tracing: fprobe: use ftrace if CONFIG_DYNAMIC_FTRACE_WITH_ARGS

For now, we will use ftrace for the fprobe if fp->exit_handler not exists
and CONFIG_DYNAMIC_FTRACE_WITH_REGS is enabled.

However, CONFIG_DYNAMIC_FTRACE_WITH_REGS is not supported by some arch,
such as arm. What we need in the fprobe is the function arguments, so we
can use ftrace for fprobe if CONFIG_DYNAMIC_FTRACE_WITH_ARGS is enabled.

Therefore, use ftrace if CONFIG_DYNAMIC_FTRACE_WITH_REGS or
CONFIG_DYNAMIC_FTRACE_WITH_ARGS enabled.

Link: https://lore.kernel.org/all/20251103063434.47388-1-dongml2@chinatelecom.cn/
Signed-off-by: Menglong Dong <dongml2@chinatelecom.cn>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c
index ecd623eef68b1c6a88dd35bbe8aca20828c8c815..0b1ee8e585f2e3633fe95bf9ccf155f4c8574e93 100644 (file)
--- a/kernel/trace/fprobe.c
+++ b/kernel/trace/fprobe.c
@@ -44,6 +44,7 @@
 static struct hlist_head fprobe_table[FPROBE_TABLE_SIZE];
 static struct rhltable fprobe_ip_table;
 static DEFINE_MUTEX(fprobe_mutex);
+static struct fgraph_ops fprobe_graph_ops;
 
 static u32 fprobe_node_hashfn(const void *data, u32 len, u32 seed)
 {
@@ -254,7 +255,7 @@ static inline int __fprobe_kprobe_handler(unsigned long ip, unsigned long parent
        return ret;
 }
 
-#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
+#if defined(CONFIG_DYNAMIC_FTRACE_WITH_ARGS) || defined(CONFIG_DYNAMIC_FTRACE_WITH_REGS)
 /* ftrace_ops callback, this processes fprobes which have only entry_handler. */
 static void fprobe_ftrace_entry(unsigned long ip, unsigned long parent_ip,
        struct ftrace_ops *ops, struct ftrace_regs *fregs)
@@ -295,7 +296,7 @@ NOKPROBE_SYMBOL(fprobe_ftrace_entry);
 
 static struct ftrace_ops fprobe_ftrace_ops = {
        .func   = fprobe_ftrace_entry,
-       .flags  = FTRACE_OPS_FL_SAVE_REGS,
+       .flags  = FTRACE_OPS_FL_SAVE_ARGS,
 };
 static int fprobe_ftrace_active;
 
@@ -335,6 +336,15 @@ static bool fprobe_is_ftrace(struct fprobe *fp)
 {
        return !fp->exit_handler;
 }
+
+#ifdef CONFIG_MODULES
+static void fprobe_set_ips(unsigned long *ips, unsigned int cnt, int remove,
+                          int reset)
+{
+       ftrace_set_filter_ips(&fprobe_graph_ops.ops, ips, cnt, remove, reset);
+       ftrace_set_filter_ips(&fprobe_ftrace_ops, ips, cnt, remove, reset);
+}
+#endif
 #else
 static int fprobe_ftrace_add_ips(unsigned long *addrs, int num)
 {
@@ -349,7 +359,15 @@ static bool fprobe_is_ftrace(struct fprobe *fp)
 {
        return false;
 }
+
+#ifdef CONFIG_MODULES
+static void fprobe_set_ips(unsigned long *ips, unsigned int cnt, int remove,
+                          int reset)
+{
+       ftrace_set_filter_ips(&fprobe_graph_ops.ops, ips, cnt, remove, reset);
+}
 #endif
+#endif /* !CONFIG_DYNAMIC_FTRACE_WITH_ARGS && !CONFIG_DYNAMIC_FTRACE_WITH_REGS */
 
 /* fgraph_ops callback, this processes fprobes which have exit_handler. */
 static int fprobe_fgraph_entry(struct ftrace_graph_ent *trace, struct fgraph_ops *gops,
@@ -596,14 +614,8 @@ static int fprobe_module_callback(struct notifier_block *nb,
        } while (node == ERR_PTR(-EAGAIN));
        rhashtable_walk_exit(&iter);
 
-       if (alist.index > 0) {
-               ftrace_set_filter_ips(&fprobe_graph_ops.ops,
-                                     alist.addrs, alist.index, 1, 0);
-#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
-               ftrace_set_filter_ips(&fprobe_ftrace_ops,
-                                     alist.addrs, alist.index, 1, 0);
-#endif
-       }
+       if (alist.index > 0)
+               fprobe_set_ips(alist.addrs, alist.index, 1, 0);
        mutex_unlock(&fprobe_mutex);
 
        kfree(alist.addrs);