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    Subject[PATCH 11/12] perf probe: Search concrete out-of-line instances
    Date
    From: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>

    gcc 4.6 generates a concrete out-of-line instance when there is a
    function which is implicitly inlined somewhere but also has its own
    instance. The concrete out-of-line instance means that it has an
    abstract origin of the function which is referred by not only
    inlined-subroutines but also a concrete subprogram.

    Since current dwarf_func_inline_instances() can find only instances of
    inlined-subroutines, this introduces new die_walk_instances() to find
    both of subprogram and inlined-subroutines.

    e.g. without this,
    Available variables at sched_group_rt_period
    @<cpu_rt_period_read_uint+9>
    struct task_group* tg

    perf probe failed to find actual subprogram instance of
    sched_group_rt_period().

    With this,

    Available variables at sched_group_rt_period
    @<cpu_rt_period_read_uint+9>
    struct task_group* tg
    @<sched_group_rt_period+0>
    struct task_group* tg

    Now it found the sched_group_rt_period() itself.

    Cc: Frederic Weisbecker <fweisbec@gmail.com>
    Cc: Ingo Molnar <mingo@elte.hu>
    Cc: Paul Mackerras <paulus@samba.org>
    Cc: Pekka Enberg <penberg@kernel.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: yrl.pp-manager.tt@hitachi.com
    Link: http://lkml.kernel.org/r/20110811110311.19900.63997.stgit@fedora15
    Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
    Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
    ---
    tools/perf/util/dwarf-aux.c | 58 ++++++++++++++++++++++++++++++++++++++++
    tools/perf/util/dwarf-aux.h | 4 +++
    tools/perf/util/probe-finder.c | 56 ++++++++++++++------------------------
    3 files changed, 83 insertions(+), 35 deletions(-)

    diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c
    index 425703a..d0f4048 100644
    --- a/tools/perf/util/dwarf-aux.c
    +++ b/tools/perf/util/dwarf-aux.c
    @@ -453,6 +453,64 @@ Dwarf_Die *die_find_inlinefunc(Dwarf_Die *sp_die, Dwarf_Addr addr,
    return die_mem;
    }

    +struct __instance_walk_param {
    + void *addr;
    + int (*callback)(Dwarf_Die *, void *);
    + void *data;
    + int retval;
    +};
    +
    +static int __die_walk_instances_cb(Dwarf_Die *inst, void *data)
    +{
    + struct __instance_walk_param *iwp = data;
    + Dwarf_Attribute attr_mem;
    + Dwarf_Die origin_mem;
    + Dwarf_Attribute *attr;
    + Dwarf_Die *origin;
    +
    + attr = dwarf_attr(inst, DW_AT_abstract_origin, &attr_mem);
    + if (attr == NULL)
    + return DIE_FIND_CB_CONTINUE;
    +
    + origin = dwarf_formref_die(attr, &origin_mem);
    + if (origin == NULL || origin->addr != iwp->addr)
    + return DIE_FIND_CB_CONTINUE;
    +
    + iwp->retval = iwp->callback(inst, iwp->data);
    +
    + return (iwp->retval) ? DIE_FIND_CB_END : DIE_FIND_CB_CONTINUE;
    +}
    +
    +/**
    + * die_walk_instances - Walk on instances of given DIE
    + * @or_die: an abstract original DIE
    + * @callback: a callback function which is called with instance DIE
    + * @data: user data
    + *
    + * Walk on the instances of give @in_die. @in_die must be an inlined function
    + * declartion. This returns the return value of @callback if it returns
    + * non-zero value, or -ENOENT if there is no instance.
    + */
    +int die_walk_instances(Dwarf_Die *or_die, int (*callback)(Dwarf_Die *, void *),
    + void *data)
    +{
    + Dwarf_Die cu_die;
    + Dwarf_Die die_mem;
    + struct __instance_walk_param iwp = {
    + .addr = or_die->addr,
    + .callback = callback,
    + .data = data,
    + .retval = -ENOENT,
    + };
    +
    + if (dwarf_diecu(or_die, &cu_die, NULL, NULL) == NULL)
    + return -ENOENT;
    +
    + die_find_child(&cu_die, __die_walk_instances_cb, &iwp, &die_mem);
    +
    + return iwp.retval;
    +}
    +
    /* Line walker internal parameters */
    struct __line_walk_param {
    bool recursive;
    diff --git a/tools/perf/util/dwarf-aux.h b/tools/perf/util/dwarf-aux.h
    index 6f46106..6ce1717 100644
    --- a/tools/perf/util/dwarf-aux.h
    +++ b/tools/perf/util/dwarf-aux.h
    @@ -80,6 +80,10 @@ extern Dwarf_Die *die_find_realfunc(Dwarf_Die *cu_die, Dwarf_Addr addr,
    extern Dwarf_Die *die_find_inlinefunc(Dwarf_Die *sp_die, Dwarf_Addr addr,
    Dwarf_Die *die_mem);

    +/* Walk on the instances of given DIE */
    +extern int die_walk_instances(Dwarf_Die *in_die,
    + int (*callback)(Dwarf_Die *, void *), void *data);
    +
    /* Walker on lines (Note: line number will not be sorted) */
    typedef int (* line_walk_callback_t) (const char *fname, int lineno,
    Dwarf_Addr addr, void *data);
    diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
    index 114542a..555fc38 100644
    --- a/tools/perf/util/probe-finder.c
    +++ b/tools/perf/util/probe-finder.c
    @@ -924,42 +924,39 @@ static int find_probe_point_lazy(Dwarf_Die *sp_die, struct probe_finder *pf)
    return die_walk_lines(sp_die, probe_point_lazy_walker, pf);
    }

    -/* Callback parameter with return value */
    -struct dwarf_callback_param {
    - void *data;
    - int retval;
    -};
    -
    static int probe_point_inline_cb(Dwarf_Die *in_die, void *data)
    {
    - struct dwarf_callback_param *param = data;
    - struct probe_finder *pf = param->data;
    + struct probe_finder *pf = data;
    struct perf_probe_point *pp = &pf->pev->point;
    Dwarf_Addr addr;
    + int ret;

    if (pp->lazy_line)
    - param->retval = find_probe_point_lazy(in_die, pf);
    + ret = find_probe_point_lazy(in_die, pf);
    else {
    /* Get probe address */
    if (dwarf_entrypc(in_die, &addr) != 0) {
    pr_warning("Failed to get entry address of %s.\n",
    dwarf_diename(in_die));
    - param->retval = -ENOENT;
    - return DWARF_CB_ABORT;
    + return -ENOENT;
    }
    pf->addr = addr;
    pf->addr += pp->offset;
    pr_debug("found inline addr: 0x%jx\n",
    (uintmax_t)pf->addr);

    - param->retval = call_probe_finder(in_die, pf);
    - if (param->retval < 0)
    - return DWARF_CB_ABORT;
    + ret = call_probe_finder(in_die, pf);
    }

    - return DWARF_CB_OK;
    + return ret;
    }

    +/* Callback parameter with return value for libdw */
    +struct dwarf_callback_param {
    + void *data;
    + int retval;
    +};
    +
    /* Search function from function name */
    static int probe_point_search_cb(Dwarf_Die *sp_die, void *data)
    {
    @@ -996,14 +993,10 @@ static int probe_point_search_cb(Dwarf_Die *sp_die, void *data)
    /* TODO: Check the address in this function */
    param->retval = call_probe_finder(sp_die, pf);
    }
    - } else {
    - struct dwarf_callback_param _param = {.data = (void *)pf,
    - .retval = 0};
    + } else
    /* Inlined function: search instances */
    - dwarf_func_inline_instances(sp_die, probe_point_inline_cb,
    - &_param);
    - param->retval = _param.retval;
    - }
    + param->retval = die_walk_instances(sp_die,
    + probe_point_inline_cb, (void *)pf);

    return DWARF_CB_ABORT; /* Exit; no same symbol in this CU. */
    }
    @@ -1452,16 +1445,14 @@ static int find_line_range_by_line(Dwarf_Die *sp_die, struct line_finder *lf)

    static int line_range_inline_cb(Dwarf_Die *in_die, void *data)
    {
    - struct dwarf_callback_param *param = data;
    -
    - param->retval = find_line_range_by_line(in_die, param->data);
    + find_line_range_by_line(in_die, data);

    /*
    * We have to check all instances of inlined function, because
    * some execution paths can be optimized out depends on the
    * function argument of instances
    */
    - return DWARF_CB_OK;
    + return 0;
    }

    /* Search function from function name */
    @@ -1489,15 +1480,10 @@ static int line_range_search_cb(Dwarf_Die *sp_die, void *data)
    pr_debug("New line range: %d to %d\n", lf->lno_s, lf->lno_e);
    lr->start = lf->lno_s;
    lr->end = lf->lno_e;
    - if (dwarf_func_inline(sp_die)) {
    - struct dwarf_callback_param _param;
    - _param.data = (void *)lf;
    - _param.retval = 0;
    - dwarf_func_inline_instances(sp_die,
    - line_range_inline_cb,
    - &_param);
    - param->retval = _param.retval;
    - } else
    + if (dwarf_func_inline(sp_die))
    + param->retval = die_walk_instances(sp_die,
    + line_range_inline_cb, lf);
    + else
    param->retval = find_line_range_by_line(sp_die, lf);
    return DWARF_CB_ABORT;
    }
    --
    1.6.2.5


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