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Date:   Wed, 26 Sep 2018 11:18:19 -0300
From:   Arnaldo Carvalho de Melo <acme@kernel.org>
To:     Milian Wolff <milian.wolff@kdab.com>
Cc:     jolsa@kernel.org, yao.jin@linux.intel.com, namhyung@kernel.org,
        Linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org,
        Sandipan Das <sandipan@linux.ibm.com>
Subject: Re: [PATCH 1/3] perf report: don't try to map ip to invalid map
Message-ID: <20180926141819.GD25764@kernel.org>
References: <20180926135207.30263-1-milian.wolff@kdab.com>
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Em Wed, Sep 26, 2018 at 03:52:05PM +0200, Milian Wolff escreveu:
> Fixes a crash when the report encounters an address that
> could not be associated with an mmaped region:

Milian, can you spot which cset introduced this problem? So that we can
add a "Fixes: sha" tag in this (and the others, if needed) to help the
stable kernel maintainers to find which kernels this has to be
backported to?

Thanks for working on this!

- Arnaldo
 
> #0  0x00005555557bdc4a in callchain_srcline (ip=<error reading variable: Cannot access memory at address 0x38>, sym=0x0, map=0x0) at util/machine.c:2329
> #1  unwind_entry (entry=entry@entry=0x7fffffff9180, arg=arg@entry=0x7ffff5642498) at util/machine.c:2329
> #2  0x00005555558370af in entry (arg=0x7ffff5642498, cb=0x5555557bdb50 <unwind_entry>, thread=<optimized out>, ip=18446744073709551615) at util/unwind-libunwind-local.c:586
> #3  get_entries (ui=ui@entry=0x7fffffff9620, cb=0x5555557bdb50 <unwind_entry>, arg=0x7ffff5642498, max_stack=<optimized out>) at util/unwind-libunwind-local.c:703
> #4  0x0000555555837192 in _unwind__get_entries (cb=<optimized out>, arg=<optimized out>, thread=<optimized out>, data=<optimized out>, max_stack=<optimized out>) at util/unwind-libunwind-local.c:725
> #5  0x00005555557c310f in thread__resolve_callchain_unwind (max_stack=127, sample=0x7fffffff9830, evsel=0x555555c7b3b0, cursor=0x7ffff5642498, thread=0x555555c7f6f0) at util/machine.c:2351
> #6  thread__resolve_callchain (thread=0x555555c7f6f0, cursor=0x7ffff5642498, evsel=0x555555c7b3b0, sample=0x7fffffff9830, parent=0x7fffffff97b8, root_al=0x7fffffff9750, max_stack=127) at util/machine.c:2378
> #7  0x00005555557ba4ee in sample__resolve_callchain (sample=<optimized out>, cursor=<optimized out>, parent=parent@entry=0x7fffffff97b8, evsel=<optimized out>, al=al@entry=0x7fffffff9750,
>     max_stack=<optimized out>) at util/callchain.c:1085
> 
> Signed-off-by: Milian Wolff <milian.wolff@kdab.com>
> Cc: Sandipan Das <sandipan@linux.ibm.com>
> Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
> ---
>  tools/perf/util/machine.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
> index c4acd2001db0..0cb4f8bf3ca7 100644
> --- a/tools/perf/util/machine.c
> +++ b/tools/perf/util/machine.c
> @@ -2312,7 +2312,7 @@ static int unwind_entry(struct unwind_entry *entry, void *arg)
>  {
>  	struct callchain_cursor *cursor = arg;
>  	const char *srcline = NULL;
> -	u64 addr;
> +	u64 addr = entry->ip;
>  
>  	if (symbol_conf.hide_unresolved && entry->sym == NULL)
>  		return 0;
> @@ -2324,7 +2324,8 @@ static int unwind_entry(struct unwind_entry *entry, void *arg)
>  	 * Convert entry->ip from a virtual address to an offset in
>  	 * its corresponding binary.
>  	 */
> -	addr = map__map_ip(entry->map, entry->ip);
> +	if (entry->map)
> +		addr = map__map_ip(entry->map, entry->ip);
>  
>  	srcline = callchain_srcline(entry->map, entry->sym, addr);
>  	return callchain_cursor_append(cursor, entry->ip,
> -- 
> 2.19.0