1 files changed, 80 insertions, 23 deletions

diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c
index e8143e368074..18d36842faf5 100644
--- a/kernel/trace/fprobe.c
+++ b/kernel/trace/fprobe.c
@@ -17,57 +17,98 @@
 struct fprobe_rethook_node {
 	struct rethook_node node;
 	unsigned long entry_ip;
+	unsigned long entry_parent_ip;
+	char data[];
 };
 
-static void fprobe_handler(unsigned long ip, unsigned long parent_ip,
-			   struct ftrace_ops *ops, struct ftrace_regs *fregs)
+static inline 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;
-	int bit;
+	void *entry_data = NULL;
+	int ret = 0;
 
 	fp = container_of(ops, struct fprobe, ops);
-	if (fprobe_disabled(fp))
-		return;
-
-	bit = ftrace_test_recursion_trylock(ip, parent_ip);
-	if (bit < 0) {
-		fp->nmissed++;
-		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) {
 			fp->nmissed++;
-			goto out;
+			return;
 		}
 		fpr = container_of(rh, struct fprobe_rethook_node, node);
 		fpr->entry_ip = ip;
-		rethook_hook(rh, ftrace_get_regs(fregs), true);
+		fpr->entry_parent_ip = parent_ip;
+		if (fp->entry_data_size)
+			entry_data = fpr->data;
 	}
 
-out:
+	if (fp->entry_handler)
+		ret = fp->entry_handler(fp, ip, ftrace_get_regs(fregs), entry_data);
+
+	/* If entry_handler returns !0, nmissed is not counted. */
+	if (rh) {
+		if (ret)
+			rethook_recycle(rh);
+		else
+			rethook_hook(rh, ftrace_get_regs(fregs), true);
+	}
+}
+
+static void fprobe_handler(unsigned long ip, unsigned long parent_ip,
+		struct ftrace_ops *ops, struct ftrace_regs *fregs)
+{
+	struct fprobe *fp;
+	int bit;
+
+	fp = container_of(ops, struct fprobe, ops);
+	if (fprobe_disabled(fp))
+		return;
+
+	/* recursion detection has to go before any traceable function and
+	 * all functions before this point should be marked as notrace
+	 */
+	bit = ftrace_test_recursion_trylock(ip, parent_ip);
+	if (bit < 0) {
+		fp->nmissed++;
+		return;
+	}
+	__fprobe_handler(ip, parent_ip, ops, fregs);
 	ftrace_test_recursion_unlock(bit);
+
 }
 NOKPROBE_SYMBOL(fprobe_handler);
 
 static void fprobe_kprobe_handler(unsigned long ip, unsigned long parent_ip,
 				  struct ftrace_ops *ops, struct ftrace_regs *fregs)
 {
-	struct fprobe *fp = container_of(ops, struct fprobe, ops);
+	struct fprobe *fp;
+	int bit;
+
+	fp = container_of(ops, struct fprobe, ops);
+	if (fprobe_disabled(fp))
+		return;
+
+	/* recursion detection has to go before any traceable function and
+	 * all functions called before this point should be marked as notrace
+	 */
+	bit = ftrace_test_recursion_trylock(ip, parent_ip);
+	if (bit < 0) {
+		fp->nmissed++;
+		return;
+	}
 
 	if (unlikely(kprobe_running())) {
 		fp->nmissed++;
 		return;
 	}
+
 	kprobe_busy_begin();
-	fprobe_handler(ip, parent_ip, ops, fregs);
+	__fprobe_handler(ip, parent_ip, ops, fregs);
 	kprobe_busy_end();
+	ftrace_test_recursion_unlock(bit);
 }
 
 static void fprobe_exit_handler(struct rethook_node *rh, void *data,
@@ -75,13 +116,26 @@ static void fprobe_exit_handler(struct rethook_node *rh, void *data,
 {
 	struct fprobe *fp = (struct fprobe *)data;
 	struct fprobe_rethook_node *fpr;
+	int bit;
 
 	if (!fp || fprobe_disabled(fp))
 		return;
 
 	fpr = container_of(rh, struct fprobe_rethook_node, node);
 
-	fp->exit_handler(fp, fpr->entry_ip, regs);
+	/*
+	 * we need to assure no calls to traceable functions in-between the
+	 * end of fprobe_handler and the beginning of fprobe_exit_handler.
+	 */
+	bit = ftrace_test_recursion_trylock(fpr->entry_ip, fpr->entry_parent_ip);
+	if (bit < 0) {
+		fp->nmissed++;
+		return;
+	}
+
+	fp->exit_handler(fp, fpr->entry_ip, regs,
+			 fp->entry_data_size ? (void *)fpr->data : NULL);
+	ftrace_test_recursion_unlock(bit);
 }
 NOKPROBE_SYMBOL(fprobe_exit_handler);
 
@@ -136,7 +190,10 @@ static int fprobe_init_rethook(struct fprobe *fp, int num)
 	}
 
 	/* Initialize rethook if needed */
-	size = num * num_possible_cpus() * 2;
+	if (fp->nr_maxactive)
+		size = fp->nr_maxactive;
+	else
+		size = num * num_possible_cpus() * 2;
 	if (size < 0)
 		return -E2BIG;
 
@@ -146,7 +203,7 @@ 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);
 		if (!node) {
 			rethook_free(fp->rethook);
 			fp->rethook = NULL;