On Tue, 17 Jan 2023 20:43:09 -0500
Steven Rostedt [off-list ref] wrote:

On Wed,  9 Nov 2022 00:49:23 +0900
"Masami Hiramatsu (Google)" [off-list ref] wrote:

quoted

diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c
index e8143e368074..fa25d09c9d57 100644
--- a/kernel/trace/fprobe.c
+++ b/kernel/trace/fprobe.c

@@ -17,14 +17,16 @@
 struct fprobe_rethook_node {
 	struct rethook_node node;
 	unsigned long entry_ip;
+	char data[];
 };
 
 static void fprobe_handler(unsigned long ip, unsigned long parent_ip,
 			   struct ftrace_ops *ops, struct ftrace_regs *fregs)
 {
 	struct fprobe_rethook_node *fpr;
-	struct rethook_node *rh;
+	struct rethook_node *rh = NULL;
 	struct fprobe *fp;
+	void *entry_data = NULL;
 	int bit;
 
 	fp = container_of(ops, struct fprobe, ops);

@@ -37,9 +39,6 @@ static void fprobe_handler(unsigned long ip, unsigned long parent_ip,
 		return;
 	}
 
-	if (fp->entry_handler)
-		fp->entry_handler(fp, ip, ftrace_get_regs(fregs));
-
 	if (fp->exit_handler) {
 		rh = rethook_try_get(fp->rethook);
 		if (!rh) {

@@ -48,9 +47,16 @@ static void fprobe_handler(unsigned long ip, unsigned long parent_ip,
 		}
 		fpr = container_of(rh, struct fprobe_rethook_node, node);
 		fpr->entry_ip = ip;
-		rethook_hook(rh, ftrace_get_regs(fregs), true);
+		if (fp->entry_data_size)
+			entry_data = fpr->data;
 	}
 
+	if (fp->entry_handler)
+		fp->entry_handler(fp, ip, ftrace_get_regs(fregs), entry_data);
+
+	if (rh)
+		rethook_hook(rh, ftrace_get_regs(fregs), true);
+
 out:
 	ftrace_test_recursion_unlock(bit);
 }

@@ -81,7 +87,8 @@ static void fprobe_exit_handler(struct rethook_node *rh, void *data,
 
 	fpr = container_of(rh, struct fprobe_rethook_node, node);
 
-	fp->exit_handler(fp, fpr->entry_ip, regs);
+	fp->exit_handler(fp, fpr->entry_ip, regs,
+			 fp->entry_data_size ? (void *)fpr->data : NULL);
 }
 NOKPROBE_SYMBOL(fprobe_exit_handler);
 

@@ -146,7 +153,7 @@ static int fprobe_init_rethook(struct fprobe *fp, int num)
 	for (i = 0; i < size; i++) {
 		struct fprobe_rethook_node *node;
 
-		node = kzalloc(sizeof(*node), GFP_KERNEL);
+		node = kzalloc(sizeof(*node) + fp->entry_data_size, GFP_KERNEL);

		node = kzalloc(struct_size(node, data, fp->entry_data_size), GFP_KERNEL);

Should use struct_size() for any tail structure allocations.

OK, I'll use that.

Thank you!

-- Steve

quoted

 		if (!node) {
 			rethook_free(fp->rethook);
 			fp->rethook = NULL;

diff --git a/lib/test_fprobe.c b/lib/test_fprobe.c
index e0381b3ec410..34fa5a5bbda1 100644

-- 
Masami Hiramatsu (Google) [off-list ref]