netdev - [RFC bpf-next 05/16] ftrace: Add register_ftrace_direct

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Message-Id: <20201022082138.2322434-6-jolsa@kernel.org>
Date:   Thu, 22 Oct 2020 10:21:27 +0200
From:   Jiri Olsa <jolsa@...nel.org>
To:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andriin@...com>
Cc:     netdev@...r.kernel.org, bpf@...r.kernel.org,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...omium.org>, Daniel Xu <dxu@...uu.xyz>,
        Steven Rostedt <rostedt@...dmis.org>,
        Jesper Brouer <jbrouer@...hat.com>,
        Toke Høiland-Jørgensen <toke@...hat.com>,
        Viktor Malik <vmalik@...hat.com>
Subject: [RFC bpf-next 05/16] ftrace: Add register_ftrace_direct_ips function

Adding register_ftrace_direct_ips function that llows
to register array of ip addresses and trampolines
for direct filter. the interface is:

  int register_ftrace_direct_ips(unsigned long *ips,
                                 unsigned long *addrs,
                                 int count);

It wil be used in following patches to register bpf
trampolines in batch mode.

Signed-off-by: Jiri Olsa <jolsa@...nel.org>
---
 include/linux/ftrace.h |  2 ++
 kernel/trace/ftrace.c  | 75 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 77 insertions(+)

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index d71d88d10517..9ed52755667a 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -291,6 +291,8 @@ int ftrace_modify_direct_caller(struct ftrace_func_entry *entry,
 				unsigned long old_addr,
 				unsigned long new_addr);
 unsigned long ftrace_find_rec_direct(unsigned long ip);
+int register_ftrace_direct_ips(unsigned long *ips, unsigned long *addrs,
+			       int count);
 #else
 # define ftrace_direct_func_count 0
 static inline int register_ftrace_direct(unsigned long ip, unsigned long addr)
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 44c2d21b8c19..770bcd1a245a 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -5231,6 +5231,81 @@ int register_ftrace_direct(unsigned long ip, unsigned long addr)
 }
 EXPORT_SYMBOL_GPL(register_ftrace_direct);
 
+int register_ftrace_direct_ips(unsigned long *ips, unsigned long *addrs,
+			       int count)
+{
+	struct ftrace_hash *free_hash = NULL;
+	struct ftrace_direct_func *direct;
+	struct ftrace_func_entry *entry;
+	int i, j;
+	int ret;
+
+	mutex_lock(&direct_mutex);
+
+	/* Check all the ips */
+	for (i = 0; i < count; i++) {
+		ret = check_direct_ip(ips[i]);
+		if (ret)
+			goto out_unlock;
+	}
+
+	ret = -ENOMEM;
+	if (adjust_direct_size(direct_functions->count + count, &free_hash))
+		goto out_unlock;
+
+	for (i = 0; i < count; i++) {
+		entry = kmalloc(sizeof(*entry), GFP_KERNEL);
+		if (!entry)
+			goto out_clean;
+
+		direct = get_direct_func(addrs[i]);
+		if (!direct) {
+			kfree(entry);
+			goto out_clean;
+		}
+
+		direct->count++;
+		entry->ip = ips[i];
+		entry->direct = addrs[i];
+		__add_hash_entry(direct_functions, entry);
+	}
+
+	ret = ftrace_set_filter_ips(&direct_ops, ips, count, 0);
+
+	if (!ret && !(direct_ops.flags & FTRACE_OPS_FL_ENABLED)) {
+		ret = register_ftrace_function(&direct_ops);
+		if (ret)
+			ftrace_set_filter_ips(&direct_ops, ips, count, 1);
+	}
+
+ out_clean:
+	if (ret) {
+		for (j = 0; j < i; j++) {
+			direct = get_direct_func(addrs[j]);
+			if (!direct)
+				continue;
+
+			if (!direct->count)
+				put_direct_func(direct);
+
+			entry = ftrace_lookup_ip(direct_functions, ips[j]);
+			if (WARN_ON_ONCE(!entry))
+				continue;
+			free_hash_entry(direct_functions, entry);
+		}
+	}
+ out_unlock:
+	mutex_unlock(&direct_mutex);
+
+	if (free_hash) {
+		synchronize_rcu_tasks();
+		free_ftrace_hash(free_hash);
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(register_ftrace_direct_ips);
+
 static struct ftrace_func_entry *find_direct_entry(unsigned long *ip,
 						   struct dyn_ftrace **recp)
 {
-- 
2.26.2