linux-kernel - Re: [PATCH 2/6] uprobes/tracing: Introduce is_ret_probe() and uretprobe

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Message-ID: <20130407141250.GB8672@linux.vnet.ibm.com>
Date:	Sun, 7 Apr 2013 19:42:50 +0530
From:	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Ananth N Mavinakayanahalli <ananth@...ibm.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Anton Arapov <anton@...hat.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/6] uprobes/tracing: Introduce is_ret_probe() and
 uretprobe_dispatcher()

* Oleg Nesterov <oleg@...hat.com> [2013-04-01 18:08:48]:

> Create the new functions we need to support uretprobes, and change
> alloc_trace_uprobe() to initialize consumer.ret_handler if the new
> "is_ret" argument is true. Curently this argument is always false,
> so the new code is never called and is_ret_probe(tu) is false too.
> 
> Signed-off-by: Oleg Nesterov <oleg@...hat.com>

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

> ---
>  kernel/trace/trace_uprobe.c |   42 ++++++++++++++++++++++++++++++++++++++++--
>  1 files changed, 40 insertions(+), 2 deletions(-)
> 
> diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
> index 2ea9961..e91a354 100644
> --- a/kernel/trace/trace_uprobe.c
> +++ b/kernel/trace/trace_uprobe.c
> @@ -75,6 +75,8 @@ static DEFINE_MUTEX(uprobe_lock);
>  static LIST_HEAD(uprobe_list);
> 
>  static int uprobe_dispatcher(struct uprobe_consumer *con, struct pt_regs *regs);
> +static int uretprobe_dispatcher(struct uprobe_consumer *con,
> +				unsigned long func, struct pt_regs *regs);
> 
>  static inline void init_trace_uprobe_filter(struct trace_uprobe_filter *filter)
>  {
> @@ -88,11 +90,16 @@ static inline bool uprobe_filter_is_empty(struct trace_uprobe_filter *filter)
>  	return !filter->nr_systemwide && list_empty(&filter->perf_events);
>  }
> 
> +static inline bool is_ret_probe(struct trace_uprobe *tu)
> +{
> +	return tu->consumer.ret_handler != NULL;
> +}
> +
>  /*
>   * Allocate new trace_uprobe and initialize it (including uprobes).
>   */
>  static struct trace_uprobe *
> -alloc_trace_uprobe(const char *group, const char *event, int nargs)
> +alloc_trace_uprobe(const char *group, const char *event, int nargs, bool is_ret)
>  {
>  	struct trace_uprobe *tu;
> 
> @@ -117,6 +124,8 @@ alloc_trace_uprobe(const char *group, const char *event, int nargs)
> 
>  	INIT_LIST_HEAD(&tu->list);
>  	tu->consumer.handler = uprobe_dispatcher;
> +	if (is_ret)
> +		tu->consumer.ret_handler = uretprobe_dispatcher;
>  	init_trace_uprobe_filter(&tu->filter);
>  	return tu;
> 
> @@ -314,7 +323,7 @@ static int create_trace_uprobe(int argc, char **argv)
>  		kfree(tail);
>  	}
> 
> -	tu = alloc_trace_uprobe(group, event, argc);
> +	tu = alloc_trace_uprobe(group, event, argc, false);
>  	if (IS_ERR(tu)) {
>  		pr_info("Failed to allocate trace_uprobe.(%d)\n", (int)PTR_ERR(tu));
>  		ret = PTR_ERR(tu);
> @@ -529,6 +538,12 @@ static int uprobe_trace_func(struct trace_uprobe *tu, struct pt_regs *regs)
>  	return 0;
>  }
> 
> +static void uretprobe_trace_func(struct trace_uprobe *tu, unsigned long func,
> +				struct pt_regs *regs)
> +{
> +	uprobe_trace_print(tu, func, regs);
> +}
> +
>  /* Event entry printers */
>  static enum print_line_t
>  print_uprobe_event(struct trace_iterator *iter, int flags, struct trace_event *event)
> @@ -799,6 +814,12 @@ static int uprobe_perf_func(struct trace_uprobe *tu, struct pt_regs *regs)
>  	uprobe_perf_print(tu, 0, regs);
>  	return 0;
>  }
> +
> +static void uretprobe_perf_func(struct trace_uprobe *tu, unsigned long func,
> +				struct pt_regs *regs)
> +{
> +	uprobe_perf_print(tu, func, regs);
> +}
>  #endif	/* CONFIG_PERF_EVENTS */
> 
>  static
> @@ -853,6 +874,23 @@ static int uprobe_dispatcher(struct uprobe_consumer *con, struct pt_regs *regs)
>  	return ret;
>  }
> 
> +static int uretprobe_dispatcher(struct uprobe_consumer *con,
> +				unsigned long func, struct pt_regs *regs)
> +{
> +	struct trace_uprobe *tu;
> +
> +	tu = container_of(con, struct trace_uprobe, consumer);
> +
> +	if (tu->flags & TP_FLAG_TRACE)
> +		uretprobe_trace_func(tu, func, regs);
> +
> +#ifdef CONFIG_PERF_EVENTS
> +	if (tu->flags & TP_FLAG_PROFILE)
> +		uretprobe_perf_func(tu, func, regs);
> +#endif
> +	return 0;
> +}
> +
>  static struct trace_event_functions uprobe_funcs = {
>  	.trace		= print_uprobe_event
>  };
> -- 
> 1.5.5.1
> 

-- 
Thanks and Regards
Srikar Dronamraju

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