linux-kernel - Re: [PATCH 4/6 V2] perf, sort: Add physid sorting based on mmap2 data

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Date:	Sat, 29 Mar 2014 18:11:52 +0100
From:	Jiri Olsa <jolsa@...hat.com>
To:	Don Zickus <dzickus@...hat.com>
Cc:	acme@...stprotocols.net, LKML <linux-kernel@...r.kernel.org>,
	jmario@...hat.com, fowles@...each.com, peterz@...radead.org,
	eranian@...gle.com, andi.kleen@...el.com
Subject: Re: [PATCH 4/6 V2] perf, sort:  Add physid sorting based on mmap2
 data

On Mon, Mar 24, 2014 at 04:57:18PM -0400, Don Zickus wrote:
> In order for the c2c tool to work correctly, it needs to properly
> sort all the records on uniquely identifiable data addresses.  These
> unique addresses are converted from virtual addresses provided by the
> hardware into a kernel address using an mmap2 record as the decoder.
> 
> Once a unique address is converted, we can sort on them based on
> various rules.  Then it becomes clear which address are overlapping
> with each other across mmap regions or pid spaces.
> 
> This patch just creates the rules and inserts the records into a
> sort entry for safe keeping until later patches process them.
> 
> The general sorting rule is:

SNIP

> +
> +static int64_t
> +sort__physid_major_cmp(struct hist_entry *left, struct hist_entry *right)
> +{
> +	struct map *l = left->mem_info->daddr.map;
> +	struct map *r = right->mem_info->daddr.map;
> +
> +	return r->maj - l->maj;

I got segfault here, and consequently in all other sorting
functions, because it failed to resolve map earlier in
ip__resolve_data

we need to check it here, or before adding to the tree

thanks,
jirka
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