linux-kernel - Re: [PATCH 2/2] perf tools: Support end symbols with no size for filters

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Date:   Mon, 6 Feb 2017 15:15:42 +0200
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Andi Kleen <andi@...stfloor.org>, peterz@...radead.org
Cc:     alexander.shishkin@...ux.intel.com, linux-kernel@...r.kernel.org,
        Andi Kleen <ak@...ux.intel.com>
Subject: Re: [PATCH 2/2] perf tools: Support end symbols with no size for
 filters

On 04/02/17 00:18, Andi Kleen wrote:
> From: Andi Kleen <ak@...ux.intel.com>
> 
> Currently a filter like
> --filter "filter _text / _end"
> doesn't work because _end doesn't have a size. The
> filter resolution always wants to use the end of the function
> as end.
> 
> Allow this case by assuming the filter just spawns to the
> start of the end symbol when there is no size. This makes
> the above useful filter work.
> 
> Cc: adrian.hunter@...el.com
> Signed-off-by: Andi Kleen <ak@...ux.intel.com>
> ---
>  tools/perf/util/auxtrace.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/perf/util/auxtrace.c b/tools/perf/util/auxtrace.c
> index c5a6e0b12452..4c5ccb2b1298 100644
> --- a/tools/perf/util/auxtrace.c
> +++ b/tools/perf/util/auxtrace.c
> @@ -1840,7 +1840,12 @@ static int addr_filter__resolve_kernel_syms(struct addr_filter *filt)
>  		if (err)
>  			return err;
>  		filt->size = start + size - filt->addr;
> -		no_size = !!size;

Erk!  Isn't the logic is the wrong way around here.  Sorry!
i.e. should be:

diff --git a/tools/perf/util/auxtrace.c b/tools/perf/util/auxtrace.c
index c5a6e0b12452..78bd632f144d 100644
--- a/tools/perf/util/auxtrace.c
+++ b/tools/perf/util/auxtrace.c
@@ -1826,7 +1826,7 @@ static int addr_filter__resolve_kernel_syms(struct addr_filter *filt)
 		filt->addr = start;
 		if (filt->range && !filt->size && !filt->sym_to) {
 			filt->size = size;
-			no_size = !!size;
+			no_size = !size;
 		}
 	}
 
@@ -1840,7 +1840,7 @@ static int addr_filter__resolve_kernel_syms(struct addr_filter *filt)
 		if (err)
 			return err;
 		filt->size = start + size - filt->addr;
-		no_size = !!size;
+		no_size = !size;
 	}
 
 	/* The very last symbol in kallsyms does not imply a particular size */

> +		/*
> +		 * When to has no size assume it's a end symbol.
> +		 * This allows filters like _text / _end
> +		 */
> +		if (size == 0)
> +			filt->size = start - filt->addr;
>  	}
>  
>  	/* The very last symbol in kallsyms does not imply a particular size */
>