From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
To: Sven Schnelle <svens@linux.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>,
Mark Rutland <mark.rutland@arm.com>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Paul Walmsley <paul.walmsley@sifive.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Albert Ou <aou@eecs.berkeley.edu>, Guo Ren <guoren@kernel.org>,
linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org,
linux-riscv@lists.infradead.org, linux-csky@vger.kernel.org
Subject: Re: [PATCH 0/7] add function arguments to ftrace
Date: Fri, 20 Sep 2024 10:17:58 +0200 [thread overview]
Message-ID: <20240920101758.60419ec040c6f0643b475720@kernel.org> (raw)
In-Reply-To: <yt9djzfgccoo.fsf@linux.ibm.com>
On Fri, 13 Sep 2024 08:03:51 +0200
Sven Schnelle <svens@linux.ibm.com> wrote:
> Sven Schnelle <svens@linux.ibm.com> writes:
>
> > Masami Hiramatsu (Google) <mhiramat@kernel.org> writes:
> >
> >> On Fri, 6 Sep 2024 10:07:38 -0400
> >> Steven Rostedt <rostedt@goodmis.org> wrote:
> >>
> >>> On Fri, 06 Sep 2024 08:18:02 +0200
> >>> Sven Schnelle <svens@linux.ibm.com> wrote:
> >>>
> >>>
> >>> > One thing i learned after submitting the series is that struct
> >>> > ftrace_regs depends on CONFIG_FUNCTION_TRACER, so it cannot be used
> >>> > with the graph tracer.
> >>
> >> Yeah, this is solved by my series [1].
> >>
> >> [1] https://patchwork.kernel.org/project/linux-trace-kernel/patch/172398532480.293426.13232399076477198126.stgit@devnote2/
> >>
> >> So I think this series is easier to apply after my series, which
> >> passes fgraph_regs in return handler.
> >
> > Thanks, i'll rebase my changes on top of your patches then.
>
> While doing so i noticed that i completely forgot about arguments
> located on the stack. The current patchset tries to read from the
> current kernel stack, which is obviously wrong. So either the tracer
> needs to save the stack frame in the ringbuffer (which would be quite
> a lot of data), or ftrace only prints arguments located in registers.
> Also not nice. Opinions?
We can limit it to first 6 arguments in the ftrace_regs by default,
no need to save all of them. We can add an option to specify how
many stack entries (but it is set 0 by default).
Thank you,
>
> Thanks
> Sven
--
Masami Hiramatsu (Google) <mhiramat@kernel.org>
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prev parent reply other threads:[~2024-09-20 8:28 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-09-04 6:58 [PATCH 0/7] add function arguments to ftrace Sven Schnelle
2024-09-04 6:58 ` [PATCH 1/7] tracing: add ftrace_regs to function_graph_enter() Sven Schnelle
2024-09-05 15:16 ` [PATCH 0/7] add function arguments to ftrace Steven Rostedt
2024-09-06 6:18 ` Sven Schnelle
2024-09-06 14:07 ` Steven Rostedt
2024-09-08 13:28 ` Masami Hiramatsu
2024-09-09 7:52 ` Sven Schnelle
2024-09-13 6:03 ` Sven Schnelle
2024-09-20 8:17 ` Masami Hiramatsu [this message]
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