linux-kernel - Re: [Patch 11/11] ftrace plugin for kernel symbol tracing using HW Breakpoint interfaces

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Message-ID: <alpine.DEB.2.00.0903250923340.5675@gandalf.stny.rr.com>
Date:	Wed, 25 Mar 2009 09:24:25 -0400 (EDT)
From:	Steven Rostedt <rostedt@...dmis.org>
To:	"K.Prasad" <prasad@...ux.vnet.ibm.com>
cc:	Ingo Molnar <mingo@...e.hu>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Alan Stern <stern@...land.harvard.edu>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Benjamin Herrenschmidt <benh@....ibm.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	maneesh@...ux.vnet.ibm.com, Roland McGrath <roland@...hat.com>
Subject: Re: [Patch 11/11] ftrace plugin for kernel symbol tracing using HW
 Breakpoint interfaces - v3


On Wed, 25 Mar 2009, K.Prasad wrote:

> On Tue, Mar 24, 2009 at 08:58:11PM +0530, K.Prasad wrote:
> > This patch adds an ftrace plugin to detect and profile memory access over
> > kernel variables. It uses HW Breakpoint interfaces to 'watch memory
> > addresses.
> > 
> > Signed-off-by: K.Prasad <prasad@...ux.vnet.ibm.com> 
> > ---
> >  kernel/trace/Kconfig          |   21 +
> >  kernel/trace/Makefile         |    1 
> >  kernel/trace/trace.h          |   25 +
> >  kernel/trace/trace_ksym.c     |  555 ++++++++++++++++++++++++++++++++++++++++++
> >  kernel/trace/trace_selftest.c |   36 ++
> >  5 files changed, 638 insertions(+)
> >
> 
> Submitting the revised patch 11/11 and not reposting the entire
> patchset.
> 
> Changelog
> ---------
> - Checking for the appropriate tracer type in the .print_line handler function
> 
> Please find the new patch below.
> 
> Thanks,
> K.Prasad
> 
> 
> ftrace plugin for kernel symbol tracing using HW Breakpoint interfaces - v2
> 
> This patch adds an ftrace plugin to detect and profile memory access over
> kernel variables. It uses HW Breakpoint interfaces to 'watch memory
> addresses.
> 
> Signed-off-by: K.Prasad <prasad@...ux.vnet.ibm.com> 
> ---
>  kernel/trace/Kconfig          |   21 +
>  kernel/trace/Makefile         |    1 
>  kernel/trace/trace.h          |   25 +
>  kernel/trace/trace_ksym.c     |  558 ++++++++++++++++++++++++++++++++++++++++++
>  kernel/trace/trace_selftest.c |   36 ++
>  5 files changed, 641 insertions(+)
> 
> +static enum print_line_t ksym_trace_output(struct trace_iterator *iter)
> +{
> +	struct trace_entry *entry = iter->ent;
> +	struct trace_seq *s = &iter->seq;
> +	struct trace_ksym *field;
> +	char str[KSYM_SYMBOL_LEN];
> +	int ret;
> +
> +	if (entry->type != TRACE_KSYM)
> +		return TRACE_TYPE_UNHANDLED;

Looks good.

Acked-by:Steven Rostedt <srostedt@...hat.com>

Thanks,

-- Steve

> +
> +	trace_assign_type(field, entry);
> +
> +	ret = trace_seq_printf(s, "%-15s %-5d %-3d %-20s ", field->p_name,
> +				entry->pid, iter->cpu, field->ksym_name);
> +	if (!ret)
> +		return TRACE_TYPE_PARTIAL_LINE;
> +
> +	switch (field->ksym_hbp->info.type) {
> +	case HW_BREAKPOINT_WRITE:
> +		ret = trace_seq_printf(s, " W  ");
> +		break;
> +	case HW_BREAKPOINT_RW:
> +		ret = trace_seq_printf(s, " RW ");
> +		break;
> +	default:
> +		return TRACE_TYPE_PARTIAL_LINE;
> +	}
> +
> +	if (!ret)
> +		return TRACE_TYPE_PARTIAL_LINE;
> +
> +	sprint_symbol(str, field->ip);
> +	ret = trace_seq_printf(s, "%-20s\n", str);
> +	if (!ret)
> +		return TRACE_TYPE_PARTIAL_LINE;
> +
> +	return TRACE_TYPE_HANDLED;
> +}
> +
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