From: Steven Rostedt <rostedt@goodmis.org>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
X86 ML <x86@kernel.org>, Nadav Amit <nadav.amit@gmail.com>,
Andy Lutomirski <luto@kernel.org>,
Dave Hansen <dave.hansen@linux.intel.com>,
Song Liu <songliubraving@fb.com>,
Masami Hiramatsu <mhiramat@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Daniel Bristot de Oliveira <bristot@redhat.com>,
Josh Poimboeuf <jpoimboe@redhat.com>
Subject: Re: [PATCH 03/10] ftrace: Add register_ftrace_direct()
Date: Thu, 14 Nov 2019 14:05:59 -0500 [thread overview]
Message-ID: <20191114140559.5dd40402@gandalf.local.home> (raw)
In-Reply-To: <20191114134827.555e9b31@gandalf.local.home>
On Thu, 14 Nov 2019 13:48:27 -0500
Steven Rostedt <rostedt@goodmis.org> wrote:
> The main reason, is that then we need to add another arch specific
> change, where as, the solution I suggested doesn't need anything new.
> The less arch specific code we need the better.
Here's the change, to see how easy it is (compiled tested only):
/* still needs comments */
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 82ef8d60a42b..4231571db30f 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -5160,6 +5160,59 @@ int unregister_ftrace_direct(unsigned long ip, unsigned long addr)
return ret;
}
EXPORT_SYMBOL_GPL(unregister_ftrace_direct);
+
+static struct ftrace_ops stub_ops = {
+ .func = ftrace_stub,
+};
+
+int modify_ftrace_direct(unsigned long ip,
+ unsigned long old_addr, unsigned long new_addr)
+{
+ struct ftrace_func_entry *entry;
+ struct dyn_ftrace *rec;
+ int ret = -ENODEV;
+
+ mutex_lock(&direct_mutex);
+ entry = __ftrace_lookup_ip(direct_functions, ip);
+ if (!entry) {
+ /* OK if it is off by a little */
+ rec = lookup_rec(ip, ip);
+ if (!rec || rec->ip == ip)
+ goto out_unlock;
+
+ entry = __ftrace_lookup_ip(direct_functions, rec->ip);
+ if (!entry)
+ goto out_unlock;
+
+ WARN_ON(!(rec->flags & FTRACE_FL_DIRECT));
+ }
+
+ ret = -EINVAL;
+ if (entry->direct != old_addr)
+ goto out_unlock;
+
+ ret = ftrace_set_filter_ip(&stub_ops, ip, 0, 0);
+ if (ret)
+ goto out_unlock;
+
+ ret = register_ftrace_function(&stub_ops);
+ if (ret) {
+ ftrace_set_filter_ip(&stub_ops, ip, 1, 0);
+ goto out_unlock;
+ }
+
+ entry->direct = new_addr;
+
+ unregister_ftrace_function(&stub_ops);
+ ftrace_set_filter_ip(&stub_ops, ip, 1, 0);
+
+ ret = 0;
+
+ out_unlock:
+ mutex_unlock(&direct_mutex);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(modify_ftrace_direct);
#endif /* CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS */
/**
-- Steve
next prev parent reply other threads:[~2019-11-14 19:06 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-08 21:28 [PATCH 00/10] ftrace: Add register_ftrace_direct() Steven Rostedt
2019-11-08 21:28 ` [PATCH 01/10] ftrace: Separate out the copying of a ftrace_hash from __ftrace_hash_move() Steven Rostedt
2019-11-08 21:28 ` [PATCH 02/10] ftrace: Separate out functionality from ftrace_location_range() Steven Rostedt
2019-11-08 21:28 ` [PATCH 03/10] ftrace: Add register_ftrace_direct() Steven Rostedt
2019-11-09 2:29 ` Alexei Starovoitov
2019-11-09 12:33 ` Steven Rostedt
2019-11-14 18:29 ` Steven Rostedt
2019-11-14 18:34 ` Alexei Starovoitov
2019-11-14 18:48 ` Steven Rostedt
2019-11-14 19:05 ` Steven Rostedt [this message]
2019-11-13 14:13 ` Miroslav Benes
2019-11-13 14:34 ` Steven Rostedt
2019-11-08 21:28 ` [PATCH 04/10] ftrace: Add ftrace_find_direct_func() Steven Rostedt
2019-11-08 21:28 ` [PATCH 05/10] ftrace: Add sample module that uses register_ftrace_direct() Steven Rostedt
2019-11-08 21:28 ` [PATCH 06/10] ftrace/selftest: Add tests to test register_ftrace_direct() Steven Rostedt
2019-11-08 21:28 ` [PATCH 07/10] ftrace: Add another example of register_ftrace_direct() use case Steven Rostedt
2019-11-08 21:28 ` [PATCH 08/10] ftrace/selftests: Update the direct call selftests to test two direct calls Steven Rostedt
2019-11-08 21:28 ` [PATCH 09/10] ftrace/x86: Add register_ftrace_direct() for custom trampolines Steven Rostedt
2019-11-14 15:34 ` Miroslav Benes
2019-11-14 16:19 ` Steven Rostedt
2019-11-15 9:32 ` Miroslav Benes
2019-11-08 21:28 ` [PATCH 10/10] ftrace/x86: Add a counter to test function_graph with direct Steven Rostedt
2019-11-08 22:51 ` [PATCH 00/10] ftrace: Add register_ftrace_direct() Josh Poimboeuf
2019-11-09 1:00 ` Steven Rostedt
2019-11-11 8:47 ` Peter Zijlstra
2019-11-11 14:15 ` Josh Poimboeuf
2019-11-13 15:10 ` Miroslav Benes
2019-11-13 16:31 ` Steven Rostedt
2019-11-14 9:05 ` Miroslav Benes
2019-11-14 14:36 ` Steven Rostedt
2019-11-14 15:42 ` Miroslav Benes
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