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    Subject[PATCH 3/5] perf: Catch and handle out-of-date hist entry maps.
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    When a process exec()'s, all the maps are retired, but we keep the
    hist entries around which hold references to those outdated maps.

    If the same library gets mapped in for which we have hist entries, a
    new map will be created. But when we take a perf entry hit within
    that map, we'll find the existing hist entry with the older map.

    This causes symbol translations to be done incorrectly. For example,
    the perf entry processing will lookup the correct uptodate map entry
    and use that to calculate the symbol and DSO relative address. But
    later when we update the histogram we'll translate the address using
    the outdated map file instead leading to conditions such as
    out-of-range offsets in symbol__inc_addr_samples() which now has an
    assertion for this situation.

    Therefore, update the map of the hist_entry dynamically at
    lookup/creation time.

    Signed-off-by: David S. Miller <davem@davemloft.net>
    ---
    tools/perf/util/hist.c | 9 +++++++++
    1 files changed, 9 insertions(+), 0 deletions(-)

    diff --git a/tools/perf/util/hist.c b/tools/perf/util/hist.c
    index 3dc99a9..b7ab3b9 100644
    --- a/tools/perf/util/hist.c
    +++ b/tools/perf/util/hist.c
    @@ -253,6 +253,15 @@ static struct hist_entry *add_hist_entry(struct hists *hists,
    if (!cmp) {
    he->period += period;
    ++he->nr_events;
    +
    + /* If the map of an existing hist_entry has
    + * become out-of-date due to an exec() or
    + * similar, update it. Otherwise we will
    + * mis-adjust symbol addresses when computing
    + * the history counter to increment.
    + */
    + if (he->ms.map != entry->ms.map)
    + he->ms.map = entry->ms.map;
    goto out;
    }

    --
    1.7.9.1


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