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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 05/13 v2] ftrace/x86: Add separate function to save regs
Date: Fri, 15 Jun 2012 17:15:20 +0900	[thread overview]
Message-ID: <4FDAEF18.6040703@hitachi.com> (raw)
In-Reply-To: <20120612225425.218922417@goodmis.org>

(2012/06/13 7:43), Steven Rostedt wrote:
> From: Steven Rostedt <srostedt@redhat.com>
> 
> Add a way to have different functions calling different trampolines.
> If a ftrace_ops wants regs saved on the return, then have only the
> functions with ops registered to save regs. Functions registered by
> other ops would not be affected, unless the functions overlap.
> 
> If one ftrace_ops registered functions A, B and C and another ops
> registered fucntions to save regs on A, and D, then only functions
> A and D would be saving regs. Function B and C would work as normal.
> Although A is registered by both ops: normal and saves regs; this is fine
> as saving the regs is needed to satisfy one of the ops that calls it
> but the regs are ignored by the other ops function.
> 
> x86_64 implements the full regs saving, and i386 just passes a NULL
> for regs to satisfy the ftrace_ops passing. Where an arch must supply
> both regs and ftrace_ops parameters, even if regs is just NULL.
> 
> It is OK for an arch to pass NULL regs. All function trace users that
> require regs passing must add the flag FTRACE_OPS_FL_SAVE_REGS when
> registering the ftrace_ops and either check if regs is not NULL or
> check if ARCH_SUPPORTS_FTRACE_SAVE_REGS. If the arch supports passing
> regs it will set this macro and pass regs for ops that request them.
> All other archs will just pass NULL.

Hmm, so would you mean that user is responsible for checking
whether the arch supports save_regs or not?
I would rather like ftrace to check it as my patch has done.
I think ARCH_SUPPORTS_FTRACE_SAVE_REGS macro checking in all
handler code is something like odd...

Thank you,


-- 
Masami HIRAMATSU
Software Platform Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@hitachi.com

  reply	other threads:[~2012-06-15  8:15 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 [this message]
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 ` [RFC][PATCH 00/13 v2] kprobes/ftrace: Making ftrace usable for kprobes Masami Hiramatsu
2012-06-13 11:12   ` Steven Rostedt

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