Subject: [RFC PATCH v3 1/9] ftrace: Add ftrace_set_filter_ips function

From: Masami Hiramatsu <[email-masked]>
Date: Wed, 19 Jan 2022 23:56:45 +0900

From: Jiri Olsa <[email-masked]>

Adding ftrace_set_filter_ips function to be able to set filter on
multiple ip addresses at once.

With the kprobe multi attach interface we have cases where we need to
initialize ftrace_ops object with thousands of functions, so having
single function diving into ftrace_hash_move_and_update_ops with
ftrace_lock is faster.

The functions ips are passed as unsigned long array with count.

Signed-off-by: Jiri Olsa <[email-masked]>
---
 include/linux/ftrace.h |    3 +++
 kernel/trace/ftrace.c  |   53 ++++++++++++++++++++++++++++++++++++++++--------
 2 files changed, 47 insertions(+), 9 deletions(-)

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 9999e29187de..60847cbce0da 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -512,6 +512,8 @@ struct dyn_ftrace {
 
 int ftrace_set_filter_ip(struct ftrace_ops *ops, unsigned long ip,
 			 int remove, int reset);
+int ftrace_set_filter_ips(struct ftrace_ops *ops, unsigned long *ips,
+			  unsigned int cnt, int remove, int reset);
 int ftrace_set_filter(struct ftrace_ops *ops, unsigned char *buf,
 		       int len, int reset);
 int ftrace_set_notrace(struct ftrace_ops *ops, unsigned char *buf,
@@ -802,6 +804,7 @@ static inline unsigned long ftrace_location(unsigned long ip)
 #define ftrace_regex_open(ops, flag, inod, file) ({ -ENODEV; })
 #define ftrace_set_early_filter(ops, buf, enable) do { } while (0)
 #define ftrace_set_filter_ip(ops, ip, remove, reset) ({ -ENODEV; })
+#define ftrace_set_filter_ips(ops, ips, cnt, remove, reset) ({ -ENODEV; })
 #define ftrace_set_filter(ops, buf, len, reset) ({ -ENODEV; })
 #define ftrace_set_notrace(ops, buf, len, reset) ({ -ENODEV; })
 #define ftrace_free_filter(ops) do { } while (0)
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index be5f6b32a012..39350aa38649 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -4958,7 +4958,7 @@ ftrace_notrace_write(struct file *file, const char __user *ubuf,
 }
 
 static int
-ftrace_match_addr(struct ftrace_hash *hash, unsigned long ip, int remove)
+__ftrace_match_addr(struct ftrace_hash *hash, unsigned long ip, int remove)
 {
 	struct ftrace_func_entry *entry;
 
@@ -4976,9 +4976,25 @@ ftrace_match_addr(struct ftrace_hash *hash, unsigned long ip, int remove)
 	return add_hash_entry(hash, ip);
 }
 
+static int
+ftrace_match_addr(struct ftrace_hash *hash, unsigned long *ips,
+		  unsigned int cnt, int remove)
+{
+	unsigned int i;
+	int err;
+
+	for (i = 0; i < cnt; i++) {
+		err = __ftrace_match_addr(hash, ips[i], remove);
+		if (err)
+			return err;
+	}
+	return 0;
+}
+
 static int
 ftrace_set_hash(struct ftrace_ops *ops, unsigned char *buf, int len,
-		unsigned long ip, int remove, int reset, int enable)
+		unsigned long *ips, unsigned int cnt,
+		int remove, int reset, int enable)
 {
 	struct ftrace_hash **orig_hash;
 	struct ftrace_hash *hash;
@@ -5008,8 +5024,8 @@ ftrace_set_hash(struct ftrace_ops *ops, unsigned char *buf, int len,
 		ret = -EINVAL;
 		goto out_regex_unlock;
 	}
-	if (ip) {
-		ret = ftrace_match_addr(hash, ip, remove);
+	if (ips) {
+		ret = ftrace_match_addr(hash, ips, cnt, remove);
 		if (ret < 0)
 			goto out_regex_unlock;
 	}
@@ -5026,10 +5042,10 @@ ftrace_set_hash(struct ftrace_ops *ops, unsigned char *buf, int len,
 }
 
 static int
-ftrace_set_addr(struct ftrace_ops *ops, unsigned long ip, int remove,
-		int reset, int enable)
+ftrace_set_addr(struct ftrace_ops *ops, unsigned long *ips, unsigned int cnt,
+		int remove, int reset, int enable)
 {
-	return ftrace_set_hash(ops, NULL, 0, ip, remove, reset, enable);
+	return ftrace_set_hash(ops, NULL, 0, ips, cnt, remove, reset, enable);
 }
 
 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
@@ -5634,10 +5650,29 @@ int ftrace_set_filter_ip(struct ftrace_ops *ops, unsigned long ip,
 			 int remove, int reset)
 {
 	ftrace_ops_init(ops);
-	return ftrace_set_addr(ops, ip, remove, reset, 1);
+	return ftrace_set_addr(ops, &ip, 1, remove, reset, 1);
 }
 EXPORT_SYMBOL_GPL(ftrace_set_filter_ip);
 
+/**
+ * ftrace_set_filter_ips - set a functions to filter on in ftrace by addresses
+ * @ops - the ops to set the filter with
+ * @ips - the array of addresses to add to or remove from the filter.
+ * @cnt - the number of addresses in @ips
+ * @remove - non zero to remove ips from the filter
+ * @reset - non zero to reset all filters before applying this filter.
+ *
+ * Filters denote which functions should be enabled when tracing is enabled
+ * If @ips array or any ip specified within is NULL , it fails to update filter.
+ */
+int ftrace_set_filter_ips(struct ftrace_ops *ops, unsigned long *ips,
+			  unsigned int cnt, int remove, int reset)
+{
+	ftrace_ops_init(ops);
+	return ftrace_set_addr(ops, ips, cnt, remove, reset, 1);
+}
+EXPORT_SYMBOL_GPL(ftrace_set_filter_ips);
+
 /**
  * ftrace_ops_set_global_filter - setup ops to use global filters
  * @ops - the ops which will use the global filters
@@ -5659,7 +5694,7 @@ static int
 ftrace_set_regex(struct ftrace_ops *ops, unsigned char *buf, int len,
 		 int reset, int enable)
 {
-	return ftrace_set_hash(ops, buf, len, 0, 0, reset, enable);
+	return ftrace_set_hash(ops, buf, len, NULL, 0, 0, reset, enable);
 }
 
 /**