[tip:perf/core] perf probe: Search concrete out-of-line instances

tip-bot for Masami Hiramatsu
2011-08-14T15:49:14Z

Commit-ID: db0d2c6420eeb8fd669bac84d72f1ab828bbaa64
Gitweb: http://git.kernel.org/tip/db0d2c6420eeb8fd669bac84d72f1ab828bbaa64
Author: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
AuthorDate: Thu, 11 Aug 2011 20:03:11 +0900
Committer: Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Fri, 12 Aug 2011 09:32:10 -0300

perf probe: Search concrete out-of-line instances

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;
}