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Date:   Mon, 7 Jan 2019 12:29:51 -0500
From:   Steven Rostedt <rostedt@goodmis.org>
To:     Andrea Righi <righi.andrea@gmail.com>
Cc:     Masami Hiramatsu <mhiramat@kernel.org>,
        Ingo Molnar <mingo@redhat.com>, peterz@infradead.org,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 2/2] kprobes: Mark ftrace mcount handler functions
 nokprobe
Message-ID: <20190107122951.1f843dc6@gandalf.local.home>
In-Reply-To: <20190107145536.GA1944@xps-13>
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        <20190107145536.GA1944@xps-13>
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On Mon, 7 Jan 2019 15:55:36 +0100
Andrea Righi <righi.andrea@gmail.com> wrote:

> On Mon, Jan 07, 2019 at 10:32:32PM +0900, Masami Hiramatsu wrote:
> > Mark ftrace mcount handler functions nokprobe since
> > probing on these functions with kretprobe pushes
> > return address incorrectly on kretprobe shadow stack.
> > 
> > Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
> > Reported-by: Francis Deslauriers <francis.deslauriers@efficios.com>
> > ---
> >  kernel/trace/ftrace.c |    5 ++++-
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> > 
> > diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
> > index f0ff24173a0b..ad4babad4a03 100644
> > --- a/kernel/trace/ftrace.c
> > +++ b/kernel/trace/ftrace.c
> > @@ -6250,7 +6250,7 @@ void ftrace_reset_array_ops(struct trace_array *tr)
> >  	tr->ops->func = ftrace_stub;
> >  }
> >  
> > -static inline void
> > +static nokprobe_inline void  
> 
> I think we need to #include <linux/kprobes.h>, otherwise:
> 
>   CC      kernel/trace/ftrace.o
> kernel/trace/ftrace.c:6219:24: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘void’
>  static nokprobe_inline void
>                         ^~~~
> 
>  kernel/trace/ftrace.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
> index 3a58ad280d83..0333241034d5 100644
> --- a/kernel/trace/ftrace.c
> +++ b/kernel/trace/ftrace.c
> @@ -32,6 +32,7 @@
>  #include <linux/sort.h>
>  #include <linux/list.h>
>  #include <linux/hash.h>
> +#include <linux/kprobes.h>
>  #include <linux/rcupdate.h>
>  
>  #include <trace/events/sched.h>

And zero day just caught it too.

Masami, want to fold this into your patch and send out a v2?

-- Steve