From: Steven Rostedt <rostedt@goodmis.org>
To: Jinyang He <hejinyang@loongson.cn>
Cc: Qing Zhang <zhangqing@loongson.cn>,
Huacai Chen <chenhuacai@kernel.org>,
Ingo Molnar <mingo@redhat.com>, WANG Xuerui <kernel@xen0n.name>,
loongarch@lists.linux.dev, linux-kernel@vger.kernel.org,
linux-arch@vger.kernel.org, Jiaxun Yang <jiaxun.yang@flygoat.com>
Subject: Re: [PATCH 1/9] LoongArch/ftrace: Add basic support
Date: Fri, 19 Aug 2022 21:52:40 -0400 [thread overview]
Message-ID: <20220819215240.3caf89e2@gandalf.local.home> (raw)
In-Reply-To: <246779c0-b834-16a6-ec68-c06d8f9a375d@loongson.cn>
On Sat, 20 Aug 2022 09:38:21 +0800
Jinyang He <hejinyang@loongson.cn> wrote:
> I think we have implemented CONFIG_FTRACE_WITH_ARGS in dynamic ftrace
> in the [Patch3/9].
Sorry, I must have missed it.
> But, for non dynamic ftrace, it is hardly to
> implement it. Because the LoongArch compiler gcc treats mount as a
Don't bother implementing it for non-dynamic. I would just add a:
config HAVE_FTRACE_WITH_ARGS if DYNAMIC_FTRACE
and be done with it.
> really call, like 'call _mcount(__builtin_return_address(0))'. That
> means, they decrease stack, save args to callee saved regs and may
> do some optimization before calling mcount. It is difficult to find the
> original args and apply changes from tracers.
Right, there's no point in implementing it for non dynamic. Like I said,
non-dynamic is just a stepping stone for getting dynamic working. Once you
have dynamic working, it's up to you to throw out the non-dynamic. It's not
useful for anything other than porting to a new architecture or for
academic purposes.
-- Steve
next prev parent reply other threads:[~2022-08-20 1:52 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-19 8:13 [PATCH 0/9] LoongArch: Add ftrace support Qing Zhang
2022-08-19 8:13 ` [PATCH 1/9] LoongArch/ftrace: Add basic support Qing Zhang
2022-08-19 9:29 ` Jinyang He
2022-08-19 16:53 ` Steven Rostedt
2022-08-20 1:34 ` Qing Zhang
2022-08-20 2:16 ` Huacai Chen
2022-08-19 17:25 ` Steven Rostedt
2022-08-20 1:35 ` Qing Zhang
2022-08-20 1:38 ` Jinyang He
2022-08-20 1:52 ` Steven Rostedt [this message]
2022-08-20 3:16 ` Jinyang He
2022-08-19 8:13 ` [PATCH 2/9] LoongArch/ftrace: Add recordmcount support Qing Zhang
2022-08-19 8:13 ` [PATCH 3/9] LoongArch/ftrace: Add dynamic function tracer support Qing Zhang
2022-08-19 8:13 ` [PATCH 4/9] Loongarch/ftrace: Add dynamic function graph " Qing Zhang
2022-08-19 8:13 ` [PATCH 5/9] Loongarch/ftrace: Add DYNAMIC_FTRACE_WITH_REGS support Qing Zhang
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