From mboxrd@z Thu Jan  1 00:00:00 1970
Date: Tue, 13 Nov 2018 10:21:45 -0800
From: Masami Hiramatsu <mhiramat@kernel.org>
Subject: Re: [PATCH 1/1] stackleak: Disable ftrace for stackleak.c
Message-Id: <20181113102145.2274aedc6f9edaba681bfd3a@kernel.org>
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To: Steven Rostedt <rostedt@goodmis.org>
Cc: Alexander Popov <alex.popov@linux.com>, Masami Hiramatsu <mhiramat@kernel.org>, kernel-hardening@lists.openwall.com, Kees Cook <keescook@chromium.org>, Jann Horn <jannh@google.com>, Ingo Molnar <mingo@kernel.org>, Andy Lutomirski <luto@kernel.org>, Joerg Roedel <joro@8bytes.org>, Borislav Petkov <bp@alien8.de>, Thomas Gleixner <tglx@linutronix.de>, Dave Hansen <dave.hansen@linux.intel.com>, Peter Zijlstra <peterz@infradead.org>, Jan Kara <jack@suse.cz>, Mathieu Desnoyers <mathieu.desnoyers@efficios.com>, Dan Williams <dan.j.williams@intel.com>, Masahiro Yamada <yamada.masahiro@socionext.com>, x86@kernel.org, linux-kernel@vger.kernel.org
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On Mon, 12 Nov 2018 12:21:48 -0500
Steven Rostedt <rostedt@goodmis.org> wrote:

> On Mon, 12 Nov 2018 19:51:00 +0300
> Alexander Popov <alex.popov@linux.com> wrote:
> 
> > By the way, are there any other tracing/instrumentation mechanisms that should
> > be disabled?
> 
> ftrace and kprobes are pretty much the only ones that currently do self
> modification of code all over the kernel. Kprobes even more so than
> ftrace.

Right, since kprobes uses int3 or sw breakpoint exception for hooking into
the code, it consumes stack much more.

Thank you,

-- 
Masami Hiramatsu <mhiramat@kernel.org>