• Stephane Eranian's avatar
    perf/core: Restore mmap record type correctly · 103eb70c
    Stephane Eranian authored
    [ Upstream commit d9c1bb2f6a2157b38e8eb63af437cb22701d31ee ]
    
    On mmap(), perf_events generates a RECORD_MMAP record and then checks
    which events are interested in this record. There are currently 2
    versions of mmap records: RECORD_MMAP and RECORD_MMAP2. MMAP2 is larger.
    The event configuration controls which version the user level tool
    accepts.
    
    If the event->attr.mmap2=1 field then MMAP2 record is returned.  The
    perf_event_mmap_output() takes care of this. It checks attr->mmap2 and
    corrects the record fields before putting it in the sampling buffer of
    the event.  At the end the function restores the modified MMAP record
    fields.
    
    The problem is that the function restores the size but not the type.
    Thus, if a subsequent event only accepts MMAP type, then it would
    instead receive an MMAP2 record with a size of MMAP record.
    
    This patch fixes the problem by restoring the record type on exit.
    Signed-off-by: 's avatarStephane Eranian <eranian@google.com>
    Acked-by: 's avatarPeter Zijlstra (Intel) <peterz@infradead.org>
    Cc: Andi Kleen <ak@linux.intel.com>
    Cc: Jiri Olsa <jolsa@redhat.com>
    Cc: Kan Liang <kan.liang@linux.intel.com>
    Fixes: 13d7a241 ("perf: Add attr->mmap2 attribute to an event")
    Link: http://lkml.kernel.org/r/20190307185233.225521-1-eranian@google.comSigned-off-by: 's avatarArnaldo Carvalho de Melo <acme@redhat.com>
    Signed-off-by: 's avatarSasha Levin <sashal@kernel.org>
    103eb70c
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