LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Jiri Olsa <jolsa@redhat.com>
To: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
Cc: bpf@vger.kernel.org, linux-kernel@vger.kernel.org,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andriin@fb.com>
Subject: [PATCH 7/8] ftrace: Add multi direct modify interface
Date: Fri,  8 Oct 2021 11:13:35 +0200	[thread overview]
Message-ID: <20211008091336.33616-8-jolsa@kernel.org> (raw)
In-Reply-To: <20211008091336.33616-1-jolsa@kernel.org>

Adding interface to modify registered direct function
for ftrace_ops. Adding following function:

   modify_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr)

The function changes the currently registered direct
function for all attached functions.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 include/linux/ftrace.h |  6 ++++
 kernel/trace/ftrace.c  | 62 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 68 insertions(+)

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index ba5d02ba8166..c15b767f39cf 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -318,6 +318,8 @@ int ftrace_modify_direct_caller(struct ftrace_func_entry *entry,
 unsigned long ftrace_find_rec_direct(unsigned long ip);
 int register_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr);
 int unregister_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr);
+int modify_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr);
+
 #else
 struct ftrace_ops;
 # define ftrace_direct_func_count 0
@@ -357,6 +359,10 @@ static inline int unregister_ftrace_direct_multi(struct ftrace_ops *ops, unsigne
 {
 	return -ENODEV;
 }
+static inline int modify_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr)
+{
+	return -ENODEV;
+}
 #endif /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */
 
 #ifndef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index f9df7bffb770..d92f2591c3fc 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -5547,6 +5547,68 @@ int unregister_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr)
 	return err;
 }
 EXPORT_SYMBOL_GPL(unregister_ftrace_direct_multi);
+
+/**
+ * modify_ftrace_direct_multi - Modify an existing direct 'multi' call
+ * to call something else
+ * @ops: The address of the struct ftrace_ops object
+ * @addr: The address of the new trampoline to call at @ops functions
+ *
+ * This is used to unregister currently registered direct caller and
+ * register new one @addr on functions registered in @ops object.
+ *
+ * Note there's window between ftrace_shutdown and ftrace_startup calls
+ * where there will be no callbacks called.
+ *
+ * Returns: zero on success. Non zero on error, which includes:
+ *  -EINVAL - The @ops object was not properly registered.
+ */
+int modify_ftrace_direct_multi(struct ftrace_ops *ops, unsigned long addr)
+{
+	struct ftrace_hash *hash = ops->func_hash->filter_hash;
+	struct ftrace_func_entry *entry, *iter;
+	int i, size;
+	int err;
+
+	if (check_direct_multi(ops))
+		return -EINVAL;
+	if (!(ops->flags & FTRACE_OPS_FL_ENABLED))
+		return -EINVAL;
+
+	mutex_lock(&direct_mutex);
+	mutex_lock(&ftrace_lock);
+
+	/*
+	 * Shutdown the ops, change 'direct' pointer for each
+	 * ops entry in direct_functions hash and startup the
+	 * ops back again.
+	 *
+	 * Note there is no callback called for @ops object after
+	 * this ftrace_shutdown call until ftrace_startup is called
+	 * later on.
+	 */
+	err = ftrace_shutdown(ops, 0);
+	if (err)
+		goto out_unlock;
+
+	size = 1 << hash->size_bits;
+	for (i = 0; i < size; i++) {
+		hlist_for_each_entry(iter, &hash->buckets[i], hlist) {
+			entry = __ftrace_lookup_ip(direct_functions, iter->ip);
+			if (!entry)
+				continue;
+			entry->direct = addr;
+		}
+	}
+
+	err = ftrace_startup(ops, 0);
+
+ out_unlock:
+	mutex_unlock(&ftrace_lock);
+	mutex_unlock(&direct_mutex);
+	return err;
+}
+EXPORT_SYMBOL_GPL(modify_ftrace_direct_multi);
 #endif /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */
 
 /**
-- 
2.31.1


  parent reply	other threads:[~2021-10-08  9:14 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-08  9:13 [PATCHv2 0/8] x86/ftrace: Add direct batch interface Jiri Olsa
2021-10-08  9:13 ` [PATCH 1/8] x86/ftrace: Remove extra orig rax move Jiri Olsa
2021-10-08  9:13 ` [PATCH 2/8] x86/ftrace: Remove fault protection code in prepare_ftrace_return Jiri Olsa
2021-10-08  9:13 ` [PATCH 3/8] x86/ftrace: Make function graph use ftrace directly Jiri Olsa
2021-10-08  9:13 ` [PATCH 4/8] tracing: Add trampoline/graph selftest Jiri Olsa
2021-10-08  9:13 ` [PATCH 5/8] ftrace: Add ftrace_add_rec_direct function Jiri Olsa
2021-10-08  9:13 ` [PATCH 6/8] ftrace: Add multi direct register/unregister interface Jiri Olsa
2021-10-08  9:13 ` Jiri Olsa [this message]
2021-10-14 20:28   ` [PATCH 7/8] ftrace: Add multi direct modify interface Steven Rostedt
2021-10-15 12:05     ` Jiri Olsa
2021-10-15 14:05       ` Steven Rostedt
2021-10-16 11:39         ` Jiri Olsa
2021-10-19  2:10           ` Steven Rostedt
2021-10-19 13:19             ` Jiri Olsa
2021-10-19 13:26               ` Jiri Olsa
2021-10-19 13:32                 ` Steven Rostedt
2021-10-19 14:03                   ` Jiri Olsa
2021-10-19 14:44                     ` Steven Rostedt
2021-10-19 14:47                       ` Jiri Olsa
2021-10-08  9:13 ` [PATCH 8/8] ftrace/samples: Add multi direct interface test module Jiri Olsa
2021-10-26 19:23   ` Guenter Roeck
2021-10-26 19:29     ` Steven Rostedt
2021-10-13  9:01 ` [PATCHv2 0/8] x86/ftrace: Add direct batch interface Heiko Carstens
2021-10-13 12:25   ` Jiri Olsa
  -- strict thread matches above, loose matches on Subject: below --
2021-08-31  9:50 [PATCH " Jiri Olsa
2021-08-31  9:50 ` [PATCH 7/8] ftrace: Add multi direct modify interface Jiri Olsa
2021-09-14 21:41   ` Steven Rostedt
2021-09-15 21:47     ` Steven Rostedt
2021-09-16 19:49       ` Jiri Olsa
2021-09-16 20:41         ` Steven Rostedt

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20211008091336.33616-8-jolsa@kernel.org \
    --to=jolsa@redhat.com \
    --cc=andriin@fb.com \
    --cc=ast@kernel.org \
    --cc=bpf@vger.kernel.org \
    --cc=daniel@iogearbox.net \
    --cc=linux-kernel@vger.kernel.org \
    --cc=rostedt@goodmis.org \
    --subject='Re: [PATCH 7/8] ftrace: Add multi direct modify interface' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).