linux-kernel - Re: [PATCH 2/2] ftrace - add ftrace function

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Date:	Sat, 6 Mar 2010 04:28:13 +0100
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Tim Bird <tim.bird@...sony.com>
Cc:	Tony Lindgren <tony@...mide.com>,
	Russell King <rmk@....linux.org.uk>,
	linux-arm-kernel <linux-arm-kernel@...ts.arm.linux.org.uk>,
	linux kernel <linux-kernel@...r.kernel.org>,
	Steven Rostedt <rostedt@...dmis.org>
Subject: Re: [PATCH 2/2] ftrace - add ftrace function_graph support on ARM

On Fri, Mar 05, 2010 at 04:31:26PM -0800, Tim Bird wrote:
> +++ b/arch/arm/kernel/ftrace_graph.c
> @@ -0,0 +1,46 @@
> +/*
> + * function graph tracing support.
> + *
> + * Copyright (C) 2009 Tim Bird <tim.bird@...sony.com>
> + *
> + * For licencing details, see COPYING.
> + *
> + * Defines routine needed for ARM return trampoline for tracing
> + * function exits.
> + */
> +
> +#include <linux/ftrace.h>
> +
> +/*
> + * Hook the return address and push it in the stack of return addrs
> + * in current thread info.
> + */
> +void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
> +			   unsigned long frame_pointer)
> +{
> +	unsigned long old;
> +
> +	struct ftrace_graph_ent trace;
> +	unsigned long return_hooker = (unsigned long)
> +				&return_to_handler;
> +
> +	if (unlikely(atomic_read(&current->tracing_graph_pause)))
> +		return;
> +
> +	old = *parent;
> +	*parent = return_hooker;
> +
> +	if (ftrace_push_return_trace(old, self_addr, &trace.depth,
> +		    frame_pointer) == -EBUSY) {
> +		*parent = old;
> +		return;
> +	}
> +
> +	trace.func = self_addr;
> +
> +	/* Only trace if the calling function expects to */
> +	if (!ftrace_graph_entry(&trace)) {
> +		current->curr_ret_stack--;
> +		*parent = old;
> +	}
> +}




This could have been done in ftrace.c

Other than that,
Acked-by: Frederic Weisbecker <fweisbec@...il.com>

Thanks.

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