functions_after_ipmodify(struct ftrace_ops *ops)
 
 			/* The cleanup is optional, ignore any errors */
 			if (found_op && op->ops_func)
-				op->ops_func(op, FTRACE_OPS_CMD_DISABLE_SHARE_IPMODIFY_PEER);
+				op->ops_func(op, ip, FTRACE_OPS_CMD_DISABLE_SHARE_IPMODIFY_PEER);
 		}
 	}
 	mutex_unlock(&direct_mutex);
-- 
2.50.1