linux-kernel - Re: [PATCH v2 4/7] uprobes/tracing: Make uprobe_{trace,perf}

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Date:	Sat, 13 Apr 2013 15:03:01 +0530
From:	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Steven Rostedt <rostedt@...dmis.org>,
	Ananth N Mavinakayanahalli <ananth@...ibm.com>,
	Anton Arapov <anton@...hat.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 4/7] uprobes/tracing: Make
 uprobe_{trace,perf}_print() uretprobe-friendly

* Oleg Nesterov <oleg@...hat.com> [2013-04-09 21:32:35]:

> Change uprobe_trace_print() and uprobe_perf_print() to check
> is_ret_probe() and fill ring_buffer_event accordingly.
> 
> Also change uprobe_trace_func() and uprobe_perf_func() to not
> _print() if is_ret_probe() is true. Note that we keep ->handler()
> nontrivial even for uretprobe, we need this for filtering and for
> other potential extensions.
> 
> Signed-off-by: Oleg Nesterov <oleg@...hat.com>

Acked-by: Srikar Dronamraju <srikar@...ux.vnet.ibm.com>

> Tested-by: Anton Arapov <anton@...hat.com>
> ---
>  kernel/trace/trace_uprobe.c |   34 +++++++++++++++++++++++++---------
>  1 files changed, 25 insertions(+), 9 deletions(-)
> 
> diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
> index 72aa45e..0ed99a2 100644
> --- a/kernel/trace/trace_uprobe.c
> +++ b/kernel/trace/trace_uprobe.c
> @@ -516,15 +516,22 @@ static void uprobe_trace_print(struct trace_uprobe *tu,
>  	int size, i;
>  	struct ftrace_event_call *call = &tu->call;
> 
> -	size = SIZEOF_TRACE_ENTRY(false) + tu->size;
> +	size = SIZEOF_TRACE_ENTRY(is_ret_probe(tu));
>  	event = trace_current_buffer_lock_reserve(&buffer, call->event.type,
> -						  size, 0, 0);
> +						  size + tu->size, 0, 0);
>  	if (!event)
>  		return;
> 
>  	entry = ring_buffer_event_data(event);
> -	entry->vaddr[0] = instruction_pointer(regs);
> -	data = DATAOF_TRACE_ENTRY(entry, false);
> +	if (is_ret_probe(tu)) {
> +		entry->vaddr[0] = func;
> +		entry->vaddr[1] = instruction_pointer(regs);
> +		data = DATAOF_TRACE_ENTRY(entry, true);
> +	} else {
> +		entry->vaddr[0] = instruction_pointer(regs);
> +		data = DATAOF_TRACE_ENTRY(entry, false);
> +	}
> +
>  	for (i = 0; i < tu->nr_args; i++)
>  		call_fetch(&tu->args[i].fetch, regs, data + tu->args[i].offset);
> 
> @@ -535,7 +542,8 @@ static void uprobe_trace_print(struct trace_uprobe *tu,
>  /* uprobe handler */
>  static int uprobe_trace_func(struct trace_uprobe *tu, struct pt_regs *regs)
>  {
> -	uprobe_trace_print(tu, 0, regs);
> +	if (!is_ret_probe(tu))
> +		uprobe_trace_print(tu, 0, regs);
>  	return 0;
>  }
> 
> @@ -784,7 +792,7 @@ static void uprobe_perf_print(struct trace_uprobe *tu,
>  	void *data;
>  	int size, rctx, i;
> 
> -	size = SIZEOF_TRACE_ENTRY(false);
> +	size = SIZEOF_TRACE_ENTRY(is_ret_probe(tu));
>  	size = ALIGN(size + tu->size + sizeof(u32), sizeof(u64)) - sizeof(u32);
>  	if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE, "profile buffer not large enough"))
>  		return;
> @@ -795,8 +803,15 @@ static void uprobe_perf_print(struct trace_uprobe *tu,
>  		goto out;
> 
>  	ip = instruction_pointer(regs);
> -	entry->vaddr[0] = ip;
> -	data = DATAOF_TRACE_ENTRY(entry, false);
> +	if (is_ret_probe(tu)) {
> +		entry->vaddr[0] = func;
> +		entry->vaddr[1] = ip;
> +		data = DATAOF_TRACE_ENTRY(entry, true);
> +	} else {
> +		entry->vaddr[0] = ip;
> +		data = DATAOF_TRACE_ENTRY(entry, false);
> +	}
> +
>  	for (i = 0; i < tu->nr_args; i++)
>  		call_fetch(&tu->args[i].fetch, regs, data + tu->args[i].offset);
> 
> @@ -812,7 +827,8 @@ static int uprobe_perf_func(struct trace_uprobe *tu, struct pt_regs *regs)
>  	if (!uprobe_perf_filter(&tu->consumer, 0, current->mm))
>  		return UPROBE_HANDLER_REMOVE;
> 
> -	uprobe_perf_print(tu, 0, regs);
> +	if (!is_ret_probe(tu))
> +		uprobe_perf_print(tu, 0, regs);
>  	return 0;
>  }
> 
> -- 
> 1.5.5.1
> 

-- 
Thanks and Regards
Srikar Dronamraju

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