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SubjectRe: [PATCH V2] perf tools: Fix maps__find_symbol_by_name()
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On 10/09/18 17:34, Arnaldo Carvalho de Melo wrote:
> Em Fri, Sep 07, 2018 at 11:51:16AM +0300, Adrian Hunter escreveu:
>> Commit 1c5aae7710bb ("perf machine: Create maps for x86 PTI entry
>> trampolines") revealed a problem with maps__find_symbol_by_name() that
>
> Can we have this with a Fixes: 1c5aae7710bb?
>
> So that that, combined with the CC: stable, tells which stable kernels
> should get that fix, I think there are scripts harvesting Fixes: tags to
> help stable maintainers :-)

It seemed like potentially an existing issue so I did not want to limit how
far back it got applied.

>
> - Arnaldo
>
>> resulted in probes not being found e.g.
>>
>> $ sudo perf probe xsk_mmap
>> xsk_mmap is out of .text, skip it.
>> Probe point 'xsk_mmap' not found.
>> Error: Failed to add events.
>>
>> maps__find_symbol_by_name() can optionally return the map of the found
>> symbol. It can get the map wrong because, in fact, the symbol is found
>> on the map's dso, not allowing for the possibility that the dso has more
>> than one map. Fix by always checking the map contains the symbol.
>>
>> Reported-by: Björn Töpel <bjorn.topel@intel.com>
>> Tested-by: Björn Töpel <bjorn.topel@intel.com>
>> Cc: stable@vger.kernel.org
>> Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
>> ---
>>
>>
>> Changes in V2:
>>
>> Expanded commit message
>> Corrected email address
>>
>>
>> tools/perf/util/map.c | 11 +++++++++++
>> 1 file changed, 11 insertions(+)
>>
>> diff --git a/tools/perf/util/map.c b/tools/perf/util/map.c
>> index 3f07a587c8e6..354e54550d2b 100644
>> --- a/tools/perf/util/map.c
>> +++ b/tools/perf/util/map.c
>> @@ -574,6 +574,13 @@ struct symbol *map_groups__find_symbol(struct map_groups *mg,
>> return NULL;
>> }
>>
>> +static bool map__contains_symbol(struct map *map, struct symbol *sym)
>> +{
>> + u64 ip = map->unmap_ip(map, sym->start);
>> +
>> + return ip >= map->start && ip < map->end;
>> +}
>> +
>> struct symbol *maps__find_symbol_by_name(struct maps *maps, const char *name,
>> struct map **mapp)
>> {
>> @@ -589,6 +596,10 @@ struct symbol *maps__find_symbol_by_name(struct maps *maps, const char *name,
>>
>> if (sym == NULL)
>> continue;
>> + if (!map__contains_symbol(pos, sym)) {
>> + sym = NULL;
>> + continue;
>> + }
>> if (mapp != NULL)
>> *mapp = pos;
>> goto out;
>> --
>> 2.17.1
>

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