linux-kernel - Re: [RFC PATCH 3/8] perf probe: Improve detection of file/function name in the probe pattern

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Message-ID: <1418205606.9279.6.camel@ellerman.id.au>
Date:	Wed, 10 Dec 2014 21:00:06 +1100
From:	Michael Ellerman <mpe@...erman.id.au>
To:	"Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>
Cc:	linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
	acme@...nel.org, ananth@...ibm.com
Subject: Re: [RFC PATCH 3/8] perf probe: Improve detection of file/function
 name in the probe pattern

On Tue, 2014-12-09 at 23:04 +0530, Naveen N. Rao wrote:
> Currently, perf probe considers patterns including a '.' to be a file.
> However, this causes problems on powerpc ABIv1 where all functions have
> a leading '.':
> 
>   $ perf probe -F | grep schedule_timeout_interruptible
>   .schedule_timeout_interruptible
>   $ perf probe .schedule_timeout_interruptible
>   Semantic error :File always requires line number or lazy pattern.
>     Error: Command Parse Error.
> 
> Fix this by checking the probe pattern in more detail.
> 
> Signed-off-by: Naveen N. Rao <naveen.n.rao@...ux.vnet.ibm.com>
> ---
>  tools/perf/util/probe-event.c | 23 ++++++++++++++++++++---
>  1 file changed, 20 insertions(+), 3 deletions(-)
> 
> diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
> index c150ca4..c7e01ef 100644
> --- a/tools/perf/util/probe-event.c
> +++ b/tools/perf/util/probe-event.c
> @@ -999,6 +999,24 @@ static int parse_perf_probe_point(char *arg, struct perf_probe_event *pev)
>  		arg = tmp;
>  	}
>  
> +	/*
> +	 * Check arg is function or file name and copy it.
> +	 *
> +	 * We consider arg to be a file spec if and only if it satisfies
> +	 * all of the below criteria::
> +	 * - it does not include any of "+@%",
> +	 * - it includes one of ":;", and
> +	 * - it has a period '.' in the name.

I don't think we need to be this elaborate.

AFAIK there are no source files in the kernel that start with '.'

So if the arg starts with '.' it must be a function?

cheers


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