From: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>,
Andrew Morton <akpm@linux-foundation.org>,
Frederic Weisbecker <fweisbec@gmail.com>,
yrl.pp-manager.tt@hitachi.com
Subject: Re: [RFC][PATCH 00/13 v2] kprobes/ftrace: Making ftrace usable for kprobes
Date: Wed, 13 Jun 2012 17:25:40 +0900 [thread overview]
Message-ID: <4FD84E84.1090001@hitachi.com> (raw)
In-Reply-To: <20120612224327.426900129@goodmis.org>
(2012/06/13 7:43), Steven Rostedt wrote:
> If an arch supports passing of ftrace ops, it must also pass regs.
> But it does not need to support passing regs. By default
> an arch can just pass NULL. If it supports regs, then
> it can allow tools like kprobes to ask for regs. Otherwise the
> regs parameter should just be NULL.
Hmm, by default, will the ftrace_ops be also NULL? or NULL only if
the arch doesn't support passing ftrace ops?
I mean, should the generic handler always check if ftrace_ops
isn't NULL before using it?
> The second set is Masami's patches ported on top of these changes.
>
> This is v2, and I've cleaned the patches up a bit and added a lot more
> comments. This is a more serious RFC as this is the current way I plan
> on pushing it to mainline. But I'm posting first in case someone spots
> something that I missed. I'll also be doing more testing on it and if
> someting comes up I'll obviously will fix it before pushing.
>
> Some change since v1:
>
> Added fix for undefined ftrace_location() when compiling with !DYNAMIC_FTRACE.
>
> Added missing regs passed for x86_64 (segment regs, and r11).
>
> Saved flags for when regs are being saved. The cmp in the mcount trampoline
> that checks if function tracing is disabled will save flags before
> the compare, and restore flags before returning back to the function.
Nice! :) this is what I hope in previous thread.
> Decided that passing partial regs is a bad idea. Either the arch should
> pass all regs or NULL. Even though partial regs are saved for calling the
> function, it does't make sense to give that to the callback. By making
> regs be full pt_regs or NULL, then the callbacks can simply check if
> regs is NULL and if it isn't it can do more functionality, but if it
> is NULL then it just does limited work. Having 'partial regs' would just
> complicate that for no good reason. If in the future we want partial regs,
> we can add another flag to request it.
Agreed.
Thank you,
--
Masami HIRAMATSU
Software Platform Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@hitachi.com
next prev parent reply other threads:[~2012-06-13 8:25 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-12 22:43 [RFC][PATCH 00/13 v2] kprobes/ftrace: Making ftrace usable for kprobes Steven Rostedt
2012-06-12 22:43 ` [RFC][PATCH 01/13 v2] ftrace: Pass ftrace_ops as third parameter to function trace callback Steven Rostedt
2012-06-15 3:02 ` Masami Hiramatsu
2012-08-21 14:58 ` [tip:perf/core] " tip-bot for Steven Rostedt
2012-06-12 22:43 ` [RFC][PATCH 02/13 v2] ftrace: Consolidate arch dependent functions with list function Steven Rostedt
2012-06-15 3:02 ` Masami Hiramatsu
2012-08-21 14:59 ` [tip:perf/core] ftrace: Consolidate arch dependent functions with 'list' function tip-bot for Steven Rostedt
2012-06-12 22:43 ` [RFC][PATCH 03/13 v2] ftrace: Return pt_regs to function trace callback Steven Rostedt
2012-06-15 3:02 ` Masami Hiramatsu
2012-06-15 3:17 ` Steven Rostedt
2012-06-12 22:43 ` [RFC][PATCH 04/13 v2] ftrace/x86_32: Push ftrace_ops in as 3rd parameter to function tracer Steven Rostedt
2012-06-15 3:03 ` Masami Hiramatsu
2012-08-21 15:01 ` [tip:perf/core] " tip-bot for Steven Rostedt
2012-06-12 22:43 ` [RFC][PATCH 05/13 v2] ftrace/x86: Add separate function to save regs Steven Rostedt
2012-06-15 8:15 ` Masami Hiramatsu
2012-06-15 11:33 ` Steven Rostedt
2012-06-18 9:14 ` Masami Hiramatsu
2012-06-12 22:43 ` [RFC][PATCH 06/13 v2] ftrace/x86: Add save_regs for i386 function calls Steven Rostedt
2012-06-15 6:03 ` Masami Hiramatsu
2012-06-15 11:29 ` Steven Rostedt
2012-06-12 22:43 ` [RFC][PATCH 07/13 v2] ftrace: add ftrace_set_filter_ip() for address based filter Steven Rostedt
2012-06-12 22:43 ` [RFC][PATCH 08/13 v2] kprobes: Inverse taking of module_mutex with kprobe_mutex Steven Rostedt
2012-06-12 22:43 ` [RFC][PATCH 09/13 v2] kprobes: cleanup to separate probe-able check Steven Rostedt
2012-06-12 22:43 ` [RFC][PATCH 10/13 v2] kprobes: Move locks into appropriate functions Steven Rostedt
2012-06-12 22:43 ` [RFC][PATCH 11/13 v2] ftrace: Make ftrace_location() a nop on !DYNAMIC_FTRACE Steven Rostedt
2012-08-21 15:12 ` [tip:perf/core] " tip-bot for Steven Rostedt
2012-06-12 22:43 ` [RFC][PATCH 12/13 v2] kprobes: introduce ftrace based optimization Steven Rostedt
2012-06-12 22:43 ` [RFC][PATCH 13/13 v2] kprobes/x86: ftrace based optimization for x86 Steven Rostedt
2012-06-13 8:25 ` Masami Hiramatsu [this message]
2012-06-13 11:12 ` [RFC][PATCH 00/13 v2] kprobes/ftrace: Making ftrace usable for kprobes Steven Rostedt
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