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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 03/13 v2] ftrace: Return pt_regs to function trace callback
Date: Fri, 15 Jun 2012 12:02:58 +0900	[thread overview]
Message-ID: <4FDAA5E2.1040608@hitachi.com> (raw)
In-Reply-To: <20120612225424.709165437@goodmis.org>

(2012/06/13 7:43), Steven Rostedt wrote:
> From: Steven Rostedt <srostedt@redhat.com>
> 
> Return as the 4th paramater to the function tracer callback the pt_regs.
> 
> Currently x86_64 just passes NULL as the regs arguement. Later patches
> that implement regs passing will require having the ftrace_ops set the
> SAVE_REGS flag, which will tell the arch to take the time to pass a
> full set of pt_regs to the ftrace_ops callback function. If the arch
> does not support it then it should pass NULL.

Hmm, I think the x86-64 part of this patch would be better to be separated
with x86-64 part of [5/13], so that I can easily review the change...
Another reason is that this patch doesn't define ARCH_SUPPORTS_FTRACE_SAVE_REGS
on x86_64 too...


> A ftrace_ops call back can either check if the macro ARCH_SUPPORTS_FTRACE_SAVE_REGS
> is defined, or it can check if regs is NULL. As it will be NULL if
> it is not supported by the arch even if the SAVE_REGS flag is set.
> 
> If an arch can pass full regs, then it should define:
>  ARCH_SUPPORTS_FTRACE_SAVE_REGS to 1
> 
> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
[...]
> diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
> index 2b4f94c..83d8ae0 100644
> --- a/arch/x86/kernel/entry_64.S
> +++ b/arch/x86/kernel/entry_64.S
> @@ -80,7 +80,11 @@ ENTRY(ftrace_caller)
>  	MCOUNT_SAVE_FRAME
>  
>  	leaq function_trace_op, %rdx
> -	movq 0x38(%rsp), %rdi
> +
> +	/* regs go into 4th parameter (but make it NULL) */
> +	movq $0, %rcx

There is no ARCH_SUPPORTS_FTRACE_SAVE_REGS, so I think you
don't need to clear rcx at least this time.

Another generic ftrace part of this patch is good to me :)

Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>

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  3:03 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 [this message]
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 ` [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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