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    Subject[PATCH AUTOSEL 5.4 236/350] perf probe: Skip overlapped location on searching variables
    Date
    From: Masami Hiramatsu <mhiramat@kernel.org>

    [ Upstream commit dee36a2abb67c175265d49b9a8c7dfa564463d9a ]

    Since debuginfo__find_probes() callback function can be called with the
    location which already passed, the callback function must filter out
    such overlapped locations.

    add_probe_trace_event() has already done it by commit 1a375ae7659a
    ("perf probe: Skip same probe address for a given line"), but
    add_available_vars() doesn't. Thus perf probe -v shows same address
    repeatedly as below:

    # perf probe -V vfs_read:18
    Available variables at vfs_read:18
    @<vfs_read+217>
    char* buf
    loff_t* pos
    ssize_t ret
    struct file* file
    @<vfs_read+217>
    char* buf
    loff_t* pos
    ssize_t ret
    struct file* file
    @<vfs_read+226>
    char* buf
    loff_t* pos
    ssize_t ret
    struct file* file

    With this fix, perf probe -V shows it correctly:

    # perf probe -V vfs_read:18
    Available variables at vfs_read:18
    @<vfs_read+217>
    char* buf
    loff_t* pos
    ssize_t ret
    struct file* file
    @<vfs_read+226>
    char* buf
    loff_t* pos
    ssize_t ret
    struct file* file

    Fixes: cf6eb489e5c0 ("perf probe: Show accessible local variables")
    Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
    Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
    Cc: Jiri Olsa <jolsa@redhat.com>
    Cc: Namhyung Kim <namhyung@kernel.org>
    Link: http://lore.kernel.org/lkml/157241938927.32002.4026859017790562751.stgit@devnote2
    Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    tools/perf/util/probe-finder.c | 20 ++++++++++++++++++++
    1 file changed, 20 insertions(+)

    diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
    index 4079ed617f53c..e4ef8f4935b2a 100644
    --- a/tools/perf/util/probe-finder.c
    +++ b/tools/perf/util/probe-finder.c
    @@ -1425,6 +1425,18 @@ static int collect_variables_cb(Dwarf_Die *die_mem, void *data)
    return DIE_FIND_CB_END;
    }

    +static bool available_var_finder_overlap(struct available_var_finder *af)
    +{
    + int i;
    +
    + for (i = 0; i < af->nvls; i++) {
    + if (af->pf.addr == af->vls[i].point.address)
    + return true;
    + }
    + return false;
    +
    +}
    +
    /* Add a found vars into available variables list */
    static int add_available_vars(Dwarf_Die *sc_die, struct probe_finder *pf)
    {
    @@ -1435,6 +1447,14 @@ static int add_available_vars(Dwarf_Die *sc_die, struct probe_finder *pf)
    Dwarf_Die die_mem;
    int ret;

    + /*
    + * For some reason (e.g. different column assigned to same address),
    + * this callback can be called with the address which already passed.
    + * Ignore it first.
    + */
    + if (available_var_finder_overlap(af))
    + return 0;
    +
    /* Check number of tevs */
    if (af->nvls == af->max_vls) {
    pr_warning("Too many( > %d) probe point found.\n", af->max_vls);
    --
    2.20.1
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