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From: Namhyung Kim <namhyung@kernel.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: ahmadkhorrami <ahmadkhorrami@ut.ac.ir>,
	"Linux-trace Users" <linux-trace-users@vger.kernel.org>,
	lttng-dev@lists.lttng.org,
	"Mathieu Desnoyers" <mathieu.desnoyers@efficios.com>,
	"Jérémie Galarneau" <jeremie.galarneau@efficios.com>
Subject: Re: Capturing User-Level Function Calls/Returns
Date: Thu, 16 Jul 2020 10:04:15 +0900	[thread overview]
Message-ID: <CAM9d7chE3WQm2e4EA4i09Q1hOaGt2hrPHoF2d0tjqhciPceB9g@mail.gmail.com> (raw)
In-Reply-To: <20200715142849.0bfe909a@oasis.local.home>

Hi all,

On Thu, Jul 16, 2020 at 3:28 AM Steven Rostedt <rostedt@goodmis.org> wrote:
>
> On Wed, 15 Jul 2020 20:37:16 +0430
> ahmadkhorrami <ahmadkhorrami@ut.ac.ir> wrote:
>
> > Hi,
> > What is the most efficient way to capture occurrence of a function
> > call/return of a binary program in userspace?
> > It seems the answer is Uprobes. 1) Am I right?
> > But Uprobes use "int" instruction which leads to a switch into kernel
> > mode. 2) Wouldn't it be better to avoid this transition?
> > I'm looking forward to your reply and will be happy to read your
> > opinions.
> > Regards.
>
>
> Hi, I believe LTTng has utilities that can help you trace user space
> programs.
>
> I think there's also a users ftrace like utility that Namhyung was
> working on. But I don't know where in the development that is.

It's in https://github.com/namhyung/uftrace

Basically it also requires recompilation to add mcount calls for each function.
But it now also supports dynamic tracing without any recompilation.. :)
It's still experimental and has some limitation, but the idea is to copy
first 5 bytes (on x86_64) somewhere and replace it to a call instruction.

Thanks
Namhyung

WARNING: multiple messages have this Message-ID
From: Namhyung Kim via lttng-dev <lttng-dev@lists.lttng.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: ahmadkhorrami <ahmadkhorrami@ut.ac.ir>,
	Linux-trace Users <linux-trace-users@vger.kernel.org>,
	lttng-dev@lists.lttng.org
Subject: Re: [lttng-dev] Capturing User-Level Function Calls/Returns
Date: Thu, 16 Jul 2020 10:04:15 +0900	[thread overview]
Message-ID: <CAM9d7chE3WQm2e4EA4i09Q1hOaGt2hrPHoF2d0tjqhciPceB9g@mail.gmail.com> (raw)
Message-ID: <20200716010415.qoDJoYJ4W9OhBmQxIvdVPMtFbWMdzpaHfiRyvfFZk34@z> (raw)
In-Reply-To: <20200715142849.0bfe909a@oasis.local.home>

Hi all,

On Thu, Jul 16, 2020 at 3:28 AM Steven Rostedt <rostedt@goodmis.org> wrote:
>
> On Wed, 15 Jul 2020 20:37:16 +0430
> ahmadkhorrami <ahmadkhorrami@ut.ac.ir> wrote:
>
> > Hi,
> > What is the most efficient way to capture occurrence of a function
> > call/return of a binary program in userspace?
> > It seems the answer is Uprobes. 1) Am I right?
> > But Uprobes use "int" instruction which leads to a switch into kernel
> > mode. 2) Wouldn't it be better to avoid this transition?
> > I'm looking forward to your reply and will be happy to read your
> > opinions.
> > Regards.
>
>
> Hi, I believe LTTng has utilities that can help you trace user space
> programs.
>
> I think there's also a users ftrace like utility that Namhyung was
> working on. But I don't know where in the development that is.

It's in https://github.com/namhyung/uftrace

Basically it also requires recompilation to add mcount calls for each function.
But it now also supports dynamic tracing without any recompilation.. :)
It's still experimental and has some limitation, but the idea is to copy
first 5 bytes (on x86_64) somewhere and replace it to a call instruction.

Thanks
Namhyung
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  parent reply	other threads:[~2020-07-16  1:04 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <e9c7400ff0075f3beba2863c4432a905@ut.ac.ir>
2020-07-15 18:28 ` Steven Rostedt
2020-07-15 18:28   ` [lttng-dev] " Steven Rostedt via lttng-dev
2020-07-15 18:45   ` Mathieu Desnoyers
2020-07-15 18:45     ` [lttng-dev] " Mathieu Desnoyers via lttng-dev
2020-07-15 21:39     ` ahmadkhorrami
2020-07-15 21:39       ` [lttng-dev] " ahmadkhorrami via lttng-dev
2020-07-15 21:48       ` Steven Rostedt
2020-07-15 21:48         ` [lttng-dev] " Steven Rostedt via lttng-dev
2020-07-15 22:25         ` ahmadkhorrami
2020-07-15 22:25           ` [lttng-dev] " ahmadkhorrami via lttng-dev
2020-07-16  1:06         ` Michel Dagenais via lttng-dev
2020-07-16  1:06           ` [lttng-dev] " Michel Dagenais via lttng-dev
2020-07-16  1:49           ` Frank Ch. Eigler
2020-07-16  1:49             ` Frank Ch. Eigler via lttng-dev
2020-07-16 16:26             ` ahmadkhorrami
2020-07-16 16:26               ` ahmadkhorrami via lttng-dev
2020-07-16 16:20           ` ahmadkhorrami
2020-07-16 16:20             ` ahmadkhorrami via lttng-dev
2020-07-16 16:34           ` ahmadkhorrami
2020-07-16 16:34             ` ahmadkhorrami via lttng-dev
2020-07-16  1:04   ` Namhyung Kim [this message]
2020-07-16  1:04     ` Namhyung Kim via lttng-dev
2020-07-16 16:07     ` ahmadkhorrami
2020-07-16 16:07       ` [lttng-dev] " ahmadkhorrami via lttng-dev

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